Recent Facts about Photovoltaic in Germany

Current version available: https://www.ise.fraunhofer.de/en/publications/studies/recentfacts-about-pv-in-germany.html

Compiled by
Dr. Harry Wirth
Division Director Photovoltaics
Modules and Power Plants
Fraunhofer ISE
Contact:
Sophia Judith Bächle
Communications
Telefon: +49 (0) 7 61 / 45 88 — 5215
Fraunhofer Institute for Solar Energy Systems ISE
Heidenhofstrasse 279110 Freiburg, Germany
presse@ise.fraunhofer.deCitation note: Recent Facts about Photovoltaics in Germany, Harry Wirth, Fraunhofer ISE,
Download from https://www.pv-fakten.de/, version of 3.4.2024.

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Table of Contents
1

What purpose does this guide serve?.............................................................. 52

How much photovoltaics is needed for the energy transition? ..................... 5

3

Does PV contribute significantly to the power supply? ................................. 6

4

Is PV power too expensive? .............................................................................. 7

5

4.1

Levelized Cost of Electricity.................................................................................8

4.2

Feed-in Tariff .........................................................................................................9

4.3

Pricing on the energy exchange and the merit order effect .............................11

4.4

Determining the differential costs .....................................................................12

4.5

EEG levy ..............................................................................................................13

Subventions and Electricity Prices .................................................................14
5.1

Is PV power subsidized? ....................................................................................14

5.2

Is fossil fuel power production subsidized? .....................................................14

5.3

Do tenants subsidize well-positioned homeowners?.......................................16

5.4

Does PV increase electricity consumption costs? ...........................................16

6

Are we exporting large amounts of PV power to other European nations? 18

7

Can small PV systems generate attractive returns? ........................................18

8

Is the supply of solar components ensured? ...................................................20

9

Does installing PV only create jobs in Asia? ..................................................22

10 What funding is being directed to PV research? ............................................24
11 Does PV power overload our energy system? ...............................................24
11.1

Transmission and distribution ...........................................................................24

11.2

Volatility ...............................................................................................................26

11.2.1 Solar power production is predictable ............................................................................. 26
11.2.2 Peak production is significantly lower than installed PV capacity .......................... 26
11.2.3 Solar and wind energy complement each other .............................................................. 26

11.3

Controllability ......................................................................................................28

11.4

Conflicts with slow-response power plants ......................................................28

11.5

Does volatile solar power endanger security of supply? .................................30

11.6

Does the expansion of PV have to wait for more storage? ..............................30

12 Is there enough space for PV in Germany? ....................................................31
13 Is PV electricity a privilege reserved for homeowners? ..................................35
14 Do PV systems destroy ecologically valuable areas? ...................................35

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15 Do PV power plants find acceptance in the population? ................................36
16 Are PV plants in Germany efficient? ................................................................37
16.1

Are PV systems only viable on roofs that are optimally oriented? ..................39

16.1.1 High-pitched rooftops facing east/west ............................................................................. 40
16.1.2 Vertical south-facing façade .............................................................................................. 41

16.2

Do PV plants degrade? ........................................................................................41

16.3

Can PV modules become soiled? ......................................................................42

16.4

Do PV plants seldom operate at full capacity? .................................................42

17 Does PV make relevant contributions to climate protection? .......................45
17.1

Do anthropogenic CO2 emissions danger the climate? ...................................45

17.2

Does PV make a significant contribution to CO2 emission reduction? ...........46

17.3 Does the production of PV modules use more energy than they can deliver
during operation? ...........................................................................................................50
17.4 Are there other environmentally harmful gases released during the
production of PV? ..........................................................................................................50

18 Do PV modules heat up their environment significantly? .............................50
19 Can PV modules cause glare? ...........................................................................52
20 Do PV modules emit irradiation that is harmful to health? ............................52
21 Are PV systems capable of replacing fossil fuel and nuclear power plants? .53
22 Are we capable of covering a significant proportion of our energy demandwith PV power? .................................................................................................53
22.1

Starting point: energy demand and energy supply ..........................................53

22.2

Energy scenarios ................................................................................................56

22.3

Transformation steps .........................................................................................60

21.3.1 Steady PV power generation ............................................................................................. 60
21.3.2 Complementary operation of power plants ........................................................................ 61
21.3.3 Increasing energy efficiency ................................................................................................. 62
21.3.3.1 Transport ......................................................................................................................... 62
21.3.3.2 Private households ......................................................................................................... 64
21.3.4 Load management ............................................................................................................. 64
21.3.5 Balanced addition of PV and wind power capacities ......................................................... 65
21.3.6 Combined heat and power generation .............................................................................. 65
21.3.7 Energy storage .................................................................................................................. 66
21.3.7.1 Low-temperature heat accumulator ................................................................................ 66
21.3.7.2 High-temperature heat storage ....................................................................................... 67
21.3.7.3 Cold accumulator ............................................................................................................ 67
21.3.7.4 Stationary batteries ......................................................................................................... 68
21.3.7.5 Vehicle batteries ............................................................................................................. 69
21.3.7.6 Mechanical storage facilities ........................................................................................... 71
21.3.7.7 Hydrogen and synthesis products .................................................................................. 71
21.3.7.8 Overview ......................................................................................................................... 72
21.3.8 Grid expansion ................................................................................................................... 73
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21.3.8.1 National grid expansion .................................................................................................. 73
21.3.8.2 Strengthening the European interconnected grid ........................................................... 74
21.3.9 Importing energy sources .................................................................................................. 75
21.3.10 Overview .......................................................................................................................... 75

22.4

Does the energy transition have to wait for federal policy? ............................77

23 Do we need PV production in Germany? ........................................................77
23 Do we need a Renewable Energy Sources Act (EEG)? ...................................77
24. Do PV modules contain toxic substances? ....................................................7824.2 Thin-film modules ...................................................................................................79

25. Are raw materials for the production of PV modules sufficiently available?
............................................................................................................................80
26. Do PV systems increase the risk of fire? ........................................................80
26.2 Do PV systems endanger firefighters? .................................................................81
26.3 Do PV modules hinder direct firefighting access via the roof? ...........................82
26.4 Do toxic emissions occur when PV modules burn? ...............................................82

27 Appendix: Technical terms ................................................................................8327.1 Module efficiency....................................................................................................8327.2 Nominal power of a PV power plant .....................................................................83
27.3

Annual full load hours (annual full operating hours) ........................................83

27.4

Annual utilization rate (capacity factor) ............................................................83

27.5 Specific yield............................................................................................................83
27.6 System efficiency ....................................................................................................83
27.7 Performance Ratio...................................................................................................84
27.8 Base load, medium load, peak load, grid load and residual load .........................84
27.9 Electricity generation and consumption ................................................................84

28 Appendix: Abbreviations ...................................................................................86
30 Appendix: Sources ..............................................................................................88
31 Appendix: Figures ..............................................................................................95

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1 What purpose does this guide serve?
Germany is leaving the fossil-nuclear age behind, paving the way for photovoltaics (PV)to play a central role in a future shaped by sustainable power production. This compilationof current facts, figures and findings is regularly updated. It aims to help create an overall
assessment of the progress in the PV expansion in Germany.

2 How much photovoltaics is needed for the energy transition?

Installed capacity PV [GWp]

In order to cover our entire energy demand from renewable energies (RE), a massive expansion of installed PV capacity is necessary, in addition to a number of other measures.
Figure 1 shows the required nominal PV power according to a selection of studies andscenarios from the year of publication 2021 ([ISE3], [ISI], [DIW], [ARIA], [BDI], [ESYS],[Prog], [IEE], [HTW2], [ÜNB2], [AGORA2]).
600

500
400
300
200
100
0

Figure 1: Installed PV capacity necessary to reach climate neutrality as determined by different
studies. (The studies are named according to the institutions and, if applicable, the scenario).

The scenarios make different assumptions on boundary conditions, e.g., for energy imports, efficiency increases and acceptance. Some studies only consider the electricity system, others the entire energy system.
The EEG 2023 envisages a PV expansion to 215 GWp by 2030 and to 400 GWp by 2040.
The annual net addition is to climb to a maximum of 22 GWp within a few years. Increasingly, old installations also need to be replaced.

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These replacement installations are currently of little significance, but they will increase toapprox. 15 GWp per year in fully developed condition with an assumed useful life of justunder 30 years. In the years 2013‒2018, an average of only 1.9 GWp/a was installed(Figure 2). With the deployment of 14,6 GWp in 2023, the total number of systems is
now 3.7 million including plug-in solar units [BSW1], with a total capacity of 82 GWp[ISE4].

Figure 2: Net PV additions: actual values until 2022, expansion path to achieve the legal targets[BMWK1], [EEG2023].

3 Does PV contribute significantly to the power supply?
Yes.
With an estimated electricity generation of 61.1 TWh in 2023, photovoltaics covered
12 percent of gross electricity consumption [AGEE] in Germany (Figure 3). All renewableenergies (RE) together came to 52 percent.

Figure 3: Development of the share of renewable energies in gross electricity consumption inGermany [ISE4], [UBA1], [AGEE].

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Gross electricity consumption is the reference value for the statutory expansion targets ofthe energy transition and includes grid, storage, and self-consumption losses (Section
27.9). On sunny days, PV electricity may temporarily cover more than two thirds of ourelectricity demand. Based on a forecasted gross electricity consumption of 658 TWh in
2030, the planned PV expansion to 215 GWp would lead to a PV power share of about
30 percent, with renewable energies generally covering 80 percent.

4 Is PV power too expensive?
PV electricity was once very expensive.
If one compares the electricity production costs of new power plants of different technologies, PV comes off very favorably [ISE1]. Large PV power plants in particular produce
unrivaled cheap electricity. However, the cost comparison is still considerably distorted aslong as the supply costs for fuels are considered, but neither the full cycle costs with CO2
recovery nor the follow-up costs of interrupted cycles, i.e., the costs of the climate crisis.
The marginal costs for nuclear power are in the order of 1 ct/kWh, for coal-fired power3‒7 ct/kWh, for gas-fired power 6‒9 ct/kWh, plus the fixed costs of the power plants(e.g., investment, capital). The marginal costs essentially cover the provision of the fuel,but not the neutralization of the radiating waste or environmentally harmful emissions(CO2, NOx, SOx, Hg). So far, external costs and risks relating to environmental, climate
and health damage have largely been disregarded in pricing ([UBA3], [FÖS1], [FÖS2]). The
ignoring of these external costs represents a massive subsidization of the energy sources
concerned (Section 5.2).
In order to promote the energy transition and to stimulate investments in PV systems ofvarious sizes, the Renewable Energy Sources Act (EEG) came into force on 1 April 2000.
It is intended to enable plant operators to operate economically at a reasonable profit
with guaranteed power purchase. The aim of the Renewable Energy Sources Act is tocontinuously reduce the LCOE from RE by securing a substantial market for RE systems(see Section 4.1).
The development of PV generation capacities is only one part of the transformation costs
associated with the energy transition. For a long time, this part was at the forefront of
the discussion. In recent years, PV has become increasingly system-relevant, which meansthat other transformation steps and cost types have come into focus. In addition to thepure generation costs for electricity from RE, there are also the costs of building gridserving storage and conversion capacities (e-mobility and stationary batteries, heat pumps
and heat storage, Power-To-X, flexible gas-fired power plants, pumped storage). These
costs are not caused by the PV expansion, they go — just like the PV expansion itself —to the account of the energy transition. The costs of the energy transition are incurred by
all energy consumers, for whom a sustainable energy supply must be created. Without
knowing the costs of an omitted energy transition, it is difficult to assess the costs of thetransition.

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4.1 Levelized Cost of Electricity
The levelized cost of electricity (LCOE) for a PV power plant is the ratio between the total
costs of the plant (€) and its total electricity production (kWh) over its economic lifetime.
The total costs for PV power plants are based primarily on:
1.
2.
3.
4.

purchase investments to construct and install the plant
financing conditions (return on investment, interest, plant lifetime)
operating costs over the lifetime of the plant (insurance, maintenance, repairs)
deconstruction costs

Investment costs are the dominant cost component of PV power plants. The price of the
PV modules is only responsible for about one third of the investment costs, and the shareis higher for large PV ground-mounted systems (PV FFA) than for small rooftop systems.
History shows that the price development for PV modules follows a so-called “price-experience curve", i.e., when cumulative production doubles, prices fall by a constant percentage. Figure 4 shows the inflation-adjusted world market prices. Between the years
2010 and 2020, PV module prices have decreased by 90 percent. In the long term, module
prices [€/WP] are expected to continue to fall in line with this regularity, provided thatmajor efforts continue to be made in the further development of products and manufacturing processes.

Figure 4: Historical development of prices for PV modules (PSE Projects GmbH/Fraunhofer ISE,
data source: Strategies Unlimited/Navigant Consulting/EuPD). The straight line shows the trend
in price development.

Prices for PV power plants have fallen by over 75 percent since 2006 thanks to technological progress, economies of scale and learning effects. Figure 5 shows the price development for rooftop systems of 10 to 100 kWp nominal power in Germany. The annual
operating costs of a PV power plant are comparatively low at approx. 1-2 percent of theinvestment costs; the financing costs increase as interest rate levels rise.
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Figure 5: Development of the average end customer price (net system price) for installed rooftop
systems with rated nominal power from 10‒100 kWp [ISE5], data BSW-Solar.

New MW-sized power plants produce PV electricity at costs of approx. 5–7 ct/kWh (estimated on the basis of current BNA tender results). For small rooftop plants the costs range
from 11‒13 ct/kWh. These cost estimates always assume that the volatile electricity iscompletely purchased. Over the long term, further decreases in the LCOE can be expected.
Due to the very high investment costs in the past, older PV power plants are significantly
more expensive. An orientation value for the development of the electricity generation
costs from new PV ground-mounted plants is provided by the tenders of the German
Federal Network Agency (following Section).
4.2 Feed-in Tariff
The energy transition requires massive investments in renewable generation capacities forsolar power, among other things. However, given the cost reduction dynamics to date
(Section 4.1), there is a risk that investments will be postponed in anticipation of a continued trend (deflation effect). Moreover, since PV power plants largely produce electricity
at the same time, the more expensive electricity from the power plant built today would
no longer be competitive in the future (crowding-out effect). To nevertheless mobilize
actors beyond the classic energy suppliers, in particular homeowners, businesses and small
and medium-sized companies, a purchase guarantee for electricity that cannot be usedby the investor is necessary for the economic service life of the power plant at a fixed
remuneration or a minimum remuneration. The basis for the expansion of PV has been
the various versions of the Renewable Energy Sources Act since 2000. The various amendments have increasingly tried to promote and hinder PV expansion at the same time. The“breathing cap” (e.g., 1.5 GWp according to the EEG 2017) limited the annual expansion,
while low tendering volumes slowed down the free-field segment. In addition, there were

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a number of restrictions, e.g., with regard to area coverage, system sizes and self-consumption.
There are three basic EEG remuneration models, depending on the size and type of the
PV power plant: fixed tariff [BNA3] or market premiums (Marktprämie) for direct marketing. For large-scale power plants, the remuneration is determined by the bidding rounds
for the German Federal Network Agency’s tender [BNA4]. The purpose of the market
premium is to balance negative differences between the market price of solar electricity(monthly average day-ahead exchange electricity price) and a legally defined reference
value (der anzulegende Wert) [BNA3]. Surcharges are provided for certain cases of fullfeed-in, for landlord-to-tenant electricity supply and for elevated agrivoltaic installations.
The feed-in tariff for small rooftop systems with self-consumption that go into operationin January 2024 is up to 8.2 ct/kWh for 20 years, depending on the size of the system.
The Federal Network Agency’s bidding round for the bidding deadline of 1 February 2018
determined the lowest average surcharge value to date of 4.33 ct/kWh, and the lowest
individual surcharge of 3.55 ct/kWh dates from February 2020.

Vergütung und Preise [ct/kWh]

60
50
40
30

20
10
0
2000
2000

2005

PV Gebäude, klein
PV Ausschreibung
Strompreis Industrie klein

2010

2015

2020

2024

PV Gebäude/Sonstige
Strompreis Haushalte, brutto
Marktwert Solar

Figure 6: Fixed EEG feed-in tariff for PV power as a function of commissioning date according tosystem types „Building PV with up to 10 kWP excess feed-in“ and „Other systems up to 100 kW“from [Netz2] and [BNA3], average remuneration of the bidding rounds of the German Federal
Network Agency [BNA3], electricity prices [BMWK1], [BDEW1] and average compensation for PV
power [NETZ1].

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Since the introduction of the EEG in 2000, the remuneration for PV electricity from new
power plants has fallen by approx. 85‒90 percent (Figure 6). The average fixed tariff for
PV electricity is expected to have fallen to 21.3 ct/kWh by 2022 (source: statista).
Internationally, PV electricity at locations with high solar radiation has already been offered at rock-bottom prices of up to 1.12 €ct/kWh (Portugal) and 0.87 €ct/kWh (Saudi
Arabia). For comparison: for the planned nuclear power plant “Hinkley C”, which is to go
into operation in the UK in 2025, a feed-in tariff of the equivalent of 12 ct/kWh plus
inflation compensation has been guaranteed for a period of 35 years.
4.3

Pricing on the energy exchange and the merit order effect

PV electricity purchased under the EEG must be traded on the day-ahead market of theexchange. Because this turns it into “gray electricity”, the supplier cannot put a price on
the sustainable quality of the green electricity. To estimate sales revenues from PV electricity, a mean electricity price (“market value solar” in Figure 6) is calculated based on
the prices achieved on the European Energy Exchange (Figure 7).

Price

Figure 7: Exchange electricity and certificate prices in Germany [ISE4].

Ongoing price determination on the exchange takes place according to the “merit order”
principle (Figure 8). The electricity producers’ sales offer for certain quantities of electricity,usually defined by the respective marginal costs, are sorted by price in ascending order.
The electricity buyers’ purchase offers are sorted in descending order. The intersection of
the curves results in the exchange price for the entire traded quantity. The most expensive
offer that comes into play thus determines the profit margins of all cheaper suppliers.

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The feed-in of solar electricity has legal priority, so it is at the beginning of the offer pricescale. With fictitious marginal costs equal to zero, solar power always comes into play.
But when solar power comes on, it comes on a massive scale in the core time of the day,when the load — and with it the electricity price in the past — reaches its midday peak.
There it predominantly displaces expensive peak-load power plants (especially gas-fired
power plants and pumped storage). This displacement lowers the total resulting exchange
electricity price and leads to the merit order effect of PV feed-in. With the prices, therevenues of all fossil electricity producers (gas, coal, oil) fall, but also the revenues forelectricity from RE (solar power, wind power, hydropower). Furthermore, solar power reduces the utilization of the classic peak load power plants (gas, hydro) in particular.

Figure 8: Merit order for conventional power plants in 2018 with an average CO 2 certificate priceof €16 per ton [FFE].

With further expansion of volatile RE, their market value factor will decrease in themedium term, because the electricity supply grows at times of high feed-in and both PV
and wind electricity have a high simultaneity. For PV, the market value factor is expected
to drop to just under 0.8 by 2026 [UNB1].
With the increasing feed-in of RES-E, the Leipzig power exchange has become a residual
power exchange. It generates a price for the demand-based supplementation ofrenewable electricity generation and no longer reflects the value of the electricity.

4.4

Determining the differential costs

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The remuneration for PV electricity feed-in according to the EEG is determined annuallyby the transmission grid operators. The differential costs are intended to cover the gap
between remuneration and revenues for PV electricity. The increasing feed-in of PV electricity and wind power lowers the market prices via the merit order effect and thus paradoxically increases the calculated differential costs; the more PV is installed, the more expensive the kWh of PV electricity appears in the subsidy according to this method.
Figure 9 shows the development of the differential costs for the annual remuneration of
the PV electricity generated. After a strong increase until 2014, the amount has stabilized
between 9 and 10 billion euros.
The value of PV electricity is measured via the electricity exchange price. According to thismethod, its value was systematically underestimated: on the one hand, PV electricity has
long since influenced the exchange price in the intended direction, namely downwards.
On the other hand, the exchange price still largely ignores important external costs offossil and nuclear power generation (Section 5.2).
A study by the Friedrich-Alexander University Erlangen-Nuremberg has shown that in theyears 2011 to 2018 a total of 157 billion euros in EEG differential costs were incurred,
while in the same period cost savings of 227 billion euros were realized through the feedin of PV and wind power [FAU]. The bottom line is that consumers saved 71 billion euros
in costs.

Figure 9: PV expansion and differential costs, data from [BMWK1], [BMWK3].

4.5

EEG levy

The difference between remuneration payments and sales revenues for RES-E, supplemented by other items, was compensated by the EEG levy until June 2022. The levy was
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borne by those electricity consumers who could not be exempted. Politicians had defined
who had to finance the switch to renewable energies [BAFA]. It had decided to largely
exempt energy-intensive industrial companies with a high share of electricity costs fromthe EEG levy. In 2021, 44 percent of industrial consumption was thus privileged. This
comprehensive exemption increased the burden for other electricity customers, especiallyprivate households. Final consumers had to pay an additional 19 percent VAT on the levy.
In 2021, there was a subsidy from the federal budget (Energy and Climate Fund, EKF) of
10.8 billion euros for the levy account for the first time. From July 2022, the EEG levy
was abolished, and the differential costs will be covered by the EKF.

5 Subventions and Electricity Prices
5.1

Is PV power subsidized?

Yes, since 2021.
A subsidy is defined as a benefit from public funds. Up to and including 2020, however,the subsidy for PV electricity generation did not come from public funds, but from a selective consumption levy (Section 4.5), which was also partly levied on PV electricity produced and consumed by the consumer. Part of the energy consumers paid a compulsory
levy for the necessary transformation of our energy system. This view was also confirmedby the EU Commission. The amount of the levy did not correspond to the total remuneration, but to the differential costs. On the cost side, the cumulative differential costs ofthe feed-in tariff for PV electricity amount to approximately 100 billion euros up to andincluding 2020 [BMWK3]. In 2021, there was a contribution from the EKF for the EEG
account for the first time (Section 4.5). The revenues of the EKF come from emissions
trading and federal subsidies, thus a subsidy will take effect from 2021. In 2020, EnBW
built the “Weesow-Willmersdorf” solar park, the first large-scale PV power plant in Germany without electricity purchase via the EEG. This is a 187 MWP project in Brandenburg[EnBW1].
5.2

Is fossil fuel power production subsidized?

Yes, the future costs of the subsidy are still difficult to estimate.
Policy makers influence the electricity price of fossil and nuclear power plants. Policy decisions define the price of CO2 emission allowances, the conditions for smoke filters, thepermanent storage of CO2, the taxation, the insurance, and safety requirements for nuclear power plants. Policy makers thus determine the extent to which electricity consumers
bear the elusive risks and burdens of fossil and nuclear power generation. These effects
largely arise in the future through CO2-induced climate crisis, the final disposal of nuclear
waste and the perpetual loads of hard coal mining. If these costs are consequently priced,
PV power generation will make the electricity mix cheaper. Until we get to that point,
fossil power will be sold at prices that mask their external costs and pass the burden on
to future generations.
In 2005, an EU-wide emissions trading scheme (European Union Emissions Trading System, EU ETS) was introduced to make CO2 emissions more expensive and to begin
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internalizing the costs. However, due to an oversupply of allowances, the price had collapsed by the end of 2017 and was thus practically ineffective (Figure 7). Across Europe,
certificate trading also covers only 45 percent of greenhouse gas emissions, because important sectors beyond industry and the energy sector are excluded [UBA5]. An expansion
to about 85 percent of emissions has now been decided.
In Germany, a national emissions trading system for the heating and transport sectors
was launched in January 2021 with the Fuel Emissions Trading Act (BEHG). Initially, only
heating oil, natural gas, petrol, and diesel were considered, from 2023 coal and waste
fuels will be included. A fixed price per emission allowance of EUR 45 in 2024 and EUR
55 in 2025 has been in place since 01.01.2024. These prices are offset by considerably
higher costs caused by climate damage and the necessary recycling of CO2 from the atmosphere:
1) The direct and indirect consequential costs of global climate change, which will
also affect Germany, are difficult to estimate. According to calculations by the Federal Environment Agency, the emission of one ton of CO2 causes damages ofaround 195‒680 €/t, depending on the higher or equal weighting of the welfareof current versus future generations [UBA3]. In Germany, almost 810 million tonsof carbon dioxide and CO2 equivalents were emitted in 2019, with corresponding
damages of 157 billion euros or 551 billion euros, depending on the welfare
weighting. For lignite-based electricity generation with an emission factor of 1075
g CO2/kWh (Figure 10), the derived CO2 price premiums are 21 and 73 ct/kWh,respectively. Considering the external effects, the costs to society as a whole forlignite-based electricity are thus many times higher than the pure electricity generation costs of 3.4‒4.7 ct/kWh [FÖS2].
2) All climate protection scenarios assume that direct carbon capture (DCC) will benecessary to contain the climate crisis. Direct Air Carbon Capture and Sequestration (DACCS) with air filtration systems offers potential for permanent recapture
without further intervention in the biosphere (Figure 10). In pilot plants, recapture
via DACCS currently costs about 550 €/t, the cost potential with successful scalingis estimated at 90‒260 €/t [MCC]. Some questions about the final storage of therecycled CO2 are still open.

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Afforestation
and reforestation
Tree growth removes CO2 fromthe atmosphere

Bioenergy plantation
CO2 becomes biomass that is burnedin power plants. In
the process, it iscaptured, then injected undergroundAccelerated weathering
Crushed minerals
distributed on land
help to chemicallybind CO2 from theair

Accumulation ofcarbon in fields
By adding biochar
and through climatefriendly practices inagriculture

Ocean alkalization
Natural substances,such as crushed
minerals, increase
the pH value andthus CO2 storage inthe sea

Air filter systems
CO2 is extracted
from the ambient
air by chemical processes and then injected undergroundFigure 10: Process for removing CO2 from the atmosphere and storing carbon [MCC].

A study by the International Monetary Fund estimates that global subsidies for coal, oiland natural gas, including external costs, will amount to 5.9 trillion US dollars in 2020
[IMF].
5.3

Do tenants subsidize well-positioned homeowners?

No.
This popular headline, quoted here from the “Zeit” of 8 December 2011, is a distorted
portrayal. The costs of the conversion of our energy system to RE have been passed on to
all electricity consumers until 2021 - with the politically intended exception of electricityintensive industry — according to the polluter-pays principle, including households ofhomeowners and tenants. These costs cover not only PV but also wind power and other
RE. All electricity customers can influence their electricity consumption through the choice
and use of their appliances; many municipalities offer free energy-saving advice and subsidies for the purchase of efficient new appliances (examples at https://www.stromspiegel.de/beratung/foerderung-und-zuschuesse/).
Systems in the power class below 10 kWp, which are often purchased by homeowners,
account for approx. 15 percent of the total installed capacity (Figure 19). Larger systems
are often financed through citizen participation or funds, in which tenants can, of course,
also participate.
5.4

Does PV increase electricity consumption costs?

No, since the abolishment of the EEG levy in mid-2022, the electricity price does not include any components for the remuneration of PV electricity.
A sample household with an annual consumption of 3,500 kilowatt hours will pay anaverage gross electricity price of 47 ct/kWh in 2021 [BDEW1]. Figure 11 shows an
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exemplary price structure. The electricity tax was introduced in 1999 in order to makeenergy more expensive through higher taxation; the revenues flow mainly into the pension fund. Private households pay value-added tax on electricity tax. The concession levy
is a charge for the use of public roads. The Electricity Grid Charges Ordinance (Section 19
Strom-NEV) is designed to reduce the burden on electricity-intensive industrial companies
at the expense of other final consumers. The Combined Heat and Power Act (KWKG)
promotes the operation of combined heat and power plants for electricity generation.

Average electricity pricefor households in 2023:
46.91 ct/kWh
Tax duties
and levies
26.8%

Electricity Procurement/
Sales by market
52.9%

Measurement/measuring
point
Operation market/regulated
0.6%

Regulated network
charges
19.7%

Figure 11: Composition of the average household electricity price in 2023 [BDEW1].

The electricity price for private households in Germany is about 50 percent higher thanthe European average (source: stromreport.de, reference year 2020), but the purchasing
power per inhabitant is also 60 percent higher here (source: statista.de, reference year2019). If electricity prices and purchasing power are taken into account, Germany is in
the middle of the European field. Added to this is the high security of supply. In low-pricecountries, power outages are commonplace.
With an average price of 27 ct/kWh net excluding electricity tax for new contracts, electricity consumption for small and medium-sized industrial customers will not become
more expensive as a result of the expansion of PV in Germany.

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6 Are we exporting large amounts of PV power to other European
nations?
No.
The monthly values of the Energy Charts (www.energy-charts.de) show that electricity
imports are conspicuously high in summer, i.e. in months with particularly high PV electricity production (Figure 12).

month

Figure 12: Net Electricity import (purple) and solar electricity production (yellow) in 2023 for Germany [ISE4].

7 Can small PV systems generate attractive returns?
Yes.
In principle, small PV systems can generate income via the EEG remuneration for feeding
into the grid and via the reduction in electricity consumption thanks to self-consumption. Systems without self-consumption (”full feed-in”) receive higher remuneration
than systems with self-consumption (”partial feed-in”, Figure 13). Attractive returns are
possible due to the sharp drop in prices for PV modules, the sharp rise in electricity consumption costs and the increased remuneration for full feed-in.
The greater the difference between the purchase costs for electricity and the electricity
production costs of the PV system, the more worthwhile self-consumption becomes. In
systems without storage, the potential for self-consumption depends on the coincidence
between the generation and consumption profiles. Depending on the size of the system,
households achieve 20‒40 percent self-consumption in relation to the electricity generated [Quasch]. Larger systems increase the degree of coverage of the total electricity demand with PV electricity but reduce the share of self-consumption. Commercial or
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industrial consumers achieve particularly high self-consumption values if their consumption profile does not drop significantly at the weekend (e.g., cold stores, hotels and restaurants, hospitals, server centers, retailers). Energy storage and transformation technologies offer considerable potential for increasing self-consumption (see Section 21.3).
The yield of a system is higher in sunny regions. In fact, the regional difference in theannual sum of irradiation is not transferred 1:1 to the specific yield (kWh/kWp, Section27.5) because, for example, the operating temperature of the modules, pollution effects
or the duration of snow accumulation also play a role.

Figure 13: Estimation of the LCOE for small PV systems under different irradiation conditions, plus
remuneration according to [EEG2023].

•
•
•
•
•
•

Performance Ration of 85 percent (see Section 27.7)
Annual yield degradation of 0.5 percent
Lifetime of 20 years
Annual operating costs of 1 percent (of plant price)
Inflation rate of 2 percent
Nominal imputed interest rate of 4 percent (average of own and borrowed capital investments)
The Levelized Costs of Electricity (LCOE) are estimated on the basis of the net present
value method. The current expenditure and the LCOE are discounted to the time of commissioning using the specified interest rate. In the case of full financing through equity,
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Federal Network Agency has set the return on equity for investments in electricity and gas
grids for new plants at 6.91 percent before corporate income tax [BNA1].
The return on a PV system is not risk-free during the EEG remuneration period. Neither
manufacturer guarantees nor plant insurance reduce the investor risk to zero. The utilization of electricity from the 21st year of operation is regulated for the first time by the[EEG2021]. Self-consumption capability plays a major role in calculating the continued
operation of “de-subsidized” plants [SCBW].

8 Is the supply of solar components ensured?
No, China has built up a critical monopoly.
The complete PV value-added cycle based on silicon wafer technology (Figure 14) begins
with the production of high-purity polysilicon and continues with the crystallization ofsilicon ingots and the sawing of silicon wafers. This is followed by cell production andmodule production. If the coverage of more than one stage is to be emphasized, one
speaks of (vertically) integrated PV production.
polysilicon
recycables

scrap

silicon block

Photovoltaic
value-added
cycle

silicon wafer

cellsystemmoduleFigure 14: Value Chain for Photovoltaics.

Many material and component manufacturers are part of the extended PV value cycle.
These include suppliers of silver pastes for solar cells, special films, wires, solar glass, andjunction boxes for solar modules. Other players complete the cycle with additional components for power plants through to recycling:
1. Material production: solar silicon, metal pastes, connector wires, plastic foils, solar
glass, glass coating
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2. Manufacture of intermediate and final products: modules, cables, inverters, mounting
structures, tracker systems
3. Mechanical engineering for cell and module production
4. Installation (especially trade)
5. Power plant operation and maintenance
6. Recycling
In 2023, China was dominating all value chain stages with market shares of more than
80 percent (Figure 15).

Figure 15: Production capacity according to value chain stage and country, data: Wood Mackenzie,
2023

While there was still a complete PV supply chain in Germany and Europe around 2010,
the production of some feedstocks has been discontinued due to the regional demandthat has decreased in the meantime. Figure 16 shows the current production landscapein Germany for the most important components and intermediate products. Notableshares of the global market are held by inverter manufacturers and silicon manufacturer
Wacker. In Europe, there are small module production facilities and hardly any cell or
wafer production. A slump in trade with China would seriously jeopardize the expansionof PV in Germany and also severely impair local module production due to a lack of intermediate products.

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ModuleCell
Inverter
Block & Wafer
Poly-silicon

Figure 16: PV production sites in Germany and other European countries [SPE].

9 Does installing PV only create jobs in Asia?
No, but Germany has lost many jobs in the PV industry in the last decade.

Figure 17 shows the number of jobs in the renewable energies sector. By comparison: in
2015, just under 21,000 people were still working in lignite mining and in lignite-fired
power plants [ÖKO1]. In the decade, many jobs were lost in Germany due to company
closures and insolvencies, affecting not only cell and module producers but also mechanical engineering and installers.
According to calculations by Fraunhofer ISE, a vertically integrated 10 GW production
from silicon ingot via wafer and cell to module creates approx. 7500 full-time jobs [ISE8].
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time employees are needed to install 10 GW of PV [EuPD]. In 2022, the solar industry (PVand thermal) employed 84,100 people [BMWK press report from January 24, 2024].
The hope that the combination of the Renewable Energy Sources Act (EEG), investment
subsidies in the new federal states and research funding would be enough to establish
Germany as a world-leading production location for PV cells and modules seemed to be
fulfilled as recently as 2007, when a German company topped the international rankingsin terms of production volume. Since then, German manufacturers have dramatically lost
market share because of the decisive industrial policy in the Asian region and the massive
investments in production capacities generated there. Labor costs play a subordinate rolein this development, as PV production has reached a very high degree of automation.
Turnkey production lines that deliver very good PV modules have been available “off the
shelf” for several years, which has enabled a rapid transfer of technology.

Wind

Biomass

Solar

Geothermal

Hydropower* Preliminary data for 2021

Figure 17: Number of jobs in the renewable energy sector [UBA11]

Effective laws on feed-in tariffs have triggered massive investments in PV power plants inGermany and Europe. However, there was a lack of economic policy support to ensurethat production capacities remained competitive. On the other hand, China and other
Asian countries have succeeded in mobilizing many billions of domestic and foreign capital for the construction of large-scale production lines by creating attractive investment
and credit conditions.
Despite the high import quota for PV modules, a large part of the value added associatedwith a PV power plant remains in the country. In the long term, falling manufacturingcosts of PV modules on the one hand and rising freight costs and long freight times on
the other will improve the competitive position for module production in Germany.
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10 What funding is being directed to PV research?
In 2022, the German government invested almost 70 million euros to support photovoltaic research (Figure 18), mostly in production technologies.

quality assurance
PV technologies
production technologies
basic research photovoltaic
otherscircular economy

system capability

Figure 18: Funding for PV research categorized by technology in € million [BMWK2].

11 Does PV power overload our energy system?
11.1 Transmission and distribution
Most solar power plants in Germany are connected to the low-voltage grid; Figure 19
illustrates how they are distributed according to plant size. Many systems generate solar
power decentralized and close to consumption; they hardly place any demands on the
expansion of the transmission or medium-voltage grid. On sunny days, a high density ofPV systems in a low-voltage grid can lead to electricity production exceeding electricity
consumption locally due to the high simultaneity factor. Transformers then feed powerback into the medium-voltage grid. With very high system densities, the transformer station can reach its capacity limit. Large-scale PV power plants or local clusters of systems
in sparsely populated areas sometimes require an enhancement of the power grid and/ortransformer stations, or the installation of storage capacities.
An even distribution of PV installations across the grid sections reduces the need for grid
expansion. PV expansion should be geographically even more consumption-based to facilitate the distribution of solar power. Per inhabitant, Brandenburg or MecklenburgWestern Pomerania, for example, have four to five times more PV capacity installed thanNorth Rhine-Westphalia or Hesse [AEE2].

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Figure 19: Distribution of installed PV power according to plant size in 2021 [ISE4].

When grid bottlenecks are currently discussed, photovoltaics are rarely mentioned (Figure20). In 2021, 5.8 TWh of electricity from renewable energies was regulated, corresponding to around 1 percent of total electricity consumption. Solar power only made up 4
percent of the regulated electricity [BNA2]. The derating mainly affects wind power, which
is mostly produced in the north and for which there is not yet sufficient transmission
capacity to southern Germany. When wind levels are high, the remuneration for regulated
power in the north and the procurement of the missing power in the south (redispatch
measures) lead to significant costs.
Electricity: Outage work caused by feed-inmanagement measuresin GWh

Solar

ener

Biomass

Wind Energy (Onshore/Offshore)

Figure 20: Regulated electrical energy [BNA2].

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11.2 Volatility
11.2.1 Solar power production is predictable

Power forecast (ante) / GW

Reliable performance forecasts based on satellite data can be created for individual
power plants or regional clusters, with local sky imagers or monitoring stations being
added as needed. On a national level, the generation of solar electricity can also beplanned very well thanks to reliable national weather forecasts and yield models (Figure21). Due to decentralized generation, regional changes in cloud cover cannot lead to serious fluctuations in Germany-wide PV electricity production. Even the effects of a solar
eclipse with a high, trans-regional simultaneity factor can be reliably forecasted.

Power (post)/ GW

Power (post) / GW
Figure 21: Actual and predicted hourly generation of power in 2021 [ISE4].

11.2.2 Peak production is significantly lower than installed PV capacity
Due to technically induced losses with performance ratio values below 90 percent, (cf.
Section 27.7) and often inconsistent weather conditions, real electricity generation above
65 percent of the installed nominal capacity is very rare throughout Germany (cf. Section
3 and Figure 22).
11.2.3 Solar and wind energy complement each other
Due to the climate, solar radiation and wind strength in Germany correlate negatively ontime scales of hours to months.
On a quarter-hourly basis, with an average installed capacity of approx. 57 GW# PV
and 63 GWP wind power at the end of the year, in 2021 practically never more than 60
GW of capacity (i.e., 50 percent of the nominal PV + wind capacity) entered the electricity
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grid (Figure 22). Viewed on an hourly basis, less than 1 percent of the electricity generated would have been lost if the combined PV + wind capacity had been limited to a
maximum of 40 GW (i.e., 33 percent of the nominal PV + wind capacity).

Figure 22: Average power for the supply of solar and wind power in 2021, 15-minute values [ISE4].

On a daily basis, the combination of PV and wind power also leads to a stabilization of
the yield. While the relative mean absolute deviation of daily electricity production fromthe arithmetic mean in 2021 was 55 percent for PV and 56 percent for wind, the value
for PV + wind was only 37 percent.

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PV
Wind
PV+WindPV, moving average
Wind, moving average
PV+Wind, moving average

Figure 23: Monthly totals of PV and wind power production, data from [ISE4].

Figure 23 shows the monthly totals of electricity production from PV and wind power,
as well as the moving annual averages. The average relative deviation of the monthly
values from the moving annual value is 53 percent for PV and 30 percent for wind. The
sum of PV and wind power is significantly more stable than the individual sectors, with avalue of 14 percent.
11.3 Controllability
With increasing output, PV is increasingly being called upon as a stabilizing control variable. The amendment to the Renewable Energy Sources Act (EEG) on 1 January 2012 also
requires systems connected to the low-voltage grid to participate in feed-in management
via remote control by the grid operator or via automatic derating at 70 percent of theactive power, except in the case of small systems. According to the Low Voltage Directive
VDE AR-N-4105, in force since 1 January 2012, inverters must provide grid support functions.
11.4 Conflicts with slow-response power plants
The generation profile of PV electricity with peaks around noon matches the load profileof the power grid well. However, conflicts are increasing with sluggish power plants thatcan only follow a fluctuating residual load to a very limited extent for technical and economic reasons. Older coal-fired power plants, especially lignite-fired power plants, cannot
contribute balancing power in an economically justifiable way. Run-of-river hydro andcurrent biomass power plants also offer little flexibility. In principle, however, volatile generators with their negligible marginal costs must be given priority.
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These unresolved conflicts can briefly lead to significant overproduction and negative exchange electricity prices, as the example in Figure 24 shows.
During hot spells in the past, fossil and nuclear power plants caused critical heating of therivers used as cooling reservoirs. Photovoltaics installed in Germany have eliminated thisproblem and can also ease such situations in neighboring countries such as France, because they fundamentally reduce the load on fossil and nuclear power plants, especiallyon summer days.

Price (Euro/MWh, Euro/tCO2)

Date (CEST)
Import balance
Renewable
Day ahead auction

Not Renewable
Load
Intraday continuous, index price

Figure 24: Example showing the course of electricity trading price, conventional and renewableelectricity in the 22th calendar week in 2023 [ISE 4].

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11.5 Does volatile solar power endanger security of supply?

installed PV power [GW]No.
The security of supply for end consumers actually improved with the photovoltaic expansion (Figure 25).

Figure 25: System Average Interruption Duration Index (SAIDI) for low and medium. Data from
[BNA2].

11.6 Does the expansion of PV have to wait for more storage?
No, not in the next few years.
When price differences in electricity consumption are large and frequent enough, it isworth investing in load management measures, stationary battery storage systems or
pumped-storage power plants. The 2010s saw postponements in investments in storage– specifically pumped storage – because their operation was not financially feasible.
Further expansion of PV and wind power will lower the energy exchange prices more
frequently and massively. On the other hand, an increase in the price of electricity generated from fossil fuels due to CO2 certificates or taxes, will increase EEX prices during
periods of high residual load. Price spreads create the basis for load shifting, profitablestorage operations and the production of green hydrogen. If the price spread is passed
on to the end user through tariffs, storage facilities also become interesting for them.
This would increase the capacity to absorb the volatile energy from the sun and thewind.

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12 Is there enough space for PV in Germany?
Yes, and without any significant conflicts with agriculture or nature conservation.
An important concept for the development of significant land potential is integration.
Integrated photovoltaics (www.integrierte-pv.de) enables double land use, additional landconsumption for new PV power plants is significantly reduced or avoided altogether. PV
systems specially tailored to the application are combined with agriculture, erected on
artificial lakes, used as the shell of buildings, car parks, traffic routes and vehicles, or they
provide ecosystem services on re-naturalized biotopes and moorland (Figure 26).
vehicle-integrated PV

building-integrated PV

urban PV

Agri-photovoltaics

road-integrated PV

floating PV

Figure 26: Applications for the integration of photovoltaics.

Relying exclusively on one or a few of these possible applications today does not do justiceto the urgency of the energy transition. We no longer have the time to try out options
one after the other. All technically and socio-economically promising application options
must be tested quickly and promoted in a dedicated start-up phase to explore optimization and cost reduction potentials through scaling and learning effects. Only after thisbroad start-up phase can well-founded decisions be made in favor of certain applications
and technologies.
In the following analysis of potentials, a distinction is made between a theoretical, a technical and an economic-practical or realizable or developable potential. The theoreticalpotential considers the maximum possible implementation of a technology based on theentire supply (physical rough calculation). The technical potential is lower because it
already considers basic technical boundary conditions (technical rough calculation). The
economic-practical potential considers all relevant boundary conditions, legally (incl.
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e.g., competing uses (e.g., solar thermal and PV on roofs). Different sources draw slightly
different boundaries between the categories.
The area used for agriculture in Germany is just under 17 million hectares (Figure 27).
Agrivoltaics (APV) uses land simultaneously for agricultural crop production (photosynthesis) and PV electricity production (photovoltaics). APV covers a broad spectrum in theintensity of agriculture and in the additional effort required for PV system construction. It
ranges from intensive crops with special PV mounting systems to extensively used grassland with marginal adaptations on the PV side and high potential for eco-system services.
APV increases land efficiency and enables a massive increase in PV power, while preserving
fertile soils for agriculture or in combination with the creation of species-rich biotopes onpoor soils. APV is already being used on a GW scale worldwide, but there are only a few
systems in Germany.

Figure 27: Land use in Germany [FNR].

Agri-PV with high-mounted modules allows cultivation in partial shade under the modules. A number of crops show hardly any yield losses with reduced irradiation, some evenbenefit. If permanent crops (e.g., orchards and vineyards) are considered in their entirety
and one-third of arable land (without maize) as technical potential, an occupancy densityof 0.6 MWP/ha results in a technical potential of 1.7 TWP. Modules mounted close to theground with wide row spacing enable cultivation between the rows. At an occupancy
density of 0.25 MWP/ha, the cultivation of forage crops on permanent grassland alone
opens up a technical potential of a further 1.2 TWP.
Energy crops are grown on 13 percent of agricultural land, especially for the productionof biogas, biodiesel, vegetable oil and bioethanol [FNR]. The land efficiency is significantly
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below what would be possible with Agri-PV plants (Section 15). Energy maize alone iscultivated on 1 million ha; this area corresponds to 600 GWp of nominal capacity if converted to APV with suitable crops (or to solar biotopes, see Section 13).
Opencast lignite mining has destroyed an area of 1773 km2 [UBA4] in Germany, morethan three times the area of Lake Constance. Parts of this mining area have already been
flooded or are still being flooded, and there are many more artificial lakes. In total, thisopens up a technical potential of 44 GWp for floating PV (FPV). In the case of active
quarry lakes, the PV can contribute to the self-sufficiency of the production facilities.
Worldwide, more than 3 GWp of floating PV systems have already been installed.
In Germany, there are about 40 million buildings (Figure 28). Building envelopes, i.e., roofs
and façades, offer a technical potential in the order of 1000 GWp [Eggers]. The analysis
only includes areas that receive a minimum of 500 kWh/(m2a) of irradiation and have aconnected minimum size. Today, less than 10 percent of the rooftop potential and lessthan 1 per mille of the façade potential is used.

Single family housesTwo-family houses
Multi-family houses
Thermally conditioned non-residential buildings
Thermally non-conditioned non-residential buildings

Figure 28: Building stock in millions, data from [DENA], [IWU].

As yet, PV use is largely limited to rooftop systems, even though numerous building-integrated products (BIPV, “building-integrated PV“) are certified and commercially available. These include PV panels and PV tiles for pitched roofs, lightweight PV systems forroofs with low load-bearing capacity, PV systems for green roofs, PV modules for cold
façades (curtain-type, rear-ventilated façades), external thermal insulation composite systems (ETICS) with PV, opaque and semi-transparent PV insulating glass and PV solar control louvres (Figure 29). BIPV offers material-efficient solutions for high-pitched rooftops,
enabling surface areas to be used that would not be suitable for roof-mounted systems
for aesthetic reasons. The advantage of roof-mounted systems is that they are less tied toconstruction and renovation cycles.

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Roof-mounted: high-pitched roof

Flat roof

Integrated PV: high-pitched
roof

Cold façades,
opaqueFlat roof, bifacial(Opaque and semi-transparent) PV insulating
glass for façades, shedroofs

Flat roof, green roof

Flat roof, east/west-facing

PV solar control louvres(fixed or adjustable)

Figure 29: PV solutions for roofs and façades (top row: roof-mounted systems, bottom row: integrated PV).

A study by the Federal Environment Agency assumes 670 km2 of sealed settlement areas[UBA10]. This includes built-up settlement areas, but not building areas or traffic areas
such as roads or railways. Part of this area can be covered with PV modules to provide
shade or can be covered with PV modules that can be walked on (UPV, “urban PV”). The
more than 300,000 large car parks in Germany alone would open up the technical potential of 59 GWP if covered with PV modules.
Further potential on a GW scale is offered by the integration of PV into traffic routes(RIPV, from “Road Integrated PV”), including PV noise barriers, horizontal surfaces (as PV
canopies or road surfaces) and rail tracks. PV canopies are particularly suitable for tunnel
entrances and for highly emitting motor roads in urban areas. With the switch to electric
mobility, the envelope surfaces of electric vehicles are being added as vehicle-integrated
PV (VIPV).
Which part of the aforementioned technical potential can be used economically and practically depends on complex economic, regulatory and technical boundary conditions, aswell as questions of acceptance. In principle, integrated PV, which merges with the envelope of buildings, traffic routes and vehicles, uses land together with agriculture or occupies water surfaces in flooded opencast mines, will have somewhat higher electricity generation costs than simple open-space power plants. On the other hand, integrated PV
avoids conflicts of use and creates synergies, for example by replacing a building façade,using the substructure of a noise barrier, or increasing the range of electric vehicles.
From a current energy law perspective, the available potential for ground-mounted PV
includes verges along motorways and railway lines, conversion areas and, if a federal state
uses the state opening clause of the EEG, also disadvantaged agricultural areas. In BadenWürttemberg alone, the restriction-free area suitable for PV FFA according to these criteria
amounts to 3850 km2 (https://www.energieatlas-bw.de/sonne/freiflachen/potenzialanalyse). This is predominantly permanent grassland and arable land according to the stateRecent PV Facts 16.01.2024

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specific “Open Space Ordinance” (FFÖ-VO). With an occupancy density of 0.6 MWP/ha,this area absorbs 230 GWP PV, for example as agri-photovoltaics or as a solar biotope(Section 13). Current figures for the whole of Germany are not yet available. A study
commissioned by the Federal Ministry of Transport and Digital Infrastructure with figuresfrom 2014 estimated the expansion potential of restriction-free open spaces for PV at
3164 km2 [BMVI].

13 Is PV electricity a privilege reserved for homeowners?
No.
There are various operator models for PV systems that are suitable for co-owned roofs ofcondominium buildings, individual owners and construction companies [EAFR]. Tenants
can install plug-in solar panels (balcony modules), on their balcony balustrades, walls or
terraces. These solar modules can be plugged into the tenant’s household grid to supply
electricity
forself-consumption,
loweringthetenant’s
electricity
bills(https://www.pvplug.de/). Depending on the intended location of the module, the landlord’s permission may be required. It is estimated that nearly one million plug-in solar
panels were in operation at the end of 2023.
If a building is not suited for a PV installation, community energy cooperatives provide theopportunity to contribute to the construction of PV power plants. Anyone who is notinterested in investing can still choose a utility company with a sizable portfolio of PV
power plants, for example, Elektrizitätswerke Schönau (EWS) or Energie Baden-Württemberg (EnBW).

14 Do PV systems destroy ecologically valuable areas?
No, quite the opposite, they usually promote renaturation.
If an area is taken out of intensive agriculture, e.g., from energy crop cultivation, converted into grassland and an open space PV plant (PV FFA) is built on it, then biodiversity
basically increases [ESD]. In PV-FFAs, fertilizer is not used, so that less demanding plants
are given a chance. The fencing of the PV-FFA protects the area against unauthorizedaccess and free-roaming dogs, which is good for ground-nesting birds, among others.
Further improvements can be achieved through small adjustments to the PV plant. Increased row spacing of the module tables, slightly higher elevation of the modules, sowing of wild plant mixtures instead of grass monoculture and careful green maintenancecreate a solar biotope. The larger row spacing also allows a greater module inclination,with higher electricity yields in the winter half-year at higher market value factors of solar
electricity and lower yield losses due to pollution and snow cover.
According to the Federal Agency for Nature Conservation, peatland soils cover 1.4 million
ha in Germany, of which about 50 percent is used as grassland and 25‒30 percent asarable land. The draining of peatlands for intensive agricultural use leads to a dramaticincrease in their CO2 emissions. Alternatively, on already used peatland, adapted PV power
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plants with reduced occupancy density could produce an area yield without intensive agriculture. The partial shading by PV counteracts the drying out of peatlands or supports
rewetting. Based on an agriculturally used peatland area of 1.1 million ha and an occupancy density of 0.25‒0.6 MWP/ha, the technical potential is 270‒660 GWp.

15 Do PV power plants find acceptance in the population?
Yes.
The free scalability of PV power plants enables decentralized expansion, down to so-called“balcony modules” (”plug-in PV”) with a few hundred watts of nominal power. The highnumber of more than 2 million PV systems in Germany, of which about 64 percent aresmall systems with outputs below 10 kW [ISE5], shows that these technical possibilities
are being used extensively. Photovoltaics is ideal for implementing the concept of community energy and promoting acceptance of the energy transition through participation.
According to a representative survey by Lichtblick, solar systems are among the most popular power plants. Figure 30 shows the distribution of answers to the question “Whenyou think about the construction of new energy generation plants in Germany, on whichtypes of plants should the focus be?

Figure 30: Survey results on the construction of new power plants, data from [Licht2].

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RE plants in general
Solar parks
Solar roofs
Wind energy plants
Biomass plants
Geothermal plants
Pylons for overhead
power lines
Figure 31: Survey results on the acceptance of different types of power plants [AEE2].

PV power plants are also by far the most popular power plants from the point of view ofresidents, as a survey by the Renewable Energy Agency shows (Figure 31). The popularity increases when such power plants can be practically experienced in one’s own neighborhood.

16 Are PV plants in Germany efficient?
Yes and no, depending on the reference value.
For newer installations, the effective energy conversion efficiency is around 17–19 percent
in relation to the irradiated solar energy, but the sun shines for free. The effects of efficiency on electricity production costs, space requirements, use of resources and CO2 savings are the deciding factors.
The nominal efficiency (see Section 27.1) of commercial wafer-based PV modules (i.e.,
modules with solar cells based on silicon wafers) from new production has increased inrecent years by an average of approx. 0.3‒0.5 percentage points per year to 21 percent[ISE5]. Per square meter of module, they thus produce a nominal output of 210 W; peakmodules are 10–15 percent higher.
PV systems do not work with the nominal module efficiency because losses occur during
operation and because the initial efficiency of the modules degrades (Section 15.2).
These effects are summarized in the so-called performance ratio (PR). A PV system installed today achieves PR values of 80‒90 percent on an annual average (typical value),
including all losses due to increased operating temperature, unfavorable irradiation conditions in terms of intensity, spectrum and angle of incidence, soiling, shading, snow accumulation, line resistance, conversion losses in the inverter, peak capping of the inverter (DC/AC ratio typically > 1) and, in some cases, downtimes due to malfunctions.
Additional yields increase the PR of bifacial modules through rear-side irradiation, as thereference value of the PR only factors in front-side irradiation. Yield assessments provide
information on the performance and yields that can be expected from PV power plants

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for concrete locations, components and system designs based on historical irradiation
data.
The DC current delivered by the modules is adapted by inverters for grid feeding. The
efficiency of new PV inverters is around 98 percent. Ground-mounted PV systems usuallyshow slightly higher PR than systems on pitched roofs, thanks to better convective cooling,
optimal orientation, better maintenance, less of shading, more efficient inverters, andpossibly bifacial additional yields. In terms of irradiation, newly installed PV power plants
therefore operate with average efficiencies of around 18 percent.
The average electricity consumption in households for electrical appliances, lighting, hotwater (hygiene purposes) and space heating was 1.6 MWh per household member in2018 [DESTATIS]. Average values for 1-person households are slightly higher per capita,
for multi-person households significantly lower. On average, rooftop PV systems achieve
922 hours of full use in 2021 in the trend scenario [ÜNB1], cf. Section 15.4. 21 m2 of aroof area of a house facing roughly south and with a moderate slope are thus sufficientto generate an amount of electricity with 12 370 WP modules that corresponds to theaverage annual electricity demand of a family (4 MWh).
On flat roofs and in open spaces, modules are elevated to increase their yield. Because of
the spacing required for this, they occupy several times their own area when oriented tothe south, depending on the angle of installation. Today, PV FFAs are usually built with
reduced tilt angles (approx. 20°‒25°) and row spacing, resulting in an occupancy densityof around 1 MW/ha at module efficiencies of 21 percent. In 2010, this value was still 0.35
MW/ha [ZSW]. With a view to optimal development of biodiversity, larger row spacing isadvantageous (Section 13).
By way of comparison, the efficiency of electricity generation from energy crops based onirradiation is well below 1 percent; for electricity generation from energy maize, for example, it is 0.2 percent. The efficiency related to irradiation for the conversion of fossilorganic matter such as coal, oil or natural gas into electricity is likely to be in a similarorder of magnitude. However, corresponding combustion power plants normally only relate their efficiency figures to the conversion of the chemical energy already present in
the fossil energy source. For coal-fired power plants in Germany, for example, an average
efficiency of around 38 percent is given.
When biofuels are burnt in vehicles, modest efficiencies are achieved in relation to theenergy radiated and the land use. A passenger car with a diesel combustion engine that
consumes 5.5 l of biodiesel per 100 km can travel about 32000 km with the annual yieldof a 1-hectare rapeseed field of 1775 l/(ha*a) [FNR]. With the annual yield of a new PV
system (1 MWP/ha, 980 MWh/MWP) on the same area, a battery electric vehicle (e-car,consumption 16 kWh per 100 km) travels approx. 6.1 million km, the range is higher bya factor of 190 (Figure 32). Even an agri-PV system (Section 11), which allows simultaneous agricultural use of the land, would take an e-car a factor of 116 further. This comparison does not take into account charging losses for e-cars, energy consumption for
rapeseed cultivation or energy supply from by-products of rapeseed use.
If one compares the efficiency of land use for electricity production, then agri-PV performs
better than maize by a factor of 32, for example. Silage maize, which is cultivated on anarea of approx. 0.9 million ha in Germany, yields 18.7 MWhel/ha of electricity [FNR],

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whereas the figure for high altitude APV (Section 11) is approx. 600 MWhel/ha. This comparison does not consider waste heat utilization (CHP) from methane combustion.
E-car + PV plant
E-car + APV
Bio-diesel

E-car 16 kWh/100km
Diesel engine 5.5 l/100km

Range
Figure 32: Range of electric and biodiesel vehicles per hectare of land used.

In southern Spain or North Africa, specific yields of up to 1600 kWh/kWp can beachieved, but long transmission lines to Germany would lead to energy losses and costsurcharges. With 800 kV extra-high voltage lines, power losses can be reduced to about
0.5 percent per 100 km. Lines for high-voltage direct current transmission (HVDC) reduce transport losses to just under 0.3 percent per 100 km, plus conversion losses. A
5000 km HVDC line would thus have about 14 percent pure line losses.

PV plant
APV
Silage corn

Factor 32

Electricity yield
Figure 33: Electricity yields of PV power plants and silage maize per hectare of land used.

16.1 Are PV systems only viable on roofs that are optimally oriented?
No, it is worth considering the overall profitability.
Figure 34 shows the relative annual yield potential in Freiburg in relation to the orientationof the roof or façade area. The maximum yield with a south orientation and an inclinationof 40° shows a flat line, with small deviations having little effect on the yield. Installations
located in more northern latitudes require a steeper inclination to achieve their maximum
yield.

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Neigung

Horiz.

Vert.

Orientierung
Ost-90° -75°
0° 84% 84%
10° 83% 85%
20° 82% 86%
30° 81% 86%
40° 78% 84%
50° 74% 81%
60° 70% 77%
70° 64% 71%
80° 57% 64%
90° 50% 56%

-60°
84%
87%
90%
90%
90%
87%
83%
77%
70%
62%

Südost-45° -30°
84% 84%
89% 90%92% 95%
94% 97%
94% 97%
92% 96%
88% 92%
83% 86%
75% 79%66% 69%

Süd
-15°
0°
84% 84%
91% 91%
96% 96%
99% 99%100% 100%98% 99%94% 95%
89% 89%81% 81%
70% 71%

15°
84%
91%
96%
98%
99%
97%
94%
88%
80%
70%

30°
84%
90%
94%
96%
97%
95%
91%
85%
77%
68%

Südwest45°
60°
84% 84%
89% 87%
92% 89%93% 89%93% 88%91% 85%
87% 81%
81% 75%
73% 68%
64% 60%

75°
84%
85%
85%
84%
82%
79%
75%
69%
62%
54%

West
90°
84%
83%
81%
79%
76%
72%
68%
62%
55%
48%

105°
84%
81%
77%
74%
69%
65%
60%
54%
48%
41%

Nordwest
120° 135° 150°
84% 84% 84%
79% 77% 76%
73% 70% 67%
68% 63% 59%
63% 56% 51%
57% 50% 44%
52% 45% 38%
46% 39% 32%
40% 33% 27%
34% 28% 23%

165°
84%
75%
66%
57%
48%
40%
33%
27%
23%
19%

Nord
180°
84%
75%
65%
56%
47%
39%
31%
26%
21%
17%

Figure 34: Relative yield potential, no shade, located in Freiburg, calculated online using
https://re.jrc.ec.europa.eu/pvg_tools/en/.

16.1.1 High-pitched rooftops facing east/west

Specific output [Wh/Wp]

In a direct comparison, PV on a west-facing roof with an inclination of 40°, for example,
produces about 24 percent less electricity than an optimal south-facing roof, which increases the levelized cost of electricity accordingly. A PV installation on a west-facing roof
can still be worth-while, in particular when electricity prices are high and self-consumption
is employed.

South 45° 1
kWpWest 45° 1 kWp
Total

Time

Figure 35: Power yield profile by hour for different roof orientations and a 45° roof slope on asunny day in April, no shade, located in Freiburg, calculated online using https://re.jrc.ec.europa.eu/pvg_tools/en/.

The question of whether a west-facing roof should be used in addition to a south-facing
roof can be answered by reviewing marginal costs. Additional PV modules can be expected to come at comparatively lower installation costs, and their orientation towards
the west and late-afternoon generation profile should increase the self-consumption potential (Figure 35).

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16.1.2 Vertical south-facing façade

Monthly specific yield [kWh/ kWp]

A PV system on a south-facing façade produces about 29 percent less electricity per year
than an installation with a module inclination of 30° on a south-facing roof (Figure 36).
The same applies to vertically mounted, south-facing plug-in solar panels. A vertical installation’s monthly fluctuation between the summer and winter yield is considerably
smaller when compared to horizontal installations, making it much easier to integrate PV
electricity into the system. The lower yield of vertical systems is only a concern during thesunny half of the year, when installations on south-facing roofs often “overproduce”,
which leads to a lower share of self-consumption, or when the market value factor ofsolar energy decreases (Section 4.3). The financial viability of a façade installation is therefore only marginally affected by the reduction of the annual electricity yield.

South
30°

South 90°

Jan Feb Mar Apr May June July Aug Sep Oct Nov Dec

Figure 36: Monthly specific yield potential for different inclinations, no shade, located in Freiburg,
calculated online using https://re.jrc.ec.europa.eu/pvg_tools/en/; the percentages provide the relative annual yield in relation to an inclination of 30°.

16.2 Do PV plants degrade?
Yes, but normally very slowly.
Wafer-based PV modules age so slowly that it can be a challenge for scientists to evenprove power losses. A study by Fraunhofer ISE on 44 larger, quality-tested rooftop systems in Germany showed an average annual degradation of the nominal power of themodules of approx. 0.15 percent [ISE2]. Manufacturers’ guarantees for a maximum
power loss of their PV modules of 10‒15 percent over 25‒30 years of operation arecommon.
These values do not take into account failures due to production defects. Faults in thematerial composition or defects that arise during production, transportation or mounting
may accelerate degradation or even lead to the modules failing altogether. Degradation
may affect the appearance of the modules (e.g., delamination), their yield and/or their
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electrical safety. A damage analysis serves to quantify deviations, identify causes and create forecasts for further degradation dynamics.
The declared nominal power of modules usually refers to operation after initial degradation. Depending on the material of the solar cells, light-induced degradation (LID) of 1‒
2 percent occurs in the first days of operation, as extensive measurements at Fraunhofer
ISE have shown.
For systems with quality assurance for component selection, design, installation and operation, the frequently made assumption of 0.5 percent average yield loss per year seems
very conservative in this context.
16.3 Can PV modules become soiled?
Yes.
In many cases, this keeps the resulting yield loss during the modules’ service life at a
manageable level. Local effects such as leaf litter, bird droppings, dust from construction
sites or agriculture, soot from nearby chimneys, regional effects such as pollination ortrans-regional effects such as Saharan dust events may cause problematic soiling. While
heavy rain will mostly clean the modules, soiling does accumulate over the years, increasing yield losses. This especially applies to regions experiencing longer periods without
rainfall as a result of the climate crisis.
Modules with a very flat inclination (less than 15°) are particularly affected. The bottomedge and especially the bottom corners of modules are the areas that collect the mostdirt. When solar cells are connected in series, extreme soiling of partial surfaces can cause
yield losses that are much higher than should be the case in relation to the surface area.
Whether, when and how frequently it pays to have the modules cleaned varies dependingon many influential parameters.
16.4 Do PV plants seldom operate at full capacity?
Yes.
Due to the irradiation conditions, PV plants only operate for slightly less than half of thetotal 8760 annual hours, and then mostly at partial load. The key figure “full load hours”,
also “full utilization hours” (VBh) or specific yield is determined as the quotient of theamount of electricity actually generated in the course of a year and the nominal outputof the power plant (kWh/kWp). In their 2021 trend scenario, the transmission system operators assume 987 VBh for ground-mounted PV systems in Germany, and 922 VBh forroof systems [TSO1]. The values correspond to annual utilization rates (”capacity factors”)
of 11.1 percent and 10.3 percent, respectively, calculated as the ratio of VBh to total
annual hours. The specific annual yield is usually higher in sunny, south-facing locations
when the module has a slight inclination, but it does not depend on the nominal module
efficiency. Figure 37 shows the overview of the projections for electricity generation fromRE, adjusted for losses due to feed-in management (Section 10.1). Due to the low VBh,
increasing shares of solar electricity in the grid increasingly require accompanying
measures (Section 21).

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Figure 37: Forecast full utilization hours for electricity generation from EE, data from [ÜNB1].

The mean annual sum of horizontal global radiation in Germany for the years 2001-2020(Figure 38) is 1102 kWh/m2/a with a linear trend of +0.3 %/a between 1991 and 2020,
according to figures from the German Weather Service. Between 1981 and 2010, theaverage value was still at 1055 kWh/m2/a. To maximize the annual electricity yield, PV
modules are often mounted with an inclination of approx. 30° to the horizontal and oriented to the south. This increases the irradiation sum in relation to the module level byapprox. 15 percent in relation to the horizontal irradiation sum and results in a geographical average for Germany of approx. 1270 kWh/m2/a.
With a performance ratio (PR, see Section 27.7) of 85 percent for a new, unshaded systemwith yield-optimized alignment, a geographical average of 1077 full-load hours could beachieved across Germany. Because not all rooftop systems are aligned to optimize yield,
partial shading occurs and because the PR decreases slightly with age, the actual average
number of full load hours is somewhat lower.
Technical improvements to the modules and the installation can increase the usable irradiation, the PR, the yield and thus the number of full load hours of a PV system. These
include:• Tracking (Section 21.3.1)• bifacial PV technology• Reduction of losses due to shading• Reducing the temperature coefficient of the solar cells• Reducing the operating temperature of the modules through good rear ventilation• Improvement of the modules’ low-light and oblique light behavior• Reduction of losses due to snow cover and soiling• early detection and correction of underperformance• Reduction of degradation over the lifetime
Unlike wind power plants, where the hub height is a decisive factor, the size of a PV
power plant has no direct influence on the number of full load hours.
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Nuclear, coal and gas-fired power plants can produce almost continuously at their rated
output if sufficient fuel and cooling water are available.

Figure 38: Horizontal annual global radiation total in Germany, averaged over the period 20012020 [DWD].

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17 Does PV make relevant contributions to climate protection?
17.1 Do anthropogenic CO2 emissions danger the climate?

temperature
CO2 (ppm)
sun
ice core CO2 (ppm)

CO2 concentration (ppm)

temperature deviation (C)Yes.
Increasing global warming has been proven beyond doubt [IPCC]. Compared to the preindustrial era, the average global temperature has risen by 1.1 °C, and by as much as 1.6°C over the land surface. The vast majority of scientists are convinced that anthropogenic
emissions of CO2 and other greenhouse gases are causing the increase in atmosphericgreenhouse gas concentrations and thus the global temperature rise.

Figure 39: Development of atmospheric CO2 concentration, mean global temperature change andsolar activity (http://herdsoft.com/climate/widget/).

In May 2013, the atmospheric CO2 concentration reached 400 ppm for the first time inat least 800,000 years. Figure 39 and Figure 40 show the development of the atmospheric
CO2 concentration alongside the global, or rather, the Antarctic temperature up to thispoint.
A fast and global temperature rise endangers the stability of the global climate system toa hitherto little understood extent, with effects on the lives of people threatened by extreme weather conditions, the word population’s primary food production,

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infrastructures, populated coastal zones, adding additional pressure on biodiversity andthe preservation of biotopes.

Figure 40: Estimates of atmospheric CO2 concentration and temperature difference in Antarctica
based on ice cores [EPA]; red: two recent CO2 measurements from Mauna Loa Observatory[https://www.esrl.noaa.gov/gmd/ccgg/trends/data.html].

17.2 Does PV make a significant contribution to CO2 emission reduction?
Yes.
The CO2 equivalent (GHG) emission factor for the electricity mix in Germany, including
upstream emissions, has dropped from 860 g CO2 e/kWh in 1990 to about 498 g

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CO2/kWh in 2022 [UBA6]. The expansion of RE has been a major contributor to this reduction.
To estimate the overall emission factors of individual fuels for electricity generation, it isnecessary to differentiate, amongst other factors, between the country of origin, the materials handling technology used, the primary energy concentration, the primary energy
content of the raw material deposits, methane leaks during natural gas production, as
well as the total (for combined heat and power) and the effective electrical efficiency of
power plants.
While PV systems do not release any CO2 during operation, a holistic assessment mustalso take into account the production and disposal of the system. The specific yield[kWh/(kWP·a)] and thus the annual irradiation sum at the operation site play a major role,as does the lifetime of the PV system. Thanks to advances in production and efficiency,
the carbon footprint of PV electricity has been dramatically reduced in recent decades. It
is therefore important to consider life cycle assessments (LCAs) of current technologies
when evaluating new systems.
The IEA PVPS Task 12 has found that a large ground-mounted PV system in Piacenza inNorthern Italy (GHI 1,368 kWh/(m2·a) with 85 MWP, modern PERC technology and21.2 percent module efficiency, has an emission factor of 25.7 g CO2-eq/kWh [IEA5]. In
Germany, only about 30–35 g CO2-eq/kWh could potentially be achieved due to thesomewhat lower solar radiation (approx. 20 percent lower on average).
The German Federal Environment Agency has compared the greenhouse gas potentialof PV electricity from ground-mounted and pitched roof mounted PV systems based onolder data and only found little difference between the two ([UBA9], see Figure 41 ). PV
modules produced in Europe together with their feedstocks are particularly favorable
because the electricity mix here contains a higher share of renewable energy and thetransport distances are significantly shorter. Glass-glass modules are favorable due totheir lower degradation and the absence of aluminum frames [LCA]. With the continued
increase in efficiency and the share of RE in production, GHG emissions per kWh of PV
electricity will continue to decrease.
Roof-mounted and ground-mounted systems, solar radiation 1,200 kWh/(m²*a)c-Si (mono) (18%), EU, scenario AB, ground-mountedc-Si (mono) (18%), CN, scenario AB, ground-mountedc-Si (mono) (18%), EU, scenario AB, roof-mountedc-Si (mono) (18%), CN, scenario AB, roof-mounted
global-warming-potential [kg Co2eq/kWh]
PV module

invertermounting structure

electrical conductors (DC)transport

Figure 41: Global warming potential of electricity generation with mono c-Si PV for roof-mounted
and ground-mounted systems [UBA7].

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g CO2eq/kWhFigure 42 shows the GHG potential of PV compared with coal, natural gas and nuclear
power. The emission factor of power generation from biogas with energy crops is around
160–184 g CO2-Eq./kWh [UBA9].
In 2022, the use of PV in Germany avoided a net 41,7 million tons of greenhouse gas
emissions (Figure 43). In the calculations, the emissions from the production of the PV
system components were taken into account approximately.

Figure 42: Global warming potential of different electricity generation technologies [UBA7].

Electricity: 181.1 Mio. t

Heat: 36.3 Mio. t
Total GHGavoidance:
226.6 Mio. t CO2
equivalents
Transport*: 9.3 Mio. t

Greenhouse gas avoidance [Mio. t CO2 equivalents]
Biomass

Hydro
power

Wind energy

Photovoltaic

Solar thermal energy

Geothermal energy
Source: Umweltbundesamt (UBA)

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Figure 43: Avoided greenhouse gas emissions through the use of renewable energies in 2022
[UBA1].

PV addition [GWp/a]

German energy policy also has a high international relevance. With a production volumeof 171 Mt in 2016, Germany was number one internationally in the extraction of lignite,ahead of China. Germany accounts for less than 3 percent of global electricity consumption, and the trend is still downwards. However, German policy has played a pioneeringrole in the development of instruments to promote RE, first and foremost the EEG. The
EEG instruments have received considerable international attention and have served as amodel for similar regulations in dozens of countries. China has now become a pioneer in
PV expansion and has overtaken Germany many times over in terms of annual installedcapacity. In its country report “Germany 2013”, the International Energy Agency (IEA)
praised the Renewable Energy Sources Act (EEG) as a very effective expansion instrumentthat has significantly reduced the costs of generating renewable energy in recent years[IEA1]. The Germans’ departure from nuclear energy has also attracted international attention. Other European countries have decided to phase out nuclear power (e.g., Belgium, Switzerland, Spain) or have already done so (Italy, Lithuania).
However, the EEG achieved the highest impact in terms of CO2 avoidance in its earlyyears through a “side effect”: by creating the largest and most secure international sales
market for PV over several years, it has significantly accelerated global scaling, technology development and price reduction (Figure 44). PV reduces the consumption of fossil
raw materials for electricity generation worldwide.

Figure 44: Development of annual PV additions [IEA3], estimations by BloombergNEF and averageannual growth rate.

The German EEG has thus made PV electricity more affordable for many people in developing countries. From this perspective, the EEG is also “probably the most successful development aid program of all time in this area” (Bodo Hombach in Handelsblatt
11.1.2013), which also saves considerable amounts of CO2 in developing countries.
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17.3 Does the production of PV modules use more energy than they can deliver
during operation?
No.
The Energy Payback Time (EPBT) indicates the period of time that a power plant has to be
operated in order to replace the primary energy invested. The harvest factor (Energy Returned on Energy Invested, ERoEI or EROI) describes the ratio of the energy provided by apower plant and the energy expended for its life cycle.
The energy return time and harvest factor of PV plants vary with technology and plant
location. An analysis commissioned by the Federal Environment Agency has determined
EPBT for PV power plants for a plant operation in Germany (assumed average annual
irradiation sum at the module level of 1200 kWh/(m2-a)) of 1.6 years for multi- and 2.1
years for monocrystalline Si modules [UBA7]. With a lifetime of 25-30 years and an annual
yield degradation of 0.35 percent, this results in harvest factors of 11-18. Calculations by
Fraunhofer ISE based on the latest production data indicate an EPBT of under 1.3 years
for systems with commercially available monocrystalline Si modules in Germany [ISE5].
Component production in Europe further reduces the EPBT due to the higher share ofgreen electricity compared to imported components from China.
17.4 Are there other environmentally harmful gases released during the production of PV?
Yes, for some thin-film technologies.
In the production of thin-film PV and flat screens, nitrogen trifluoride (NF3) is still sometimes used to clean coating systems. Residual amounts of this gas can escape into theatmosphere. NF3 is more than 17,000 times more harmful to the climate than carbon
dioxide. Current emission levels are not known, but NF3 emissions will be determined in
37 countries from 2013 in accordance with the amended Kyoto Protocol.

18 Do PV modules heat up their environment significantly?
Locally, it depends on what is being compared. Globally, the indefinite cooling effect isdecisive in terms of avoided greenhouse gas emissions in electricity production.
17.1 Solar reflection and absorption
Light-colored surfaces reflect more of the incident solar radiation, while dark surfaces
absorb more and thus heat up more. The solar albedo (solar reflectance) of a surface
indicates the percentage of incoming solar radiation that is reflected. Asphalt has an
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albedo of 12‒25 percent, concrete 14‒22 percent, a grey wall 20‒45 percent, roof tiles
10 (dark)‒30 (light) percent, green grass 26 percent (https://www.stadtklimastuttgart.de/index.php?klima_klimaatlas_5_grund).
The latest designs of conventional PV modules have a solar reflectance in the order of 5–
10 percent, depending on the choice of material and module design. Light-colored frames
and back sheet foils increase reflection. PV modules are optimized to absorb as much solar
radiation as possible in the active layer. Thermal insulation glazing, especially solar control
glazing, reflects many times more (in the order of 10‒30 percent). If one compares a glassbuilding façade with a PV façade, the PV façade reflects significantly less solar radiation
downwards to the street level. Ordinary PV modules can be blinding, but they reflect
extremely little solar radiation.
For example, when new PV modules convert solar radiation into electrical energy on a hot
day with an operating efficiency of 18 percent, and also reflect part of the irradiation(approx. 5–10 percent), they generate as much local heat as a comparable surface withan albedo of 23–28 percent. When it comes to PV modules in operation, this is referred
to as effective albedo. In the example above, it ranges from 23 to 28 percent. Only
when PV modules are not supplying electricity does their effective albedo drop to thevalue of their solar reflectance of 5–10 percent.
17.2 Evaporative cooling
Although the difference between the albedo of a green area and the effective albedo ofa PV module is not very large during operation, the green area remains significantly cooler
than the PV modules on hot days due to evaporative cooling. This is true at least as longas the plants can draw enough water from the soil. After that, evaporative cooling stops
and the plants dry out. Conversely, partial shading of plants by PV modules can reduce
the water demand of the plants and the soil remains moist longer. This effect argues for
a combination of PV with, for example, agriculture, dry moorland soils and green roofs(Sections 11 and 13).
17.3 Heat storage
The heat storage capacity of ordinary PV modules is significantly lower compared to, forexample, a solid concrete wall. As a result, the PV module heats up faster than a concrete wall under solar radiation with the same effective albedo, but also cools down
faster in the evening. The actual impact of PV modules on the urban climate, comparedto other building materials, depends on numerous factors and may need to be analyzed
on a case-by-case basis.
17.4 Greenhouse effect
PV electricity in particular replaces electricity from fossil-fuel power plants, which not
only generate waste heat during operation (order of magnitude 2 kWh waste heat per
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released into the atmosphere, where it acts as a greenhouse gas for an unlimited periodof time (Section 17.1). Compared to fossil power plants, electricity generation via PV
massively reduces the release of CO2 and thus effectively slows down the greenhouseeffect (Section 16).

19 Can PV modules cause glare?
Yes.
Similar to window glass, the cover glass of PV modules can cause glare, depending the
sun’s position, the orientation of the module, glass texture and the observer’s field ofvision. The effect will only occur at certain times of the day and on certain days in theyear. A glare analysis can provide details. When it comes to PV modules, it is usually notabout a measurable impairment of vision (disability glare) but a sense of disturbance due
to high luminance (discomfort glare). The cover glass of PV modules only has a one boundary surface that may cause glare, which usually has a slight surface texture and an additional antiglare (AR) coat, the maximum luminance of its reflection is significantly lower
than that of windows with up to 6 smooth boundary surfaces that lack AR coating. In
particularly critical cases, for instance, when a PV system is located near an airport, PV
modules with special, more strongly textured cover glass can reduce the risk of glare.

20 Do PV modules emit irradiation that is harmful to health?
No, provided the components are certified and have been mounted properly.
The term “electromagnetic pollution” includes static, electric and magnetic fields as wellas electromagnetic (EM) fields that are generated by technological devices.
Static electric fields are caused by charge imbalances (potential) between two objects, forinstance between module string cables, or between live and grounded components. The
field strength depends on the voltage and the distance between the live objects. A module
string typically provides voltages between 400 – 1000 V, depending on the number ofmodules connected in series. There is no knowledge of cases of damage to health fromstatic electric fields associated with PV systems.
Static magnetic fields surround electrical currents, for instance in live cables. A rooftop PV
module typically produces a current in the range of 10 – 15 A. While magnetic fields canmagnetize certain materials, the magnetic field strength decreases rapidly with increasing
distance from the cables, and is further weakened by the usual paired arrangement of thewires carrying currents in opposite directions. The live wires of a PV system should not berouted through living or bedrooms. There is now knowledge of cases of damage to healthfrom static magnetic fields associated with PV systems.
Electromagnetic fields (“waves”, “radiation”) are created by accelerating or decelerating
electrical loads. Solar cells produce a direct current (DC) that does not generate EM fields,
neither within the PV modules nor in the DC power lines. Inverters convert the direct
current from the module string or individual module to 50 Hz alternating current (AC) for
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grid feeding. Most small PV systems use a central inverter, though some use moduleintegrated inverters located on the rear side of the modules.
Currents in the kilohertz frequency range flow through such inverters, and these alternating currents generate EM fields. The law requires manufacturers to shield inverters so that
the EM value near the device stays below the threshold value. Inverters must be mounted
outside living and bedrooms, with the distance and shielding effect of the material between the inverter and the dwelling area being the determining factor. During operation,
inverters can feed a portion of high-frequency electricity back into the DC circuit, andtherefore also into the PV modules. Transformerless inverters transmit low-frequency(e.g., 50 Hz or 150 Hz) voltages to the DC side. There is now knowledge of cases of damage to health from electromagnetic fields associated with PV systems. A study commissioned by EnergieSchweiz [BFE] provides numerical values and comparisons with typicaldomestic electrical appliances. Low- and high-frequency currents in inverters may also
produce audible sound during operation and although this may cause disturbance depending on the inverter’s location, this is not EM radiation.

21 Are PV systems capable of replacing fossil fuel and nuclear power
plants?
No, at least not in the next few years.
As long as no significant power-to-power storage capacities or storage power plants areavailable in the grid, PV and wind power will reduce fossil fuel consumption, energy imports and CO2 emissions, but they will not replace power capacities. The acid test is windless, cloudy winter days, when electricity consumption can reach maximum levels without
solar or wind power being available. On the other hand, PV and wind power increasingly
collide with inert conventional power plants (nuclear power, old lignite). These — almost
exclusively base-load capable — power plants must therefore be replaced as quickly as
possible by flexible power plants, preferably in multifunctional, electricity-led CHP technology with thermal storage (Section 21.3.6).

22 Are we capable of covering a significant proportion of our energy
demand with PV power?
Yes, to the extent that we adapt our energy system and the energy-related structures tothe requirements of the energy transformation.

22.1 Starting point: energy demand and energy supply
The traditional energy industry extracts fossil and nuclear energy sources (primary energy),
converts them and prepares them for end consumers (Figure 45).
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Figure 45: Energy flow diagram 2022 for Germany, figures in petajoules [AGEB2].

There are dramatic efficiency deficits in conversion and final energy consumption (cf. Section 21.3.3). Our future energy demand is by no means the same as today’s primary energy consumption, neither in terms of quantities nor in terms of energy carriers.
Up to now, Germany has been highly dependent on energy imports, associated with therisk of volatile prices, political influence by producing and transit countries and the risk of
disruptions in raw material logistics, e.g., pipeline blockages or low water in rivers.
The costs of fossil energy imports are in the order of 40‒130 billion euros annually (Figure46). A large part of the money went to supporting autocratic regimes.

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Coal, coke and briquettes
Oil, oil products and related products

Natural gas
Total fossil-based energies
Electrical power

Total
Including in-transit quantities

Figure 46: Balance of Germany’s foreign trade in energy sources from 2017 to 2022 [AGEB1].]

Most final energy (36 percent) is used to generate mechanical energy (”power”) for
transport and in stationary engines (Figure 47). Approximately 800 TWh of final energy isused annually for space heating and hot water [BMWK1].
Final energy consumption [TWh]Figure 47: Structure of final energy consumption by application area for Germany in 2020, figuresfrom [BMWK1].

The electricity load fluctuates periodically: less electricity is needed at night, on weekends
and holidays. Electricity suppliers distinguish in the load profile between base, medium
and peak load, cf. Section 27.8. The base load is the load share around 30‒40 GW, whichhardly changes over 24 h. The medium load fluctuates slowly, the peak load comprises
the rapidly changing load share above the base load. The medium load fluctuates slowly,
the peak load comprises the rapidly changing load share above the base and medium
load. Electricity consumption and energy demand for water heating are slightly lower insummer than in winter. Mineral oil sales (petrol and diesel fuel) show very little seasonal
fluctuation [MWV]. The heating demand correlates negatively with global radiation, withthe highest coincidence in spring.
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22.2 Energy scenarios
Our current energy system in Germany, based on fossil and nuclear generation, is a discontinued model. There is a plethora of energy scenarios for the coming decades, andthey increasingly count on RE [UBA, ACA, ISE3]. Researchers at the Fraunhofer Institutefor Solar Energy Systems ISE have investigated different transformation paths to a climateneutral energy system for Germany in simulations based on hourly time series with consideration of sector coupling (Figure 48). In an economically optimized generation mix, PV
contributes an installed capacity of 300‒450 GW, depending on the boundary conditions[ISE3].
Figure 49 shows a schematic residual load curve for Germany with a 100 percent renewable electricity supply. The hourly values of the residual load (Section 10.4) for one year
are shown in descending order. Although volatile electricity production can be technicallyshut down at any time, this is at the price of a total economic loss of the corresponding
electricity quantity. An electricity price with a meaningful control function would fall fromleft to right along the residual load curve of Figure 49.

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Energy source
Regenerative

Wind
Solar
Water
Environmental
heath
Biomass
Imports

Energy conversion and storage Consumption sectors
Energy transformation

Run-of-river
power plant
Photovoltaic

Car battery

Transport

Geothermal
Methanation
Electrolysis
BiofuelSynthetic
fuelsPower-to-liquid

Stationary
battery

Process heat

Gas

Building heat
Hydrogen

Cogeneration

Natural gas

Fuels
Biomass
Nuclear power
plantElectricity

Pumpedstorage

Conventional
power plant

Coal & oil

Uranium

Consumption
sectors

Wind turbine

Electricity

Fossil & uranium

Storage

Gas
Heat
Biomass
Liquidfuels
HydrogenElectricity
Coal

Figure 48: Schematic representation of the REMod model (KW: power plant, KWK: combined heatand power, [ISE3]).

On the demand side, flexible loads are reduced, batteries and pumped storage are discharged, fuel cells, steam turbines, gas-and-steam generators (CCGT) and gas turbines
are activated in the order of their marginal costs to cover the residual load. Hydrogen or
methane, produced with RE, serve as energy carriers. In the case of local heat demand,
electricity generators are designed with combined heat and power (CHP) and produce
usable waste heat. CHP gas turbines provide high-temperature heat for industrial processes. Batteries can also be charged on the demand side to balance out predictable peaks
in demand. This reduces the capacity required from peak-load power plants with marginalfull load hours.
On the surplus side, flexible loads are increased, batteries and pumped storage arecharged, electrolyzers, heat pumps and resistance heaters (”heating rods”) are activatedwhen electricity prices increasingly fall in order to take the electricity that is not currently
needed. Electrolyzers can also be operated as CHP plants and produce usable waste heat.
Resistance heaters and high-temperature heat pumps can provide heat for industrial processes. The last resort is to shut down electricity production if the installed output or the

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grid capacities are not sufficient for a few hours of the year. Batteries can also be discharged on the demand side to reduce derating of anticipated generation peaks.

Figure 49: Schematic representation of a residual load curve for Germany with electricity supply
with 100 percent RE.

In order for heat-generating converters on both sides of the curve to be operated withelectricity, they require local thermal storage and heat consumers or connection to heat
grids (Section 21.3.6). Generators (e.g., simple gas turbines) and consumers (e.g., resistance heaters) with particularly low performance-related investment and maintenancecosts (€/W) are required for the two-sided spurs of the residual load curve. Since they are
rarely in operation, they do not have to be highly efficient. The electrolytically producedhydrogen can be stored directly or after methanization in pressure tanks or in the gas grid.
From there, it can be converted back into electricity (gas turbine, combined cycle gas
turbine, fuel cell), further processed into synthetic fuels or used as a material in the chemical industry.
The storage capacity of the system must be designed for the worst case of a primaryenergy failure (sun and wind) lasting several weeks, i.e., a prolonged lull in winter, possibly
exacerbated by a closed snow cover. For this, sufficient quantities of hydrogen and synthetic energy carriers and raw materials derived from it must be kept in stock. If there
were no support for PV from wind power, then the worst case in winter would lastmonths, not weeks, and many times more storage capacity would be needed.
Due to their limited capacity, stationary batteries and pumped storage fail relatively quickly
as generators in continuous operation (minutes to a few hours). The same applies to vehicle batteries, which can be operated bidirectionally on the grid, but primarily have tocover the mobility demand. The benefit of these storage systems lies in the frequentchange of operation between charging and discharging, which they implement more
quickly and, above all, more energy-efficiently compared to the electricity-to-electricity
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path via hydrogen. Many load management options also only have a short effect in thehourly range.
The power generation capacity of the system on the left side of Figure 49 must be
sufficient to take over the complete supply in the order of 100‒150 GW when the hourly
reserves (load management, pumped storage, battery) are exhausted. This situation occurs frequently, e.g., on low-wind nights, and can last for several weeks in a worst-casescenario.
The power purchase capacity of the system on the right-hand side of Figure 49 in theorder of several 100 GW must be sufficient to absorb the electricity production from volatile RE minus the current electricity consumption as far as possible as soon as the hourly
reserves (load management, pumped storage, battery) are exhausted. If the power demand is not sufficient during rare production peaks, the system must be regulated. Thiscan happen, for example, on stormy nights or on sunny and very windy weekend days,
when low demand and very high electricity production coincide. For these few hours ofoperation, it is not worthwhile to further expand the power output.
Converters that allow reversible operation work on both sides of the curve in Figure 48
and thus achieve a higher utilization. In addition to batteries and pumped storage, these
may also include reversible fuel cells that operate electrolysis in the case of excess electricity and are currently under development.
The technologies and measures mentioned in Figure 49 are scalable, except for turbinesand pumped storage. They can not only be operated centrally on a multi-MW scale, butalso on a single-digit kW scale. Corresponding devices are commercially available as domestic technology.

Figure 50: Development of global electricity generation by technologies in the Sky scenario; thediameter of the pie charts corresponds to global electricity demand [Shell].

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A brief sideways glance at global energy scenarios: the study “Shell Scenarios Sky —Meeting the goals of the Paris agreement” by Shell International B.V. from March 2018sees PV growing to become the most important source of electricity globally (Figure 50).
Global electricity consumption increases from 22 PWh today to 100 PWh in 2100.
The International Energy Agency (IEA) predicts that photovoltaics will play a major role in
the global primary energy supply: in its report “Net Zero by 2050: A Roadmap for the
Global Energy Sector”, the IEA assumes a 20-fold expansion of the currently installed PV
capacity to over 14,000 GWP [IEA2].
22.3 Transformation steps
For a massive, technologically, and economically controllable integration of volatile PV
electricity into our energy system, there is no single patent solution, but a multitude ofcomplementary measures. The most important steps are addressed in the following sections.
21.3.1 Steady PV power generation
How can the PV power supply be stabilized in the grid?
Stabilization during the day increases the full load hours of a PV power plant and reduces
the need for balancing, e.g., through load management and batteries. One of the simplest
measures is to install PV modules with an east/west orientation, either on roofs or on open
spaces (Figure 51). This mounting variant reduces land consumption, but the specific annual yield per installed module output decreases compared to the south orientation. 1- or
2-axis tracking systems not only stabilize the electricity production over the course of theday (Figure 51), they also increase the specific annual yield by approx. 15‒30 percent.
Compared to stationary installation, they can also reduce losses caused by snow cover orincreased operating temperatures. Another option is vertically mounted, bifacial modules
with a north-south orientation, which deliver more electricity in the morning and afternoon than at noon.

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Figure 51: Power yield profiles of PV systems in different mounting variants, calculated with the
PVsol software for a predominantly clear July day at the Freiburg site.

The very pronounced seasonal fluctuation of PV electricity generation can be dampened
by mounting south-facing modules with higher tilt angles; vertical south-facing façades
are particularly effective (Figure 36).
The somewhat higher electricity production costs for the alternative installation variants
mentioned can pay off in the context of increased self-consumption and the associatedsavings on electricity purchases, especially for commercial customers. Feed-in tariffs thatreward a higher value of electricity in the morning and evening hours promote the construction of systemically advantageous PV power plants that are not only optimized for
maximum annual electricity yield. The measures to increase the number of full-load hours
mentioned in Section 15.4 also contribute to the stabilization of PV electricity generation.
21.3.2 Complementary operation of power plants
Power plants for complementary operation must also be highly efficient in partial load
operation, allow for rapid load changes and, in the case of gas-fired power plants, be able
to cope with increasing hydrogen shares.
Gas-fired power plants are very well suited to cover fluctuating loads. In combination withcombined heat and power (CHP), high overall efficiencies of up to 95 percent are achieved[UBA2]. Simple gas power plants based on gas engines have an investment cost (€/kW)
that is a fraction of the cost of combined cycle power plants. Today, gas-fired power
plants burn natural gas and biogas. Natural gas must be imported for the most part (approx. 95 percent in 2017 [AGEB1]), especially from Russia and Norway. In the course of
the energy transition, gas-fired power plants will switch from natural gas to mixed gaseswith increasing proportions of electrolytically produced hydrogen.

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It is technically possible to operate, design or retrofit many coal-fired power plants so thatthey can partially follow the residual load (Figure 52). The partial load operation itself, theincreased wear and the possibly necessary retrofitting increase the production costs forelectricity. In some coal-fired power plants, steam generation can be converted from coal
to gas burners (fuel switch) so that the steam turbine and generator can continue to be
used [EnBW2].

Figure 52: Availability of power plants [VGB].

Depending on the type, biomass power plants can burn solid biomass (residual wood,
waste wood), liquid biomass (vegetable oil) or biogas (from agriculture or sewage treatment plants). At the end of 2019, biomass power plants with a capacity of over 8 GWp
were installed throughout Germany [ISE4]. Power plants that burn solid or liquid biomass
are very easy to operate as electricity-generating plants due to the simple storage of thefuel material. There are limitations with biogas power plants when the fermentation
throughput can only be controlled to a limited extent and the gas cannot be stored in thegas grid. The cultivation of biomass for the purpose of energy use will decrease due tolow land efficiency (Section 15), and use will concentrate on agricultural residues (biogenic
waste).
21.3.3 Increasing energy efficiency
21.3.3.1 Transport
Most of the final energy consumed in traffic is converted into waste heat by combustion
engines; only a small part reaches the drive train as mechanical energy. Diesel engines forpassenger cars achieve an efficiency of up to approx. 42 percent at their peak, while inurban traffic the average efficiency is only approx. 20 percent due to partial load operation[Sprin]. For passenger car petrol engines, the values are even lower, at up to 37 percent
at the peak and approx. 10‒15 percent in urban traffic. In urban traffic in particular, aconsiderable proportion of the drive energy gained is irreversibly burnt up during braking,because vehicles with internal combustion engines can hardly recuperate via their alternator. Thus, motorized road traffic burns fossil fuels with a very low efficiency, related tothe transport performance.
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90 percent. Losses during charging of the vehicle battery are in the order of 15 percent
and are particularly high during fast (DC) charging. Electric vehicle drives can recover alarge part of the kinetic energy; according to the manufacturer, the efficiency of recuperation for the BMW i3, for example, is around 63 percent. For reasons of energy efficiency
alone, it makes sense to switch to electric drives, in addition to the considerable storage
potential (Section 21.3.7.5). Figure 53 shows the accumulated greenhouse gas emissionsof average compact cars (Volkswagen Golf) with different drives in relation to their total
mileage in 2022 [ADAC].
Preferred charging with solar or wind power (cf. Section 21.3.7.5) leads to a particularly
flat course of the emission line (Elektro3). If the BEV is sold together with a small PV systemof 3 kWp nominal power, the vehicle runs on 100 percent solar power on a bi-lobal basis,
with an average annual mileage of over 15000 km, a specific annual yield of 950 kWh/kWp
and 15 percent charging losses. Especially in city traffic with its typical stop-and-go operation, consumption and GHG emissions per km for BEVs decrease thanks to recuperation,
while they increase for internal combustion vehicles due to braking losses and inefficientpartial load operation.
For city operation, smaller batteries are usually sufficient, which further reduces GHG
emissions for production and operation. In the future, the production of BEVs will use
increasing shares of RE with correspondingly decreasing greenhouse gas emissions.

Figure 53: Greenhouse gas emissions (CO2-Eq. in tons) of an average compact car with different
drives in 2022, in relation to the total mileage [ADAC].

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The CO2 balance can be evaluated as follows: an electric car with a small battery, whichmostly drives in town, prefers to charge with renewable electricity and covers many (necessary) km per year, has a particularly clear advantage in terms of the GHG balance. The
advantage shrinks for Sunday drivers with a large battery, a high proportion of car journeys and gray charging current.
21.3.3.2 Private households
Private households use about 75 percent of the final energy consumed for heating. On
average, this consumption can be halved by simple thermal insulation measures.
Stiftung Warentest has determined that a household completely equipped with old appliances consumes twice as much electricity as one that uses only efficient appliances [test].
Measures that reduce night-time electricity consumption are particularly effective whensolar power (and wind power when there is a night-time lull) can only be made available
through comparatively expensive storage.

21.3.4 Load management
Grid-serving load management (”demand side management”) aims at a supply-oriented,
temporal shift of electricity consumption. When the residual load is high (Section 10.4),
consumption is temporarily reduced or stopped, but is made up for when the residualload is low. If the CO2 price is sufficiently high to determine the merit order (Section 4.3),
load management can already save CO2 emissions today, because the dirtiest power
plants are then needed less often.
Prerequisites for load management are flexibility options through material storage orreserves on the demand side. A washing machine can often wait a few hours, while apassenger train must depart on time. For electrical systems in continuous operation,
power reserves are necessary that enable a compensatory increase above normal power
after a reduction below normal power. The interaction between load management andenergy storage systems is discussed in Section 21.3.7. They are charged in accordancewith their intended use for the grid (e.g., pumped-storage power plants) or with consideration for grid efficiency (in the future, e.g., heat pumps and batteries for electric cars).
Several studies have identified load management potentials in the order of 20 GW andmore for private households and up to 14 GW for commercial consumers [AEE1]. Household appliances whose operation is allowed to start with a delay in a defined time interval
according to the user’s decision must be technically enabled to wait for grid-serving operating times. The electricity supplier can offer time-based tariffs for this, but
direct control is even more effective. Some appliances with particularly high output, suchas washing machines, dishwashers, and tumble dryers, come into question.
The technical prerequisites and economic incentives for tapping this potential still must
be created for the most part. Dynamic electricity tariffs and electricity meters that enable
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time-dependent billing (”smart meters”) are of decisive importance. In the best case, dynamic tariffs reflect the current residual load. The current composition of electricity prices
for households (Figure 11) with very high fixed costs per kWh would hardly create incentives for load management given the usual price fluctuations on the electricity exchange.
According to the EU Electricity Market Directive 2019/944, end customers with smart meters should be able to choose dynamic electricity tariffs from 1.1.2021, and the German
federal government’s plan is to make these electricity tariffs mandatory by 2025 at thelatest.
In the electricity-intensive industry, e.g., electrolytic aluminum production, there is also
potential for adjusting consumption profiles. Companies that accept temporary power
cuts in electricity supply announced at short notice can already receive a contractuallyagreed compensation payment from their transmission system operator (Ordinance on
Disconnectable Loads — AbLaV). The electrolytic production of green hydrogen as a raw
material in metallurgy, e.g. for the direct reduction of iron ore, and in the chemical industry, e.g. via methanization and ammonia synthesis, will also contribute to load management.
As soon as particularly cheap daily electricity is available more frequently because the installed PV capacity grows and variable electricity tariffs are offered, flexibility on the partof industry and consumers will also increase. Self-consumption of solar power has ananalogous effect to dynamic electricity tariffs because it significantly reduces the price ofelectricity when it is purchased directly from one’s own roof. The promotion of PV selfconsumption for households and businesses is a highly effective means of incentivizing
load management.
21.3.5 Balanced addition of PV and wind power capacities
Due to the weather conditions, there is a high degree of complementarity between thehourly and monthly generation of PV and wind power in Germany (Section 10.2.3). If theinstalled capacities for PV and wind power can be expanded to similar levels, their combination will reduce the need for balancing.
21.3.6 Combined heat and power generation
Low-temperature heat for space heating and hot water, as well as industrial process heatat a high temperature level, are still mainly produced by burning fossil resources and inconnection with small heat storage capacities. In a renewable energy system, large
amounts of useful heat are generated during the transformation of electrical energy, fromthe waste heat of converters.
Large heat storage capacities for low-temperature heat (Section 21.3.7.1) enable the current-controlled operation of the converters. The expansion of heat distribution networks
is limited by distance-dependent transport losses to a much greater extent than in theelectricity sector. For this reason, plants with electricity-heat coupling (Figure 49) must be
tailored in their output and placement to local heat consumption and usable heat grids.
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These can be local heating networks with heat transport between neighboring buildings
or district heating networks that supply city districts or entire cities. High-temperature heat
for industrial processes can be generated from the waste heat of CHP gas turbines (up to
approx. 550°C) if electricity is required.
In Germany, about 39 GW of electrical CHP capacity was on the grid at the end of 2020([ÖKO2], statista.com), using mainly natural gas, biomass, and coal. CHP plants achieve
overall efficiencies of up to 90 percent, and as gas CHPs even up to 95 percent [UBA2].
Even micro-CHP units for single-family homes can achieve electrical efficiencies of up to
25 percent and overall efficiencies of up to 90 percent [Licht1]. They use combustion or
Stirling engines to generate mechanical power. As the energy transition progresses, CHP
plants are being converted from fossil fuels to hydrogen and methane; some continue toburn bio methane/mass from biogenic waste.
21.3.7 Energy storage
Energy storage systems are components that can absorb energy and release it again as
usable energy. Energy converters such as water or heat pumps, electrolyzers or fuel cells
are used for charging and discharging. In some energy storage systems, energy can only
be extracted in a converted form, e.g., in the case of heat storage systems charged withelectricity. A hydrogen storage unit is used as an energy storage unit when hydrogen orits derivatives serve as an energy source, otherwise as a material storage unit, e.g., for thechemical industry. The loading of material storage by energy-intensive processes, e.g.,
aluminum production, can serve the grid via load management (Section 21.3.4).
21.3.7.1 Low-temperature heat accumulator
Electric heat pumps consume electricity to provide useful heat from ambient heat (heating) or to dissipate heat into the environment (cooling). In the building sector, the efficiency of a heat pump is indicated as the annual performance factor (APF) and is around
300 percent in heating mode, depending on the technology and load. Efficient operationis achieved by heat pumps with surface heating systems, mostly underfloor heating systems, which manage with low flow temperatures. Resistance heaters (heating rods) convert electricity into heat with 100 percent efficiency, but with a low exergetic efficiency
when generating low-temperature heat.
Thermal storage capacity can be provided much more cheaply than electricity-to-electricity
storage capacity. If the thermal storage capacity and the heat pump or heating system
output are sufficiently dimensioned, the storage load can be supply-oriented, dependingon the current residual load. For this purpose, heat storage units and cold storage units,e.g., of air-conditioning systems, cold stores, and food markets, are preferably charged
during the core time of the day or according to electricity price signals. However, if generously dimensioned thermal heat storage systems are lacking, the thermosensitivity ofthe electricity load increases and larger power reserves must be kept available at power
plants.
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Low-temperature thermal storage, especially hot-water thermal storage, enables the electricity-led, highly efficient operation of CHP plants on both sides of the residual load curve(Figure 49), as well as of heat pumps and heating rods on the electricity consumer side.
The same storage unit can, for example, be charged simultaneously by heat pump andheating rod when there is a high electricity surplus, and by a CHP when there is a demandfor electricity. Heat storage systems are scalable from single-family homes to multi-family
homes and commercial enterprises to neighborhood supply. The relative storage losses
and the specific costs decrease with the size of the storage tank. Large storage facilities
of several thousand m3 or more, e.g., neighborhood storage facilities, can be operated
as seasonal heat storage facilities (http://www.saisonalspeicher.de). They enable the transfer of useful heat from the summer to the winter half-year with its much higher heat
demand.
For the estimation of the maximum electrical load that can be switched on (peak load) via
remote-controlled heat pumps, partly combined with heating rods, an average thermal
rated output of 15 kWP,th per unit is assumed. With a coefficient of performance (COP)of 3, this corresponds to a nominal electrical capacity of 5 kWP,el. In normal operation,
heat pumps usually work with a COP of 3‒5. By the end of 2023, around 1.8 million heatpumps were in use [BWP], which, under the same assumptions, is equivalent to an electrical nominal capacity of 9 GWp.
Heat storage systems increase the self-consumption of PV systems if they are charged via
the heat pump and the heating rod, especially in the summer half-year. The PV system
can take over the domestic hot water heating seasonally, all the more so if the PV modules
are mounted with a high inclination on steep south-facing roofs or on south-facing façades. As soon as price signals become available, decentralized heat storage systems canalso be selectively charged with surplus wind power from the grid.
21.3.7.2 High-temperature heat storage
Surplus electricity can be converted very efficiently into high-temperature heat (order ofmagnitude 650 °C) via resistance heaters. High-temperature heat can be stored as latent
heat in liquid salt storage tanks or as sensible heat in rock fill [Siem] or steel bodies [Vatt].
If required, the heat can be used for industrial processes or to drive a conventional steam
turbine, possibly with further utilization of the low-temperature heat. The first pilot plants
are currently being tested; the manufacturer Lumenion states an electricity-to-electricity
efficiency of 25 percent.
21.3.7.3 Cold accumulator
At the point of cold generation and use, e.g., in building air conditioning or in refrigerated
warehouses, cold can be stored with comparatively simple means. Another prerequisite
for grid-friendly operation is a sufficiently dimensioned output of the cooling generator.

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At very low temperatures, power-to-power operation is also possible. Liquid air energy
storage (LAES) systems based on liquid air (-195°C) are currently being tested. The planned
power-to-power efficiency is approx. 25 percent; it can be significantly increased by adding further thermal system components.
21.3.7.4 Stationary batteries
At the end of 2023, the installed capacity of stationary batteries (large-scale, commercial
and residential storage systems) was 12 GWh, with an output of 8 GWP (ISE4, https://battery-charts.rwth-aachen.de/). Stationary batteries can be used for a variety of applications:• Increase self-consumption from own PV power plant to reduce electricity drawn
from the power grid
• Cut PV generation peaks to eliminate connection/grid capacity bottlenecks to connect more PV capacity and prevent derating• Cut peaks in demand too lower the costs of electricity drawn from the grid in capacity-limited tariffs
o eliminate connection/grid capacity bottlenecks, for example in the case of
fast-charging e-vehicles• Prevent grid disturbances aso short-time reserve for demand/supply fluctuations
o emergency power supply• Electricity trade/energy arbitrage
With stationary batteries, households can extend their own consumption of PV electricity
into the evening hours and thus massively increase it (typically doubling it, see Figure 54).
A grid-serving system management of the batteries relieves the grid by selectively reducing the midday feed-in peak (Figure 55). Storage systems would thus enable an increased
PV expansion [ISE7].

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Share of energy consumption

Usable battery capacity in kWh

PV output in kWp

Battery operation (conventional)

Battery operation (grid-serving)
PV feed-in
PV electricity
consumed on
site
Storage
Sourced frompower gridElectricity
consumption

PV feed-in
PV electricity consumed on site
Storage
Sourced frompower gridElectricity consumption

Output [kW]Share of on-site consumption
Output [kW]Figure 54: Self-consumption share as a function of battery capacity and power of the solar generator for a single-family household with an annual electricity consumption of 4,700 kWh.
[Quasch].

PV-Power in kWh
Time of day

Time of day

Figure 55: Comparison of conventional and grid-serving operation [ISE7].

21.3.7.5 Vehicle batteries
Electric vehicles use batteries as electro-chemical energy storage devices, in hybrid vehicles supported by an internal combustion engine or a fuel cell. At the end of 2023, 1,4
million purely electric cars (BEV, without plug-in hybrid) were registered in Germany,out of a total of approx. 49 million passenger cars (de.statista.com, www.kba.de). Assuming an average battery capacity of 60 kWh, there are 84 GWh of storage capacity
on Germany’s roads. If 10 percent of the fully electric vehicles had a switchable
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69 (97)connection to the power grid at a power of 50 kW, this would create a balancing powerof 7 GWp. The total mileage of passenger cars in Germany of 726 billion km in 2023
[KBA] with a consumption of 160 Wh/km corresponds to an annual electricity consumption by electric cars of 116 TWh, plus approx. 15 percent charging losses.
E-buses are state of the art in urban transport, along with small electric cargo vans for
distribution logistics. The use of larger commercial vehicles with electric drives and reasonable battery capacities is still limited today by their short range. For e-trucks, solutions for recharging the batteries while driving on sections of track with overhead lines
were tested.
Several measures are necessary to activate vehicle batteries as grid-serving energy storage systems. Supply-dependent electricity prices will motivate private and businesscustomers to choose low-cost charging times with a high share of RE in the electricity
mix. Variable fuel prices are not new; petrol stations also vary their prices depending on
the time of day.
The current share of electricity from renewable sources covering the grid load in Germany
fluctuated between 13 and 112 % in 2022 [ISE4]. Those who already want to supply theire-car with especially green electricity from the grid prefer to charge on sunny days aroundmidday, otherwise on windy nights. Weekends are usually advantageous because thelower electricity consumption tends to improve the CO2 balance. Unfortunately, most ecars are charged at home in the evening, adding to the evening peak demand while also
not using any direct PV electricity. Precise information on the current and planned shareof RE in the German electricity mix is shown in the Energy Charts [ISE4]. Actual CO 2 savings through supply-side charging are achieved when:• the CO2 price is sufficiently high to determine the merit order of fossil-fuelpower plants (Section 4.3), or• when surplus RES-E is used, which would otherwise have to be regulated or
consumed in heating plants.
In order to be able to supply PV electricity for direct consumption, charging stations must
be located in typical daytime parking areas, e.g., at the workplace, in multi-story car parks
or in public car parks. Remote control of the charging power, taking into account themobility needs in individual cases, allows grid operators to stabilize the grid.
Bidirectional energy management systems allow electric vehicles to be operated aselectricity storage units when they are connected to the grid and do not have to keep thefull range on standby at all times. Private cars park for an average of 23 hours per day,and the limited capacity of traffic routes alone forces most cars to be parked for most of
this time. E-vehicles connected to the grid can also provide an economic benefit when
stationary, unlike their predecessors with combustion engines. In the expansion scenarios[ISE3], it is assumed that at least 10 percent of the mobile batteries are connected to thegrid at all times via bidirectional remote control. This means that with 40 million e-cars(reference scenario), at least 4 million would be available for grid service, provided there
are enough fast charging stations. With 50 kW fast charging capacity per charging point,
this would provide 200 GWp of bidirectional controllable capacity. The German federal
government has set the goal of bringing at least 15 million e-cars to the streets by 2030.

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21.3.7.6 Mechanical storage facilities
The currently installed pumped storage capacity in the German electricity grid is justunder 38 GWh, the nominal capacity is 10 GWP, and the average efficiency is around70 percent, excluding electrical supply and discharge losses. For size comparison: the storage capacity mentioned corresponds mathematically to the yield of the German PV power
plant park from less than one operating hour under full load.
Due to a lack of storage capacity, run-of-river power plants can hardly make any control contributions in complementary operation. Their contribution of approx. 3.8 GWP
nominal output [ISE4] is only slightly expandable, their electricity production (annual fullload hour) is generally declining due to the increasing drought. The mechanical storageof electrical energy in compressed air storage (Compressed Air Energy Storage, CAES) is
currently being tested.
21.3.7.7 Hydrogen and synthesis products
The electrolytic conversion of surplus solar and wind power into hydrogen, possibly withsubsequent methanation and further processing into synthetic liquid fuels (e.g., methanol)
or for the production of ammonia, is currently being scaled up and tested [AMP].
Commercial alkaline electrolyzers achieve efficiencies of up to 80 percent, high-temperature electrolyzers over 80 percent. Additional energy is required for gas compression, possibly liquefaction (20‒30 percent loss) and subsequent synthesis steps. By the end of2023, electrolyzers with a total electrical capacity of around 200 MWP were connectedto the grid (https://www.wasserstoff-kompass.de/elektrolyse-monitor). Figure 56 shows
current and projected investment costs for various electrolysis technologies.
The conversion of renewable electricity into storable energy sources (”Power-to-X”) opens
up huge, already existing storage possibilities. It is already technically possible today toincrease the proportion of hydrogen in the gas grid to up to 20 percent. In German salt
caverns, 9.4 PWh of energy can be stored in the form of hydrogen [Hydro], which corresponds to 2.6 times Germany’s primary energy consumption.
Synthetic energy carriers can be converted back into electricity via stationary fuel cells(efficiency up to approx. 65 percent) or thermal power plants, used as fuels in thetransport sector (e.g., hydrogen for fuel cell vehicles, diesel substitutes for shipping, paraffin substitutes in aviation) or as feedstock for the chemical industry.

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Figure 56: Specific investment costs for different electrolyzers technologies (PEMEL: membraneelectrolysis, AEL: alkaline electrolysis, HTEL: high-temperature electrolysis, [NOW]).

Reversible high-temperature fuel cells (rSOC), which can also be operated as electrolyzers,
are currently being developed and currently achieve a current-to-current efficiency of
43 percent [FZJ]. Compared to a combination of pure electrolyzers with pure fuel cells,
these bidirectional converters promise a higher number of full load hours and lower investment costs per total installed capacity as stationary power plants in the electricity grid.
21.3.7.8 Overview
Figure 57 shows paths for storage and conversion of PV and wind electricity. For thepractical relevance of these paths, the costs of the nominal power of converters to beinstalled (€/W) and capacity of storage (€/Wh), among others, must be considered in addition to the technical efficiency.

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Figure 57: Technologies for energy storage devices and inverters with current efficiency at theend of the inverter chain, without co-generation (GT: gas turbine, CCGT: combined cycle gas turbine).

21.3.8 Grid expansion
Grid-bound, supra-regional energy transport takes place via the extra-high voltage gridand the gas transmission grid. In the course of the energy transition, the gas transmission
grid will increasingly transport renewable gases (hydrogen or methane). Gas transportwith reconversion in the target region reduces the need for expansion of the electricity
grid.
21.3.8.1 National grid expansion
The energy flows in an energy system with 100 percent renewables are fundamentallydifferent from the situation at the turn of the millennium. PV is ideally suited for decentralized expansion close to consumption. The need for expansion of electricity and gas
transmission lines can be minimized with a spatially distributed development of batteries
and converters (e.g., electrolysis, gas power plants, fuel cells, heat pumps) that is also
close to consumption. A strong concentration of wind power generation in the north or
offshore, on the other hand, leads to a high demand for transmission line capacity (electricity or gas).
The production of PV electricity is characterized by a high simultaneity factor. In order toavoid local grid overloads due to generation peaks, battery storage is considered an economically interesting alternative to grid expansion in some places.

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Figure 58: Extra-high voltage grid [VDE] and gas transmission grid [Fern].

21.3.8.2 Strengthening the European interconnected grid
The German electricity grid is part of the European interconnected grid. Strengthening
the cross-border interconnection capacity of currently approx. 20 GW enables a betterbalancing of volatile PV electricity production via European electricity trading.

Figure 59: Installed capacity of hydropower plants in neighboring countries, figures from [IHA].

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Figure 59 shows the installed capacity of run-of-river and storage hydropower plants aswell as pumped storage power plants. Storage power plants can be operated as a complement to PV generation, while pumped storage plants act as efficient power-to-power
storage.
21.3.9 Importing energy sources
For some applications, such as aviation and shipping, there are no alternatives to liquid
fuels in the longer term. The production of synthetic fuels from PV electricity requires a
lot of energy. Liquid fuels can be produced particularly cheaply in sun-rich countries andimported by sea; the logistics chain required for this is in principle in place.
21.3.10 Overview
From today’s perspective, an energy system based on 100 percent RE is technically andeconomically feasible. Figure 60 shows the most important elements connected to theelectricity grid, from generation to conversion and storage to consumption. To reduce theneed for storage, electricity consumption in households and industry is partly made more
flexible.
In the “heat” sector (red), combined heat and power plants, heat pumps and — in theevent of supply peaks on the electricity side — heating rods load the heat storage facilities
with electricity. Where the density of demand permits, e.g., in neighborhoods, efficientstorage takes place centrally in large heat storage facilities.
In the “Gas” sector (green), biomass fermenters produce methane from biogenic waste
and electrolyzers produce hydrogen, which can also be methanized or processed into
synthetic fuels. In some cases, biomass is burned directly in the CHP unit. When electricity
is needed, combined gas and steam turbines, fuel cells and — at peak demand — puregas turbines are used. Hydrogen electric vehicles fill up their fuel from stationary gas storage, vehicles for long ranges (especially aircraft) fill up with liquid synthetic fuels.
In the “Battery” sector (yellow), stationary, centralized, or decentralized electrochemicalstorage facilities are charged or discharged depending on the residual load. Mobile batteries in electric vehicles primarily serve the mobility demand but can also provide bidirectional support for the grid if a connection exists. In most electrochemical storage systems,
the converter and storage are structurally fused; only so-called redox flow batteries haveexternal, independently scalable storage tanks.
In the mechanical sector (blue), water storage power plants are operated bidirectionally
via pumps and turbines, analogously compressed air storage power plants via compressors
and turbines.
Figure 61 summarizes the most important expansion measures for an energy transition in
the electricity sector with coupling to the transport and heat sectors.

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Figure 60: Simplified schematic representation of a renewable energy system with the most important electricity grid-related components of generation, conversion, storage, and consumption;
ICT: information and communication technology, CHP: combined heat and power, CCGT: combined cycle gas and steam power plant.
Rated capacity

Reference scenario

Primary
production

PV, im Netz max. 300 GW (70%)
Wind, Land, Sea

Gas power plants

H2 ready, also CCGT, CHP, partial
conversion of coal and oil

Stationary
batteries
E-mobility

Capacity 180 GWh

A total of 270 GWCO2, of which atleast 10% in the grid, capacity
270 GWh

Heat pumps

15 million units, 15kWth perunit, COP > 3

Electrolysis

Capacity 9400 TWh H2 in salt
caverns

Figure 61: Important power generators, converters and storage units, additional estimates andassumptions in square brackets, for sources see section 22.3.7.
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22.4 Does the energy transition have to wait for federal policy?
No, even if federal policy can make it easier for everyone.
As legislator, the Bundestag determines the framework for the energy transition.
In addition, there are several important actors who can move a lot in their fields of action,even independently of the regulatory framework. Action by these actors also sends clear
signals to politicians. Consumers can demand renewable energies and energy efficiency
when purchasing electricity and heat, when choosing their means of transport and in theiroverall consumption. Investors are called upon to invest in the energy transition, whether
on their own roofs, in investment companies or funds. Decision-makers in commercial
and industrial enterprises or in municipal utilities can examine which measures pay offsustainably and at the same time advance the energy transition. Finally, federal states,
cities and municipalities can promote the energy transition through a wide range ofmeasures, from advising stakeholders, providing investment grants and other forms of
support for projects, providing land, obliging building owners to install solar panels, andeven making their own investment decisions.

23 Do we need PV production in Germany?
Yes, if we want to avoid new dependencies in energy supply.
As the energy transition progresses, Germany will leave the “fossil” century behind, acentury in which we spend up to 90 billion euros a year on oil and gas imports. The pricesof these imports are influenced by cartels, the revenues largely finance authoritarian regimes, and often there are political costs as well as monetary ones. The energy transition
offers a historic opportunity to break out of this economic and political dependency: thesun shines in Germany too, raw materials for PV production are available and technologies
for solar power generation were significantly co-developed in Germany. The German PV
sector, with its material producers, mechanical engineering, component manufacturers,
R&D facilities, and teaching, still occupies a leading position worldwide despite the slowdown in national expansion. An energy system converted to renewables is based, among
other things, on approx. 300‒450 GW of installed PV capacity. Annual installations of
12‒20 GW are required for the construction and increasingly for the ongoing renewal ofthis plant park, corresponding to approx. 40 million PV modules at a cost of several billion
euros. PV production in Germany offers long-term security of supply with high environmental, social, and quality standards.

23 Do we need a Renewable Energy Sources Act (EEG)?
Yes, whereby the energy transition legislation as a whole must come into focus.
The current market mechanisms would provide too little incentive for long-term investments in the energy transition if they were not accompanied by an EEG. The main reason
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is the far too low pricing of CO2 emissions across all sectors, measured against theactual recovery costs or the currently foreseeable follow-up costs of the climate crisis. Thisde-facto subsidy for fossil energy supply must be dismantled, also in order to secure themarket value of solar power with increasing PV expansion. A rapid reduction in EU-ETS
certificates and a rapid increase in the national CO2 tax, combined with compensation
measures, are necessary.
For the social acceptance of the energy transition, a broad participation and diversity ofactors is beneficial, which can be realized especially in the decentralized generation of PV
electricity. Therefore, the regulatory hurdles, especially for small plants, must be lowered or smoothed out by a law such as the EEG. PV power plants of all sizes generally
need a grid connection to deliver electricity that can neither be consumed nor stored onsite. A legal framework must move the grid operator towards uncomplicated connectionof even smaller plants.
Furthermore, PV power plants for electricity production beyond self-consumption requirea long-term purchase agreement. Small private investors in particular can neither control the price risks on the electricity exchange nor keep up with the electricity production
costs of large PV power plants. They must be able to sell surplus electricity at secured
conditions. A PV power plant built today will soon be competing with PV power plants
built in later years, which will supply solar power at the same time as the cost of electricity
is expected to fall further. The deflationary effect is compounded by the long-term decline
in the market value factor for solar power.
In order to better match the daily profiles of PV electricity production and electricity consumption, transformation incentives are necessary for the steps described in Section
21.3. They aim, among other things, at supply-oriented electricity consumption, demandoriented electricity feed-in, and overall grid efficiency in the electrification of the heat andtransport sectors.
Innovative technologies such as integrated PV (Section 11) have slightly higher LCOE in
direct comparison with simple PV ground-mounted systems. However, they do not require
additional land and create synergies. In order to accelerate their market entry and thus
mitigate land conflicts at an early stage, they require targeted start-up support, e.g., in
the form of dedicated feed-in tariffs or tender segments.

24. Do PV modules contain toxic substances?
Often yes, which is why PV modules do not belong in the residual waste.
Toxic substances can leach out of modules over long periods of time if the cover glass isbroken, the edge seal is damaged, or the module is fragmented [IPV]. The leaching ratedepends in particular on the pH value and temperature. Because of the above-mentioned
risks, disused PV modules should not be disposed of in residual waste or landfills, anddamaged modules should not be left exposed to the weather for long periods of time.

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24.1 Wafer-based modules
Modules based on silicon wafers (over 90 percent market share) often still contain lead in
the cell metallization (approx. 2 g lead per 60-cell module) and in the solders used (approx.
10 g lead). Lead, a toxic heavy metal, is soluble in certain strongly acidic or basic environments, and lamination in the module does not permanently prevent mass transfer [IPV].
In wafer-based modules, lead can be completely substituted by harmless materials at low
additional cost. Some module manufacturers use backsheet foils that contain fluoropolymers, e.g., polyvinyl fluoride.
24.2 Thin-film modules
Thin-film modules based on CdTe (approx. 5 percent market share) contain cadmium insalt form; it cannot be substituted in this technology. The metallic cadmium and cadmiumoxide are classified as very toxic, CdTe as harmful to health. There are alternative thin-film
technologies based on amorphous silicon or copper indium selenide (CIS) that contain noor very little Cd.
CIS solar cells contain selenium, which can have a toxic effect, especially as an oxide (e.g.,after fires), depending on the amount absorbed. Some manufacturers explain the conformity of their CIS solar modules with the RoHS Directive (Restriction of certain Hazardous Substances) and the EU chemicals regulation REACH (Registration, Evaluation, Authorization and Restriction of Chemicals). For a differentiated assessment, reference ismade to independent investigations of the respective module type.
24.3 Solar glass
Common solar modules require a glass with a very low absorption (solar glass quality) asa front panel. Some glass manufacturers purify the molten glass and increase the lighttransmission by adding antimony (Sb). When this glass is disposed of in landfills, antimony
can enter the groundwater. Alternative refining processes without antimony addition areavailable.
24.4 Take-back and recycling
In June 2010, PV producers launched a cross-manufacturer recycling system (PV Cycle),which currently has over 300 members. The version of the European WEEE Directive(Waste Electrical and Electronic Equipment Directive) that came into force on 13 August2012 had to be implemented in all EU countries by the end of February 2014. It obliges
producers to take back PV modules free of charge and return them to the recycling system. In October 2015, the Act on the Marketing, Return and Environmentally Sound Disposal of Electrical and Electronic Equipment (Electrical and Electronic Equipment Act —ElektroG) came into force in Germany. It classifies PV modules as large appliances andregulates take-back obligations and financing. The proportion of recovery (collection rate)
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must be at least 85 percent and the proportion of preparation for reuse and recycling atleast 80 percent (recycling rate).
In the recycling process, the aluminum frame, junction box and glass are separated fromthe laminate. Aluminum and glass are recycled. Processes for separating materials for theremaining laminate are being tested; its valuable components include silicon, silver on thesolar cells and the copper of the cell connectors. In its white paper, Deutsche Umwelthilfe(German Environmental Aid) shows clear potential for improvement in the reuse and recycling of PV modules [DUH].

25. Are raw materials for the production of PV modules sufficiently
available?
Wafer-based modules do not require raw materials for which limited availability is foreseeable. The main components by weight are glass, aluminum, polymers and silicon, withsilicon and aluminum among the most important components of the earth’s crust by
weight. Most critical is the consumption of silver for the production of solar cells. The PV
industry consumes about 1500 t of silver per year worldwide, which corresponds to justunder 6 percent of the production volume in 2020. The silver for solar cell metallization
can be technically substituted by copper to the greatest possible extent, and some manufacturers are already using this technology.
For thin-film modules, which account for about 5 percent of the world market, CdTetechnology dominates. There are contradictory statements about the long-term availability of tellurium and indium for CdTe modules.

26. Do PV systems increase the risk of fire?
26.1 Can defective PV systems cause a fire?
Yes, like all electrical installations.
Certain defects in current-conducting components of a PV system can lead to the formation of electric arcs. If there is flammable material in the immediate vicinity, for example
roofing felt or wood, a fire can occur. The current source characteristics of the solar cells
can even stabilize a fault current compared to alternating current installations. The current
can only be stopped by interrupting the circuit or irradiating all modules. For this reason,
PV systems must be installed with special care.
In some cases — with currently approx. 2 million PV systems in Germany — the combination of these factors has demonstrably led to a fire. The starting point of the fires wasusually faults in the cabling and connections.
Here is a quote from a press release by Fraunhofer ISE from 2013: “Compliance with theexisting rules by qualified specialists is the best fire protection. 0.006 percent of photovoltaic systems have caused a fire with major damage to date. In the last 20 years, there
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have been 350 fires in which the solar system was involved, in 120 of which it was thecause of the fire. In 75 cases the damage was greater, in 10 of these cases a building
burned down.
The most important special features of photovoltaic systems: They work with direct current, and you cannot simply switch them off, because as long as light falls on the modules,
they produce electricity. If, for example, an inferior or poorly installed plug connection
comes loose, this does not always interrupt the flow of current. An electric arc can occur,
which in the worst case can directly cause a fire. Accordingly, research is being done on
how to prevent arcing. In addition, work is being done on detectors that give an early
alarm if even a small arc occurs.
Compared to other technical systems, photovoltaic systems do not pose a particularly highfire risk. There are also sufficient rules for electrical safety — it is important that they areobserved. Fires often occur when inexperienced installation crews install systems on apiecework basis. If the solar plugs are attached with combination pliers instead of special
tools, or if incompatible plugs are used, then the weak spot is pre-programmed. System
operators must not save money in the wrong place.
In addition to technical improvements, it is therefore also important to have control regulations. At present, the installer of a system can confirm that it has been properly installed. One recommendation of the experts is therefore to make acceptance by an independent third-party mandatory. It is also under discussion to prescribe a recurring safety
inspection for private photovoltaic systems, as is mandatory for commercial systems every
four years.” [ISE6]
26.2 Do PV systems endanger firefighters?
Yes, but this is true for many live lines.
When fighting fires from the outside, a minimum distance of a few meters protects firefighters from electric shocks; this safety distance is generally given for roof systems. The
greatest risk for firefighters when fighting fires from the inside arises when they enterrooms where live, scorched cables of the PV system come into contact with water or thefirefighting force itself. To reduce this risk, the industry is working on emergency switches
that disconnect the modules from the descending DC cable via safety relays while they
are still near the roof.
So far, no firefighters in Germany have been injured fighting fires caused by PV electricity.
A case report that went through the press had confused solar thermal collectors with PV
modules. No PV system had been installed on the house in question at all. “Initial uncertainties could be eliminated through comprehensive training measures for the fire brigades. As with any electrical installation, depending on the type of jet, water can also be
used to safely extinguish photovoltaic systems from a distance of one to five meters. All
claims that the fire brigade did not extinguish a burning residential building because ofphotovoltaics turned out to be false in the research carried out so far.” [ISE6]

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26.3 Do PV modules hinder direct firefighting access via the roof?
Yes, the second “roof skin” created by the PV modules impedes the success of the extinguisher because the water simply runs off. From the fire brigade’s point of view, however,an object exposed to fire in this way can usually no longer be saved, i.e., the damage isalready largely present and irreversible even before the PV system impedes the extinguishing activity.
26.4 Do toxic emissions occur when PV modules burn?
With regard to CdTe modules, a dispersion calculation by the Bavarian State Office for
the Environment states that in the event of a fire, a serious danger to the surrounding
neighborhood and the general public can be safely ruled out [LFU1]. For CIS modules,
reference is made to independent investigations of the respective product.
In the case of wafer-based modules, the backsheet foils may contain fluoropolymers,
which are not toxic themselves but can decompose at high temperatures in the event ofa fire. In a study, the Bavarian State Office for the Environment concludes that whenplastics containing fluorine burn, the hazard potential is not largely determined by hydrogen fluoride, but by the other fire gases [LFU2].

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27 Appendix: Technical terms
27.1 Module efficiency
Unless otherwise stated, module efficiency refers to nominal efficiency. It is determined
under standardized conditions (”STC”, standard test conditions) as the ratio of the electrical power output to the irradiated power on the module surface. The standard conditions stipulate a module temperature of 25° C, vertical irradiation of 1000 W/m2 and a
specific irradiation spectrum. In real operation, the conditions usually deviate significantly,
so that in many cases the STC efficiency is not achieved.
27.2 Nominal power of a PV power plant
The nominal power of a power plant [kWp, MWp] is the idealized DC power of the module
array under STC conditions, i.e. the product of the generator area, standard irradiation(1000 W/m2) and the nominal efficiency of the modules. During operation, the generation capacity of a PV power plant is usually below 70 percent of its nominal capacity.
27.3 Annual full load hours (annual full operating hours)
Number of hours a PV power plant would need to generate at its nominal capacity inorder to reach its actual annual yield with frequent partial load operation and energy
standstill at night (see Section 15.4).
27.4 Annual utilization rate (capacity factor)
Ratio of annual full load hours and the 8,760 hours in a 365-day-year.
27.5 Specific yield
The specific yield [kWh/kWp] of a PV power plant is the ratio of the user yield (alternating
current yield) over a certain period of time, often a year, and nominal power. The specificannual yield corresponds to the number of full load hours.
27.6 System efficiency
The system efficiency of a PV system is the ratio of the useful yield (alternating current
yield) and the total irradiation on the generator surface. The nominal module efficiency
is included in the system efficiency.
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27.7 Performance Ratio
The term “performance ratio (PR)” refers to the ratio of the useful yield (alternating current yield) and the idealized yield (product of the total irradiation on the generator surface and the nominal module efficiency) of a system over a certain period of time, usually one year. PR is often used to compare the efficiency of grid-connected PV systems at
different locations with various PV technologies.
New, carefully planned systems achieve annual PR values between 80 and 90 percent.
27.8 Base load, medium load, peak load, grid load and residual load
“The power demand fluctuates depending on the time of day. As a rule, maxima occur
during the day and the minimum at night between 0 and 6 o’clock. The course of thepower demand is described as a load curve or load pattern. In classical energy technology,
the load curve is divided into three areas:(i) The base load(ii) The medium load(iii) The peak load
The base load describes the load band that is almost constant over 24 hours. It is coveredby so-called base load power plants such as nuclear power plants, lignite-fired power
plants and currently also run-of-river power plants.
The medium load describes predictable, closed power blocks that cover most of the daily
demand in addition to the base load. The medium load is covered by so-called medium
load power plants such as hard coal-fired power plants and methane-fired combined cycle
power plants. Oil-fired power plants are also used in rare cases. The peak load covers theremaining power demand, which is usually the daily maximum. The peak load is coveredby so-called peak-load power plants such as gas turbine power plants and pumped-storage power plants. These can be run at nominal power within a very short time and thus
compensate for load fluctuations and cover peak loads.
(...) The grid load (is) the power value of the electricity demand that is taken from thegrid. The residual load results from the grid load minus the feed-in from renewable energies” [ISET].
27.9 Electricity generation and consumption
Figure 62 shows the energy path from the primary energy source, e.g., solar radiation(irradiance [W/m2]), wind or natural gas (energy density during combustion [J/kg]), to theuseful energy that is important to the end user. Large gas turbines show conversion lossesof 60‒65 percent. PV power plants show conversion losses of 80‒85 percent, with virtually free and unlimited primary energy. The gross electricity generation, adjusted for theimport balance, corresponds to the gross electricity consumption.
Storage losses occur in the operation of pumped storage power plants or batteries. Losses
from pumped storage power plants amount to approx. 25 percent of the amount of
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electricity stored, for Li-ion batteries it is 5‒10 percent, plus the losses in the battery management system. If hydrogen is used to store electricity via stationary electrolyzers andfuel cells, the losses are about 50 percent. With the expansion of installed PV capacity,
storage losses will also play an increasingly important role for PV electricity.
The self-consumption of fossil and nuclear power plants is about 7 percent of their grosspower generation; for PV power plants it is marginal. Grid losses, especially line and transformer losses, amount to just under 6 percent in the German electricity grid. The decentralized nature of PV installations reduces grid losses for PV electricity.
The amount of electricity purchased from the end user is the net consumption (final energy). The efficiency of the devices determines the conversion losses to the final usefulenergy, e.g., power or light.

Migration
lossesPrimaryenergyuse

Gross income

ExportStorageloss

Grossconsumption

Intrin- Net
siclossesNet consumption

Conversion
lossesUsableenergyFigure 62: Electricity generation and consumption terms.

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28 Appendix: Abbreviations
BEV
BMU

Battery Electric Vehicle
German Federal Ministry for the Environment, Nature Conservation and Nuclear
SafetyBSW
German Solar Industry Association
BMWK Federal Ministry for Economic Affairs and Climate Action
CCGT Gas and steam generators
CHP
Combined heat and power, the simultaneous generation of mechanical (ultimately electrical) energy and usable heat
CHP
Combined heat and power plant – a plant that uses combustion engines or gas
plantturbines to generate electrical energy and heat
COP
Coefficient of Performance (heat pumps)
EEG
Act on Granting Priority to Renewable Energy Sources (Renewable Energy
Sources Act, EEG)
ESC
Energy supply company
GHG
Greenhouse Gas
ICTInformation and communications technology
IEA
International Energy Agency
PHEV
Plug-in hybrid electric vehicle
PV
Photovoltaics
RE
Renewable energy
Wp
Watt “peak”, unit for nominal output of a PV module, a module array or a
power plant

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29. Appendix: conversion tables [EEBW]

thousandmillion (m)billion (bn)trillion (tn)quadrillion (qa)Conversions
tce

toe

petajoulegigawatt hours
tce

million tonnes of coal equivalenttoemillion tonnes of oil equivalent

Typical Fuel Properties
Density

Heating value

Heating value

Heating value

Heating value

Rapeseed oil

PetrolTypical Properties of Solid and Gaseous Energy Yields
Density

Heating value

Heating value

Heating value

Heating value

Hard coal
Brown coal
Natural gas H (in m3)
Heating oil EL
Biogas (in m3)
Wooden pellets

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30 Appendix: Sources
AEE1

Metaanalyse: Digitalisierung der Energiewende, Agentur für Erneuerbare Energien, August 2018
ADAC
Treibhausgas-Bilanz: „Welcher Antrieb kann das Klima retten?“, Studie des
ADAC, Dezember 2022
AEE2
https://www.unendlich-viel-energie.de/presse/pressemitteilungen/erneuerbare-energien-in-deutschland-zwischen-akzeptanz-und-unsicherheit, Download im Dezember 2023
AGEB1
Energieverbrauch in Deutschland im Jahr 2012, Arbeitsgemeinschaft Energiebilanzen e. V. , März 2023
AGEB2
Energieflussbild 2020 für die Bundesrepublik Deutschland in Petajoule, Arbeitsgemeinschaft Energiebilanzen, Mai 2022
AGEE
Monatsbericht-PLUS+ mit Informationen zur quartalsweisen Entwicklung derErneuerbaren Energien in den Sektoren Strom, Wärme und Verkehr, Arbeitsgruppe Erneuerbare Energien-Statistik (AGEE-Stat), Dezember 2023
AGORA2 Klimaneutrales Stromsystem 2035. Wie der deutsche Stromsektor bis zum Jahr
2035 klimaneutral werden kann; Agora Energiewende, Prognos, Consentec(2022)
AMP
Sektorenkopplung: Amprion und Open Grid Europe geben Power-to-Gas in
Deutschland einen Schub, Pressemeldung, Amprion, Juni 2018
ARIA
Deutschland auf dem Weg zur Klimaneutralität 2045 — Szenarien und Pfade
im Modellvergleich, Kopernikus-Projekt Ariadne, Oktober 2021
ATW
Weis M, van Bevern K, Linnemann T. Forschungsförderung Kernenergie 1956
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8/9
BAFA
Hintergrundinformationen zur Besonderen Ausgleichsregelung, Antragsverfahren 2013 auf Begrenzung der EEG-Umlage 2014, Hrsg.: Bundesministerium
für Umwelt, Naturschutz und Reaktorsicherheit (BMU) und Bundesamt fürWirtschaft und Ausfuhrkontrolle (BAFA), 15. Oktober 2013
BCG
Klimapfade für Deutschland, Studie, The Boston Consulting Group (BCG) und
Prognos, im Auftrag des Bundesverbandes der Deutschen Industrie (BDI), Januar 2018
BDEW1
BDEW-Strompreisanalyse, BDEW Bundesverband der Energie- und Wasserwirtschaft e.V., April 2023
BDEW3
Stromerzeugung und -verbrauch in Deutschland, Mitteilung des BDEW
(www.bdew.de/presse/presseinformationen/erneuerbare-energien-decktenim-jahr-2021-rund-42-prozent-des-stromverbrauchs), Dezember 2021
BDEW4
Redispatch in Deutschland — Auswertung der Transparenzdaten, BDEW Bundesverband der Energie- und Wasserwirtschaft e.V., 9. August 2016
BDI
Handlungsempfehlungen zur Studie Klimapfade 2.0 — Wie wir unser Industrieland klimaneutral gestalten, Bundesverband der Deutschen Industrie, Oktober 2021

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BFE
BMEL

BMVI
BMWK1
BMWK2
BMWK3

BNA1
BNA2
BNA3
BNE
BNEF

BSW1
Bundestag
Bub

BVES
Carb
DENA
DESTATIS
DIW

Grundlagen zu Vorurteilen gegenüber der Solarenergie, Schlussbericht, Studie
im Auftrag der EnergieSchweiz, Bundesamt für Energie, 2021
Daten und Fakten, Land-, Forst- und Ernährungswirtschaft mit Fischerei und
Wein- und Gartenbau, Bundesministerium für Ernährung und Landwirtschaft(BMEL), Dezember 2017
Räumlich differenzierte Flächenpotentiale für erneuerbare Energien in Deutschland. BMVI (Hrsg.), BMVI-Online-Publikation 08/2015.
Gesamtausgabe der Energiedaten — Datensammlung des BMWK, letzte Aktualisierung: Januar 2022
Bundesbericht Energieforschung 2023, Bundesministerium für Wirtschaft und
Klimaschutz (BMWK), Mai 2023
EEG: Daten und Fakten: Vergütungen, Differenzkosten und EEG-Umlage 2000
bis 2022, Stand Oktober 2021
https://www.erneuerbare-energien.de/EE/Navigation/DE/Recht-Politik/
Das_EEG/DatenFakten/daten-und-fakten.html#doc95662bodyText2
Bundesnetzagentur legt Eigenkapitalrenditen für Strom- und Gasnetze fest,
Pressemeldung der Bundesnetzagentur vom Oktober 2016
Monitoringbericht 2022, Bundesnetzagentur für Elektrizität, Gas, Telekommunikation, Post und Eisenbahnen und Bundeskartellamt, Dezember 2022
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Solarparks – Gewinne für die Biodiversität, Studie des Bundesverbands Neue
Energiewirtschaft (bne) e.V., November 2019
Interview mit Bloomberg NEF Analyst Jenny Chase, Dezember 2022
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2023 mehr als eine Million neue Solaranlagen, Pressemeldung, Bundesverband
Solarwirtschaft e. V., Berlin, Januar 2024
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April 2022
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DESTATIS, Statistisches Bundesamt, September 2020
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DIW Wochenbericht Nr. 29+30, Juli 2021

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DUH

DVGW
DWD

EEBW
EEG
2021
EEG
2023
EGGERS

EnBW1
ENBW2

ENER
ESYS

EPA

EUPD

FAU

Fern
FFE

Kreislaufwirtschaft in der Solarbranche stärken — Alte Photovoltaik-Module
für den Klima- und Ressourcenschutz nutzen, Deutsche Umwelthilfe e.V., März
2021
Deutscher Verein des Gas- und Wasserfaches e. V., Pressemeldung vom 24.
April 2019
Rasterdaten der Jahressumme für die Globalstrahlung auf die horizontale
Ebene für Deutschland basierend auf Boden- und Satellitenmessungen, Version
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Climate Data Center (CDC), Deutscher Wetterdienst, 2022
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EnBW verstärkt Engagement im Bereich Solarenergie, Pressemeldung, Energie
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Energiewende im Kontext von Atom und Kohleausstieg, Perspektiven im
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FNR
FÖS1

FÖS2
FZJ
HTW
HTW2
Hydro

IEA1
IEA2
IEA3
IEA4
IEA5
IEE

IHA
IMF
IPCC

IPV

fachvortraege/828-merit-order-der-konventionellen-kraftwerke-in-deutschland-2018, Februar 2020
Basisdaten Bioenergie Deutschland 2022, Fachagentur Nachwachsende
Rohstoffe e.V., Juli 2022
Gesellschaftliche Kosten der Atomenergie in Deutschland, Eine Zwischenbilanz
der staatlichen Förderungen und gesamtgesellschaftlichen Kosten vonAtomenergie seit 1955, Studie des FÖS im Auftrag von Greenpeace Energy eG,
September 2020
Was Braunkohlestrom wirklich kostet, Studie des Forums Ökologisch-Soziale
Marktwirtschaft e.V. (FÖS) im Auftrag von Greenpeace Energy eG, Juni 2018
Reversible Brennstoffzelle bricht Wirkungsgrad-Rekord, Pressemeldung, Forschungszentrum Jülich, Dezember 2018
Sinnvolle Dimensionierung von Photovoltaikanlagen für Prosumer, Kurzstudie,
Hochschule für Technik und Wirtschaft Berlin, März 2019
Solarstromausbau für den Klimaschutz, Studie, Hochschule für Technik und
Wirtschaft Berlin, November 2021
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Technical potential of salt caverns for hydrogen storage in Europe, International
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Net Zero by 2050: A Roadmap for the Global Energy Sector, International Energy Agency, 2021.
Snapshot of Global PV Markets 2023, International Energy Agency PVPS, ,2023.
Special Report on Solar PV Global Supply Chains, International Energy Agency,
2022.
Environmental Life Cycle Assessment of Passivated Emitter and Rear Contact(PERC) Photovoltaic Module Technology, IEA Task 12 PV Sustainability, 2024
Neues Strommarktdesign für die Integration fluktuierender Erneuerbarer Energien, Fraunhofer-Institut für Energiewirtschaft und Energiesystemtechnik IEE,
Fraunhofer-Institut für Solare Energiesysteme ISE, Becker Büttner Held
Rechtsanwälte, November 2021
Hydropower status report, International Hydropower Association, May 2019
Parry I, Black S, Vernon N. Still Not Getting Energy Prices Right: A Global andCountry Update of Fossil Fuel Subsidies, International Monetary Fund, 2021
Climate Change 2021: The Physical Science Basis, Intergovernmental Panel on
Climate Change (IPCC), Working Group I report as contribution to the Sixth
Assessment Report (AR6), August 2021
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Energies.
14(3):6922021;
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IRENA

ISE1

ISE2

ISE3

ISE4
ISE5
ISE6

ISE7

ISE8
ISET
ISI

IVL

IWU
KBA
LCA

LFU1
LFU2

Future of Solar Photovoltaic: Deployment, investment, technology, grid integration and socio-economic aspects, Studie der International Renewable Energy Agency (IRENA), Abu Dhabi, 2019
Kost C, Shammugam S, Fluri V, Peper D, Memar A, Schlegl T. Stromgestehungskosten Erneuerbare Energien; Studie des Fraunhofer-Instituts für Solare Energiesysteme ISE, Juni 2021
Kiefer K, Farnung B, Müller B. Degradation in PV Power Plants: Theory andPractice. 36th European Photovoltaic Solar Energy Conference and Exhibition,
Marseille, 2019.
Wege zu einem klimaneutralen Energiesystem — Die deutsche Energiewende
im Kontext gesellschaftlicher Verhaltensweisen, Studie des Fraunhofer ISE. November 2021
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Burger, Fraunhofer-Institut für Solare Energiesysteme ISE
Photovoltaics Report, Fraunhofer-Institut für Solare Energiesysteme ISE, PSE
Photovoltaics Projects GmbH, Februar 2022
Photovoltaik-Brandschutz – Fakten statt Phantome, Pressemeldung, Fraunhofer ISE, Februar 2013 (Näheres zum Brandschutz unter www.pv-brandsicherheit.de)
Speicherstudie 2013 — Kurzgutachten zur Abschätzung und Einordnung energiewirtschaftlicher, ökonomischer und anderer Effekte bei Förderung von objektgebunden elektrochemischen Speichern, Studie des Fraunhofer-Instituts fürSolare Energiesysteme ISE, Januar 2013
Sustainable PV Manufacturing in Europe – An Initiative for a 10 GW GreenFab,Studie des Fraunhofer ISE, Juli 2020
Saint-Drenan Y-M et al. „Summenganglinien für Energie 2.0“, Studie des Instituts für Solare Energieversorgungstechnik, ISET e.V., April 2009
Langfristszenarien für die Transformation des Energiesystems in Deutschland,
Kurzbericht: 3 Hauptszenarien; Fraunhofer-Institut für System- und Innovationsforschung ISI, Consentec GmbH, Mai 2021
Lithium-Ion Vehicle Battery Production, Status 2019 on Energy Use, CO2 Emissions, Use of Metals, Products Environmental Footprint, and Recycling, Studie
des Swedish Environmental Research Institute im Auftrag der Swedish Energy
Agency, November 2019
Forschungsdatenbank NichtWohnGebäude, Institut Wohnen und Umwelt
GmbH, Schlussbericht, März 2022
Zahlen im Überblick – Statistik, Kraftfahrt-Bundesamt, Juni 2018
Müller A, Friedrich L, Reichel C, Herceg S, Mittag M, Neuhaus H. A comparative
life cycle assessment of silicon PV modules: Impact of module design, manufacturing location and inventory, Solar Energy Materials and Solar Cells, Volume 230, 2021
Berechnung von Immissionen beim Brand einer Photovoltaik-Anlage aus Cadmiumtellurid-Modulen, Bayerisches Landesamt für Umwelt, 11-2011
Beurteilung von Kunststoffbränden, Az: 1/7-1515-21294, Bayerisches
Landesamt für Umwelt, 1995

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Licht1

Licht2
MCC
MWV
NETZ1
NETZ2
NOW

ÖKO1
ÖKO2

Prog

Quasch
SCBW

SPE
Sprin

RWE
Shell
Siem
Test
UBA1
UBA2
UBA3

Analyse des Beitrags von Mini-BHKW zur Senkung von CO2-Emissionen undzum Ausgleich von Windenergie, Gutachten zum geplanten »ZuhauseKraftwerk« im Auftrag der LichtBlick AG, LBD-Beratungsgesellschaft mbH, 2009
Repräsentative Umfrage zu erneuerbaren Energien, Marktforschungsinstitut
YouGov im Auftrag der LichtBlick SE, Februar 2020
Wissensstand zu CO2-Entnahmen, Mercator Research Institute on Global Commons and Climate Change (MCC) gGmbH, 2021
Jahresbericht 2018, Mineralölwirtschaftsverband e.V., Juli 2018https://www.netztransparenz.de/EEG/Marktpraemie/Marktwerte
Historische Daten: https://www.netztransparenz.de/EEG/Verguetungs-undUmlagekategorien
IndWEDe — Industrialisierung der Wasserelektrolyse in Deutschland, Studie im
Auftrag des Bundesministeriums für Verkehr und digitale Infrastruktur (BMVI),
2018
Beschäftigungsentwicklung in der Braunkohleindustrie: Status quo und Projektion, Öko-Institut Berlin, Juli 2018
Aktueller Stand der KWK-Erzeugung (Dezember 2015), Studie des Ökoinstituts
e.V. im Auftrag des Bundesministeriums für Wirtschaft und Energie, Dezember
2015
Klimaneutrales Deutschland. Prognos, Öko-Institut, Wuppertal-Institut, im
Auftrag von Agora Energiewende, Agora Verkehrswende und Stiftung
Klimaneutralität, Juni 2021
Quaschning V. Solare Unabhängigkeitserklärung, Photovoltaik, Oktober 2012
Weiterbetrieb von Ü20-Photovoltaikanlagen — Möglichkeiten nach Ende ner
EEG-Förderdauer, Faktenpapier, Solar Cluster Baden-Württemberg, Januar
2021
EU Market Outlook For Solar Power 2023 – 2027, SolarPower Europe, Dezember 2023
Motorentechnik — Im Fokus, Onlineartikel, Dezember 2010https://www.springerprofessional.de/motorentechnik/pkw-antriebe-im-ueberblick-vergangenheit-gegenwart-und-zukunft/6561052
RWE nimmt Batteriespeicher in Herdecke in Betrieb — Sechs Millionen Euro
Investition, sieben MWh Kapazität, Pressemeldung, RWE, Februar 2018
Shell Scenarios Sky — Meeting the goals of the Paris agreement, Shell International B.V., März 2018
Weit mehr als nur heiße Luft, Pressemeldung, Siemens AG, März 2017
„Immer sparsamer“, test 1/2012, Stiftung Warentest
Erneuerbare Energien in Deutschland, Daten zur Entwicklung im Jahr 2022,
Umweltbundesamt, Februar 2023
Artikel auf https://www.umweltbundesamt.de/daten/energie/kraft-waermekopplung-kwk#textpart-1, Oktober 2018
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UBA4
UBA5
UBA6
UBA7

UBA8
UBA9
UBA10
UBA11

ÜNB1

ÜNB2
Vatt
VDE
VFL

VGB
ZSW

Daten und Fakten zu Braun- und Steinkohlen, Umweltbundesamt, Dezember
2017
Der Europäische Emissionshandel, https://www.umweltbundesamt.de/daten/
klima/der-europaeische-emissionshandel#textpart-1, Download im Juni 2019
Entwicklung der spezifischen Treibhausgas-Emissionen des deutschen Strommix in den Jahren 1990 – 2022, Umweltbundesamt, Mai 2023
Aktualisierung und Bewertung der Ökobilanzen von Windenergie- und Photovoltaikanlagen unter Berücksichtigung aktueller Technologieentwicklungen,Studie im Auftrag des Umweltbundesamtes, Mai 2021
Wege in eine ressourcenschonende Treibhausgasneutralität – RESCUE
Kurzfassung, Umweltbundesamt, November 2019
Emissionsbilanz erneuerbarer Energieträger, Bestimmung der vermiedenen
Emissionen im Jahr 2020, Umweltbundesamt, November 2021
Energieziel 2050: 100 % Strom aus erneuerbaren Quellen, Umweltbundesamt,
Juli 2010
Anzahl der Beschäftigten im Bereich erneuerbare Energien
Quelle: https://www.erneuerbare-energien.de/EE/Redaktion/DE/Downloads/zeitreihe-der-beschaeftigungszahlen-seit-2000.html, Download am
22.3.2023
Mittelfristprognose zur deutschlandweiten Stromerzeugung aus EEG-geförderten Kraftwerken für die Kalenderjahre 2022 bis 2026, r2b energy consulting
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TenneT TSO GmbH, TransnetBW GmbH, Oktober 2021
Szenariorahmen zum Netzentwicklungsplan Strom 2037 mit Ausblick 2045,
Version 2023; Entwurf der Übertragungsnetzbetreiber, Januar 2022
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PowerTech e.V., 2010
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31 Appendix: Figures
Figure 1: Installed PV capacity necessary to reach climate neutrality as determined bydifferent studies. (The studies are named according to the institutions and, if
applicable, the scenario). ......................................................................................... 5
Figure 2: Net PV additions: actual values until 2022, expansion path to achieve the legal
targets [BMWK1], [EEG2023]. .................................................................................. 6
Figure 3: Development of the share of renewable energies in gross electricity
consumption in Germany [ISE4], [UBA1], [AGEE]. ..................................................... 6
Figure 4: Historical development of prices for PV modules (PSE Projects
GmbH/Fraunhofer ISE, data source: Strategies Unlimited/Navigant Consulting/EuPD).
The straight line shows the trend in price development. ........................................... 8
Figure 5: Development of the average end customer price (net system price) for installedrooftop systems with rated nominal power from 10‒100 kWp [ISE5], data BSW-Solar.
............................................................................................................................... 9
Figure 6: Fixed EEG feed-in tariff for PV power as a function of commissioning dateaccording to system types „Building PV with up to 10 kWP excess feed-in“ and„Other systems up to 100 kW“ from [Netz2] and [BNA3], average remuneration of
the bidding rounds of the German Federal Network Agency [BNA3], electricity prices[BMWK1], [BDEW1] and average compensation for PV power [NETZ1]. ...................10
Figure 7: Exchange electricity and certificate prices in Germany [ISE4]. .........................11
Figure 8: Merit order for conventional power plants in 2018 with an average CO2
certificate price of €16 per ton [FFE]. .......................................................................12
Figure 9: PV expansion and differential costs, data from [BMWK1], [BMWK3]. .............13
Figure 10: Process for removing CO2 from the atmosphere and storing carbon [MCC]. 16
Figure 11: Composition of the average household electricity price in 2023 [BDEW1]. ...17
Figure 12: Net Electricity import (purple) and solar electricity production (yellow) in 2023
for Germany [ISE4]. .................................................................................................18
Figure 13: Estimation of the LCOE for small PV systems under different irradiation
conditions, plus remuneration according to [EEG2023]............................................19
Figure 14: Value Chain for Photovoltaics. ....................................................................20
Figure 15: Production capacity according to value chain stage and country, data: Wood
Mackenzie, 2023 ....................................................................................................21
Figure 16: PV production sites in Germany and other European countries [SPE]. ...........22
Figure 17: Number of jobs in the renewable energy sector [UBA11] .............................23
Figure 18: Funding for PV research categorized by technology in € million [BMWK2]. ..24
Figure 19: Distribution of installed PV power according to plant size in 2021 [ISE4]. .....25
Figure 20: Regulated electrical energy [BNA2]..............................................................25
Figure 21: Actual and predicted hourly generation of power in 2021 [ISE4]. ................26
Figure 22: Average power for the supply of solar and wind power in 2021, 15-minutevalues [ISE4]............................................................................................................27
Figure 23: Monthly totals of PV and wind power production, data from [ISE4]. ............28
Figure 24: Example showing the course of electricity trading price, conventional andrenewable electricity in the 22th calendar week in 2023 [ISE 4]. ..............................29
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Figure 25: System Average Interruption Duration Index (SAIDI) for low and medium.
Data from [BNA2]. ..................................................................................................30
Figure 26: Applications for the integration of photovoltaics. ........................................31
Figure 27: Land use in Germany [FNR]. ........................................................................32
Figure 28: Building stock in millions, data from [DENA], [IWU]. ....................................33
Figure 29: PV solutions for roofs and façades (top row: roof-mounted systems, bottom
row: integrated PV).................................................................................................34
Figure 30: Survey results on the construction of new power plants, data from [Licht2]. 36
Figure 31: Survey results on the acceptance of different types of power plants [AEE2]. 37
Figure 32: Range of electric and biodiesel vehicles per hectare of land used. ................39
Figure 33: Electricity yields of PV power plants and silage maize per hectare of land
used. ......................................................................................................................39
Figure 34: Relative yield potential, no shade, located in Freiburg, calculated online using
https://re.jrc.ec.europa.eu/pvg_tools/en/. .................................................................40
Figure 35: Power yield profile by hour for different roof orientations and a 45° roof
slope on a sunny day in April, no shade, located in Freiburg, calculated online using
https://re.jrc.ec.europa.eu/pvg_tools/en/. .................................................................40
Figure 36: Monthly specific yield potential for different inclinations, no shade, located in
Freiburg, calculated online using https://re.jrc.ec.europa.eu/pvg_tools/en/; thepercentages provide the relative annual yield in relation to an inclination of 30°. .....41
Figure 37: Forecast full utilization hours for electricity generation from EE, data from[ÜNB1]. ..................................................................................................................43
Figure 38: Horizontal annual global radiation total in Germany, averaged over the period
2001-2020 [DWD]. .................................................................................................44
Figure 39: Development of atmospheric CO2 concentration, mean global temperaturechange and solar activity (http://herdsoft.com/climate/widget/). ...............................45
Figure 40: Estimates of atmospheric CO2 concentration and temperature difference in
Antarctica based on ice cores [EPA]; red: two recent CO2 measurements from Mauna
Loa Observatory [https://www.esrl.noaa.gov/gmd/ccgg/trends/data.html]. ...............46
Figure 41: Global warming potential of electricity generation with mono c-Si PV for roofmounted and ground-mounted systems [UBA7]. .....................................................47
Figure 42: Global warming potential of different electricity generation technologies[UBA7]. ..................................................................................................................48
Figure 43: Avoided greenhouse gas emissions through the use of renewable energies in
2022 [UBA1]...........................................................................................................49
Figure 44: Development of annual PV additions [IEA3], estimations by BloombergNEF
and average annual growth rate. ............................................................................49
Figure 45: Energy flow diagram 2022 for Germany, figures in petajoules [AGEB2]. ......54
Figure 46: Balance of Germany’s foreign trade in energy sources from 2017 to 2022
[AGEB1].]................................................................................................................55
Figure 47: Structure of final energy consumption by application area for Germany in2020, figures from [BMWK1]. .................................................................................55
Figure 48: Schematic representation of the REMod model (KW: power plant, KWK:
combined heat and power, [ISE3])...........................................................................57

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Figure 49: Schematic representation of a residual load curve for Germany with electricity
supply with 100 percent RE.....................................................................................58
Figure 50: Development of global electricity generation by technologies in the Sky
scenario; the diameter of the pie charts corresponds to global electricity demand[Shell]. ....................................................................................................................59
Figure 51: Power yield profiles of PV systems in different mounting variants, calculatedwith the PVsol software for a predominantly clear July day at the Freiburg site. .......61
Figure 52: Availability of power plants [VGB]. ..............................................................62
Figure 53: Greenhouse gas emissions (CO2-Eq. in tons) of an average compact car withdifferent drives in 2022, in relation to the total mileage [ADAC]. .............................63
Figure 54: Self-consumption share as a function of battery capacity and power of thesolar generator for a single-family household with an annual electricity consumptionof 4,700 kWh. [Quasch]. .........................................................................................69
Figure 55: Comparison of conventional and grid-serving operation [ISE7]. ...................69
Figure 56: Specific investment costs for different electrolyzers technologies (PEMEL:
membrane electrolysis, AEL: alkaline electrolysis, HTEL: high-temperature electrolysis,[NOW]). ..................................................................................................................72
Figure 57: Technologies for energy storage devices and inverters with current efficiency
at the end of the inverter chain, without co-generation (GT: gas turbine, CCGT:
combined cycle gas turbine). ...................................................................................73
Figure 58: Extra-high voltage grid [VDE] and gas transmission grid [Fern]. ....................74
Figure 59: Installed capacity of hydropower plants in neighboring countries, figures from
[IHA]. ......................................................................................................................74
Figure 60: Simplified schematic representation of a renewable energy system with themost important electricity grid-related components of generation, conversion,storage, and consumption; ICT: information and communication technology, CHP:
combined heat and power, CCGT: combined cycle gas and steam power plant. ......76
Figure 61: Important power generators, converters and storage units, additional
estimates and assumptions in square brackets, for sources see section 22.3.7. ........76
Figure 62: Electricity generation and consumption terms. ............................................85

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