PV-Powered Vehicle Strategy Committee
Interim Report (2)- Preliminary Study on Solar Irradiation of
PV-Powered Vehicles -April 2019

New Energy and Industrial Technology Development Organization

Interim Report of PV-Powered Vehicle Strategy Committee (2): Table of Contents
1.

Trends in PV-Powered Vehicles .......................................................................................................... 1
1.1.

Movement toward Electrification of Automobiles ...................................................................... 1

1.2.

Potential of PV Systems in Transport Sector............................................................................... 3

1.3.

Movements toward Development and Adoption of PV-Powered Vehicles ................................. 3

1.3.1. Initiatives toward Development of PV-Powered Vehicles ........................................................... 3
1.3.2. International Discussions into Adoption of PV-Powered Vehicles .............................................. 4
2.

Preliminary Study on Solar Irradiation of PV-Powered Vehicles ........................................................ 8
2.1.

Objective ..................................................................................................................................... 8

2.2.

Method of Measuring Acquired Insolation.................................................................................. 8

2.3.

Measurement Results ................................................................................................................ 11

2.3.1. Measurement Results in Sapporo, Hokkaido ............................................................................ 11
2.3.2. Measurement Results in Miyazaki City, Miyazaki Prefecture .................................................. 29
3.

Conclusion......................................................................................................................................... 39
3.1.

Characteristics of Solar Irradiation of a Vehicle ........................................................................ 39

3.2.

Future Issues .............................................................................................................................. 40

3.3.

Future Initiatives ....................................................................................................................... 43

Introduction
The Paris Agreement, adopted at COP21 in December 2015, has a goal of keeping the rise in global averagetemperature well below 2°C above preindustrial levels and of pursuing efforts to limit the increase to 1.5°C.
In October 2018, the IPCC issued “Special Report on Global Warming of 1.5°C", which summarized thesituation and impact on society if the temperature rise were kept to 1.5°C above preindustrial levels. This
special report emphasized that limiting global warming to 1.5°C rather than 2°C or higher would greatly
reduce climate disruption. The Summary for Policymakers was approved by the signatory countries.
At present, emissions of greenhouse gases are falling in the power generation sector due to the accelerated
introduction of renewable energy, such as solar (hereinafter, photovoltaics or “PV”) and wind. In the transport
sector however, which relies on fossil fuel for most of its energy needs, a presently unforeseeable level oftechnological development will be required to outperform current greenhouse gas reduction targets. The
number of automobiles, which account for over half of transport emissions, is forecast to grow rapidly mainlyin Asia. This makes it vital to reduce greenhouse gas emissions from cars.
To reduce greenhouse gas emissions from cars, initiatives aiming at a rapid rollout of electric vehicles(EV) and plug-in hybrid vehicles (PHV) have begun in countries across the world. However, unless clean
power derived from renewable energy sources can be supplied, such vehicles will have a limited effect inreducing greenhouse gas emissions.
In response to this situation, the New Energy and Industrial Technology Development Organization(NEDO) has established a PV-Powered Vehicle Strategy Committee (secretariat: Mizuho Information &Research Institute, Inc.). This committee investigated potential benefits and outstanding issues for installinghigh-efficiency PV on automobiles and reported in January 2018 on its potential for reducing the CO2
emissions in the transport sector i. This report also indicated that solar irradiation and generated power differ
between PV on vehicle and PV installed on the roof or rooftop of a building, and stressed the need forquantitative analysis into this difference. In keeping with this recommendation, the solar irradiation ofvehicles was measured at two locations in Japan.
This report summarizes the results of the PV-Powered Vehicle Strategy Committee’s preliminary study
into the solar irradiation of PV-powered vehicles.

Reduction ofelectricity charge

Charging station

Fig. Images of PV-powered vehicles

i

NEDO, PV-Powered Vehicle Strategy Committee Interim Report, January 2018

1.

Trends in PV-Powered Vehicles
Moves toward the development and commercialization of PV-powered vehicles have begun in several

countries, though still nascent. This is underpinned by a global movement promoting the electrification of
automobiles, in the form of electric cars, plug-in hybrids, and the like.
The movement toward electrification of automobiles and the trend toward development andcommercialization of PV-powered vehicles are summarized below.
1.1.

Movement toward Electrification of Automobiles

To reduce greenhouse gas emissions in the transport sector, increasing efforts at electrifying vehicles arebeing made around the world. As shown in Table 1-1, many countries have set 2020 or 2030 targets for
introducing electric vehicles, such as electric cars 1. Hereinafter, the expression “electric cars” is used torepresent all electric vehicles.
The Electric Vehicles Initiatives (EVI) is an international multi-government policy forum to promotewidespread introduction of electric cars. The “EV30@30” campaign was launched at the 8th Clean Energy
Ministerial held in 2017. This campaign has a goal of a 30% market share (excluding motorcycles) for electriccars in EVI member countries by 2030.
Fig. 1-1 shows the cumulative numbers of electric cars in 2030 for the New Policies Scenario in the IEAWorld Energy Outlook 2017 2 (hereinafter, “WEO 2017”) and the EV30@30 campaign. While the WEO
2017 scenario foresees around 130 million electric cars on the road, the number jumps to 228 million for the
EV30@30 scenario. Achieving the target of the EV30@30 campaign will increase the number of electriccars by about 100 million, with most of this increase being in passenger cars (PLDV: Passenger Light Duty
Vehicles).

Fig. 1-1 Global EV stock in the New Policies and EV30@30 scenarios, 2017-301(Left: WEO2017 New Policies Scenario, Right: EV30@30 Scenario)

1

Table 1-1 Country targets and objectives for EV deploymentcreated from 1
Country or region
China

EV
30@30a)√2020-30 EV target or objective- 5 million EVs by 2020, including 4.6 million PLDVs, 0.2 million buses
and 0.2 million trucks- New energy vehicle (NEV)b) mandate: 12% NEV credit sales ofpassenger cars by 2020c)- NEV sales share: 7-10% by 2020, 15-20% by 2025 and 40-50% by 2030

European Union- Post 2020 proposed CO2 targets for cars and vans include benchmarks:
15% EV sales by 2025 and 30% by 2030 (exceeding these benchmarks
allows for less stringent specific emissions targets to be met by OEMs)

Finland√- 250,000 EVs by 2030

India

√

- 30% electric car sales by 2030
- 100% BEV sales for urban buses by 2030

Ireland- 500,000 EVs and 100% EV sales by 2030

Japan

√

- 20-30% electric car sales by 2030

Netherlands√- 10% electric car market share by 2020
- 100% EV sales in PLDVs by 2030
- 100% electric public bus sales by 2025 and 100% electric public bus
stock by 2030

New Zealand
Norway- 64,000 EVs by 2021√

- 100% EV sales in PLDVs, LCVs and urban buses by 2025
- 75% EV sales in long-distance buses and 50% in trucks by 2030

Korea

- 200,000 EVs in PLDVs by 2020

Slovenia- 100% electric car sales by 2030

United Kingdom- 396,000 to 431,000 electric cars by 2020

United States- 3,300,000 EVs in eight states combined by 2025d)(selected states)- ZEV mandate in ten statese): 22% ZEV credit sales in passenger cars
and light-duty trucks by 2025f)- California: 1.5 million ZEVs and 15% of effective sales by 2025, and 5
million ZEVs by 2030

Other European- 450,000 to 760,000 electric cars by 2020

Uniong)- 5.42 million to 6.27 million electric cars by 2030

a) The countries that joined the EV30@30 Campaign set a collective aspirational goal to reach a 30% sales share for EVs by
2030.
b) "New energy vehicles" include BEVs, PHEVs and FCEVs.
c) The 12% sales mandate includes multipliers depending on vehicle technology and range. Most current models are eligible formultipliers between 2 and 4.
d) California, Connecticut, Maryland, Massachusetts, New York, Oregon, Rhode Island, Vermont.
e) Eight above-cited States plus Maine and New Jerseyf) The 22% sales mandate includes multipliers depending on vehicle technology and range. Most current models are eligible toreceive credits between 0.5 and 3.
g) These include: Austria, Belgium, Bulgaria, Czech Republic, Hungary, Italy, Latvia, Lithuania, Luxemburg, Poland, Portugal,
Slovak Republic and Spain.

2

1.2.

Potential of PV Systems in Transport Sector

The market for PV systems for residential, commercial buildings, and ground-mounted power generation
projects is rapidly expanding across the globe.
At present, there is relatively little use of PV systems in the transport sector, in limited applications suchas installation on noise barriers, street lights, and other lighting. However, in some countries, there are clear
signs of new markets emerging. In the Netherlands for example, infrastructure such as roads is identified asa main field in the road map for 2050 3. Specific projects relating to PV-powered vehicles have also begun 4.
In Japan, in discussions conducted in November 2018, the installation of PV systems on automobiles wasindicated as a new market predicted for 2030 onward 5.
In an ambitious mid-to-long term vision where energy needs in 2050 are 100% covered by renewableenergy 6, the installed amount of PV generation for the transport sector in 2050 is 19.1TW, which would
supply about 80% of transport sector demand. Of this, about 40% is supplied directly to electric cars.
1.3.

Movements toward Development and Adoption of PV-Powered Vehicles

1.3.1. Initiatives toward Development of PV-Powered Vehicles
The installation of PV on automobiles was originally proposed in the 1980s and early 1990s. At that time,
use was limited to interior air conditioning and charging of electrical equipment. After Ford announced aconcept car that uses PV as an energy source in January 2014, other car manufacturers began to investigate
the potential of PV as a power source for driving an electric vehicle 7.
TOYOTA MOTOR CORPORATION launched a plug-in hybrid vehicle equipped with a 180W crystalline
Si PV panel as a power source, though not a solar car exclusively powered by PV, in 2016. Projects intodeveloping a PV-powered vehicle that uses PV as a main power source have begun in various countries
around the world, with the twin aims of creating a new market for PV systems and of developing nextgeneration vehicles.
Sono Motors of Germany has announced plans to sell passenger cars with PV mounted on all surfaces ofthe vehicle7, while in the Netherlands, development of PV-powered vehicles has begun as a joint venture
between a research institute and venture capital4,8. In Japan, in addition to the PV-Powered Vehicle Strategy
Committee project, research is being conducted by car manufacturers 9. China and South Korea are also
developing PV-powered vehicles and have announced concepts.
Projects relating to PV-powered vehicles are not limited to passenger cars and have also started forcommercial vehicles, such as trucks. In Germany for example, studies measuring power generation of
onboard PV are being conducted using trucks on the road 10, in Japan also, there are initiatives for equipping
trucks with thin film PV 11,12.

3

Courtesy of Hanergy Thin Film Power Group

Courtesy of Toyota Motor Corporation

Fig. 1-2 Examples of PV-Powered vehicles (1) 13 Fig. 1-3 Examples of PV-Powered vehicles (2)1.3.2. International Discussions into Adoption of PV-Powered Vehicles
In addition to development projects by individual countries and enterprises, to promote such efforts andfoster a base for introduction into the real market, international discussions into the adoption of PV-powered
vehicles have begun.
（1） IEA PVPS Task17: PV and Transport
The IEA PVPS (International Energy Agency - Photovoltaic Power Systems Programme, Technology
Collaboration Programme) is an international framework that operates under the IEA to hold discussions andshare information toward the introduction and adoption of PV systems 14.
Under this program, proposals were made, with Japan as leader and based on the results of discussions andinterim reports by Japan’s PV-Powered Vehicle Strategy Committee, to expand initiatives toward therealization and adoption of PV-powered vehicles onto the global stage. As a result, at the 50th IEA PVPS
Executive Committee (a committee composed of representatives of the countries participating in IEA PVPS)
held in December 2017, a new project, “Tas 17 (PV for Transport)” to promote international discussions wasapproved by the IEA PVPS. After discussions with experts from countries participating in Task 17 and “IEA
HEVs (Hybrid and Electric Vehicles)”, another technology collaboration program under the IEA that focuseson electric cars, activities of Task17 officially began in the fall of 2018. Activities under the work plan,corresponding to the actions to be taken, are expected to continue for three years.
Task17 is chaired by Japan, and among the countries participating in IEA PVPS, Australia, China, Germany,and the Netherlands have officially announced their participation. Also, many other countries in Europe andAsia have expressed an interest and the number of participants is expected to increase.
Fig. 1-4 shows the concept of Task17. In the future, more electricity for driving electric vehicles will
become necessary, and to mitigate CO2 emissions related to electric cars, it will be essential to use renewableenergy such as solar power. Although there are various methods for supplying power to charge vehicles, touse solar energy more efficiently, it would be possible to supply power directly from PV mounted on thevehicle and to supply power from a charging station that uses PV.

4Subtask1
PV

PV Powered Vehicle

EV
Battery
ChargeGrid

Subtask2
PV Charging Station

Storage

Storage

Charge

FCV

Fig. 1-4 Concept of IEA PVPS Task17: PV and Transport 15
Task17 consists of the four Subtasks shown in Fig. 1-5 and Table 1-2. Subtask 1 involves discussions into
the commercialization of PV-powered vehicles, not only passenger cars but also commercial vehicles.
Subtask 2 involves discussions about charging infrastructure that uses PV power. Although the supplying of
power from electric vehicles to nearby facilities or the grid, so-called “V2X”, is also possible, the present
focus is on charging stations. In parallel with these discussions, Subtask 3 involves discussions into effectsof the commercialization and adoption of PV-powered vehicles and PV-based charging infrastructure, andwill consider a road map or the like into the expansion of PV use in the transport sector. Subtask 4 involves
global dissemination of the results obtained by the activities of Task17 and public relations activities to forma bridge between the PV industry and the automotive industry.
The solar irradiation of a vehicle studied in this report is data that is essential in investigating the issues
toward commercialization of PV-powered vehicles and their expected benefits. The results of this report andfollow-up activities will also contribute to activities under Task 17.

Subtask 1

Subtask 2
PV-powered applications for electric
systems and infrastructures- PV-powered infrastructure forvehicles- PV-powered applications forelectric systems

Benefits and requirements for PVpowered vehicles- PV-powered passenger vehicles- Requirements, barriers andsolutions for PV and vehicles- Possible contributions andbenefits- PV-powered commercial vehicles

Subtask 3
Potential contribution of PV in transport

Subtask 4
Dissemination

Fig. 1-5 Structure of IEA PVPS Task17: PV and Transport
5

Table 1-2 Outline of IEA PVPS Task17’s Subtasks: PV and Transport16
Subtask 1：

In order to deploy PV-powered vehicles, Subtask 1 will clarify

Benefits and requirements for PV-

expected/possible benefits and requirements for utilizing PV-

powered vehicles

powered vehicles for driving and auxiliary power. Targeted PVpowered vehicles are passenger cars (PHVs and EVs) andcommercial vehicles currently, and other vehicles (buses, trains,
ships, airplanes, etc.) may be included in the future.

Subtask 2：

For promoting electrification of vehicles, not only charging

PV-powered applications forelectricity by itself on board, but also charging renewableelectric systems andelectricity at the environmental friendly infrastructure, e.g. PV-

infrastructures

powered charging stations, will be feasible. Subtask 2 will
discuss energy systems to design PV-powered infrastructures
for EVs charge.

Subtask 3：

For reducing CO2 emissions from the transport, changing

Potential contribution of PV inenergy sources from conventional to renewable energy,transport

especially PV which have a good track record in supplying
electricity by utility-scale, should be accelerated. Also, newsocial models by innovative ‘PV and Transport’ are expected. In
parallel with Subtask 1 and Subtask 2, Subtask 3 will develop aroadmapfor

deployment

ofPV-powered

vehiclesandapplications.
Subtask 4：

A considerable amount of new knowledge is expected to be

Dissemination

developed under this task. It is important that this knowledge isdisseminated to the public and end users in a timely manner.
Subtask 4 will focus on information dissemination proceduresthat effectively release key findings to stakeholders such as PV
industry, transport industry such as automobile industry, battery
industry, and energy service provider.

（2） Other Initiatives
Aside from IEA PVPS, other international discussions into the adoption of PV-powered vehicles havecommenced.
As one example, in Europe, Solar Power Europe, an industry association related to solar power and solar
energy, launched the Solar Mobility Task Force in the summer of 2018 and started discussions into expanding
the use of solar power in the transport sector. It is expected that a report (white paper) into business models
and opportunities, produced via workshops with experts from the automotive industry and focusing on
reductions in CO2 emissions in the transport sector, the importance of infrastructure for promoting fuelconversion, and the potential of the PV market, will be announced in spring 2019.
The 1st Solar Mobility Forum was also held as a side event of the 35th European Photovoltaic Solar Energy
Conference and Exhibition (35th EU-PVSEC) held in September 2018. The forum was organized by SOLAR
6

UNITED, an industry group in Europe, and featured experts in Europe and Japan describing electrification
projects by car manufacturers, the potential and expectations of solar power in the transport sector, and also
their experience and current projects of installing PV on cars. A summary of international activities was also
given by IEA PVPS Task 17. The 2nd Solar Mobility Forum will be scheduled to be held in September 2019
in conjunction with the 36th European Photovoltaic Solar Energy Conference and Exhibition (36th EUPVSEC).
The International Electrotechnical Commission (IEC), which discusses standardization of performance
evaluations of industrial products including PV, has also started to discuss the installation of PV on vehicles.
Although various initiatives into the development and adoption of PV-powered vehicles have begun, toachieve widespread adoption across the world, a certain level of standardized guidelines for productdevelopment will be necessary. For this reason, discussions are being conducted with an awareness that it
will be necessary to provide a standard method for evaluating product performance.

72.

Preliminary Study on Solar Irradiation of PV-Powered Vehicles

2.1.

Objective

When a PV system is installed on an electric vehicle (including a plug-in hybrid vehicle) and the generated
power is used to run the car, there are expected benefits such as a reduction in CO2 emissions compared towhen the vehicle is externally charged using the grid and a reduction in the frequency of external charging
operations 17. The significance of these effects is influenced by the amount of power generated by the PV
system, the driving mode of the vehicle, the balance between generated and consumed power, and thecapacity of the onboard battery.
Although the amount of power generated by a PV system depends on factors such as solar irradiation andtemperature, the most important of these factors is solar irradiation. The solar irradiation of a PV-powered
vehicle depends on the environments during parking and driving. The solar irradiation during driving
fluctuates according to the surrounding environment of the route, such as whether buildings and structuresare shading the vehicle. As a result, solar irradiation may fall compared to roof or rooftop solar radiation ona building, with large fluctuations in short cycles. To promote development and adoption of PV-powered
vehicles, it is necessary to understand the effects of onboard PV in view of such factors and appropriately
design the system.
In response to this situation, as a preliminary study on solar irradiation of a PV-powered vehicle, the solar
irradiation acquired by actual vehicles in motion was measured. The features and tendencies of this insolation
amount were identified, and a comparison with the solar irradiation of roof or rooftop PV on a building was
performed.
2.2.

Method of Measuring Acquired Insolation

Fig. 2-1 shows the measurement locations of the solar irradiation by vehicles in this preliminary study, andTable 2-1 shows the method for measuring solar irradiation. In this study, solar irradiation was measured at
two locations, Sapporo City in Hokkaido (hereinafter, simply “Sapporo”) and Miyazaki City in Miyazaki
Prefecture (hereinafter, simply “Miyazaki”). These locations are positioned in the north and south of theJapanese archipelago that extends in the north-south direction. Measurement in Sapporo was conducted incooperation with the Japan Weather Association. Measurement in Miyazaki was performed in cooperation
with University of Miyazaki. Note that since this is a preliminary study that precedes a full-scale investigation,
to make effective use of existing equipment, there were some differences in measurement methods andmeasurement conditions between the two locations.
Solar irradiation was measured at one position on the roof of a car in Sapporo using three pyranometersthat have different response speeds. In Miyazaki however, measurement was performed at a total of fivepositions which were the four sides of the vehicle, that is, the front, rear, right and left, in addition to the roof.
The sampling interval of the measurement data was set at 0.1 seconds in Sapporo and at 1 second in Miyazaki.
Measurement was conducted in the fall of 2018, and solar irradiation was measured three times a day(sometimes just once a day in Miyazaki) to investigate the influence of solar elevation.

8

To examine the influence of theenvironment (i.e., the car being
shaded by buildings and the like), a

Sapporomeasurement route including anurban section, a high-rise section,
and an open-air section was chosen.
The measurement route in Sapporo
also included an underpass section.
Note that the detailed measurement
Miyazakiroutes and their environments are
shown

together

with

the

measurement results in the next
section (2.3).
Fig. 2-1 Irradiation measurement locations in preliminary study 18

9Table 2-1 Method of measuring solar irradiation of vehicles
Measurement

Sapporo City, Hokkaido

Miyazaki City, Miyazaki Prefecture

Location(near N43°04’, E141°21’)(near N31°53’, E131°25’)

Insolation

One (Horizontal irradiation on vehicle roof)

Five (Horizontal irradiation on vehicle roof and

Measurement

four upper side surfaces of vehicle: on front, rear,

Positionsleft, and right sides)

Pyranometer-

Secondary standard (x1)(See Table 2-2)-

Second class (x1)-

Silicon type (x1)-Second class (x5)

(Data produced by these pyranometers werecompared.)
Sampling Interval

0.1 seconds

1 second

Measurement Period

Mid-September to late October, 2018

Mid-September to early October, 2018

Measurement TimeFirst run: around 08:15 to around 09:15

First run: around 09:00 to around 10:00

Zones

Second run: around 11:15 to around 12:15

Second run: around 11:30 to around 12:30

Third run: around 14:15 to around 15:15

Third run: around 15:00 to around 16:00

About 18km including the following:

About 30km including the following:

Measurement Route-Urban section-

Urban section-

High-rise section-

High-rise section-

Open-air section-

Open-air section-

Underpass section

Insolation reference

Japan Meteorological Agency (JMA), Sapporo

University

Point

Regional Headquarters

Corporation)

-

Kita

2-Jo

Nishi

18-Chome,

Chuo-ku,

SapporoofMiyazaki(National

University-

1-1 Gakuen Kibanadai-nishi, Miyazaki-near N31°49’, E131°24’
Pyranometer type: second class-near N43°3.6’, E141°19.6’--

Pyranometer type: secondary standard*Data produced as 10-second averages for data

*Data produced as one-minute totals for every-measured every second

second measurements (one-minute values of
surface observation data produced by JMA)
Measured by

Japan Weather Association

University of Miyazaki

Table 2-1 Main specifications of pyranometers used to measure solar irradiation of vehicles 19
Pyranometer Type

Secondary

Second Class

Silicon TypeStandard
Response time

<0.5s

1s

<1ms

Time taken for output to reach 95%

Stability±0.5%/5 years±1%/ year±2%/year

Change in output due to changes in

Directional±10W/m2±25W/m2±2% (45°),

Output error when light with an±5% (75°)

intensity of 1,000W/m2 is incident(Output: 95%)

sensor over time

Characteristics

from all directions and angles
Temperature<1% (⊿T50)

characteristics
Range of measurement-0.4 ±0.04%/°C<3%(-10°C to +40°C)

285 to 3,000nm

285 to 3,000nm

wavelengths

Output error due to change intemperature

360 to 1,120nm

Wavelength range that can bedetected by the sensor

10

2.3.

Measurement Results

Measurement results for Sapporo and Miyazaki are given below.
2.3.1. Measurement Results in Sapporo, Hokkaido（1） Measurement Conditions and Measurement RouteThe measurement conditions used in Sapporo are shown in Table 2-3. In Sapporo, measurements weretaken on five days between September 20, 2018 and October 22, 2018. Solar irradiation acquired by a vehicle
is influenced by the shadows of surrounding buildings and the like. Since it was assumed that this influence
depends on solar elevation, measurements were taken three times a day in different time zones.
To identify the fall in solar irradiation due to shadows and the like, comparisons were performed with theinsolation at a reference point (JMA Sapporo Regional Headquarters). Since it was assumed that this fall
would also be affected by irradiation components (whether direct solar irradiation or diffuse solar irradiation),measurement was performed on both fine and cloudy days. Solar irradiation at the reference point on themeasurement dates is shown in Fig. 2-2, and the solar elevation and solar orientation during the measurement
time zones are shown in Table 2-4.
In addition, to identify differences that depend on the direction in which the vehicle is traveling (that is,
the orientation of the sun viewed from the vehicle), measurement was also performed for both clockwise
travel and anticlockwise travel on the measurement route shown below.
Table 2-3 Measurement dates and weather in Sapporo19
Weather
Date of measurement
Sep. 20, 2018
(Thursday)
Sep. 25, 2018
(Tuesday)Sep. 28, 2018
(Friday)
Oct. 19, 2018
(Friday)
Oct. 22, 2018
(Monday)First run(around 8:15 toaround 9:15)

Second run(around 11:15 toaround 12:15)

Third run(around 14:15 toaround 15:15)

Clockwise

Sunny

Sunny

Clear

Anticlockwise

Slightly cloudy

Slightly cloudy

CloudyClockwise

Sunny,
partly cloudy

Cloudy,occasionally
scatteredshowers

Cloudy,occasionally
scatteredshowers

Anticlockwise

Very clear

Clear

Clear

Clockwise

Clear

Clear

Clear

Route

11

Time zones ofmeasurement

Irradiation

Elevation

8

4

Solar elevation [degree]

1
Irradiation

1

Elevation

Solar irradiation [W/m2]

0+

Elevation

Irradiation

10-

10-

Elevation*Marks above each graph show
amount of cloud and weather
at 9:00, 12:00 and 15.00.

Oct. 220+Solar irradiation [W/m2]

10-

0+

Clear
Sunny

Solar elevation [degree]

Oct. 19
Irradiation

10-

Solar elevation [degree]

Solar elevation [degree]

Elevation

10-

Solar elevation [degree]

0+

Solar irradiation [W/m2]

2

Solar irradiation [W/m2]

Irradiation

Sep. 28

Sep. 25
0+Solar irradiation [W/m2]

Sep. 20Slightly cloudy
CloudyRainy

Fig. 2-2 Solar Irradiation at JMA Sapporo regional headquarters (reference point)19
Table 2-4 Solar elevation and solar orientation during measurement time zones in Sapporo19
Solar elevation※1
Date of measurement

First run
Second run
Third run(around 8:15 to around (around 11:15 to around (around 14:15 to around
9:15)
12:15)
15:15)

Sep. 20, 2018 (Thu.)

31.6 to 40.2

47.9 to (48.1) to 46.3

33.7 to 22.8

Sep. 25, 2018 (Tue.)

29.0 to 37.5

46.1 to (46.2) to 44.9

31.8 to 22.7

Sep. 28, 2018 (Fri.)

27.1 to 37.1

45.0 to (45.0) to 43.0

30.9 to 20.4

Oct. 19, 2018 (Fri.)

24.2 to 31.7

37.0 to (37.0) to 35.4

23.8 to 14.5

Oct. 22, 2018 (Mon.)

19.7 to 28.3

(36.0) to 36.0 to 33.8

23.1 to 13.9

※2

Solar Orientation
Date of measurement

First run
Second run
Third run(around 8:15 to around (around 11:15 to around (around 14:15 to around
9:15)
12:15)
15:15)

Sep. 20, 2018 (Thu.)

122.7 to 138.7

173.2 to 200.1

233.8 to 248.7

Sep. 25, 2018 (Tue.)

122.5 to 137.6

175.2 to 196.9

232.9 to 245.6

Sep. 28, 2018 (Fri.)

121.9 to 139.7

177.0 to 200.9232.1 to 246.6

Oct. 19, 2018 (Fri.)

132.6 to 148.4

178.0 to 197.4

227.9 to 241.0

Oct. 22, 2018 (Mon.)

127.5 to 142.9

181.2 to 200.2

226.9 to 240.0※1: (Solar elevation) Value in brackets for the second run is elevation when the sun is due south※2: (Solar orientation) East: 90°, South-east: 135°, South: 180°, South-west: 225°, West: 270°12

Fig. 2-3 and Table 2-5 show the route ofCase of clockwise

travel in Sapporo, and Table 2-6 shows theHigh-rise section 1
Urban section 1

road width of each section on the route.
The route included an urban section, ahigh-rise section, an open-air section, andan underpass section, and it was assumed

Urban section 1

Underpass section

Referencepoint
High-rise section 2
Urban section 2that solar irradiation in the urban section
and the high-rise section would be affectedby surrounding buildings. The open-air

Openair
section(west)

section was assumed to be less affected,
Urban section 3

while the underpass section is a section

Openair
section(east)

where solar irradiation is not acquired. The
directions in which the vehicle travels areapproximately east-west (both east to west
and west to east) and north-south (bothsouth to north and north to south).

1km- Red line: Measurement route- In case of clockwise: passing open-air section (east)
twice and open-air section (west) once
- In case of anticlockwise: passing open-air section(east) once and open-air section (west) twice

Fig. 2-3 Route used for measurement in Sapporocreated from 18

13

Table 2-5 Route used for measurement in Sapporo19
Clockwise
Secti
Type

Direction

on
1-a
1-b

1-c
1-d

1-e

1-f

1-g

1-h
1-i

Urban
section 1
High-risesection 1

West to east

UnderpasssectionUrban
section 2

North to south

Open-airsection(east)
Open-airsection(west)
Open-airsection(east)
Urban
section 3
High-risesection 2
Urban
section 1

1-j

Anticlockwise
Distancefrom start
(km)
0.00
1.56
1.56
2.90

to

2.90
3.79
3.79
4.19

to

West to east,
north to south,
east to west
South to north

4.19
6.75

to

6.75
8.85

to

West to east,
north to south,
east to west
East to west,
south to northWest to east,
south to north,east to west
East to west

8.85 to11.42

West to east,
north to south

North to south

toto11.42 to13.18
13.18 to
16.13
16.13 to17.69

Sectiondistance
(km)

Secti

1.56

2-a

Type

Direction

Urban
section 1
High-risesection 2

West to east

on

1.34

2-b

0.88

2-c

0.40

2-d

2.57

2-e

2.10

2-f

2.57

2-g

1.76

2-h

2.95

2-i

1.56

2-j

Urban
section 3
Open-airsection(west)
Open-airsection(east)
Open-airsection(west)
Urban
section 2

West to east,
north to south,
east to west
North to south,
east to west
South to northDistancefrom start
(km)
0.00
1.56
1.56
4.51

to

4.51
6.27
6.27
8.37

to

to

to

Sectiondistance
(km)
1.56
2.95

1.75
2.10

West to east,
north to south,
east to west
South to north8.37 to
10.94

2.57

10.94 to
13.04

2.10

South to north

13.04 to
13.44

0.40

UnderpasssectionHigh-risesection 1

South to north13.44 to14.32
14.32 to
15.66

Urban
section 1

West to east

South to north,east to west

15.66 to
17.22

0.88
1.34

1.56

Table 2-6 Estimated road width of route sections in Sapporo19
Section
1-a

Type

2-j

Urban section 1

2-iHigh-rise section 1

Section distance(km)

Estimatedroad width

1.56

15 to 17m
18 to 21m

1-b

1.34
50m

1-c

2-h

Underpass section

0.88

1-d

2-g

Urban section 2

0.40

9m

1-e

2-e

1-f

2-d,
2-f

Open-air section(west)

2.57

7 to 12m

2.10

7 to 10m

16m

1-g

(2-e)

Open-air section(east)

2.57

1-h

2-c

Urban section 3

1.76

1-i

1-j

2-b

2-a

High-rise section 2

Urban section 1

2.95

1.56

This section passes the high-rise buildings in frontof Sapporo Station.
Four-lane road on both sides of the Sousei Riverand drainage space
Two lane underpass

50m
12m

Open-air section(east)

Comments

12m
7 to 12m
16m
20m

Minami 7-jo Ohashi bridge
There are buildings and trees to the east
Minami 19-jo Ohashi Bridge
There are buildings and trees to the west
Same as 1-e(First half) Ring road15m
16 to 17m

(Second half) Tramline in center of road
Kikusui Asahiyama Park Street

13 to 14m

South of Susukino intersection

20 to 24m

North of Susukino intersection: There are trees on
the central division

15 to 17m

Same as 1-a

14

（2） Characteristics of Solar Irradiation According to Route Section and Time Zone
The characteristics of the solar irradiation on the vehicle roof according to route section and time zone aresummarized here based on the measurement results on September 20, 2018 (Day 1). A comparison of
cumulative values of solar irradiation and the reference point, including other measurement days, is given in
Section (3).
Figs. 2-4 to 2-6 show the measurement results of the first to third runs on September 20, 2018 (Day 1).

Out of measurement
route

Day 1 – First run

1-a

1-b

1-c 1-d

1-f

1-e

Urban section 1

High-rise section 1

Reference
Underpass section

Intermittent shadows by buildings

Influences by reflection, possibly

Open-air section (east)

Urban section 3

Silicontype

Secondarystandard

1-i

Open-air section (east)

1-j

Open-air section (west)

Reference

Secondclass

Silicontype

Silicontype

Secondarystandard

Open-air section (east)

Shadows by trees

Day 1 – First run [10.0 to 15.0km]
Secondclass

Secondclass

Secondarystandard

Open-air section (east)

Underpass section

Reference

Reference

Silicontype

Day 1 – First run [5.0 to 10.0km]
Secondarystandard

Silicontype

Urban
section 2

Second
class

1-h

1-g

Day1 – First run [0.0 to 5.0km]
Secondclass

Reference

Shadow by power pole

Influences by clouds

Day 1 – First run [15.0 to 17.69km]
Secondarystandard

High-rise section 2

Urban section 1

Reference

Secondclass

Silicontype

Secondarystandard

High-rise section 2

Influences by buildings and trees
Measurement result offirst passing

Influences by clouds

Influences by clouds

Fig. 2-4 September 20, 2018 (Day 1) in Sapporo: Measurement results for solar irradiation during
the First run19

15

Day 1 – Second run
Out ofmeasurement
route

Reference

1-a

1-b

1-c 1-d

1-f

1-e

1-g

Urban section 1

Secondclass

Underpass section

Urban
section 2

Reference

Secondclass

High-rise section 1

Silicontype

Secondarystandard

Secondclass

Silicontype

Secondarystandard

1-i

1-h

1-j

Secondarystandard

Reference
ﾘﾌｧﾚﾝｽ

Open-air section (east)

Open-air section (east)

Silicontype

Silicontype

Day 1 – Second run [10.0～17.69km]

Day 1 – Second run [0.0 to 10.0km]
Reference

Secondclass

Not available(data missing)

Reference

Reference
ﾘﾌｧﾚﾝｽ
Urban section 1

High-rise section 2

Secondary
ｾｶﾝﾀﾞﾘｰ
standard
ｽﾀﾝﾀﾞｰﾄﾞ

Secondｾｶﾝﾄﾞｸﾗｽ
class

Silicon
ｼﾘｺﾝ
type
ﾀｲﾌﾟ

Secondary
ｾｶﾝﾀﾞﾘｰ
standard
ｽﾀﾝﾀﾞｰﾄﾞOpen-air section (east)

Open-air section (west)

Open-air section (east)

Silicon
ｼﾘｺﾝ
type
ﾀｲﾌﾟ

High-rise section 2

Urban section 3

Secondarystandard

Secondｾｶﾝﾄﾞｸﾗｽ
class

Fig. 2-5 September 20, 2018 (Day 1) in Sapporo: Measurement results for solar irradiation during
the Second run19
Day 1 – Third run
Secondｾｶﾝﾄﾞｸﾗｽ
class

Silicon
ｼﾘｺﾝ
type
ﾀｲﾌﾟ

Reference
ﾘﾌｧﾚﾝｽSecondｾｶﾝﾄﾞｸﾗｽ
class

Silicon
ｼﾘｺﾝ
type
ﾀｲﾌﾟ

Secondary
ｾｶﾝﾀﾞﾘｰ
standard
ｽﾀﾝﾀﾞｰﾄﾞ

Out ofmeasurement
route

Reference
ﾘﾌｧﾚﾝｽ1-a1-b1-c 1-d

1-f

1-e

1-g

Day 1 – Third run [0.0 to 10.0km]
Urban section 1

Open-air section (east)

Reference
ﾘﾌｧﾚﾝｽSecondｾｶﾝﾄﾞｸﾗｽ
class

Underpass section

Urban
section 2

Reference
ﾘﾌｧﾚﾝｽSecondｾｶﾝﾄﾞｸﾗｽ
class

High-rise section 1

Silicon
ｼﾘｺﾝ
type
ﾀｲﾌﾟ

1-h

1-i

Secondary
ｾｶﾝﾀﾞﾘｰ
standard
ｽﾀﾝﾀﾞｰﾄﾞ

1-j

Day 1 – Third run [10.0 to 17.69km]
Secondary
ｾｶﾝﾀﾞﾘｰ
standard
ｽﾀﾝﾀﾞｰﾄﾞ

Reference
ﾘﾌｧﾚﾝｽ
Open-air section (east)

Secondｾｶﾝﾄﾞｸﾗｽ
class

Silicon
ｼﾘｺﾝ
type
ﾀｲﾌﾟ

Secondary
ｾｶﾝﾀﾞﾘｰ
standard
ｽﾀﾝﾀﾞｰﾄﾞ

Silicon
ｼﾘｺﾝ
type
ﾀｲﾌﾟ

Secondary
ｾｶﾝﾀﾞﾘｰ
standard
ｽﾀﾝﾀﾞｰﾄﾞ

High-rise section 2

Urban section 3

Open-air section (east)

Silicon
ｼﾘｺﾝ
type
ﾀｲﾌﾟ

Secondary
ｾｶﾝﾀﾞﾘｰ
standard
ｽﾀﾝﾀﾞｰﾄﾞ

Reference
ﾘﾌｧﾚﾝｽ

Open-air section (west)

High-rise section 2

Secondｾｶﾝﾄﾞｸﾗｽ
class

Urban section 1

Open-air section (east)

Fig. 2-6 September 20, 2018 (Day 1) in Sapporo: Measurement results for solar irradiation during
the Third run19
16

<Characteristics according to route section>
In urban sections and high-rise sections, solar irradiation fell and fluctuated due to the shadows of buildings
and trees along the road, with this especially frequent in high-rise sections. Even in open-air sections, solar
irradiation sometimes fell due to the shadows of buildings, trees, and power poles along the road.
Although the fall in solar irradiation due to the shadows of buildings, trees, and the like may be smaller
than the influence of clouds in terms of cumulative solar irradiation over a certain period, the variations insolar irradiation that occur on a vehicle roof have a characteristic of occurring at extremely short cycles andwith a large range of fluctuation.
In urban sections and high-rise sections, solar irradiation sometimes exceeded the solar irradiation at thereference point, and it is thought that this could be due to an increase in acquired insolation caused byreflections from buildings.
Table 2-7 Measurement results of solar irradiation of vehicle roof in Sapporo: Characteristics
according to route section
Urban sections-

Shadows of buildings and trees occur intermittently, so that solar irradiation
fluctuates.

-

Solar irradiation may exceed irradiation at the reference point, and it isthought that this could be due to an increase in solar irradiation caused byreflections from buildings.

High-rise sections-

Large fall in solar irradiation due to shadows from buildings and trees.

-

Solar irradiation may exceed irradiation at the reference point, and it isthought that this could be due to an increase in solar irradiation caused byreflections from buildings.

Underpass-

These sections are underground, so there is no solar irradiation.

-

Surrounding buildings have little effect compared to urban and high-rise

sections
Open-air sections

sections. However, short-cycle fluctuations (falls) in solar irradiation still
occur due to buildings, trees, and power poles along the road.

<Characteristics according to time zone>
Shadows from buildings, trees, power poles, and the like occur in urban sections, high-rise sections, andpartly in open-air sections, causing a fall in solar irradiation. During the second run (when the sun issubstantially due south), the solar elevation is high, which means that the frequency of falls in solar irradiation
due to shadows is low. The range of fluctuations in solar irradiation though is larger.
During the first and third runs when the solar elevation is low, solar irradiation falls frequently due toshadows, but when the sun is oriented close to the direction of the road (i.e., the direction of travel), shadowsthat affect solar irradiation are produced less frequently.

17

Table 2-8 Measurement results of solar irradiation of vehicle roof in Sapporo: Characteristics
according to time zone
Urban sections

Urban section 1: East-west direction-

During both the first and second runs, shadows appeared intermittently, butthere was no large difference in the frequency of shadows. The road runs in theeast-west direction, and the lack of difference is believed to be caused by thehigh solar elevation during the second run. However, the range of fluctuations
in solar irradiation was larger during the second run.

-

During the third run, there were fewer fluctuations due to shadows. It is thoughtthat this is because the solar orientation is closer to the direction of the road(the direction of travel) than in the first and second runs.

Urban section 2: (Mostly) South-north direction to East-west direction-

There was little fluctuation during the second run, where the solar elevation ishigh and the solar orientation is close to the direction of the road.

-

There was some fluctuation during the first run, and very large fluctuations
during the third run. It is thought that this is caused by the low solar elevationand the difference between the orientation of the sun and the direction of theroad.

Urban section 3: East-west direction → (mostly) North-south direction
High-rise sections

The overall tendency was the same as in Urban section 2, but the fluctuations

and falls in solar irradiation during the second run were larger.
High-rise section 1: (Mostly) East-west direction to North-south direction-

There were large falls in solar irradiation due to the shadows of buildings andtrees during all of the first to third runs.

-

During the second run where the solar elevation was high, there were slightly
more areas where the vehicle was not shaded, but the range of fluctuations insolar irradiation was large.

High-rise section 2: East-west direction to North-south direction to East-west
direction)-

The overall tendency was the same as in High-rise section 1, however, during
the second run where the solar elevation is high and the orientation of the sun

Open-air sections

was close to the direction of the road, irradiation was less affected by shadows.
Open-air section (east): East-west direction to (mostly) North-south direction toEast-west direction-

There was no large difference in the frequency of shadows due to buildings,
trees, and power poles between the first and second runs, but the locations of
shadows differed, which is believed to be due to the orientation of the sun.

-Shadows were infrequently encountered during the third run, which is thought
to be due to buildings being located on the east side (or east-southeast side).

Open-air section (west): North-south direction-

Shadows were most frequently encountered during the third run and were
infrequent during the first and second runs. It is thought that this is due tobuildings being located mainly on the west side (west-north-west side).

Other observations(common to all sections)-

The range of fluctuation in solar irradiation due to shadows was greatest on thesecond run where the solar elevation and solar intensity were high.

18

（3） Comparison between Acquired Insolation on Vehicle Roof and at the Reference Point
The results of measurements taken three times daily for five days in Sapporo are given here.
Table 2-9 shows, for the measurement results produced on September 20, 2018 (Day 1) given in (2), thesolar intensity and cumulative solar irradiation at the reference point (JMA Sapporo Regional Headquarters),
the cumulative value of solar irradiation on the vehicle roof, and ratios between the cumulative values.
A certain fall in solar irradiation due to shadows of buildings, trees, power poles and the like was confirmed.
When the cumulative value for the acquired insolation on the vehicle roof was compared with the irradiation
at the reference point, while some of the difference will be due to the difference in pyranometer used formeasurement, the ratio was about 54% for the first run, about 69% for the second run, and about 56% for thethird run. The main factors that affect the fall in solar irradiation are thought to be the frequency of shadowsand the intensity of solar irradiation when no shadows are present, so that the fall in solar irradiation during
the second run where the solar elevation and solar intensity were high (the sun was almost due south) was
lower than for the other runs.
Table 2-9 Measurement results of solar irradiation on September 20, 2018 (Day 1) in Sapporo(Summary)19
Measurement date:
Sep 20, 2018 (Tuesday)
Reference

Solar intensity

First run (Sunny)

Second run (Sunny)

Third run (Clear)(around 8:15 toaround 9:15)(around 11:15 toaround 12:15)(around 14:15 toaround 15:15)

Around 550 to 650

Around 800 W/m2

Around 550 to 400

W/m2

point

W/m2

(increasing over time)
Cumulative solar(decreasing over time)564.2 Wh/m2

666.4 Wh/m2

462.2 Wh/m2

308.0 Wh/m2

462.5 Wh/m2

264.6 Wh/m2(54.6%)(69.4%)(57.2%)

298.6 Wh/m2

469.7 Wh/m2

264.2 Wh/m2(52.9%)(70.5%)(57.2%)

302.8 Wh/m2

445.6 Wh/m2

246.9 Wh/m2(53.7%)(66.9%)(53.4%)

irradiation
Vehicleroof

irradiation

Secondary Standard(ratio to reference point)(for each

Second Classpyranometer)(ratio to reference point)
Silicon Type(ratio to reference point)

Table 2-10 shows the cumulative solar irradiation per section of route and per pyranometer, which wasmeasured on September 20, 2018 (Day 1). Figs. 2-7 to 2-8 and Table 2-11 depict a chart of the measurement
results, and for measurement results produced using a secondary standard pyranometer out of these solar
irradiation values, the ratio of solar irradiation on a section of the route to irradiation at the reference point.

19

Table 2-10 Measurement results for solar irradiation on September 20, 2018 (Day 1) in Sapporo19<First run (8:25 to 9:27): Sunny>
Sec.

Type

Distance fromstart (km)Secondarystandard (Wh/m2)

Second class(Wh/m2)

Silicon type(Wh/m2)

Reference point(Wh/m2)

1-aUrban section 1

0.00 to 1.56

37.4

37.5

36.6

48.0

1-b

High-rise section 1

1.56 to 2.90

17.9

17.4

16.3

66.6

1-c

Underpass section

2.90 to 3.79

0.1

0.0

0.1

10.2

Urban section 2

3.79 to 4.19

15.1

15.2

15.2

16.8

4.19 to 6.75

60.8

60.5

59.5

67.8

6.75 to 8.85

30.5

34.0

32.8

49.7

8.85 to 11.42

46.5

46.7

45.6

58.8

1-d
1-e
1-f
1-g

Open-air section(east)
Open-air section(west)
Open-air section(east)

1-h

Urban section 3

11.42 to 13.18

37.1

36.4

35.0

59.3

1-i

High-rise section 2

13.18 to 16.13

39.6

37.8

38.3

139.6

1-j

Urban section 1

16.13 to 17.69

23.0

13.1

23.4

47.3

0.00 to 17.69

308.0

298.6

302.8

564.2

Total

<Second run (11:09 to 12:23): Sunny>
Sec.

Type

Distance fromstart (km)Secondarystandard (Wh/m2)

Second class(Wh/m2)

Silicon type(Wh/m2)

Reference point(Wh/m2)

1-aUrban section 1

0.00 to 1.56

37.5

37.6

35.6

1-b

High-rise section 1

1.56 to 2.90

33.9

33.9

32.4

63.4

1-c

Underpass section

2.90 to 3.79

0.9

0.8

0.9

13.1

Urban section 2

3.79 to 4.19

9.4

9.5

9.2

9.6

4.19 to 6.75

90.6

91.2

88.6

106.8

6.75 to 8.85

48.0

47.7

45.7

51.1

8.85 to 11.42

73.2

73.9

71.5

84.4

1-d
1-e
1-f
1-g

Open-air section(east)
Open-air section(west)
Open-air section(east)

46.2

1-hUrban section 3

11.42 to 13.18

38.7

38.7

38.1

57.8

1-i

High-rise section 2

13.18 to 16.13

93.1

92.0

89.4

170.8

1-j

Urban section 1

16.13 to 17.69

37.3

44.4

34.2

63.4

0.00 to 17.69

462.5

469.7

445.6

666.4

Total

<Third run (14:17 to 15:25): Clear＞
Sec.
1-a

Type
Urban section 1

Distance fromstart (km)Secondarystandard (Wh/m2)

Second class(Wh/m2)

Silicon type(Wh/m2)

Reference point(Wh/m2)0.00 to 1.56

50.1

50.1

46.0

50.9

1-b

High-rise section 1

1.56 to 2.90

22.4

21.8

20.5

64.1

1-c

Underpass section

2.90 to 3.79

0.1

0.0

0.1

8.6

Urban section 2

3.79 to 4.19

6.4

5.9

6.5

13.6

4.19 to 6.75

66.8

67.1

64.3

66.4

6.75 to 8.85

19.3

18.9

17.8

45.3

8.85 to 11.42

44.6

45.0

43.1

44.2

1-d
1-e
1-f
1-g

Open-air section(east)
Open-air section(west)
Open-air section(east)

1-h

Urban section 3

11.42 to 13.18

13.5

13.3

12.9

28.2

1-i

High-rise section 2

13.18 to 16.13

29.7

30.2

24.5

114.3

1-j

Urban section 1

16.13 to 17.69

11.7

11.8

11.2

26.7

0.00 to 17.69

264.6

264.2

246.9

462.2

Total

20

As can be seen in Figs. 2-7 to 2-8 and Table 2-11, the ratio of the solar irradiation acquired by the vehicle
to the irradiation at the reference point was high for the open-air sections and low for the high-rise sections(the underpass section was excluded). Urban sections were in the middle of these, with no great difference
between urban section 1 (1-a) and urban section 2 (1-d) and the open-air section.
Among the ratios for the first to third runs, the ratios were fundamentally highest for the second run where
the solar elevation is high and shadows are short and unlikely to shade the car. However, for urban section 1(1-a) and open-air section (east) (1-e and 1-g), the ratios in the third run were the highest. This suggests thatthe relationship between the solar orientation and the direction of the road has a great effect, even in the openair section.
Figs. 2-9 to 2-16 and Tables 2-12 to 2-15 are charts of measurement results for the second to fifth days andshow the results of comparisons between the measurement results produced by the secondary standard
pyranometer, with irradiation at the reference point for each route section.

21

Solar irradiation by section [Day 1]
 First run

Reference

Secondclass

Silicon type

Secondarystandard(8：25 to 9：27)
Sunny

1-a

1-b 1-c 1-d

1-e

1-f

1-g

 Second run

1-h

1-i

Reference

Secondclass

1-j

Silicon type

Secondarystandard(11：09 to 12：24)
Sunny

1-a

1-b 1-c 1-d

1-e

1-f

1-g

 Third run

1-h

1-i

Reference

Secondclass

1-j

Silicon type

Secondarystandard(14:16 to 15:25)
Clear

1-a

1-b 1-c 1-d

1-e

1-f

1-g

1-h

1-i

1-j

Fig. 2-7 Measurement results for solar irradiation on September 20, 2018 (Day 1) in Sapporo19
Table 2-11 Measurement results for solar irradiation on September 20, 2018 (Day 1) in Sapporo(Comparison with reference) (Pyranometer: Secondary standard)19
Sec.

1-a
1-b
1-c
1-d
1-e
1-f
1-g

First run
(8:25 to 9:27)(ratio to(Wh/m2)
referencepoint)

Second run(11:09 to 12:24)(ratio to(Wh/m2)
referencepoint)

Third run
(14:16 to 15:25)(ratio to(Wh/m2)
referencepoint)

Type

Distance fromstart (km)Urban section 1

0.00 to 1.56

37.4

77.9%

37.5

81.2%

50.1

98.4%

1.56 to 2.90

17.9

26.9%

33.9

53.5%

22.4

34.9%

2.90 to 3.79

0.1

1.0%

0.9

6.9%

0.1

1.2%

3.79 to 4.19

15.1

89.9%

9.4

97.9%

6.4

47.1%

4.19 to 6.75

60.8

89.7%

90.6

84.8%

66.8

100.1%

6.75 to 8.85

30.5

61.4%

48.0

93.9%

19.3

42.6%

8.85 to 11.42

46.5

79.1%

73.2

86.7%

44.6

100.9%

High-rise section
1
UnderpasssectionUrban section 2
Open-air section(east)
Open-air section(west)
Open-air section(east)

1-h

Urban section 3

11.42 to 13.18

37.1

62.6%

38.7

67.0%

13.5

47.9%

1-i

High-rise section
2

13.18 to 16.13

39.6

28.4%

93.1

54.5%

29.7

26.0%

1-j

Urban section 1

16.13 to 17.69

23.0

48.6%

37.3

58.8%

11.7

43.8%

0.00 to 17.69

308.0

54.6%

462.5

69.4%

264.6

57.2%

Total

Measurement results of Day 1 [pyranometer: secondary standard]
160%

First run

Ratio: Car-roof/reference [%]140%

Second run

Third run

120%
100%
80%
60%
40%
20%
1-j Urban section 1

1-i High-rise section 2

1-h Urban section 3

1-g Open-air section (east)

1-f Open-air section (west)

1-e Open-air section (east)

1-d Urban section 2

1-c Underpass section

1-b High-rise section 1

1-a Urban section 1

0%

Fig. 2-8 Measurement results for solar irradiation on September 20, 2018 (Day 1) in Sapporo(Comparison with reference) (Pyranometer: Secondary standard)19

22

Solar irradiation by section [Day 2]
 First run

Reference

Secondclass

Silicon type

Secondarystandard(8：16 to 9：17)
Slightly cloudy

2-a

2-b

2-c

2-d

2-e

2-f

 Second run

2-g 2-hReference

2-i

Secondclass

2-j

Silicon type

Secondarystandard(11：13 to 12：14)
Slightly cloudy

2-a

2-b

2-c

2-d

2-e

2-f

 Third run

2-g 2-hReference

2-i

Secondclass

2-j

Silicon type

Secondarystandard(14:17 to 15:14)
Cloudy

2-a

2-b

2-c

2-d

2-e

2-f

2-g 2-h2-i2-jFig. 2-9 Measurement results for solar irradiation on September 25, 2018 (Day 2) in Sapporo19
Table 2-12 Measurement results for solar irradiation on September 25, 2018 (Day 2) in Sapporo(Comparison with reference) (Pyranometer: Secondary standard)19
First run
(8:16 to 9:17)(ratio to(Wh/m2)
referencepoint)

Second run
Third run
(11:13 to 12:14)(14:17 to 15:14)(ratio to ref(ratio to(Wh/m2)
erence po (Wh/m2)
referenceint)
point)

Type

Distance fromstart (km)2-aUrban section 1

0.00 to 1.56

26.4

76.1%

28.6

60.9%

17.4

76.7%

2-b

High-rise section
2

1.56 to 4.51

37.3

49.6%

92.3

70.9%

31.9

58.5%

Urban section 3

4.51 to 6.27

20.9

47.9%

38.5

74.2%

14.8

72.5%

6.27 to 8.37

87.9

132.8%

35.4

80.5%

11.7

83.6%

8.37 to 10.94

57.7

94.3%

60.5

100.5%

23.9

100.0%

10.94 to 13.04

54.8

94.3%

25.7

93.5%

14.7

84.0%

13.04 to 13.44

7.6

73.1%

6.7

80.7%

5.7

70.4%

13.44 to 14.32

0.1

1.1%

0.0

0.0%

0.0

0.0%

14.32 to 15.66

13.9

28.5%

21.8

50.5%

12.0

67.0%

15.66 to 17.22

16.5

44.2%

27.4

57.7%

11.2

77.8%

0.00 to 17.22

323.1

72.7%

336.9

71.8%

143.2

72.8%

Sec.

2-c
2-d
2-e
2-f
2-g
2-h
2-i
2-j

Open-air section(west)
Open-air section(east)
Open-air section(west)
Urban section 2
UnderpasssectionHigh-rise section
1
Urban section 1
Total

Measurement results of Day 2 [pyranometer: secondary standard]

Ratio: Car-roof/reference [%]160%
First run

140%

Second run

Third run

120%
100%
80%
60%
40%
20%
2-j Urban section 1

2-I High-rise section 1

2-h Underpass section

2-g Urban section 2

2-f Open-air section (west)

2-e Open-air section (east)

2-d Open-air section (west)

2-c Urban section 3

2-b High-rise section 2

2-a Urban section 1

0%

Fig. 2-10 Measurement results for solar irradiation on September 25, 2018 (Day 2) in Sapporo(Comparison with reference) (Pyranometer: Secondary standard)19

23

Solar irradiation by section [Day 3]
 First run

Reference

Secondclass

Secondarystandard

Silicon type(8：09 to 9：21)
Sunny,
partly cloudy

1-a

1-b 1-c 1-d

1-e

1-f

1-g

 Second run

1-hReference

1-i

Secondclass

1-j

Silicon type

Secondarystandard(11：17 to 12：26)
Cloudy,occasionally
scattered showers

1-a

1-b 1-c 1-d

1-e

1-f

1-g

 Third run

1-hReference

1-i

Secondclass

1-jSecondarystandard

Silicon type(14:16 to 15:23)
Cloudy,occasionally
scattered showers
1-a

1-b 1-c 1-d

1-e

1-f

1-g

1-h

1-i

1-j

Fig. 2-11 Measurement results for solar irradiation on September 28, 2018 (Day 3) in Sapporo19
Table 2-13 Measurement results for solar irradiation on September 23, 2018 (Day 3) in Sapporo(Comparison with reference) (Pyranometer: Secondary standard)19
Sec.

1-a
1-b
1-c
1-d
1-e
1-f
1-g

First run
(8:09 to 9:21)(ratio to(Wh/m2)
referencepoint)

Second run
Third run
(11:17 to 12:26)(14:16 to 15:23)(ratio to ref(ratio to(Wh/m2)
erence po (Wh/m2)
referenceint)
point)

Type

Distance fromstart (km)Urban section 1

0.00 to 1.56

20.4

42.1%

14.8

84.6%

18.8

80.0%

1.56 to 2.90

15.0

24.0%

16.1

83.9%

24.8

42.0%

2.90 to 3.79

0.3

1.4%

0.2

7.1%

0.6

8.0%

3.79 to 4.19

4.7

70.1%

3.4

81.0%

1.8

78.3%

4.19 to 6.75

93.3

110.0%

17.2

117.0%

23.1

53.6%

6.75 to 8.85

60.6

159.5%

11.4

122.6%

8.8

45.6%

8.85 to 11.42

99.2

149.2%

46.5

116.3%

25.7

108.9%

High-rise section
1
UnderpasssectionUrban section 2
Open-air section(east)
Open-air section(west)
Open-air section(east)

1-h

Urban section 3

11.42 to 13.18

49.5

80.2%

36.5

129.4%

8.6

81.1%

1-i

High-rise section
2

13.18 to 16.13

53.7

43.2%

42

78.2%

8.3

34.4%

1-j

Urban section 1

16.13 to 17.69

13.8

41.6%

16.5

66.5%

0.0

0.0%

0.00 to 17.69

410.6

75.1%

204.6

95.5%

120.4

54.2%

Total

Measurement results of Day 3 [pyranometer: secondary standard]
160%
First run

Ratio: Car-roof/reference [%]140%

Second run

Third run

120%
100%
80%
60%
40%
20%
1-j Urban section 1

1-i High-rise section 2

1-h Urban section 3

1-g Open-air section (east)

1-f Open-air section (west)

1-e Open-air section (east)

1-d Urban section 2

1-c Underpass section

1-b High-rise section 1

1-a Urban section 1

0%

Fig. 2-12 Measurement results for solar irradiation on September 23, 2018 (Day 3) in Sapporo(Comparison with reference) (Pyranometer: Secondary standard)19

24

Solar irradiation by section [Day 4]
 First run

Reference

Secondclass

Silicon type

Secondarystandard(8：28 to 9：32)
Clear

2-a

2-b

2-c

2-d

2-e

2-f

 Second run

2-g 2-hReference

2-i

Secondclass

2-j

Silicon type

Secondarystandard(11：13 to 12：17)
Clear

2-a

2-b

2-c

2-d

2-e

2-f

 Third run

2-g 2-hReference

2-i

Secondclass

2-j

Silicon type

Secondarystandard(14:14 to 15:17)
Clear

2-a

2-b

2-c

2-d

2-e

2-f

2-g 2-h2-i2-jFig. 2-13 Measurement results for solar irradiation on October 19, 2018 (Day 4) in Sapporo19
Table 2-14 Measurement results for solar irradiation on October 19, 2018 (Day 4) in Sapporo(Comparison with reference) (Pyranometer: Secondary standard)19
First run
(8:28 to 9:32)(ratio to(Wh/m2)
referencepoint)

Second run
Third run
(11:13 to 12:17)(14:14 to 15:17)(ratio to ref(ratio to(Wh/m2)
erence po (Wh/m2)
referenceint)
point)

Type

Distance fromstart (km)2-aUrban section 1

0.00 to 1.56

40.7

43.3%

77.2

67.5%

21.5

67.2%

2-b

High-rise section
2

1.56 to 4.51

34.9

35.5%

109.6

70.7%

15.3

21.9%

Urban section 3

4.51 to 6.27

15.9

44.7%

48.3

97.2%

13.9

50.7%

6.27 to 8.37

27.7

97.5%

49.8

96.5%

10.5

45.7%

8.37 to 10.94

32.9

70.0%

55.5

91.3%

35.6

100.6%

10.94 to 13.04

37.4

99.2%

38.0

96.4%

12.4

45.8%

13.04 to 13.44

9.0

85.7%

8.5

85.9%

1.8

36.7%

13.44 to 14.32

1.4

8.0%

1.6

13.7%

0.4

9.3%

14.32 to 15.66

22.4

50.7%

9.2

15.2%

4.8

18.3%

15.66 to 17.22

9.2

24.3%

32.7

73.0%

5.0

25.3%

0.00 to 17.22

231.5

51.3%

430.6

72.0%

121.1

44.8%

Sec.

2-c
2-d
2-e
2-f
2-g
2-h
2-i
2-j

Open-air section(west)
Open-air section(east)
Open-air section(west)
Urban section 2
UnderpasssectionHigh-rise section
1
Urban section 1
Total

Measurement results of Day 4 [pyranometer: secondary standard]

Ratio: Car-roof/reference [%]160%
First run

140%

Second run

Third run

120%
100%
80%
60%
40%
20%
2-j Urban section 1

2-I High-rise section 1

2-h Underpass section

2-g Urban section 2

2-f Open-air section (west)

2-e Open-air section (east)

2-d Open-air section (west)

2-c Urban section 3

2-b High-rise section 2

2-a Urban section 1

0%

Fig. 2-14 Measurement results for solar irradiation on October 19, 2018 (Day 4) in Sapporo(Comparison with reference) (Pyranometer: Secondary standard)19

25

Solar irradiation by section [Day 5]
 First run

Reference

Secondclass

Silicon type

Secondarystandard(8：01 to 9：08)
Sunny

1-a

1-b 1-c 1-d

1-e

1-f

1-g

 Second run

1-h

1-i

Reference

Secondclass

1-j

Silicon type

Secondarystandard(11：24 to 12：27)
Clear

1-a

1-b 1-c 1-d

1-e

1-f

1-g

 Third run

1-h

1-i

Reference

Secondclass

1-j

Silicon type

Secondarystandard(14:12 to 15:15)
Clear

1-a

1-b 1-c 1-d

1-e

1-f

1-g

1-h

1-i

1-j

Fig. 2-15 Measurement results for solar irradiation on October 22, 2018 (Day 5) in Sapporo19
Table 2-15 Measurement results for solar irradiation on October 22, 2018 (Day 5) in Sapporo(Comparison with reference) (Pyranometer: Secondary standard)19
Sec.

1-a
1-b
1-c
1-d
1-e
1-f
1-g

First run
(8:01 to 9:08)(ratio to(Wh/m2)
referencepoint)

Second run(11:24 to 12:27)(ratio to(Wh/m2)
referencepoint)

Third run
(14:12 to 15:15)(ratio to(Wh/m2)
referencepoint)

Type

Distance fromstart (km)Urban section 1

0.00 to 1.56

19.2

52.6%

26.7

59.9%

12.7

49.2%

1.56 to 2.90

6.6

21.6%

21.3

37.6%

5.3

24.7%

2.90 to 3.79

0.2

3.1%

2.0

19.6%

0.3

5.5%

3.79 to 4.19

1.8

35.3%

13.8

85.7%

3.4

42.0%

4.19 to 6.75

34.8

85.9%

55.5

93.0%

25.6

99.6%

6.75 to 8.85

38.9

98.2%

50.1

97.7%

11.3

52.3%

8.85 to 11.42

40.3

84.8%

57.0

97.9%

29.3

97.3%

High-rise section
1
UnderpasssectionUrban section 2
Open-air section(east)
Open-air section(west)
Open-air section(east)

1-h

Urban section 3

11.42 to 13.18

18.6

71.8%

34.7

70.4%

11.6

45.1%

1-i

High-rise section
2

13.18 to 16.13

27.8

25.6%

44.3

31.4%

12.4

24.8%

1-j

Urban section 1

16.13 to 17.69

10.3

24.4%

11.9

29.2%

5.2

29.4%

0.00 to 17.69

198.4

51.8%

317.3

60.1%

117.2

50.5%

Total

Measurement results of Day 5 [pyranometer: secondary standard]
160%
First run

Ratio: Car-roof/reference [%]140%

Second run

Third run

120%
100%
80%
60%
40%
20%
1-j Urban section 1

1-i High-rise section 2

1-h Urban section 3

1-g Open-air section (east)

1-f Open-air section (west)

1-e Open-air section (east)

1-d Urban section 2

1-c Underpass section

1-b High-rise section 1

1-a Urban section 1

0%

Fig. 2-16 Measurement results for solar irradiation on October 22, 2018 (Day 5) in Sapporo(Comparison with reference) (Pyranometer: Secondary standard)19

26

Table 2-16 shows the ratio between total solar irradiation in every section (measured with a secondary
standard pyranometer) and irradiation at the reference point for the measurement results on Day 1 to Day 5.
On fine days, there was a tendency for a ratio of around 50% on the first and third runs and 70% on thesecond run. On cloudy days, the ratio was over 70% irrespective of time zone. This is thought to be due tocloudy days having a low solar intensity and a low amount of direct solar irradiation that could be shaded bybuildings or the like.
Table 2-16 Measurement results for solar irradiation in Sapporo (Comparison with reference:
Summary) (Pyranometer: Secondary standard)19

Day 1

Day 2

Day 3

Day 4

Day 5

Sep 20, 2018

Sep 25, 2018

Sep 28, 2018

Oct 19, 2018

Oct 22, 2018

First run

Second run

Third run(around 8:15 toaround 9:15)(around 11:15 toaround 12:15)(around 14:15 toaround 15:15)

Sunny

Sunny

Clear

Irradiation on vehicle roof

308.0 Wh/m2

462.5 Wh/m2

264.6 Wh/m2

Reference irradiation

564.2 Wh/m2

666.4 Wh/m2

462.2 Wh/m2

Vehicle roof/reference

54.6 %

69.4 %

57.2 %

Weather

Slightly cloudy

Slightly cloudy

CloudyIrradiation on vehicle roof

323.1 Wh/m2

336.9 Wh/m2

143.2 Wh/m2

Reference irradiation

444.5 Wh/m2

469.3 Wh/m2

196.8 Wh/m2

Vehicle roof/reference

72.7 %

71.8 %

72.8 %

Weather

Sunny,
partly cloudy

Cloudy,occasionally
scatteredshowers

Cloudy,occasionally
scatteredshowers

Irradiation on vehicle roof

410.6 Wh/m2

204.6 Wh/m2

120.4 Wh/m2

Reference irradiation

546.8 Wh/m2

214.3 Wh/m2

222.3 Wh/m2

Vehicle roof/reference

75.1 %

95.5 %

54.2 %

Weather

Clear

Clear

Clear

Irradiation on vehicle roof

231.5 Wh/m2

430.6 Wh/m2

121.1 Wh/m2

Reference irradiation

451.3 Wh/m2

598.1 Wh/m2

270.3 Wh/m2

Vehicle roof/reference

51.3 %

72.0 %

44.8 %

Weather

Sunny

Clear

Clear

Irradiation on vehicle roof

198.4 Wh/m2

317.3 Wh/m2

117.2 Wh/m2

Reference irradiation

382.7 Wh/m2

528.0 Wh/m2

232.0 Wh/m2

Vehicle roof/reference

51.8 %

60.1 %

50.5 %

Weather（4） Differences According to Pyranometer and Sampling Interval
Fig. 2-17 shows differences in ranking-based appearance frequency of falls according to the type of
pyranometer on the first day (September 20, 2018: sunny) and the third day (September 28, 2018: cloudy).
On Day 1 when the weather was clear, the tendencies of the overall appearance frequency are similar, but
the values produced by the silicon type tend to be slightly smaller. On the other hand, on Day 3 when it was27

cloudy, the differences due to the type of pyranometer used were small.
Table 2-17 shows the total solar irradiation in all route sections on September 20, 2018 (Day 1) for different
sampling intervals.
Although the relative magnitudes of the irradiation are the same for each sampling interval, a differenceof up to about 5% was observed between sampling intervals of 0.1 seconds to 1 minute. When identifying
the total irradiation in all route sections, the result does not greatly change even when the sampling interval
is set at one minute though, in order to observe short-cycle fluctuations caused by the shadows of buildings
and the like, it is necessary to use a pyranometer with a short sampling interval and a high response speed.
-

Day 1 (Sep 20, 2018)

Day 3 (Sep 28, 2018)-

First run

Secondclass

Second run

Secondclass

Third run

Secondclass

Silicon type

Secondarystandard(8：25 to 9：27)
SunnyFirst run

Secondclass

Silicon type

Secondarystandard

Second run

Secondclass

Silicon type

Secondarystandard

Third run

Secondclass

Silicon type

Secondarystandard(8：09 to 9：21)
Sunny,
partly cloudy

Silicon type

Secondarystandard(11：09 to 12：24)
Sunny(11：17 to 12：26)
Cloudy,occasionally
scattered showers

Silicon type

Secondarystandard(14:16 to 15:25)
Clear(14:16 to 15:23)
Cloudy ,occasionally
scattered showers

Fig. 2-17 Difference in ranking-based appearance frequency according to type of pyranometer formeasurements in Sapporo19
Table 2-17 Total Insolation in all route sections according to sampling interval on September 20,
2018 (Day 1) in Sapporo19
Sampling
interval

Secondarystandard (W/m2)

Second class(Wh/m2)

Silicon type(Wh/m2)First

0.1 sec.

308.0

298.6

302.8

run

1 sec.

308.6

298.8

302.9

10 sec.

299.5

289.7

293.1

1 minute

311.1

301.5

306.8

Second

0.1 sec.

465.8

472.9

448.9

run

1 sec.

467.2

473.6

449.9

10 sec.

464.4

466.6

449.6

1 minute

472.0

486.3

442.8

Third

0.1 sec.

264.6

264.2

246.9

run

1 sec.

265.1

264.4

247.1

10 sec.

271.5

270.5

251.9

1 minute

280.6

276.2

264.3

28

2.3.2. Measurement Results in Miyazaki City, Miyazaki Prefecture（1） Measurement Conditions and Measurement RouteThe measurement conditions in Miyazaki are shown in Table 2-18. In Miyazaki, measurements were taken
on four days between September 13, 2018 and October 1, 2018. Solar irradiation acquired by a vehicle isinfluenced by the shadows of surrounding buildings and the like. Since it was assumed that this influence
depends on solar elevation, measurements were taken three times a day in different time zones on two out of
the four days.
To identify the fall in solar irradiation due to shadows and the like, comparisons were performed with theinsolation at a reference point (the rooftop of a University of Miyazaki building). The insolation and solar
elevation at the reference point on the date of measurement are shown in Fig. 2-18, as well as for the vehicle
roof and side surfaces (the average of four directions).
Table 2-8 Measurement dates in Miyazaki 20
Date of Measurement

RouteFirst run(around 9:00 to
10:00)

Second run(around 11:30 to12:30)

Third run(around 15:00 to
16:00)

Sep. 13, 2018 (Thu.)

Anticlockwise

√

√

√

Sep. 16, 2018 (Sun.)

Anticlockwise

√

√

√

Sep. 22, 2018 (Sat.)

Anticlockwise

-

√

-

Oct. 1, 2018 (Mon.)

Anticlockwise

-

√

-

<Sep. 13, 2018><Sep. 16, 2018>
Elevation

Solar irradiation [W/m2]

Elevation

Solar elevation [degree]<Oct. 1, 2018>
Elevation

Solar elevation [degree]

Solar irradiation [W/m2]<Sep. 22, 2018>

Solar elevation [degree]

Solar irradiation [W/m2]

Solar elevation [degree]

Solar irradiation [W/m2]

Elevation

Fig. 2-18 Solar irradiation at University of Miyazaki (reference point)20
Fig. 2-19 shows the route of travel in Miyazaki. The route included an urban section (a residential area), a
high-rise section (commercial buildings and a downtown area), and an open-air section, and it was assumed
that measurements in the urban section and the high-rise section would be affected by surrounding buildings,
and also assumed that the same effects would be less likely in the open-air section.
29

High-rise section

MiyazakistationUrban section
Open-air section

N

Univ. ofMiyazaki

2 km

Fig. 2-19 Route used for measurement in Miyazakicreated from 18（2） Characteristics of Solar Irradiation According to Route Section
Based on the measurement results on September 16, 2018 (Day 2), measurements corresponding to theurban section (residential area: one lane in each direction), a high-rise section (with commercial buildings
and a downtown area: three lanes in each direction) and an open-air section (two lanes in each direction) (theparts marked with red lines in Fig. 2-19) were extracted, and the features of these measurements weresummarized.
<Urban section: Residential area>
Table 2-19 and Fig. 2-20 show the measurement results for solar irradiation on the vehicle roof and vehicle
sides (the value for the sides is an average of four directions) in the urban section (residential area). Although
the measurement periods were short at two to four minutes, vehicle roof solar irradiation relative to irradiation
at the reference point was high at 92.0% in the morning (9:40-9:42) (First run) and 83.6% at mid-day (12:1712:21) (Second run), which shows that there was little loss due to the shadows of buildings, trees, and power
poles along the road. On the other hand, the ratio was rather low at 62.5% during the afternoon (15:48-15:51)(Third run).
As shown in Fig. 2-20, there were large falls in solar irradiation for 30 to 40 seconds during 12:20 to 12:21
and 15:49 to 15:51, resulting in reduced ratios to the reference. Although this is thought to be caused by the
shadows of buildings, when the vehicle is stopped at an intersection or the like, the effect of shadows willcontinue for several tens of seconds.
Fig. 2-21 shows measurement results of the solar irradiation on the sides of the vehicle. The timing at
which the falls in solar irradiation were observed were the same as for the roof of the vehicle. When thevehicle is driving on a south-to-north road, insolation is high on the east side (mainly the left side of thevehicle) in the morning, the south side (mainly the front of the vehicle) at mid-day, and the west side (mainly
the right side of the vehicle) in the afternoon, with a characteristic that solar irradiation is a similar level tothe vehicle roof in the morning and afternoon. The average solar irradiation in the four directions was 35%of the vehicle roof in the morning, 25% at mid-day, and around 67% in the afternoon.

30

Table 2-19 Measurement results for solar irradiation of vehicle roof in urban section on
September 16, 2018 in Miyazaki20
Vehicle roof

Side irradiation

Irradiation at

Ratio of vehicle roof

time zone

irradiation(average of fourreference

irradiation to(car-roof)sides)(rooftop: fixed)

reference

9:40 – 9:42

23 Wh/m2

8 Wh/m2

25 Wh/m2

92.0 %

12:17 – 12:21

51 Wh/m2

13 Wh/m2

61 Wh/m2

83.6 %

15:48 – 15:51

15 Wh/m2

10 Wh/m2

24 Wh/m2

62.5 %

Solar irradiation [W/m2]

Solar irradiation [W/m2]

Solar irradiation [W/m2]

Solar irradiation [W/m2]

Solar irradiation [W/m2]

Solar irradiation [W/m2]

Measurement

Front

Right

Rear

Left

Front

Right

Rear

Left

Front

Right

Rear

Left

Fig. 2-20 Measurement results for solar

Fig. 2-21 Measurement results for solar

irradiation of vehicle roof in urban section on

irradiation of vehicle roof in urban section on

September 16, 2018 in Miyazaki20

September 16, 2018 in Miyazaki20<High-rise section: Commercial buildings and downtown Area>
In the high-rise section (commercial buildings and downtown area), the vehicle traveled from east to west
and then north to south on roads in the east-west direction and then north-south direction. Table 2-20 shows
the measurement results for the solar irradiation on the vehicle roof and sides (the value for the sides is theaverage in four directions) in the high-rise section. The measurement periods were short at two to four
minutes, but vehicle roof insolation relative to insolation at the reference point was 73.9% in the morning(9:22-9:24) (First run), 63.1% at mid-day (11:58-12:02) (Second run), and 58.8% in the afternoon (15:2915:33) (Third run).
Fig. 2-22 shows the measurement results of the solar irradiation on the vehicle roof. During the morning
run, falls in solar irradiation that can be attributed to shadows were observed for both travel from east to west
31

(A to B) and travel from north to south (B to C), with a larger fall being observed for travel from north tosouth (B to C). During the mid-day run, for travel from east to west (A to B), there was a continuous fall insolar irradiation which is attributable to the influence of buildings on the south side of the road. During travelfrom north to south (B to C) however, there was almost no falls in solar irradiation, and instead a tendency
for insolation to exceed insolation at the reference point. On the afternoon run, insolation was high whentraveling from east to west (A to B).
Fig. 2-23 shows the measurement results of the solar irradiation on the vehicle sides. The timing of falls
in solar irradiation coincided with the roof of the vehicle. During the morning run, solar irradiation was highon the rear (the east side of the vehicle) in the section from east to west (A to B) and on the left side of thevehicle in the section from north to south (B to C). Both were a similar level to solar irradiation on the vehicle
roof. During the mid-day run, no insolation was acquired except by the left side (south side) of the vehicle in
the first half of the section from east to west (A to B) due to a prominent effect of buildings and the like along
the road. On the other hand, insolation was high on the front of the vehicle in the section from north to south(B to C) reaching a similar level to the vehicle roof. During the afternoon run, solar irradiation was high on
the front (west) and left (south) sides of the vehicle when traveling from east to west (A to B), with solar
irradiation on the front of the vehicle exceeding the solar irradiation on the vehicle roof. The average solar
irradiation in the four directions was 41% of the vehicle roof in the morning, 28% at mid-day, and around
55% in the afternoon.
Table 2-20 Measurement results for solar irradiation of vehicle roof in high-rise section on
September 16, 2018 in Miyazaki 20
Measurement

Vehicle roof

Side irradiation

Irradiation at

Ratio of vehicle roof

time zone

irradiation(average of fourreference

irradiation to(car-roof)sides)(rooftop: fixed)

reference

9:22 – 9:24

17 Wh/m2

7 Wh/m2

23 Wh/m2

73.9 %

11:58 – 12:02

48 Wh/m2

13 Wh/m2

76 Wh/m2

63.1 %

15:29 – 15:33

20 Wh/m2

11 Wh/m2

34 Wh/m2

58.8 %

32

A

B

B

C

Solar irradiation [W/m2]

C

Front

C

Right

B

C

Front

Right

Rear

Left

Front

Right

Rear

Left

A

A

Left

Rear

A

Solar irradiation [W/m2]

A

B

Solar irradiation [W/m2]

Solar irradiation [W/m2]
Solar irradiation [W/m2]

Solar irradiation [W/m2]

A

B

B

C

C

Fig. 2-22 Measurement results for solar

Fig. 2-23 Measurement results for solar

irradiation of vehicle roof in high-rise section

irradiation of vehicle roof in high-rise section

on September 16, 2018 in Miyazaki20

on September 16, 2018 in Miyazaki20<Open-air section>
Table 2-21 shows the measurement results for solar irradiation on the vehicle roof and sides (the value forthe sides is an average of four directions) in an open-air section. The measurement periods were short at two
to four minutes, but vehicle roof solar irradiation relative to insolation at the reference point was extremely
high at 95.2% in the morning (9:05-9:07) (First run) and 96.7% at mid-day (11:31-11:35) (Second run).
Fig. 2-24 shows the measurement results of the solar irradiation on the vehicle roof. Although fluctuations
attributable to shadows of trees and power poles along the road were sometimes observed, the loss in solar
irradiation was extremely small. On the other hand, a tendency for solar irradiation on the vehicle roof toexceed insolation at the reference point was barely observed, and it is thought that this tendency observed inurban sections and high-rise sections is due to the influence of reflections from surrounding buildings. During
the afternoon run (15:04-15:08) (Third run), the ratio of solar irradiation on vehicle to the irradiation at thereference point was 124%. This is believed to be due to the reference point being cloudy while the route oftravel was fine.
Fig. 2-25 shows the measurement results of the solar irradiation on the vehicle sides. The timing of falls
in solar irradiation coincided with the roof of the vehicle. Insolation was high on the right (east) side of thevehicle during the morning run and on the left (west) side of the vehicle during the afternoon run, andexceeded the solar irradiation on the vehicle roof and at the reference point. The average amount of solar
irradiation in the four directions was 50% of the roof in the morning and afternoon, and around 28% at midday.

33

Table 2-21 Measurement results for solar irradiation of vehicle roof in open-air section on
September 16, 2018 in Miyazaki20
Vehicle roof

Side irradiation

Irradiation at

Ratio of vehicle roof

time zone

irradiation(average of fourreference

irradiation to(car-roof)sides)(rooftop: fixed)

reference

9:05 – 9:07

20 Wh/m2

10 Wh/m2

21 Wh/m2

95.2 %

11:31 – 11:35

58 Wh/m2

16 Wh/m2

60 Wh/m2

96.7 %

15:04 – 15:08

41 Wh/m2

20 Wh/m2

33 Wh/m2

124.2 %

Solar irradiation [W/m2]

Solar irradiation [W/m2]

Solar irradiation [W/m2]

Solar irradiation [W/m2]

Solar irradiation [W/m2]

Solar irradiation [W/m2]

Measurement

Front

Right

Rear

Left

Front

Right

Rear

Left

Front

Right

Rear

Left

Fig. 2-24 Measurement results for solar

Fig. 2-25 Measurement results for solar

irradiation of vehicle roof in open-air section

irradiation of vehicle roof in open-air section

on September 16, 2018 in Miyazaki20

on September 16, 2018 in Miyazaki 20

34

（3） Comparison between Solar Irradiation on Vehicle and at the Reference Point
The results of measurements taken on four days (three times daily on two days, and once a day on theremaining two days) in Miyazaki are given here.
Table 2-22 shows solar irradiation on the vehicle roof and side surfaces (the value for the side surfaces isan average of four directions) for all sections of travel and the ratios with the irradiation at a reference point.
The values are cumulative solar irradiation for a route including an urban section, a high-rise section, and an
open-air section. Figs. 2-26 to 2-29 are charts of measurement results for solar irradiation on the vehicle roof
and side surfaces (the value for the side surfaces is an average of four directions).
The weather was fine on Day 2 (September 16, 2018), if a little cloudy in the afternoon. Day 1 (September
13, 2018) was very cloudy, with very little solar irradiation in the afternoon. Out of these two days, the ratioof the solar irradiation to irradiation at the reference point was 87.5 to 92.4% for the vehicle roof on thesecond day, so only slightly lower than the reference point. On the first day, solar irradiation on the vehicle
roof exceeded the reference point. Regarding the solar irradiation on the side surfaces of the vehicle, the ratio
was higher on the first day. Although there is the possibility that there were different cloud conditions between
the reference point and the route of travel, the presence of less direct irradiation and more diffuse irradiationis also believed to be a factor. In addition, the ratio with the reference point was lower on the second run (atmid-day) compared to the morning and afternoon. It is presumed that the greater difference on the second
day was due to a difference in solar elevation.
Regarding the measurement of solar irradiation at mid-day, it was cloudy on Days 1 and 3 but fine on Days
2 and 4. On Days 2 and 4, there were falls in solar irradiation (short period fluctuations) that would appear
to be shadows of buildings, trees, power poles, and the like along the road, but the ratio of solar irradiationon the vehicle roof to the reference point was 87.5% and 92.0% on the two days, indicating that there waslittle loss due to shadows. There were also times where the solar irradiation on the vehicle roof exceeded theinsolation at the reference point. There is the possibility that this was due to reflections from surrounding
buildings and the like, but since the conditions may have differed between the reference point and the routeof travel, it is not possible to make any definite judgment on this. The solar irradiation on the vehicle sides
was below 30% of the reference point on Days 2 and 4 when the weather was clear. There was also a tendency
that when the ratio of the solar irradiation on the vehicle roof to the irradiation at the reference point was low,
the ratio for the vehicle sides was also low.

35

Table 2-22 Measurement results for solar irradiation in Miyazaki (Comparison with reference:
Summary)20

Day 1

Sep. 13, 2018

First run

Second run

Third run(around 9:00 to(around 11:30 to(around 15:00 toaround 10:00)

around 12:30)

around 16:00)

404 Wh/m2

393 Wh/m2

88 Wh/m2

169 Wh/m2

146 Wh/m2

36 Wh/m2

346 Wh/m2

329 Wh/m2

51 Wh/m2

Vehicle roof/reference

114.3 %

118.2 %

180.0 %

Vehicle sides/reference

48.8 %

44.4 %

70.6 %

617 Wh/m2

775 Wh/m2

450 Wh/m2

258 Wh/m2

205 Wh/m2

243 Wh/m2

659 Wh/m2

879 Wh/m2

459 Wh/m2

Vehicle roof/reference

92.4 %

87.5 %

91.8 %

Vehicle sides/reference

39.2 %

23.3 %

52.9 %

Vehicle roof solar
irradiation
Vehicle side surface
solar irradiation
Irradiation at reference
point

Day 2

Sep. 16, 2018

Vehicle roof solar
irradiation
Vehicle side surface
solar irradiation
Irradiation at reference
point

Day 3

Sep. 22, 2018

Vehicle roof solar

578 Wh/m2

irradiation
Vehicle side surface

203 Wh/m2

solar irradiation
Irradiation at reference

613 Wh/m2

point

Day 4

Oct. 1, 2018

Vehicle roof/reference

95.1 %

Vehicle sides/reference

33.1 %

Vehicle roof solar

804 Wh/m2

irradiation
Vehicle side surface

248 Wh/m2

solar irradiation--

Irradiation at reference
867 Wh/m
point
Vehicle roof/reference

92.0 %

Vehicle sides/reference

28.6 %

362

Solar irradiation [W/m2]

Solar irradiation [W/m2]

Solar irradiation [W/m2]

Fig. 2-26 Measurement results for solar irradiation of vehicle on September 13, 2018 (Day 1) in

Solar irradiation [W/m2]

Solar irradiation [W/m2]

Solar irradiation [W/m2]

Miyazaki20

Fig. 2-27 Measurement results for solar irradiation of vehicle on September 16, 2018 (Day 2) inSolar irradiation [W/m2]

Solar irradiation [W/m2]

Miyazaki20

Fig. 2-28 Measurement results for solar

Fig. 2-29 Measurement results for solar

irradiation of vehicle on September 22, 2018

irradiation of vehicle on October 1, 2018 (Day(Day 3) in Miyazaki204) in Miyazaki20

Fig. 2-30 shows the solar irradiation on the vehicle side surfaces per direction on Day 2 (September 16,2018) when the weather was fine. Fig. 2-31 is the measurement results on Day 3 (September 22, 2018) which
was intermittently cloudy.
As with the roof of the vehicle, falls in solar irradiation (short-period fluctuations) believed to be shadows
were frequently observed, with different behavior depending on the relationship between the solar orientationand the direction of the road (the direction of travel) and for each side surface (the front, rear, left, and rightof the vehicle). On Day 2, there were prominent changes in solar irradiation in each direction that
accompanied changes in the direction of travel. On the other hand, on Day 3, although measurement was
only performed at mid-day, in the latter half of the measurement period, there was little difference ininsolation between the different directions, which is believed to be due to a fall in direct solar irradiation
caused by clouds.

37Front

Right

Back

Left

Front

Right

Back

Left

Front

Right

Back

Left

Fig. 2-30 Measurement results for solar irradiation of vehicle sides on September 16, 2018 (Day2) in Miyazaki20
Front

Right

Back

Left

Fig. 2-31 Measurement results for solar irradiation of vehicle sides on September 22, 2018 (Day3) in Miyazaki20

38

3.

Conclusion
In this report, as a preliminary study on solar irradiation of a PV-powered vehicle, the solar irradiationacquired by a traveling vehicle was measured, the characteristics and tendencies of such irradiation wereidentified, and the result of a comparison with irradiation at a reference point (a roof or rooftop of a building
with favorable insolation) has been shown.
The characteristics of solar irradiation acquired by a vehicle and future issues that have been suggested bythis trial measurement are given below.
3.1.

Characteristics of Solar Irradiation of a Vehicle

The solar irradiation on a vehicle roof and on vehicle side surfaces has the following characteristics.
（1） Horizontal Solar Irradiation on Vehicle Roof-

Shadows are occurred by buildings, trees, power poles, and the like along the road, so thatcompared to the reference point, solar irradiation falls in corresponding locations and sections.

-Shadows are occurred by buildings frequently in high-rise sections and intermittently in urban
sections. Although infrequent, shadows are also occurred in open-air sections.

-Due to shadows from buildings and the like, fluctuations in insolation were occurred in
extremely short cycles (several hundred W/m2 in 0.1 seconds).

-

Although the solar intensity has a similar level to the reference point in sections with noshadows, there is a fall of around 50 to 100W/m2 in sections where shadows are occurred, withthe range of fluctuations in solar irradiation increasing as solar elevation increases.

-

The fall in cumulative solar irradiation depends on the length of the period where shadows
occur. This was longest in the high-rise section and shortest in the open-air section, with theurban section in between.

-

Although the buildings along the road may cast shadows across the entire vehicle roof, shadows
produced by trees and power poles do not cover the entire roof and correspond to partial
shading.

-

The occurrence of shadows on the vehicle largely depends on the relationship between the
direction of the road (the direction in which the vehicle travels) and the orientation of the sun,and when these almost match, the influence of shadows is small, even in a high-rise section.

-

The occurrence of shadows on the vehicle by buildings along the road is thought to be
influenced by road width and the lane in which the vehicle is traveling.

-

In high-rise sections and urban sections, solar irradiation at the vehicle may exceed irradiation at
the reference point. It is believed that solar irradiation may increase due to reflections frombuildings along the road.

（2） Insolation on Vehicle Sides-

Shadows are occurred by buildings, trees, and power poles along the road, and as with the roofof the vehicle, there is a fall in solar irradiation in corresponding locations and sections.

39-

Solar irradiation and the occurrence of shadows on the vehicle greatly depend on therelationship between the solar orientation and the direction of the road. Surfaces that face theorientation of the sun (one or two out of the front, rear, left, and right of the vehicle) are hardly
affected by shadows of buildings and the like along the road, but other surfaces will receive no
direct solar irradiation and irradiation is low.

-

The surface(s) where insolation is high will change as the direction in which the vehicle istraveling changes.

-

Although the average value (per square meter) of solar irradiation in the various directions issmaller than the vehicle roof, the solar irradiation of the surface facing the sun may exceed thesolar irradiation on the vehicle roof when the solar elevation is low.

-

In high-rise sections and urban sections, it is believed that solar irradiation increases due toreflections from buildings along the road. In open-air sections also, it is believed that solar
irradiation increases due to reflections from the surroundings.

3.2.

Future Issues

Data on solar irradiation acquired by a vehicle is a first step or gateway toward the use of PV in automobiles
and is vital information for evaluating the significance and effect of mounting a PV system. It is also
important for the design and operation of a control system for using generated power as power for driving
the vehicle.
This preliminary study, a trial that measured the solar irradiation of a vehicle, was conducted at limited
locations and times, and has therefore produced fragmentary data. Although it would not be appropriate to
make generalizations on the characteristics of the solar irradiation acquired by a vehicle or to conduct
quantitative evaluations into the expected level of generated power from only the results given here, thefollowing characteristics and trends were observed as indicated in Section 3.1 above.
-

Shadows of buildings, trees, power poles, and the like occur, causing a fall in solar irradiation in
affected locations and sections.

-Shadows occurred by a building or the like may cover an entire surface, such as the vehicle roof,
or may only partially shade the surface.

-

Due to reflections from buildings and the like, the solar irradiation by a vehicle in somelocations and sections may exceed the insolation on a roof or rooftop of a building.

-

Fluctuations in solar irradiation due to shadows and reflections often occur with very shortcycles (less than 0.1 seconds).

Although it is considered necessary to expand and enhance this research and measurement toward the fullscale development and adoption of PV-powered vehicles, to conduct such activities efficiently, it is also
necessary to predict in advance how such data will be used.
（1） Enhancement of Research and Data Measurement
Table 3-1 shows examples of data desired from further research and measurement.
In this trial measurement, measurement was performed for solar irradiation in the fall (September to
October) at two locations in Japan only. However, data on different regions and different seasons with other40

irradiation characteristics, data on solar irradiation and temperature conditions in various driving
environments, and data on the output and/or current of PV cells or modules is also considered necessary. Insuch studies, to understand the occurrence and influence of partial shading, it is believed effective to measuresolar irradiation at multiple points on the vehicle roof (as examples, the four corners and the center) and toanalyze images of the sky.
Although the sampling interval was set at 0.1 seconds and at 1 second for the measurements in this study,
it may be necessary to measure at even shorter intervals (that is, intervals shorter than 0.1 seconds) to estimate
power generation with highly accuracy and reflect real-life conditions in system design (such as MPPT forfluctuations in solar radiation). To perform such high-precision data measurement, system performance, suchas the response speed of the pyranometer, also becomes important.
Table 3-1 Examples of enhanced research and measurements
Expansion of-

measurement
locations and times

Regions with different irradiation characteristics(geographical conditions)-Different seasons (summer, winter, etc.)-

Various driving environments (different regions ofuse)-

Various time zones

Data that contributes-

Temperature conditions

to estimation of power-

Output, current, or the like of PV cells or modules-

Measurement at multiple points on the vehicle

generated by PV
Improving precisionroof (such as the four corners and the center)-

Analysis of sky images-

Measurement with sampling intervals shorter
than 0.1 seconds（2） Utilization of Enhanced Research and Data Measurement
Table 3-2 shows conceivable methods of using the data described above. The necessary precision andresolution of the data produced by enhanced research and measurement may differ according to how the datais to be used, and there are cases where instantaneous values are required at the sampling interval, and cases
where values produced by integration for a certain period are required.

41

Table 3-2 Example of methods of using solar irradiation of vehicle
Creation of detailed power

Insolation and generated power based on instantaneous values,

generation estimation

spectrum analysis, etc.

model in keeping with solar- Reflection in the design of 3D modules for mounting on vehicles

irradiation characteristics- Reflection in design of control system for MPPT or the like(instantaneous values)
Estimation of areal potential

Creation of potential map

based on cumulative solar- Data such as solar irradiation, generated power, ratio to roof or

irradiation

rooftop irradiation- One-hour values, for each travel section, each direction, etc.
Analysis based on map data, combining with actual measurements

Estimation of power

Estimation of power generating potential through combination withgenerating potential of avehicle travel and usage patterns

PV-powered vehicle

Derivation of generated power as a model according to typical travel
and usage patterns

Analysis of effects of PVpowered vehicles

Identify effects (potential) based on the generated power- Energy savings, reduction in CO2 emissions, reduction in cost ofelectrical charging, etc.
Identify real-world effects by combining with vehicle travel data
- Contribution of PV system based on comparison with power
consumption data of vehicle- Reductions in energy consumption, CO2 emissions, etc.
- Reduction in charging frequency

Reflection in expected and

Set target levels such as coversion efficiency and cost required torequired levels for PV

realize and enhance the effect of installing a PV systemsystems

To create a detailed power generation estimation model in keeping with solar irradiation characteristics,
calculation of solar irradiation and generated power based on instantaneous values and spectrum analysis are
believed necessary. This is expected to be beneficial when designing 3D modules for mounting on vehicles
and designing a control system for MPPT. When doing so, it is also necessary to clarify the purpose ofcreating and using the model and to investigate the sampling interval required to produce solar irradiation
amounts based on instantaneous values.
On the other hand, evaluation of potential based on cumulative solar irradiation is performed to identify
the solar irradiation that can be acquired by PV-powered vehicles on a nationwide scale. It would beconceivable to estimate based not only on direct measurements of solar irradiation and generated power, butalso in combination with an existing solar irradiation database or analysis that uses map data. Here, it isdesirable to prepare data in hourly units or data on each section of the route (by each usage region etc.), andto reflect data and characteristics for each road direction. It is also desirable to verify the estimated values

42

(against actual measurements) whenever possible.
Evaluation of the power generation potential of a PV-powered vehicle makes use of the power generation
estimation model or the results of evaluating potential based on solar irradiation, and seeks to evaluate thegenerated power of a vehicle that is actually moving. The solar irradiation and power generated by a PVpowered vehicle will change depending on the travel and usage pattern of the vehicle, but by assuming atypical driving and usage pattern, there is a goal of deriving generated power as the standard specification
and a model for analyzing effects of a PV-powered vehicle.
Based on the generated power, it will be possible to analyze the reduction in energy consumption, the effectin reducing CO2 emissions, and the effect in reducing the cost of charging as the effects of a PV-powered
vehicle. By combining this data with vehicle driving and usage data (such as the power consumed by driving)on actual roads, it will be possible to make the effect of installing a PV system more persuasive to users.
It is believed that the results of these evaluations and analysis of effects could lead to the setting of targets
for conversion efficiency and cost that are necessary to realize the installation of PV systems and increase
the effect. These targets are levels that are expected to PV installed on vehicles.
To achieve full-scale adoption and expansion of PV-powered vehicles, in addition to the evaluations andanalysis of effects described above, it is necessary to identify technical issues encountered when using PV aspart of a car body and to work toward solutions. These issues include improving PV efficiency, compatibility
with curved surfaces, maintaining and improving reliability and safety, and control in keeping with battery
specification and charging state.
In addition to being means of transport capable of generating their own power using solar energy, PVpowered vehicles can also be regarded as extremely small-scale (around 1kW or less) movable sources of
distributed power. There are also hopes for PV-powered vehicle use in highly flexible applications that
support regions and communities, such as compatibility with changing power needs with the rollout of IoT
and introduction of self-driving cars, diversification of modes of travel and transport, and usage as
independent power supplies during natural disasters. It is therefore important for studies into the effects andvalue of PV-powered vehicles to also include the effects and value of PV-powered vehicles for regions andsociety.
3.3.

Future Initiatives

To solve the above issues, we will continue to conduct studies on PV-powered vehicles.
In addition to identifying technical problems, gathering the required data and evaluating benefits throughthe activities of NEDO, we will support IEA PVPS Task17 to expand activities on an international scale.

43

PV-Powered Vehicles Strategy Committee<List of committee members (as of 31 March 2019: the end of FY2018)>
Chair of
Masafumi Yamaguchi Professor Emeritus, Senior Research Scholar, Research Center
committee
for Smart Energy Technology, Toyota Technological Institute,Japan
Committee
memberYuzuru Ueda

Associate Professor, Department of Electrical Engineering,
Faculty of Engineering, Tokyo University of Science, Japan

Akinori SatoGroup Manager, Energy Group No.2, F Mobility Infrastructure
Research Dept., S-Frontier Dev., Frontier Research Center,
TOYOTA MOTOR CORPORATION, Japan

Yusuke Zushi

Ph.D., Manager, EV System Laboratory, Research Division,
Nissan Motor Co., Ltd., Japan

Tatsuya Takamoto

Ph.D., Division Manager, Compound Business Promotion
Division, Business Solutions BU, Sharp Corporation, Japan

Toshio Hirota

Ph.D., Guest Professor, Environmental Research Institute,
Waseda University, Japan

SpecialCooperation

Japan Weather Association

Secretariat

Hiroyuki Yamada

Ph.D., Director, Solar Energy Systems, New Energy Technology
Development, New Energy and Industrial Technology
Development Organization, Japan

Mami Hasegawa

Chief Officer, Solar Energy Systems, New Energy Technology
Development, New Energy and Industrial Technology
Development Organization, Japan

Keiichi Komoto

Senior Consultant, Environment and Energy Division 2, Mizuho
Information & Research Institute, Inc., Japan

Shouhei Namikawa

Chief Consultant, Environment and Energy Division 2, Mizuho
Information & Research Institute, Inc., Japan

Takafumi Sato

Consultant, Environment and Energy Division 2, Mizuho
Information & Research Institute, Inc., Japan

University of Miyazaki<Schedule of committee meeting>
7th meeting: 9 November 2017

8th meeting: 8 February 2018

9th meeting: 5 November 2018th meeting10: 5 February 201944

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IEA, Global EV Outlook 2018

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IEA, World Energy Outlook 2017

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C. Breyer, et al., Solar Photovoltaic Capacity Demand for a Sustainable Transportation Sector to Fulfil

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Energy Source”, OYO BUTURI Vol. 88, No. 2, 20198

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Waikoloa, Hi, USA, Jun. 201810

U. Eitner, et al., Solar Potential on Commercial Trucks: Results of an Irradiance Measurement Campaign

on 6 Trucks in Europe and USA, 34th EU-PVSEC, Amsterdam, the Netherlands, Sep. 201711https://ecohd.jp/pdf/idling-stop.pdf (accessed on 25 March 2019)12https://pps-net.org/column/19534 (accessed on 25 March 2019)13

M. Nakaoka, et al., Towards New Mobility Society by Using Solar Energy, 27th PVSEC, Otsu, Japan,

Nov. 201714

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15

K. Komoto, Realizing PV-Powered Mobility ‘PVPS Task17: PV and Transport’, Solar Mobility Forumat the 35th EU-PVSEC, Brussels, Belgium, Sep. 201816

IEA PVPS Task17 Workplan ver 3.3.4, October 201817

NEDO, PV-Powered Vehicle Strategy Committee Interim Report, January 201818

Ministry of Land, Infrastructure, Transport and Tourism, Geospatial Information Authority of Japan, GSI

Maps (Electronic Land web)(In Fig. 2-1, geographic point names have been added to an outline map from GSI Maps (Electronic Landweb), in Fig. 2-3 the route of travel has been added to the relevant region map from GSI Maps (Electronic
Land web). In Fig. 2-19, the route of travel and photographs have been added to a region map from GSI
Maps (Electronic Land web))19

Data provided by Japan Weather Association (general incorporated foundation), November 201820

Data provided by University of Miyazaki (national university corporation), October 201845