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Innovation for Our Energy Future 

The Role of Polycrystalline 

Thin-Film PV Technologies in 

Competitive PV Module Markets 

Preprint 

B. von Roedern and H.S. Ullal 

National Renewable Energy Laboratory 

Presented at the 33rd IEEE Photovoltaic Specialists Conference 

San Diego, California 

May 11–16, 2008 

Conference Paper 

NREL/CP-520-42494 

May 2008 

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The Role of Polycrystalline Thin-Film PV Technologies in 

Competitive PV Module Markets 

Bolko von Roedern and Harin S. Ullal 

National Center for Photovoltaics, National Renewable Energy Laboratory 

1617 Cole Boulevard, Golden, CO 80401-3393 USA 

ABSTRACT 

This paper discusses the developments in thin-film 

PV technologies. It provides an outlook on future 

commercial module efficiencies achievable based 

on today’s knowledge about champion cell 

performance. It also provides a relative cost 

comparison of thin-film and wafer/ribbon based Si 

PV modules. In 2007, about 65% of the modules 

produced in the US were thin-film modules when 

amorphous silicon modules are also considered. 

INTRODUCTION 

This paper updates a methodology presented 

at the 31st IEEE PVSC Conference (2005) [1]. 

Different PV flat-plate technologies are compared 

on the basis of verified champion cell efficiencies; 

projections are made for commercial module 

efficiencies estimating that they will be proportional 

to verified best solar cell efficiencies. We will also 

review the technical issues affecting performance 

and commercialization of polycrystalline thin film PV 

modules. 

We update our semi-empirical methodology of 

comparing verified stabilized best or “champion” 

solar cell data with performance achieved on 

commercial manufacturing lines [2], estimating the 

performance and cost developments for future 

successful PV module candidates. Table 1 is 

compiled from a survey of manufacturer’s websites 

in April 2008. The 5th column in Table 1 indicates 

the c/c ratio, i.e., the ratio of respective module and 

best cell efficiency, where cell numbers given in 

Ref. 2 are used. 

Table 1: Module Efficiency from survey of manufacturers’ websites and “Performance Ratios [3]” 

Eff. 

(%) Module T.coeff. 

(power) Technology Current c/c performance

ratio cell/module 

19.3 SunPower 315 -0.38 %/C mono-Si, special junction 

(sp. j.) 78% 

17.4 Sanyo HIP-205BAE -0.30 %/C CZ-Si, “HIT,” sp. j. 70% 

15.1 BP7190 -0.5 %/C CZ-Si, sp. j. 61% 

14.2 Kyocera KC200GHT-2 n/a MC-Si, standard junction 

(std. j.) 70% 

14.2 Solar World SW 185 n/a CZ-Si, std. j. 70% 

14.2 BP SX3200 -0.5 %/C MC-Si, std. j. 70% 

13.4 Suntech STP 260S-24V/b n/a MC or CZ-Si, std. j. 66% 

13.4 Solar World SW 225 n/a MC-Si, std. j. 66% 

13.1 Evergreen Solar ES 195 (up to)-0.5%/C String-ribbon-Si std. j. 65% 

11.0 WürthSolar WS11007/80 -0.36%/C CIGS 55% 

10.4 First Solar FS-275 -0.25%/C CdTe 63% 

 8.5 Sharp NA-901-WP -0.24%/C a-Si/nc-Si 70% 

 8.1 GSE Solar GSE120-W -0.5%/C CIGS 41% 

 6.3 Mitsubishi Heavy MA100 -0.2 %/C a-Si, single-junction 66% 

 6.3 Uni-Solar PVL136 -0.21 %/C a-Si, triple junction 52% 

6.3 Kaneka T-SC(EC)-120 n/a a-Si single junction 66% 

5.9 Schott Solar ASI-TM86 -0.20%/C a-Si/a-Si same bangdgap 

tandem 62% 

5.3 EPV EPV-42 -0.19%/C a-Si/a-Si same bandgap 

tandem 56% 

1
In Table 2, we have listed expected future 

commercial module performance, multiplying current 

best cell performance by 0.8 (i.e., taking the future c/c 

ratio as 0.8 for all PV technologies) [4]. Future 

relative module performance was calculated by 

dividing future module efficiencies by the future 

standard Silicon efficiency number, because 

“standard Si” currently constitutes the prevailing PV 

technology (“standard Si” refers to cells fabricated by 

diffusion and screen printing processes). The last 

column of the table shows 1/relative-performance, if 

thin-film technology, hence avoiding the use of Si 

wafers, multiplied by 0.5 (the thin-film PV “advantage 

factor”). Anything in this column with a number <1 

should show a manufacturing cost advantage over 

standard silicon. Manufacturing detail and cost 

control will affect the actual values, but the strength of 

our approach is to apply the same methodology to 

different flat-plate PV technologies. Compared to 

our last paper [1], we have increased the cost 

advantage of thin film modules over wafer Si 

modules from 40% to 50%. In the past, Si feedstock 

and wafer costs were largely determined using 

‘second-grade’ electronic poly-Si feedstock, that may 

have established cost figures for wafers made from 

feedstock acquired below cost. Current analysis by 

Rogol indicates wafer cost to constitute about 60% 

of the cost of a wafer Si module [5]. Converting the 

cost figures into percentages (wafer-cost/modulecost) it is apparent that currently such percentage is 

near 60%; therefore, it appears likely that wafer 

costs could still make up approximately 50% of the 

cost of a crystalline Si PV module in years to come. 

Table 2: Anticipated Future Module Efficiency and Relative Cost Based on 

Today’s Demonstrated Champion Cell Performance 

Technology 

Future commercial module 

performance (80% of current 

record cell efficiency) 

Future Relative 

Performance 

Future Relative-cost 

(using a 50% thin film PV 

advantage) 

Silicon (non-stand) 19.8% 1.18 0.85 (competitive) 

Silicon (standard) 17.0% 1.00 1.00 (reference) 

CIS 15.9% 0.92 0.54 (highly competitive) 

CdTe 13.2% 0.78 0.64 (highly competitive) 

a-Si (1-j) 8.0% 0.47 1.06 (about the same) 

a-Si (3-jj), (or a-Si/nc-Si) 9.7% 0.57 0.88 (competitive) 

 It should be noted that in order to attain the 

relative cost given in the 4th column of Table 2, 

module efficiencies given in column 2 will have to be 

achieved. As can be seen from the 5th column of 

Table 1, many PV manufacturing schemes still show 

a c/c-ratio well below the value of 80% assumed for 

the data in Table 2, indicating that some progress with 

product performance is possible due to implementing 

better manufacturing methods. 

RESEARCH AND DEVELOPMENT ISSUES 

Our analysis above shows that module 

performance remains a significant factor for 

determining module cost. Since solar cell processing 

is often found to affect cell efficiency, it is important to 

assess (a) the true advantage of each process, and 

(b) how it can be handled in a manufacturing 

environment. It is also desirable to develop greater 

confidence and insight when chosen processes can 

be improved further by optimization, and when 

processes should be substituted or added. 

In case of the CIS PV technology, manufacturing 

scale up issues have frequently prevented companies 

from successfully using high efficiency cell recipes 

for commercial production of modules with 

commensurate efficiency. This technology is in need 

to better understand the effects of deposition 

processes, choice of cell structures, and deposition 

rates on cell and module performance and device 

stability. In case of CdTe modules, development of 

improved device schemes that lead to high 

performance, low manufacturing cost, and good 

device stability have to be investigated. 

Since 2006, DOE’s new program to assist the 

development and deployment of photovoltaic 

technology, the Solar America Initiative (SAI) 

provides the means of developing PV technologies 

and advance PV manufacturing. Programs of 

interest to cell and module manufacturing include the 

Technology Pathway Partnership, TPP, geared 

towards larger and more mature entities, the PV 

Incubator program for small businesses, as well as 

the Future Generation and University programs 

geared at longer-term technology developments or in 

support of university driven R&D aspects, 

respectively. Among different PV technologies, the 

following thin-film PV companies are being 

supported: Uni-Solar (a-Si), and Nanosolar (CIGS) 

obtained TPP awards, and AVA Solar (CdTe), 

Primestar Solar (CdTe), SoloPower (CIGS), and 

Blue Square Energy (Si film) received SAI PV 

Incubator awards. 

2
COMMERCIAL STATUS OF THIN-FILM PV 

It seems reasonable from time to time to assess 

the impact of R&D developments on actual 

commercial product. In Fig. 1, we show the progress, 

broken down by technology, by averaging by 

technology best commercial module efficiencies as 

shown in Table 1 (such data have been compiled 

since 04/2004) [6]. For this period considered, the 

most impressive progress in module efficiency has 

been obtained for the CdTe technology by First Solar. 

2007 has been considered a turning point for thin 

film PV at least for US-based PV manufacturing, with 

US thin-film shipments reaching a market share of 

about 65% [7]. First Solar and United Solar Ovonic 

became the number 1 and number 2 ranked US 

manufacturers, respectively. Using the breakdown 

provided by PV News [7], and only counting the thinfilm PV “pure play” entities First Solar, United Solar, 

and Global Solar in the thin-film category (there may 

be a small amount of thin film PV within the “others” 

category, which constitutes largely wafer/ribbon Si 

flat plate technologies), we compiled Fig. 2. 

Estimates for 2008 production are taken as 2/3 of 

the PV News published capacity numbers for 2008. 

Projections for 2009 and beyond are currently 

difficult, because it is not known where in the world 

companies will expand manufacturing and when 

exactly some announced large capacities will come 

on line. Given the size of some announcements, 

even a 3-month delay in getting such factory to 

produce at capacity could make a significant 

difference in the amounts produced. Currently, First 

Solar has announced capacity expansion greater 

than 1000 MWp annual capacity by the end of 2009, 

but those new factories are built (already under 

construction) in Malaysia. 

Fig 1: Development of Commercial Module Efficiency, from survey of manufacturers’ websites, 

broken down by PV Technology 

3
US Produced PV Shipments 

Fig 2: US produced Modules thru 2007, counting First Solar, Uni-Solar and Global Solar as “thin Film” PV and 

the rest as “other.” Projections for 2008 use 2/3 of PV News reported end of 2008 capacity figures. 

ACKNOWLEDGEMENT 

This work was supported by the U.S. Department of 

Energy under Contract No. DEAC36-99GO10337 

with the National Renewable Energy Laboratory. 

We would like to thank many colleagues in the PV 

field for fruitful interactions. 

REFERENCES 

[1] Bolko von Roedern, Harin S. Ullal, and Ken 

Zweibel, ‘Polycrystalline Thin-Film Photovoltaics: 

From the Laboratory to Solar Fields,’ Proc. 31st

IEEE PVSC (2005), p. 183. 

[2] Martin A. Green, Keith Emery, Yoshihiro 

Hishikawa and Wilhelm Warta , “Solar Cell 

Efficiency Tables (Version 31),” Prog. Photovolt: 

Res. Appl. 2008; 16:61–67 

[3] Some of the manufacturer’s spec sheet websites 

are given below. Note that product specifications 

can change, including the possibility of new 

modules becoming available or discontinuation of 

certain models. 

[4] Bolko von Roedern, refocus magazine, (July + 

August 2006) p. 34. 

[5] Michael Rogol, “Refining Benchmarks and 

Forecasts – Rogol’s Monthly Market Commentary,” 

Photon International, Jan. 2008, 84 

[6] Older module specification sheets can currently 

be found on the NREL website http://www.nrel.gov/

by searching for it “spec sheet.” 

[7] PV News, Greentech Media and Prometheus 

Institute, 03/2008 issue 

4
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This paper discusses the developments in thin-film PV technologies. It provides an outlook on future commercial 

module efficiencies achievable based on today’s knowledge about champion cell performance. It also provides a 

relative cost comparison of thin-film and wafer/ribbon based Si PV modules. In 2007, about 65% of the modules 

produced in the US were thin-film modules when amorphous silicon modules are also considered. 

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PV; polycrystalline; thin film; module; wafer; ribbon based; amorphous silicon; champion cell efficiency 

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