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Potential of Purely Organic Solar Cells to Reduce the Cost of Photovoltaics
approaches, which gave us our high and low estimates. For the first
Table 1: Estimated Materials Costs for Purely Organic Solar Cells
approach we used the average start-up capital equipment cost for a
Cost Component POSCs
POSC manufacturing company, as reported on the Internet, of
2
Type Used Cost Estimate (US$/m )
US$20 million for a 10MW plant, and backed out the per panel cost.
Low High
We assumed a plant lifetime of seven years, a discount rate of 10%
Semiconductor C
60
, CuPc and SnPc 3.30 5.00
and efficiency of 6.5%. This resulted in the high estimate shown in
Electrical contacts
and interconnects Aluminum, silver paint 3.40 5.00
Table 2. However, this estimate is much higher than the published
Substrate
7
Flexible plastic, ITO 7.90 13.68
estimates for DSSCs, whereas the conventional wisdom is that POSCs Protective cover Flexible encapsulant 2.90 4.40
should be less expensive to manufacture. Therefore, we used a second
Sealant Surlyn 2.90 4.40
Packaging material – 2.00 3.00
approach based on published estimates for the capital cost of DSSCs.
Speciality chemicals 4 TBP 1.00 2.00
We assume that since POSCs have only five steps while DSSCs have 11,
There are two substrates in dye-sensitised solar cell (DSSC) devices, hence the estimates are for the two
then five-elevenths of the lowest estimate for DSSCs provides a lower
2
substrates. For this reason, we base our estimate on US$10/m , which is the cost of one substrate.
POSCs = purely organic solar cells; ITO = indium–tin oxide; TBP = tertiarybunlphosphine.
bound for POSCs.
Table 2: Summary of Processes Costs for Purely Organic Solar Cells
The direct labour cost was calculated based on previous studies by
2
Cost Component Cost Estimate (US$/m )
Haynes et al. and Kapur and Basol
10
for TFSCs and CIS, respectively. The
Low High
following assumptions were made: a semi-automated 10MW factory Capital equipment 3.30 59.60
and three shifts per day with 10 operators/shift – thus 30 full-time
Labour 6.00 10.00
Total 9.30 69.60
operators. It was assumed that the factory would require eight hours
per shift for 350 days per year at a wage rate of US$17/hour, with a
Table 3: Summary of Overhead Cost Estimates for Purely Organic
yearly production output of 150,000m
2
.
Solar Cells and Dye-sensitised Solar Cells
No. Cost Component DSSCs POSCs
Overhead Costs
2 2
Cost (US$/m ) Cost (US$/m )
The overhead cost estimates for POSCs (including facilities, utilities,
Low High Low High
maintenance of equipment, miscellaneous costs and customer
1 Facilities (e.g. rent) 7.25 10.15 7.25 10.15
warranty costs) and those of DSSCs are shown and compared in
2 Utilities (electricity, water) 7.25 10.15 2.18 4.35
Table
3 Maintenance of equipment
3. We assumed that facilities costs for POSCs and DSSCs would be the
(4% of capital cost) – – 0.13 1.25
same but that utilities costs would be lower for POSCs since they are
4 Miscellaneous (5% of total
manufactured at room temperature and require very little water. The
manufacturing cost) – – 2.11 4.73
table also shows simplifying assumptions made on maintenance,
5 Customer warranty (5% of
total manufacturing cost) – – 2.11 4.73
customer warranty and any miscellaneous costs.
Total 14.50 20.30 13.78 25.21
DSSC = dye-sensitised solar cells; POSCs = purely organic solar cells.
Results and Sensitivity Analysis
From the above, we estimate that the total manufacturing cost,
Table 4: Summary of Total Manufacturing Costs for
Purely Organic Solar Cells
assuming a 95% cell yield (the percentage of cells that are successfully
manufactured) will range from US$48.80 to US$138.90/m
2
, as shown
Cost Category Low Estimate High Estimate
2 2
in
(US$/m ) (US$/m )
Table 4. When efficiency and module yield, which were assumed to
Materials 23.40 37.48
be 5 and 98%, respectively, were included, module cost was estimated
Capital 3.30 59.60
to range from US$1.00 to US$2.83/Wp, calculated as follows: module Labour 6.00 10.00
cost (US$/Wp) = (manufacturing cost)*1.02/(output/unit area), where
Overheads 13.78 25.21
Total manufacturing cost 46.48 132.29
output per unit area is 1000W
p
/m
2
* 5% module efficiency.
Cell yield (95%)
*
Total manufacturing cost with cell yield 48.80 138.90
Taking the low-end cost estimates shown in
Module efficiency (5%)
Table 4, materials constitute
Module yield (98%)
the largest part of the total module manufacturing cost, followed by
**
Module cost (US$/Wp) 1.00 2.83
overhead and processes costs. However, taking the high-end cost
2 2
*US$46.48 *1.05 and US$132.9 * 1.05; ** (US$48.8/m *1.02)/(1000Wp*5%) and (US$138.9/m *1.02)/
estimates, process costs constitute the largest part of the total direct (1000Wp*5%).
module manufacturing cost, followed by materials and overhead costs.
and wage rate, and is relatively insensitive to machine lifetime and
We performed sensitivity analysis on the impact of variations in substrate interest rate. There is only a small increase in module manufacturing cost
cost, wage rate, machine lifetime, interest rate and cell yield, taking as a if interest rate and machine lifetime are increased by 50%.
baseline the low estimate for manufacturing cost of about $50/m
2
. We
found that substrate cost significantly affects manufacturing cost, as Module Cost and Total Module Manufacturing Cost
shown in Figure 1, followed by cell yield and wage rate. The effect of Figure 3 shows an analysis of the effect of manufacturing cost, at
machine life and discount rate on manufacturing cost is minimal. different efficiencies, on the module cost. There is a linear relationship
Sensitivity analysis was also performed on the impact of the above between module cost in US$/Wp and module manufacturing cost per
factors, plus cell efficiency, on module cost, using a central figure of square metre as a function of efficiency. Module cost of POSC
US$1/Wp. As shown in Figure 2, module manufacturing cost is very decreases with an increase in efficiency combined with a decrease in
sensitive to cell efficiency. It is also sensitive to cell yield, substrate cost module manufacturing cost. Using the baseline manufacturing cost of
MODERN ENERGY REVIEW VOLUME 2 ISSUE 1
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