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What is the payback of thin film PV systems?
Thin-film PV modules use very little
semiconductor material.
The major energy costs for
manufacturing are the substrate on which the thin films are
deposited, the film-deposition process, and facility operation.
These energy costs are similar for
all thin-film technologies (copper indium diselenide, cadmium
telluride, amorphous silicon), varying only in the film
deposition processes themselves, so amorphous silicon is a
representative technology.
It is estimated that it takes 120 kWh/m2 to make near-future,
frameless, amorphous- silicon PV modules. Another 120 kWh/m2
would be added for a frame and a support structure for a
rooftop-mounted, grid-connected system. Assuming 6% conversion
efficiency (standard conditions) and 1700 kWh/m2 per year of
available sunlight energy, the payback is about 3 years for
current thin-film PV systems. Kato and Palz calculated shorter
paybacks for amorphous silicon, each ranging from 1-2 years.
Deleting the frame, reducing use of aluminum in the support
structure, and assuming a conservative increase to 9% efficiency
and other improvements, Alsema projected the payback for
thin-film PV ten years from now to drop to just 1 year.
So, for an investment of from 1 to 4 years worth of their energy
output, PV systems can provide as much as 30 years or more of
clean energy. Note that these figures are for rooftop systems.
Support structures for ground-mounted systems—as might be found
more advantageous for central utility generation—would add about
another year to the payback period.
(Source: Energy payback-clean energy from PV)
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