Last week when I criticized the New York Times’ Paul Krugman for emphasizing big-oil conspiracies rather than looking at the material science obstacles to solar power, I remarked that the issue for photovoltaics was not overcoming plots by oil companies but instead developing a material that can be produced cheaply and still produce high conversion rates.
Professor Richard Jones has addressed this issue in a new post over at Soft Machines. Jones examines the technical and economic issues in getting polymer solar cells to compete with everything from fossil fuels to nuclear energy and makes it clear that solving the technical issues can resolve the economic ones as well.
Jones uses as his embarkation point a paper authored by Brian Azzopardi from Manchester University in the journal Energy & Environmental Science entitled “Economic assessment of solar electricity production from organic-based photovoltaic modules in a domestic environment”.
According to Jones, Azzopardi reveals in the paper that “the so-called “levelised power cost” – i.e. the cost per unit of electricity, including all capital costs, averaged over the lifetime of the plant, comes in between €0.19 and €0.50 per kWh for 7% efficient solar cells with a lifetime of 5 years, assuming southern European sunshine.”
This is clearly more expensive than both fossil fuels and nuclear and is even short of conventional solar.
So, how is the gap to be closed? Not surprisingly the majority of the cost of the a photovoltaic system based on polymer solar cells comes from the modules, and the main cost of the modules stems from the cost of the materials, which account for anywhere between 60-80% of the modules.
One thing we can quickly see from numbers like this is that we need to find some cheaper materials and as Jones points out a good place to start is with the transparent conducting electrodes, which currently use a thin layer of indium tin oxide (ITO) and represents half of the material costs.
As we know, ITO is rare and expensive and is going to become more so as time goes on. The nanomaterials we have been looking at for providing both transparency and conductivity, like carbon nanotubes and graphene, have not presented any clear solutions as of yet. Jones does provide us with a useful link that provides us with a good summary of nanomaterial contenders for replacing ITO.
But the message is clear: We still have some technological obstacles to overcome to make the economics of polymer solar cells--and, by extension, photovoltaics in general--compete favorably with fossil fuels, no matter what conspiracy you want to blame on the lack of a wider adoption of solar.
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.