Solar Modules; Silicon vs CIGS

     With solar manufacturing, there is a close contest to see which material will be the material of choice for Photovoltaic (PV) cell/module production. The PV module field is dominated by silicon at this point. An estimated 90% of the PV modules in use today are silicon based. There is good reason for this amount of use. Silicon (along with steel and concrete) is one of the 3 most studied materials in history, and because of this, much is known about silicon and its properties. Silicon is time-tested and has shown to be very reliable for PV module production. However even silicon supporters agree that silicon is not exactly suited for its role in PV production. Silicon is not a conductor by nature. Silicon is actually very pure, to the tune of 99.9% pure and in order for silicon to be the excellent conductor that it is, it must be ‘doped’ with certain materials. Once doped, the purity of silicon is a great benefit for conductivity. Silicon is also rigid and  brittle, so the applications of silicon PV cells are somewhat limited in scope.

CIGS (copper indium gallium diselenide) PV modules are working to take silicon’s place in the solar module market. Solar modules produced using the CIGS production method have got a few things going for them that make them a very attractive over it’s silicon counterparts.

1) Flexibility. CIGS modules can be based on flexible surfaces, usually a thin, flexible metallic film. This is important for PV modules because it gives new range to the possibilities for implementation. No longer are PV modules  required to be big heavy panels that take up substantial roof space and may be considered unappealing from an architectural point of view.

2) Low Cost - CIGS production methods creates solar film, that is much thinner than the average solar wafer. Thinner means less materail (usually around 1.4 microns) and less material equals lower cost. It is forecasted that by 2010, CIGS manufacturing, will bring the price of solar modules up to 2.50 per watt. Couple that with rising oil prices and solar will be very competitive with fossil fuels

3) Efficiency. The standard for PV efficiency in the silicon world is around 13%, and climbing. Silicon supporters know that in a perfect world, silicon’s efficiency will top out at around 30%. CIGS efficiency right now is around 11% and also climbing. Because conductivity is a native ability of the  CIGS combination the upper range of efficiency is thought to be much higher. The flexiblity afforded by the CIGS process offsets the relatively low loss of efficiency for many people. The highest ever achieved with CIGS is 19.5% efficiency, which is higher than amorphous silicon or cadmium PV cells

CIGS manufacturing even has the promise of spray-on as well as printable photovoltaics. In theory, not just your roof could create power from the sun, but your entire house. Also it is very possible and likely with this technology that you will soon be able to print off PV cells from your personal printer (though they likely won’t be efficient enough to actually power your home.

 Right now, the two main players in the CIGS industry are Nanosolar and Heliovolt. Both have invested heavily into CIGS tech (along with a lot of big name private investors) and are betting that in the coming decade, CIGS will be the way to go in PV production.

Fact: Venture capitalists have poured more than $344 million into five CIGS companies in the last few years Nanosolar, Miasole, Solopower, Solyndra , and Ascent Solar