# Solar Cells

1. Nov 28, 2003

### csmines

Hey I got the oppurtunity to work in a research lab that focused on CadTel solar cells this summer and learned a fair deal about them, I also intend to take a class on Photovoltaics in the spring but I was just wondering how people feel about the cadmium in cadtel and would love some more information on PV cells. For example does anyone know what the ideal efficiency of a PV cell is? I heard it was around 30%. Also, I know that NREL has cells that can attain about a 21% efficiency through multiple stage absorption (maybe?) if you could clarify that and what the best cell around (efficiency wise) is. Anywhoo just anything general about PV technology, theory, recent advancements, job market, production techniques and so on.

Thanks a lot guys. csm

2. Nov 30, 2003

### Staff: Mentor

20% is about the limit of commercially available cells. 30% is probably stuff you only see in the lab (or maybe on the space station). "Ideal" would of course be 100%.

3. Nov 30, 2003

### csmines

I am unsure of how analogous this equation is. The ideal Carnot efficiency of any heat engine working between two thermal reservoirs is

$$\eta_{th}=1-\frac{Q_L}{Q_H}$$

It is my understanding, if I am correct, that it is impossible for an engine to even get 100% of an ideal efficiency. For example how much heat an engine produces in comparison with how much it wastes is the efficiency that you are speaking of (I think). It's been a long time since I have taken thermodynamics, and I know that this question does not refer to thermodynamics, but I vaguely remember my proffessor saying that a type of Carnot efficiency like this for PV was around 34%, however I have been unable to verify this elsewhere.