# What is the relation between efficiency of solar cella and incident light power $\eta(P_{inc})$?

What mathematical relation, if there is one usually valid, describes the variation of efficiency $\eta$ of a solar cell (i.e. the ratio of produced electrical power $P_{el}$ and incident light power $P_{inc}$) and incident light power $P_{inc}$ itself?

In other words, what is the typical form of the relation $\eta(P_{inc})=f(P_{inc})$ ?

• It's about 20%. BTW I have no idea what f(Pinc) is. – Andy aka Mar 7 '17 at 18:49
• Someone asked about this recently. After a brief google search, I learned that in principal, efficiency goes up with higher irradiance. But there is a maximum at which efficiency peaks and then starts to go back down. I believe most solar panels are designed so full direct sunlight is right at the efficiency maximum. So increasing irradiation beyond that will not improve efficiency. but there is a term you may want to google: concentrator photovoltaics. Also see this: lirias.kuleuven.be/bitstream/123456789/359665/1/4BV.4.54.pdf – mkeith Mar 8 '17 at 5:39