What is the current photovoltaic standard for number of electrons released per photon (if there is such a number)? Thanks in advance

Since electrical energy efficiency is typically 15-25% for conventional materials, quantum efficiency (which can vary wildly by frequency) must peak between 40-100%. Calculations show that the actual range is more like 40-90% and 80-90% should be a design goal.

http://books.google.com/books?id=s5NN34HLWO8C

Quantum efficiency (electron per photon) tends to be close to 100%. Power wastes have other causes:

- Photons with too little energy are not converted, but extra energy is wasted. Pity as Solar light has a wide spectrum.
- The output current is available at the direct voltage of a junction, and this voltage is quite lower than the bandgap of the semiconductor, though the bandgap determines the minimum photon energy. Example: 1.12eV photons minimum, but 0.5V direct voltage.

These two causes account for nearly all losses - and sadly, not much can be done against with a given semiconductor. Add a bit of quantum efficiency, parasitic reflection... and you get the usual figures.

Thanks guys. I am guessing the shorter wavelengths would be more effective at giving the electrons and holes a head start?

As soon as photons' energy exceeds somewhat one bandgap, they are very efficient at creating pairs, even in indirect-bandgap materials like silicon. More photon energy is just wasted.

Very nice site:
http://www.ioffe.ru/SVA/NSM/Semicond/

One the 6th diagram of page
http://www.ioffe.ru/SVA/NSM/Semicond/Si/optic.html
which is here when clicking to maximize
http://www.ioffe.ru/SVA/NSM/Semicond/Si/Figs/145.gif
you see a sharp transition at 1.12eV, indicating pair production.
The second transition is the direct gap of silicon.

I noticed the 5 eV and 10 eV absorption coefficent are very similar, but what happens for the 10 eV vs 5 eV photon? Where does the extra 5 eV go?