This is the problem with stating efficiency in terms of energy instead of exergy (work). Capturing the low-temperature waste heat of the solar panels is not comparable to capturing the same amount of energy as electricity. It's a good technology if it can be made inexpensive, but calling it "80% efficient solar" is quite misleading.
My read of the article agrees with you: they are claiming the removal of the waste heat as "efficiency" without taking into account the efficiency of using the waste heat. I was hoping they would claim better cooling made the PV cell more efficient (I know, a silly claim- but by analogy that larger temperature differences make more efficient heat engines). And there may in fact be no use at all for the waste heat (who needs waste heat in the Sahara?).
In fact cooling solar cells does make them more efficient. It's just that the effect is small because the "high" temperature is already so high (the temperature of the incoming photons is effectively that of the surface of the sun). A Carnot engine working between 330K and 5800K, ie a reversible solar cell, would be 95% efficient. If the cell's temperature were dropped to 300K it would be 94%. So we can estimate the efficiency change for a 30 Celcius cooling of the cell at 1%.
Your comment seems to imply that the main problem with temperature is radiative recombination. Is that the case? I thought heat caused other non-ideal problems.
True, it will also increase internal resistance. I'm more of a thermo guy, though, so I can't estimate the remainder.
If the heated water can be utilized, then, in a way, the energy has been captured. Even in a hot climate it's still nice to take a warm shower. I agree that the title is misleading though.
Agreed. Even worse, these percentage increases never seem to make it to market. If we got 1% of the added percentage increases to solar panel efficiency announced over the last 5 years, we'd be up to 10000% efficient solar cells. :P
Misleading, they heat the water but does not convert it to electricity (which would lead to further losses)