[email protected] wrote: > In reply to Stephen A. Lawrence's message of Mon, 06 Jul 2009 15:42:15 -0400: > Hi, > > I think you may be reaching a bit to far. I think it's just a matter of > economics. By going to 500 Suns, they reduce the size of the solar cell > required, and hence also the cost. Of course the temperature would be > prohibitive without cooling, so they may also be extracting useful energy from > the cooling fluid. (Energy concentrators are much cheaper / m^2 than solar > cells). A trough only concentrates in 1 dimension as it were, whereas a > circular > parabolic mirror of Fresnel lens will concentrate in 2 dimensions, which is > why > a trough will only achieve about 80 Suns, while the others can get up into > hundreds of Suns, depending on the accuracy and quality of the reflective > surface. > Well I actually tried googling it, and I found this:
http://pvcdrom.pveducation.org/CELLOPER/LIGHT.HTM If this is accurate, then there is a *slight* efficiency increase with increasing intensity, due to a slightly peculiar effect: The current a cell can produce varies linearly with the light intensity (as you might expect -- my "two-shot-to-go" guess appears to be dead wrong). But, the (open circuit) voltage varies with the light intensity, also -- it goes up as the log of the intensity. The result is that the maximum power the cell can put out goes up nonlinearly.
