Why can't my MH lights run my pumps? The solar panels could be behind the bulbs, instead of a reflector.
A couple problems
1) The solar output would be of DC power, so unless you had DC pumps (which SEIO doesn't make), you'd need to have a way to transform that to AC current (losses in energy)
2) Reflectors are there for a reason, they reflect otherwise "lost" light back into the tank, if you put solar cells there you'd be essentially absorbing that light instead of using it for lighting purposes, since the bulbs themselves have an inherent inefficiency in converting electricity to light, and the solar cells have a HUGE inefficiency in converting light to electricity, you'll be losing so much energy along the way that you might as well use the electricity powering the lights to light the tank with reflectors and use electricity from the wall to power the pumps. If you didn't need that light, why don't you downgrade your lighting to save electricity instead? It'd be cheaper in the long run
3) Typical solar cells have a peak absorption of light in the 600-700nm range (IIRC.. it's been a while) which is red light, which our bulbs typically don't have much of. Now the bluer light will power the cells, however one photon in = one electron out and that's it, so the higher energy photons do create a single electron, however much of this energy is lost due to phonon emission "sound particles" which cause vibrations = heat = lower efficiency in the cell. Not to mention the proximity to the lights themselves will make the cells hot and even more inefficient than they already are.
End result, you'll lose money.
Now it is possible you could put some solar cells inside your canopy where a reflector isn't and make some power, however I would estimate that the amount of energy you gain would be so insignificant that there would be no "buy-back" period for the cells (translation you're losing money and never be able to recoup it)
