Originally Posted by Jnam
the solar powered version, the solar cell sits just above your lights and charges the NiCd batteries all day when it goes dark the batteries supply the current to the lights. Pretty simple.
I see a flaw...
If the solar panel/cell is on top of your tank, it won't charge the batteries effectively, as they have to be in direct sunlight
to operate at their full voltage (which for 6v could be about 8-10V), and there are few tanks that sit in direct sunlight. If you mean that the panel sits just above the tank lights and face the lights, that too wouldn't work, yes it'll generate some
electricity, but not enough to be used for what you plan on doing...
The easiest solution to this is to site a small panel outdoors, facing due south (or north for those South of the equator), run a wire to the batteries (simple speaker wire would suffice for a small panel) through a relay, when the panel voltage drops, the relay cuts out and turns on the lights, it's just finding a suitable relay for the job...