Re: Reverse Photocell
Yes: photovoltaic cell.
Since they produce electricity when exposed to light it is quite possible to adapt one to switch a relay at the appropriate illumination level so that the pump runs.
Of course you can cut out the "middleman" and have a pump powered directly from solar. I'm not sure what size pump your looking at or what the application is or the budget, but it is technically possible.
1220 Watts of PV, OB MX60, 232 Amp hrs, OB 3524, Honda eu2000.
Ohm's Law: Amps = Volts / Ohms
Power Formula: Watts = Volts * Amps