I designed a simple 15 watt/12 volt solar panel powered attic fan system. Is there a simple way I can add a new or used 12 volt sealed lead acid battery (18 ah) to the circuit so the fan will run at least some time after sun rise. The fan is rated as 12 volt/1.2 amp. I imagine I need another panel to do so because it seems that the system as is has no reserve energy to charge the battery (i.e. P=I*E (15 watts = 12v*E...E=1.25amps)... in other words, there is only .05 amps left over to charge the battery...

In July 2009 in Energy Saving