Ok, so if i have an 80 watt solar panel and want to run a 12v dc fan and water pump ONLY when the sun is out or enough light to power them, will i need something like a voltage regulator? I would like to have the panels charge deep cycle 12 v batteries at the same time or when the fan and pump is not running. For instance, i have the panels out and my fan and pump on allowing them to run only on solar as well as charge the batteries. What diagram would i use? I would probably get a charge control for the batteries but more importantly what would i need to regulate the power from the panels? Inverter?
You may have to do some math. The 80 watt panel is only 80 watts at peak sun on a 75°F day at the equator. Chances are you will have something less than 80 watts to work with. But you can add up all the hours of partial sun to get an equivalant number of peak sun hours. An example would be a few hours in the morning and evening at partial power and a couple of hours at solar noon at nearly full power may give you 5 peak sun hours worth of light. 5 psh x 80 w/ps = 400 wh Your supply may have 400 watt hours worth of power per day. You state that the fan is 12v dc but what is the wattage? It could be a little 12v dc fan out of a computer or it could be a huge 12v dc fan out of an RV. What is the power requirements of the water pump? Is it a little 12v dc one for a foot tall decorative fountain or an industial 3 phase pump for a well? To charge the battery you need a voltage 120% higher than the battery voltage. 12v x120%=14.4 v To add up your loads convert them all the use to dc watt hours per day Here is an example to give you an idea of how to play with your numbers: Fan 12vdc x 1.5 A = 18 watts, use this for 5 hours your load would be 18w x 5hr = 90 watt hours Pump 120 vac x 2.5 amps = 300 watts (The AC will need to come from an inverter. The inverter has a certain amount of loss. How good it does the job of converting dc to ac is know as it's efficency. Lets use 90% to be safe) 300 watts / 0.90 = 333.4 watts, use this for 1/2 hour per day 333.4w x 0.5hr = 166.7 watt hours The 90 watt hours + the 167 watt hours = 257 watt hours per day. This would leave about 140 watt hours to put into the battery. Yes it would be best to use a charge controller to protect the battery from overcharging if the pump and fan are off, or from draining the battery too much if the fan or pump stays on.
