# Solar plus battery

• 06-01-2009, 08:13 PM
upper
Solar plus battery
Ok,I have a system that pumps 4.5 gpm at 360 foot head at peak.Lets say I have 6 hours peak per day.But to fulfill my needs I need an addintional 3hours per day.It takes 910 watts to get the 4.5 gallons.How many add. watts and Batteries do I need to do this.Thanks Upper
• 06-01-2009, 09:11 PM
drick
Quote:

Originally Posted by upper
Ok,I have a system that pumps 4.5 gpm at 360 foot head at peak.Lets say I have 6 hours peak per day.But to fulfill my needs I need an addintional 3hours per day.It takes 910 watts to get the 4.5 gallons.How many add. watts and Batteries do I need to do this.Thanks Upper

If you really want to know..... You need an additional 3 KWH of battery capacity. Unfortunately batteries don't like to be drained much beyond 50% very often or their life expectancy will be drastically reduced so you need at least double that and probably more unless you expect to never see a cloud in the sky. For sake of argument lets say you go with 8 KWH of batteries. If your pump is 12 volts thats 667 amp hours or 6 Trojan T105 deep cycle batteries. This still assumes that it never is really cloudy.

-rick
• 06-01-2009, 09:39 PM
upper
Thanks Rick,So how big is my battery array?
• 06-02-2009, 04:01 PM
Thatguy
Quote:

Originally Posted by upper
Lets say I have 6 hours peak per day.
But to fulfill my needs I need an addintional 3hours per day.
It takes 910 watts to get the 4.5 gallons.

910w for 6 hrs = ~5500 w-h.
For 9 hrs, ~8200 w-h.
8200-5500 = 2700 w-h.
To get this out of batts. you probably need to put in (8/5)2700 = 4300 w-h

Solar insolation is about 1kW/sq. meter and photovoltaic is probably 10% efficient.

http://www.apricus.com/html/insolation_levels_usa.htm