Aug 29, 2008 10:29 pm
Re: A Weekend Cabin System
I'll take a stab at it:
The well pump requires 2860 watt/hours.
That's 13amps X 110volts X 2 hours.
Add 300 watt/hours for lights.
That's 3 lights X 25 watts X 4 hours.
Total needs = 3160 watt/hours each day.
Lets try 8-100 watt solar panels & 4 hours of sunlight.
That' 800 watts X 4 hours, or 3200 watt/hours.
Let' shoot for enough batteries to last one day.
First convert watt/hours to amp/hours by dividing:
3160 divided by 12 = 263 amp/hours. You don't want to discharge batteries beyond 50%, so double the amp/hour rating, or 526 amp/hours. You can get by (for one day) with 5-105amp/hour deep cycle batteries.
You could get by with less batteries of course, especially if you run the well pump during the day when the sun is shining, avoiding using it at night.
That well pump represents a big load, 13 amps X 110 volts = 1430 watts. You'll need an inverter big enough to handle that, plus any lights you have running at the same time. I don't know much about well pumps, but some motors have a high starting current, which means you'll have to make sure the inverter can handle that as well. Maybe you could look into a well pump that draws less current.
You'll also need a charge controller, wire and safety devices, and panel mounting hardware.
Keep in mind that the design I proposed does not take into account system losses and inefficiencies, or extended periods of cloud cover. I don't mean to discourage you, but this will be a pretty substantial system. Good luck!
