Originally Posted by SoMoney
Okay in order to achieve Nirvana in Solar Boondocking I have a question.
Q. In IDEAL Sun conditions on a nice 70+ degree day;
How many watts total in solar panels are necessary to run:
1. The fridge
2. Water Pump/Heater
3. Run the LPG Detector
4. and Return at least 150Ah of charge back into the house batteries.
All of this in an 8 hour typical day cycle mind you!
I am not sure whether this is a real question or a "tounge in cheek" comment. I will try to answer as if you are serious.
Assuming all available output from the panels are used by your items 24/7 I will try to puzzle this out.
First the 150 AH to the batteries. This is a difficult problem since the maximum safe charge varies as the battery takes charge and the charge controller will taper off the charging current as the batteries fill. I have the graphs posted in several posts here. I will assume you have a dead bank of 150AH and need to fill it. Using shore power with an unlimited supply of amps and your 3 stage power converter as the charging source, it will take about 3 days (24/7) to replace your 150AH (The size of my bank at the moment) due to amperage step down as the battery fills.
The Fridge: It matters whether you are running on propane/battery or just battery (3 way units). For simplicity we will use propane/battery with climate control turned off. The Fridge will run on propane until the gas is exhausted or the battery drops to 9.6 VDC (Dead for all intents and purposes). When cooling (average 12/7), the fridge draws 3 amps DC or 3x12=36 watts.
Heater: Depends of course on the BTU size of your furnace. Average is 7 amps DC (12/7) 7x12= 84 watts
Water pump: Amperage depends on where your water pressure is set at. 40PSI pulls 7 amps running (4/7) 7x12=84 watts
LP Detector: 24/7 at .3 amps or 4 watts all the time
You left out the other parasite draws (Concertone instant on - when off; Fridge when not cooling; heater when not running; etc)
BUT if your panels are taking care of all your routine needs your battery most likely won't discharge at all (or very little). To be a frugal power camper you could easily be pretty near independant with 250 -300 watts of panels. If not (inverter use; lots of lights; etc) Generator usage might be limited to a few hours every other day.