Re: Boondocking and sizing solar/electrical questions
Reply #8 –
John, with two 8D batteries and 600 watts of solar, I believe you need more solar but not more batteries.
The question in my mind is, how many amphours are your batteries down each morning? Batteries are expensive, heavy, and wear out in one to ten years.
Based on trial and error over seven years, I use the following battery/solar sizing parameters:
One 8D battery (240 amphour) will provide 25 to 50 amphours (10% - 20%) at night and requires 300 watts of solar (for 60 amphours charging during a sunny day).
I have 800 watts on my U320 with two 8D AGM batteries, so 600 watts solar is for charging batteries and 200 watts of solar is for running ceiling fans and other things during the day. Using 50 amphours overnight means batteries are 10% discharged, using 100 amphours overnight means batteries are 20% discharged, using 150 amphours overnight means batteries are 30% discharged. Even at 30% discharged, the batteries will be fully charged by late afternoon on a sunny day. Batteries will last 7 to 10 years like this.
Last winter in California my batteries were down 30 to 50 amphours most mornings, but were at times down 80 amphours or more by morning. Twice, due to overcast, my batteries were not fully charged by evening.
I am very frugal with power use and so, like you, have also gone all LED lights. I also have an on-off switch for the inverter in the kitchen and only turn it on when needed. I never waste power by leaving the inverter on for convenience.
I replaced the 2500 watt "inverter/converter/battery charger" with an 1800 watt pure sign inverter and a 55 watt converter (not a battery charger). The reason for 1800 watts is that it will run any one thing that is plugged into it without overload (except A/C). I am careful to NOT overload the inverter. I run the microwave several times every day on the inverter. The reason for pure sign is that the number of amps required from batteries to run a 120V AC appliance is less with a pure sign than with a modified inverter (I measured it). I did not choose to have a second smaller inverter for small loads like TV because the new pure sign inverters today use very little power when idle compared to inverters from 15 years ago.
Running a domestic (12 volt compressor type) refrigerator on solar will require 100 amphours on a 100 degree day, or about 500 watts of dedicated solar panels. I investigated this when my cooling unit failed in January. I replaced the cooling unit because when in Canada, I do not have enough solar even without a domestic refer.
Running air conditioning on solar is possible. Solar Mike who has a solar business at Slab City in California runs air conditioning in August on solar with several thousand watts of solar panels on stationary mounts. Our motorhomes just do not have enough roof space at this time - in 50 years, who knows.
Topic: Boondocking and sizing solar/electrical questions (Read 1043 times)
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