How much solar power do you need?


The winter, snowbird season is upon us, and a parade of RVers is now underway south, many to boondock for months on end on public lands of the desert Southwest. If that’s you, then you probably already have enough solar panels to power your RV. But if you still need to get equipped, these “Rules of Thumb” from the folks at AM Solar will give you an idea of what you may need.

1. Use a minimum 65 watt solar panel for basic battery maintenance on trailers and fifth wheels.

2. Use a minimum 100 watt solar panel for basic battery maintenance on motorhomes.

3. For the more conservative consumers of electricity: Allow 200 amp-hours of battery storage capacity and 150 to 250 watts of solar panels.

4. For the more liberal consumers of electricity: Allow 400 amp-hours of battery storage capacity and 300 to 500 watts of solar panels.

5. For “hard core” boondockers with mobile offices: Allow 600 amp-hours of battery storage capacity and 500 to 800 watts of solar panels. AM Solar also encourages the use of an M.P.P.T. Current Boosting Controller.

Bear in mind that you can start with one or two solar panels and add more later if needed.

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1 year ago

“Interstate” is a battery brand in our area. We replaced the battery in our ‘new’ used truck camper with a Group 27 Interstate Deep Cycle battery. Oddly, Interstate provides no AH rating; only CCA, CA, and RC figures. After some search, I found a ham radio forum which gives an approximate conversion figure of 0.6 x RC to estimate AH of a given battery: in this case, Interstate Group 27 Deep Cycle with RC 160 is approx. 96 AH.

Our truck camper (an older model) has only the one battery compartment, which means we’re physically restricted to a little less than 100 AH capacity, half the “minimum” this article recommends. We can add more batteries in the empty pickup bed well area, forward of the rear wheels, but that would add extra cabling and significant weight increase (approx. 100 lb. per battery). So… needing only LED (conversion) lighting, the water pump, and occasional laptop/cell phone recharging, that’s our demand. Our 200 watts of auxiliary solar panels, somewhat limited by our Pac NW maritime sky conditions, is just enough for 96AH it seems.

Mark Sanders
1 year ago

We are likely in the conservative motorhome area of use. If we had 250W of solar, what could/would we be able to do throughout the day?

1 year ago
Reply to  Mark Sanders

Some bigger expert can correct me, but expect 50% of the solar rated capacity during daylight hours. Shade/rain/ non ideal pointing happen. So, 1KW solar panels deliver 500W X hours = daily KWh. Add up your expected KWh usage, and compare. I’d give yourself some surge margin as well.

A few months back, a solar supplier offered me semi-flexible panels for $1/W…I was VERY tempted to get 2KW or so, but finances are tight. Now more seriously looking at typical pricing, i’m kicking myself for not FINDING the money… 🙁