how big a solar panel do i need to charge a 12 volt battery?

I have a camper with 12 volt lights and want to recharge my battery after use using a solar panel

Super_Dave4 years ago
Adding to Jeff-O's response, panels in the 30W and under range are considered battery tenders and are customarily used to keep a RV battery topped off while being stored.
Hmmm, good to know!  In that case yeah, go for something in the 100-150W range.
Super_Dave4 years ago
Companies that sell solar panels for RV use have a draw survey that tells them how much of the battery you use in a day.  That along with the amp hours available in your battery bank will determine what size you need.  As a fellow camper, I suggest something in the 100W to 140W for boondocking longer than 3 - 4 days at a time.
jeff-o4 years ago
I recommend looking for a 30W, 12V solar panel.  These can usually be found at some hardware stores (like Canadian Tire in Canada), auto parts stores, RV stores, and online.  It should cost about $100-$150.  You'll also need a charge controller, which will likely be available from the same place you got your solar panel.  It should be rated for at least the same power as your panel, but I suggest getting double in case you want to add a second solar panel later on.
Well, for a start, you'll need a panel with a voltage output > 12V ! Then you need to find out how much you lose running the lights, and how fast you need to recharge the battery.

.  Yep. What steveastrouk said. You could charge the battery with a panel just a few inch2 in size ... but it might take a week-and-a-half of strong sunlight to do it.
.  You'll probably want a PV panel that is rated to put out 24V or more (you can regulate it down to the 13-15V you need) or more at x(1) amps, to make sure you can charge on cloudy days.

(1)x will depend on how fast you want to charge the battery.

Get More Out of Instructables

Already have an Account?


PDF Downloads
As a Pro member, you will gain access to download any Instructable in the PDF format. You also have the ability to customize your PDF download.

Upgrade to Pro today!