What Size RV Solar Panel Kit Do You Need? Sizing and Kit Contents

An RV needs enough solar to replace one day of battery use in the sun you will actually get. Divide daily watt-hours by peak sun hours, then add about 25% for losses. A camper using 1,200 Wh a day at 5 sun hours needs about 300 W, so a 400 W kit leaves room for cloudy days.

How to work out your RV’s daily watt-hours

Daily use is the number that sets everything else. List each 12 V and 120 V device, multiply its watts by the hours you run it, and add them up. Battle Born suggests a faster route: put a battery monitor on the system, read the amp-hours used over 24 hours, and multiply by the battery voltage.

A battery monitor reading beats a guess, because loads such as a compressor fridge cycle on and off. A roof air conditioner is the load that breaks most solar plans: Renogy puts a typical 13,500 BTU unit at about 1,500 to 1,800 W while running. Leave it out and run it from shore power or a generator.

Peak sun hours for RV solar sizing

Peak sun hours are the equivalent hours per day of full-strength sun. Renogy gives these average ranges by state:

These are averages across the year. Renogy notes that northern states swing much more between summer and winter than southern states, so size for the season and place you camp most, not the best month. A kit that covers a summer trip in Arizona may cover only part of a winter trip in Washington.

RV solar kit sizes, worked through

Daily watt-hours divided by peak sun hours gives the bare minimum; Victron’s example is 720 Wh ÷ 5 hours = 144 W. Renogy notes that panels never run at 100% efficiency, and BLUETTI suggests a 25% buffer on top. Using 5 peak sun hours and that buffer:

The usage rows are examples for the math, not measured figures for any RV. Victron also points out that an array sized only to match daily use refills a drained battery slowly, so many off-grid RVs go well above the minimum. Driving with a DC to DC charger and shore power fill the gap on other days.

What comes in an RV solar panel kit

Kit contents vary by model, so read the box list before comparing prices. Renogy’s 400 W 12 V Essential kit with DC-DC assembly shows what a fuller kit looks like. It comes with four 100 W rigid panels, two 200 W rigid panels or two 200 W flexible panels. Every version adds a 50A DC to DC charger with built-in MPPT, which takes both solar and alternator input. The box also holds cables, branch connectors, fuses and a cable entry gland, plus Z brackets with the rigid panels.

What to check in any kit:

• Charge controller type: MPPT harvests more energy than PWM, which matters on a big roof array.
• Cable lengths: the run from roof to battery bay needs to reach without extra splices.
• Roof entry: a cable entry gland seals the hole where wires pass through the roof.
• Battery: many kits leave it out, so budget for one sized to your daily use.

Flexible RV solar panels or rigid panels

Flexible panels weigh less, sit nearly flat and can bond to a curved roof without drilling. Renogy recommends them for curved RV and van roofs, boats and spots where drilling is not an option, and rigid panels for flat roofs.

Rigid panels on brackets have air flowing underneath, which keeps them cooler. Battle Born notes that flexible panels bonded flat absorb heat from the roof and tend to convert less sunlight, and makers quote shorter lifespans for flexible panels than for rigid ones. Adhesive also needs care: Go Power! says the sealant depends on your roof membrane and is not included with its Solar Flex kit.

Portable panels as an RV kit alternative

A folding portable panel set up beside the camper can follow the sun and park the RV in the shade. It also works with a power station instead of a fixed battery bank. Our guide to how to charge a solar generator covers solar input limits, and the solar generator gift guide matches power station sizes to RV owners. For battery chemistry, see LiFePO4 vs NMC. More panel guides are in the solar panels section. For a fixed system, solar charge controllers and the 12V LiFePO4 100Ah battery guide cover the parts behind the panels.