Off-grid, RV & cabin

RV solar wattage calculator

Enter your daily electrical load, how you travel, and your local sun hours. Get a panel wattage target sized to how you actually use your rig.

Your numbers

1 Project details Optional
Shown on your exported report. Leave blank to skip.
2 How you use your RV
Add up every appliance's watts times hours used. The RV daily load calculator does this math for you.
Full-time and frequent boondocking add margin for consecutive low-sun days.
3 Where you'll park
Desert Southwest averages 6 to 6.5. Pacific Northwest and eastern Canada average 3 to 4. Check NREL's PVWatts for your route.
Covers controller loss, wiring loss, and panel angle relative to the sun.
Feet of usable roof, clear of vents, AC units, and antennas.
Feet, typically 7.5 to 8.5 ft on most travel trailers and Class A/C rigs.

How it works

Three steps to a wattage target

Step 1

Total your daily load

List every appliance you actually run: fridge, water pump, lights, laptop, CPAP. The RV daily load calculator builds this list and totals the watt-hours for you.

Step 2

Set your travel pattern and sun hours

Full-time boondocking needs more margin than weekend trips, since a string of cloudy days has to be covered without a shore power backup. Check PVWatts for your typical route's sun hours.

Step 3

Confirm your roof actually fits it

Measure the clear roof space around your AC unit, vents, and antennas. If your load calls for more wattage than your roof holds, the portable vs fixed panel comparison shows how ground panels can close the gap.

Understanding your RV solar wattage

The direct answer for a typical rig

An RV using 1,800Wh a day, parked somewhere averaging 5 peak sun hours, with typical roof-mount wiring losses, needs about 450 watts of solar panel. Weekend campers running lighter loads often land at 300 watts, while full-time boondockers running a residential fridge and AC-dependent electronics can need 800 to 1,200 watts. You can check the knock-on effects with the panel lifespan estimator. Panel wattage means little if the inverter cannot carry your loads. The solar inverter size calculator in our Inverters & Equipment section can help you size it for the biggest appliance you run.

Why travel pattern changes the number

A weekend camper who plugs into shore power between trips only needs solar to cover the days between hookups, so a tighter margin works fine. A full-time boondocker has no fallback if three cloudy days hit in a row, so the math needs extra headroom built in. That's why the same daily load produces a different wattage recommendation depending on how you actually travel. The system autonomy days calculator goes deeper on sizing for consecutive low-sun days. Current figures live on the DOE's solar photovoltaic technology basics, which updates them when the program changes.

Roof space is often the real limit, not budget

Standard rigid panels produce roughly 17 to 20 watts per square foot, so a travel trailer with 20 feet of usable roof length and 8 feet of width holds around 700 to 800 watts before running out of room. Class B vans and smaller rigs hit this ceiling faster. If your load calls for more than your roof fits, higher-efficiency panels or a portable ground panel setup can add capacity without more roof space.

Regional sun hours shift the target a lot

A rig parked in Arizona or the Southwest desert averages 6 to 6.5 peak sun hours and needs meaningfully less panel wattage than the same rig in the Pacific Northwest or eastern Canada, where 3 to 4 peak sun hours is typical. Travelers who follow a seasonal route between regions should size for the cloudiest stretch of their route, not the sunniest. These regional sun-hour figures trace back to NREL's PVWatts solar calculator.

What to check once you have a wattage number

Once you know your target wattage, run the RV battery bank sizing calculator to size storage that matches it, and check the charge controller sizing tool to make sure your controller can handle the panel array's output current. The general solar panel calculator in our system sizing tools is a useful second reference if you want to compare an RV-specific result against a general household calculation, and the panel lifespan estimator in our maintenance and lifespan tools projects how this array's output holds up over its warranty period. DOE's solar photovoltaic technology basics is a solid starting point if any of the fundamentals here need more background.

Questions Panels are only half an off-grid system. The backup runtime estimator in our Battery & Storage section sizes the battery bank your daily load needs to get through cloudy stretches.

Frequently asked

Most RVs need 300 to 600 watts for weekend or occasional boondocking, and 600 to 1,200 watts for full-time off-grid living. An RV using 1,800Wh a day with 5 peak sun hours and typical wiring losses needs about 450 watts of panel.

100 watts covers light use like phone charging, LED lights, and a small fan, producing roughly 350 to 450Wh a day in good sun. It falls short for a fridge, CPAP machine, or regular laptop use, which typically need 300 watts or more.

Size for power needs first, then check if your roof fits it. A typical travel trailer or Class C roof fits 400 to 800 watts of rigid panels; if your load calls for more than your roof holds, portable ground panels or higher-efficiency panels close the gap.

Yes. Regions with 3 to 4 peak sun hours a day need roughly 25% to 40% more panel wattage than sunbelt regions with 5.5 to 6.5 peak sun hours to produce the same daily energy.

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