Free Tool
RV Solar Calculator
Tick the appliances you run, drag the hours per day, and get a recommended solar panel wattage and 12V battery bank size. No signup, no email, just math.
How do you use your RV?
Presets are starting points, not promises — every RV's usage differs. Tune below.
Your appliances
Tick what you run. Adjust hours per day.
Refrigeration 1/2
Lighting 1/1
Fans & ventilation 1/1
Water 0/1
Electronics & charging 2/4
Kitchen 0/2
Heating & cooling 0/2
Medical / continuous 0/1
Custom appliances 0
System design
Recommended RV solar system
1,250 Wh/day · 5 sun hours · 1-day backup · LiFePO4 (lithium) · 12V
⚠️ Starting surge not verified — confirm motor/compressor starting watts from manufacturer specs before buying.
☀️ Solar array
2 × 200W panels (raw need 391W)
Under your assumptions — not guaranteed
🔋 Battery bank
1,645 Wh nominal
1.0 days of your daily use at 80% DoD
⚡ Inverter & controller
From 60W simultaneous load + 25% headroom
Raw 41.7A (400W ÷ 12V × 1.25). Verify panel Voc/Isc against the controller's limits.
📋 Your plan, step by step
- Your loads use ~1,250 Wh per day — biggest: 12V fridge.
- Solar: ~400W of panels (2 × 200W) replaces that energy in 5 sun hours.
- Batteries: ~140 Ah at 12V (LiFePO4 (lithium)) covers 1 day without sun.
- Electronics: ~1,000W inverter, ~50A MPPT controller.
- Before buying: confirm panel Voc vs controller max input, battery charge settings, and wire/fuse sizing with manufacturer docs.
How we calculate · sources
- NREL PVWatts — solar production modelling and real-world loss factors
- NREL solar research — photovoltaic technical resources
- Battery usable capacity, charging and temperature limits: follow your battery manufacturer's documentation
- Inverter surge and controller voltage/current limits: follow the equipment manufacturer's manuals
Planning estimates only — not a certified electrical design. Losses applied once via system efficiency; battery path efficiency 0.95 applied once.
What the numbers don't cover
- Startup surge: microwaves and air conditioners draw 2-3x their running watts for a few seconds at startup. Size your inverter for surge, not just the average.
- Shading: even partial shade on one panel can cut a whole string's output dramatically. The 25% margin helps but isn't a substitute for good placement.
- Season: 5 peak sun hours is a fair US average. Winter or northern latitudes may give you 2-3; desert summer can give 6+.
- Lead-acid batteries: only about 50% of rated capacity is usable without damage. Double the Ah figure if you're not on lithium.
Next steps
Got your numbers? These guides take you from planning to buying to installing.
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