RV Solar Sizing Calculator
Size solar panels, batteries, and a charge controller for your RV.
Size solar panels, batteries, and a charge controller for your RV. Free, private, and it shows its working.
How to use this tool
Start from daily watt-hours. If you do not know yours, add up your devices with the Portable Power Station Selector first.
Sun hours drop sharply in winter and at higher latitudes, so size for the season you will actually camp in.
This tool is for planning and education only. It does not store your entries. Read our disclaimer.
Worked example
Here is what the RV Solar Sizing Calculator returns with its starting values. Replace them with your own numbers for a real plan.
| Input | Example value |
|---|---|
| Daily energy use | 2400 Wh/day |
| Peak sun hours where you camp | 4.5 hours |
| System losses (heat, wiring, angle) | 25 % |
| Days of battery reserve | 1.5 days |
| Usable depth of discharge (LiFePO4 ~80, lead-acid ~50) | 80 % |
| Battery bank voltage | 12 V |
| Result | Value |
|---|---|
| Solar array | 750 W |
| Battery bank | 380 Ah at 12 V |
| Battery energy | 4.5 kWh nominal |
| Charge controller (MPPT) | at least 80 A |
How the calculation works
- Panel watts = daily Wh / (sun hours x (1 – losses)) = 711 W, rounded up to the next 50 W.
- Battery Wh = daily Wh x reserve days / usable depth = 4,500 Wh; Ah = Wh / 12 V.
- Controller amps = array watts / battery volts x 1.25 safety factor.
Tips for more accurate results
- Size for the season you will actually camp in, because winter sun hours can be a fraction of summer’s.
- Match panels to your charge controller and battery chemistry, and add a satellite dish to your loads if you use one.
Related guides
When this tool helps most
Use it after you know your daily energy use. It turns watt-hours into panel, battery and charge controller sizes for the season you will actually camp in.
Common mistakes to avoid
- Sizing for summer sun when you plan to camp in winter.
- Forgetting large loads such as a satellite dish or a compressor fridge.
- Mixing battery chemistries or using a charge controller that does not match the battery.
Step-by-step guides that use this tool
These guides explain the decisions behind the numbers, so you can act on your result with confidence.
Understanding your results
- Panel watts: the array size that replaces your daily use in the sun hours you entered.
- Daily energy: the watt-hours your loads use; this number drives everything else.
- Margin: extra capacity for cloudy days, shade and panel angle.
Two quick scenarios
Summer vs winter
The same RV needs far more panel watts in winter, when sun hours are shorter and lower. Size for the season you actually camp in.
Portable panel
A portable panel you can aim at the sun often outproduces a flat roof panel of the same rating, which helps when you park in shade.
Before you rely on the numbers
- Add up real loads with the Battery Runtime Calculator.
- Check your charge controller’s input limits.
- Leave roof space for vents and walkways.
- Plan a backup charging source for cloudy stretches.
Keep planning with RV solar panels guide and Battery Runtime Calculator.
Official references
Frequently asked questions
The equivalent number of hours per day of full-strength sunlight. They vary by location and season, and are much lower in winter at northern latitudes. It can power many loads for light users. Heavy loads like air conditioning usually need shore power or a generator.What are peak sun hours?
Can solar alone power an RV?