How to Calculate Your RV Solar Panel Size
Published: March 2026
Sizing your solar array correctly is the most critical step in building an off-grid electrical system. Too little, and you'll run out of power. Too much, and you've wasted money and roof space.
The Basic Formula
To determine your needed solar wattage, follow this formula:
- Calculate your daily Watt-hour (Wh) usage.
- Divide by the average peak sun hours in your camping locations (usually 4-5 hours).
- Add 20% to account for system inefficiencies.
Example Calculation
If you consume 1,200Wh per day and expect 5 hours of peak sun:
1200Wh / 5 hours = 240W
240W * 1.2 (inefficiency buffer) = 288W
In this scenario, a 300W solar array would be perfectly sized for your needs.
Use Our Automated Tool
Don't want to do the math manually? Head over to our Homepage Calculator to get instant recommendations based on your battery size and off-grid goals.