Solar Panel Size Calculator
Calculate the solar array size you need to offset your daily energy use, based on peak sun hours and system efficiency.
Use the Power Planner or another calculator to work this out if you're not sure.
Not the same as daylight hours — peak sun hours estimate the equivalent hours of full-strength sun. Typically 3–4 in poor conditions, 4–6 in average conditions, and 6+ in strong, unobstructed sun.
Accounts for cabling losses, MPPT conversion, panel angle, dust and temperature. Default 80%.
Recommended Solar Array
Minimum recommended
300W
Practical range
300–400W
allows for cloudy days and less-than-ideal angles
Minimum W = daily Wh ÷ (peak sun hours × system efficiency). A 400W-rated solar panel will not produce exactly 400W continuously — real output varies constantly with weather, shading, time of day and panel angle, which is why a practical range is shown rather than a single figure.
Worked example
Daily consumption: 1,000Wh. Peak sun: 5 hours. System efficiency: 80%. Recommended array ≈ 1,000 ÷ (5 × 0.8) = 250W minimum, with a practical range of roughly 250–350W to allow for cloudy days, shade and imperfect panel angle.
What affects real-world solar output
Weather (cloud cover can cut output by 50% or more), shading (even partial shade on one cell can disproportionately cut a panel's output), panel angle relative to the sun, dust or dirt on the panel surface, and temperature (panels lose some efficiency as they heat up) all affect how close real production gets to the rated wattage.
Affiliate disclosure: we may earn a commission if you buy through links on this site, at no extra cost to you. Recommendations are based on product suitability and published specifications, not commission rates. Read our full affiliate disclosure.
Frequently Asked Questions
How many watts of solar do I need for camping?+
It depends on your daily energy use and how much sun you'll realistically get. Enter your daily Wh figure above — from the Power Planner or Camping Power Calculator — to get a tailored recommendation.
Will more solar than the minimum help?+
Yes — a larger array reaches full daily charge faster on average and copes better with cloudy days, at the cost of more weight, space and expense. The practical range above reflects that trade-off.
Related Calculators
Solar Charging Time Calculator
Estimate how many hours of sun it will take to recharge your battery or power station with a given solar panel wattage.
Solar vs Battery Balance Calculator
Model your battery capacity, solar input, daily consumption and trip length together to see whether solar or battery capacity is your bottleneck.
Power Station Size Calculator
Work out what size portable power station you need in Wh, based on the devices you want to run, how many hours per day, and how many days off-grid.
Camping Power Calculator
Calculate your camping power needs — fridge, lights, phones, Starlink and more — and get a recommended power station and solar size for your next trip.