A campervan solar calculator is most useful after you have estimated the electricity you use each day. Panel wattage describes a rated output. Your actual daily energy depends on the weather, season, shade and the way the system is installed. Start with loads in watt-hours and compare the result with a realistic charging plan.
Make a short load table
List the fridge, lights, fan, phone charger and other equipment. For loads with a reasonably steady draw, multiply watts by hours to get watt-hours. For cycling equipment, use measured daily consumption or a suitable manufacturer figure rather than assuming it runs continuously at its maximum rating. Keep inverter losses and standby loads visible in the estimate.
Check the numbers with a small example
Two 6-watt lights used for four hours take 48 watt-hours. A 20-watt fan used for three hours takes 60 watt-hours. Those two loads total 108 watt-hours before the fridge, charging and losses are added. Repeat the exercise for a rainy day when you spend more time inside and the roof produces less energy.
Match the roof plan to a charging design
Draw where panels can sit around vents and roof bars. Note the seasons and places where you expect to park. Ask a qualified installer to confirm storage, charge sources and equipment limits. The Victron solar controller resources include a sizing tool for matching equipment. Keep a second way to charge if you expect extended periods with low solar output.
Frequently asked questions
Can I add up the panel wattage and compare it directly with a daily load?
Convert both sides to energy over time. Rated panel watts and daily watt-hours describe different quantities.
What should I measure after the build?
Check actual daily consumption and charge on a typical trip, including an overcast day. Update your estimate with those figures.
For the next step, read our guide to planning a self-sufficient campervan. Include the electrical equipment footprint in the sketch you share with us. Start your NEVAN layout enquiry.
