Solar Panel Size Calculator
Find the panel wattage needed to break even on a typical day.
About the Solar panel size calculator
Use this solar panel size calculator for van leisure battery & solar setup. Find the panel wattage needed to break even on a typical day.
Enter your solar panel size details
UK summer ≈ 4–5, winter ≈ 1–1.5.
MPPT, wiring, temp, dirt — typical 20–30%.
Cushion for cloudy days.
Why headroom matters
Sun hours are an average — there will be cloudy days. 20% extra panel capacity means fewer "battery low" mornings and shorter generator runs.
Your solar panel size results
Break-even
500 W
Just covers daily load
Recommended
600 W
+20% headroom
Panel options
6× 100W
or 4× 175W
Why solar panel size matters for van leisure battery & solar setup
Plan with confidence
Getting your solar panel size numbers right early avoids costly rework, undersized components and surprises on the road.
Related battery & solar tools
Pair this with the rest of our battery & solar calculators to plan your full van conversion.
Solar panel size calculator FAQ
- What does the Solar Panel Size Calculator do?
- Find the panel wattage needed to break even on a typical day. It is designed for van leisure battery and solar so you can plan with confidence.
- Is the solar panel size calculator free to use?
- Yes. All VanTools calculators, including the Solar Panel Size Calculator, are free to use with no sign-up required.
- How accurate are the solar panel size results?
- Results are estimates based on the values you enter and standard van leisure battery and solar assumptions. Always sanity-check against manufacturer data and your real-world conditions.
- Can I share or save my solar panel size calculation?
- Yes. Use the Share button to copy a link that includes your inputs, or use Export to download a PDF or image of your results.