Van Solar Calculator
Van life solar sizing — enter your rig and loads, get a complete system spec.
How to Use This Calculator
Select your van type and roof dimensions
The van type pre-fills roof dimensions, but adjust them to your actual build. A Sprinter high-roof has about 65 sq ft of usable flat roof; a standard Transit cargo van has around 40 sq ft. Measure your actual roof minus any vents, skylights, or obstructions.
Choose 12V vs 24V system
Most van builds use 12V — components are widely available and compatible with standard automotive wiring. If your build draws more than 3,000W continuously or has very long wire runs (skoolie/bus), a 24V system reduces current by half, allowing smaller wire gauges and lower losses.
Enter your appliances
The fridge is typically the largest constant draw. A quality 12V compressor fridge (BougeRV, Alpicool, ARB) draws 35-60W on average over 24 hours. The diesel heater blower motor only draws 10-20W — far less than electric space heaters. Laptop usage hours are the second biggest variable for digital nomads.
Days of autonomy
How many nights can you survive on battery alone? For van life, 2-3 days is standard — enough to ride out cloudy days in cities. If you frequently park in underground garages or forested areas with no sun, size for 4-5 days.
The Formula
The calculator uses 100W slim panels (about 8 sq ft each) which are the most common van life panel format. If you use larger 200W panels (~16 sq ft each), divide the panel count by 2 for a rough roof fit check. Lithium batteries allow 80% DoD — so your actual battery needs are about 60% of the number shown if you use LiFePO4.
Example
Jake — Sprinter 144" build, van life + remote work
Jake lives in his Sprinter full-time, works as a freelance developer (laptop 8 hours), runs a BougeRV 12V fridge 24/7, and a Maxxair fan for ventilation. He travels the western US (5.0 peak sun hours average) and wants 3 days of battery backup.
Result
Six 100W slim panels fit easily on a Sprinter roof (65 sq ft available, panels use 48 sq ft). Jake chose two 200Ah lithium batteries in parallel for a compact, lightweight bank. Total build cost for the electrical system: approximately $1,800-2,200 DIY.