Van Life Solar System Checklist: What You Need Before Buying
Before you spend a dollar on a van electrical system, work through this checklist in order. Skipping a step is how builders end up with a battery that dies overnight or a cable that runs hot. The calculator produces most of these numbers and exports them as a printable parts list.
1. Nail your daily energy budget
List every appliance with its watts and realistic daily hours, and total the watt-hours. Use compressor runtime for the fridge, not 24 hours. This one number drives the entire system, so get it right before anything else.
2. Decide system voltage
12V is standard and has the widest appliance support. Consider 24V if your array climbs past ~800 W or your inverter is 3,000 W or larger — higher voltage halves the current, so wiring and controllers get smaller and cheaper.
3. Choose chemistry and size the battery
LiFePO4 for most builds, AGM for tight budgets. Size from daily Wh × days of autonomy ÷ depth of discharge. Two days of autonomy is a sensible default. Add about 20% if you travel below freezing.
4. Size the solar array to your sun
Use winter peak sun hours if you travel in winter, not the annual average. Confirm the panels physically fit your roof around fans, vents, and racks — roof space, not budget, is often the real limit.
5. Pick the charge controller
MPPT for almost every build. Size it at array watts ÷ system volts × 1.25, rounded up to a standard amperage, and check the controller's maximum PV input voltage against your panels in series.
6. Size the inverter (if you need one)
Only if you run 120V AC loads. Size continuous watts at 1.25× your largest simultaneous load, and confirm the surge rating covers motor startups. Skip it entirely if everything you use is 12V DC.
7. Size wire and fuses — do not guess here
The battery-to-inverter cable carries the most current in the van. Use ABYC 105°C ampacity to cover the fuse, and keep voltage drop under 3% over the round-trip length. Every unprotected positive run needs a fuse at the source. The wire and fuse guide covers this in detail.
8. Add the protection and connection parts
Budget for a main battery fuse or breaker, fuses for each branch, a bus bar for positive and negative, quality lugs, and a battery disconnect switch. These small parts are where safety lives — do not cut them to save $50.
9. Plan charging beyond solar
Most full-timers add a DC-DC charger so the alternator tops up the battery while driving, plus a shore-power charger for hookups. Solar alone struggles in winter and dense forest — redundancy keeps you powered.
10. Price it and sanity-check
Total a budget and a premium build so you know the range. Re-check that the battery, array, and charging sources are balanced — a huge battery with a tiny array only means a slow, permanent deficit.
Run your loads through the calculator to fill in every number above, then download the PDF parts list to price-compare components.