What you need
Every setup does four things: make power, move it, store it, and let you use it. Here's yours.
| 4 | Solar panelsMake the power |
| 1 | Charge controller + inverterMoves it into the batteries, gives you outlets |
| 3 | BatteriesStore it for night and grey days |
| 1 | Wiring, fuses & mountsHold it together, keep it safe |
Also worth having: a small generator for the very darkest weeks. It's far cheaper than doubling the batteries.
More: The complete parts list · What not to buy
By van: Mercedes Sprinter · Ram ProMaster · Ford Transit
How much power you use
Your answers come to about 2.4 kilowatt-hours a day — the same unit on a power bill. That one number sizes everything else.
In your darkest weeks the sun doesn't quite keep up, so the batteries end each day a little lower. A charger that tops up while you drive covers the gap.
In summer they're full again by 11am, and the extra sun is yours to use.
Starting full at 6pm, the batteries run the night, drop to their lowest around 6pm (5%), then the panels make about 0.7 kWh a day in your darkest month against about 2.4 kWh used. After two days they sit at 5%.
Go deeper: the math
Your answers add up to about 2.4 kWh a day.
Oregon gets about 1.1 hours of strong sun a day on panels lying flat on a roof in December, its darkest month (NASA data). Wires and heat lose about a quarter, plus 10% for luck.
2.4 ÷ 1.1 ÷ 0.77 × 1.1 = 3.1 kW → 4 × 200 W (roof limit)To cover the night and a cloudy day or two, you need about 3.6 kWh stored. Each battery holds about 1.2 kWh you can actually use.
2.4 × 1.5 = 3.6 kWh → 3 batteriesWant to plug in your own numbers? Use the sizing calculator. More: How much power do you use? · Peak sun hours · kW vs kWh
Panels make it
4 panels. Sized for your darkest month, so you have enough all year — plenty, not barely. That's as many as your roof fits, so a charger that tops up while you drive fills the gap.
Rigid if your roof is flat; flexible only if it curves.
The catchRoof space runs out fast.
Recommended. In your darkest month it takes 32+ days to refill — more panels or a generator helps.
Go deeper: panels
- Roof space is your limit, so fewer, higher-watt panels usually win.
- Flexible panels only for curved roofs; rigid lasts longer.
- They last 30+ years and lose about half a percent a year. Wipe them once a year if you feel like it.
Batteries store it
3 batteries. They save the day's sun for later — enough to run your normal life for about 1.5 days with no sun at all.
The battery that made lithium normal in vans21. US-made, US support, and a warranty people have actually used.
The catchPricey per amp-hour. You're paying for US support and a proven warranty.
Buy once, set for good: double batteries (they last far longer used gently), plus a spare inverter and panels.
Go deeper: batteries
- LiFePO4: light, lasts 10+ years, and you can use nearly all of it.
- Mixing old and new lead-acid ruins the new ones. Lithium doesn't have that problem.
- In freezing weather, get the heated version.
More: Server-rack batteries, explained · LiFePO4 vs lead-acid · Batteries in cold weather
Controller + inverter move it & use it
Two small boxes: one moves panel power into the batteries, the other turns it into normal outlets. Makes normal outlet power in a 12-volt rig and charges from panels, shore power or your engine.
The standard in vans and boats for over a decade12. Tough, and the warranty is real.
The catchCosts more than lookalikes, and the phone app has a small learning curve.
More: Inverter vs inverter-charger · 12V vs 24V vs 48V · MPPT vs PWM
Putting it together
Most people do some of it themselves and hire help for the rest. Pick what sounds like you.
What it costs, and what it saves
You pay once. After that, the power is yours.
| One-time cost | $6,000 – $7,500, parts and wiring |
|---|---|
| Power bill | None — and no campground hookups needed |
Over a lifetime
- TodayBuy it once
- ~15 yrsSwap the batteries — about $2,700 at today's prices.
- 30+ yrsPanels still making power
- Any timeAdd batteries as life grows
Prices move. This is a ballpark from the last price check. More: What off-grid solar costs
See it running
Real setups like this one. Watch how it's going for them.
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1
EXPLORIST.life YouTube · wiring diagrams · Step-by-step wiring diagrams and builds for vans, buses and RVsWatch
The go-to wiring reference for rigs. (Victron & Battle Born ambassador)
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2
Getaway Couple YouTube (with Mortons on the Move) · A 42-foot RV: 10 panels, 6 Battle Born batteries, 2 Victron invertersWatch
The classic big-rig setup, close to the van and bus setup here. (Affiliate links)
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3
Will Prowse YouTube · DIY Solar Forum · Independent teardowns and tests of batteries, inverters and power stationsWatch
Tests the gear so you don't have to. (Earns from affiliate links too)
Running something like this yourself? Share your setup and help the next person.
Parts checklist
Everything in one list. Tick things off as you get them.
Never type this again. A free account keeps this setup, your location and these checkmarks on any device.
Some links are affiliate links.
Questions people ask
How many batteries do I need for a van?
For typical van use (about 2.4 kWh a day) with a cloudy day or two, about 3 Battle Born 100Ah batteries. Tap the questions above to size it for your exact life and location.
How many solar panels do I need?
About 4 × 200 W panels (0.8 kW), sized for your darkest month rather than the average, so winter doesn't catch you out.
How much does it cost?
Roughly $6,000 – $7,500 one time for parts and wiring. After that the power is free.
Make this guide better
Know a cheaper, better way? Every idea gets read, the good ones get tested, and when one changes a pick, you get the credit.
If it saved you time or money, chip in to keep it free and fund the next guide.