Complete build
The Classic 400W RV/Van Build
The build most people actually want. 400W of solar, a 200Ah lithium battery, and a 2000W inverter give you enough power to run a fridge, lights, and all your devices comfortably, with a DC-DC charger so your engine helps out on cloudy days. It is the proven, do-it-all setup for RVs, camper vans, and bus conversions.
Who this is for
This is for the person who plans to spend real time off-grid in a van, RV, or bus and does not want to ration power. If you want to keep a fridge cold, run lights and a fan, charge a laptop, and occasionally use a coffee maker or microwave without thinking too hard about it, this is the system that gets you there. It is also the most popular build for a reason, it balances cost, capability, and complexity.
What it powers
Day to day, this setup runs a 12V compressor fridge around the clock, LED lighting, roof fans, water pump, and all your charging. Through the 2000W inverter it also handles a microwave, a coffee maker, a blender, or power tools, one at a time. It is not sized for air conditioning or all-day high-draw appliances, but for comfortable full-time-ish van and RV living, it covers nearly everything.
Complete parts list
| Part | Recommended pick | Why | Get it |
|---|---|---|---|
| Solar panels | 2x Renogy 200W mono panels | 400W of solar is the sweet spot. It keeps a 200Ah battery charged even with daily fridge use. | Check Price |
| Battery | LiTime 12V 200Ah LiFePO4 | 200Ah of lithium runs a fridge plus lights and devices overnight, with depth to spare. | Check Price |
| Charge controller | Victron SmartSolar MPPT 100/30 | A 30A MPPT comfortably handles 400W on a 12V system, with Bluetooth so you can watch it charge. | Check Price |
| Inverter | Renogy 2000W pure sine inverter | 2000W of clean power runs a coffee maker, a microwave, or a laptop without straining. | Check Price |
| DC-DC charger | Renogy 40A DC-DC charger | Lets your engine charge the house battery as you drive, so you stay topped up on cloudy days. | Check Price |
| Wiring & fuses kit | Heavy-gauge wiring + fuse kit | Bigger loads need thicker cable and the right fuses. This kit ties the whole system together safely. | Check Price |
Wiring overview
Skill level: Intermediate. Install time: A long weekend, or a couple of unhurried days.
Want to swap parts?
Each part links to a deeper roundup so you can choose a different brand or size for your rig and budget.
- Other panels: best solar panels
- Other batteries: best 12V LiFePO4 batteries
- Other inverters: best inverters for off-grid solar
- Other controllers: best MPPT charge controllers
Frequently Asked Questions
Why is 400W the classic size?
Because it is the point where an off-grid rig stops feeling like a compromise. 400W of solar paired with a 200Ah lithium battery keeps a 12V fridge running, charges all your devices, and still has headroom for a microwave or coffee maker through the inverter. It fits most van and RV roofs without crowding them.
Do I really need the DC-DC charger?
If you drive regularly, yes, it is one of the best upgrades in this build. It uses your engine's alternator to safely charge the lithium house battery while you drive, which means you stay powered through a string of cloudy days that solar alone could not cover.
Can this run an air conditioner?
Not a rooftop RV air conditioner, no. That needs far more battery and solar than a 400W build provides. This system is built for a fridge, lights, electronics, and occasional appliance use. If AC is a must, you are looking at a much larger system.
Is 200Ah enough battery?
For most people, yes. 200Ah of usable lithium runs a compressor fridge overnight plus lights and charging with room left over. If you camp in shade often or run heavy loads daily, you can add a second 200Ah battery in parallel later.
How hard is this to install?
It is a step up from the minimalist build but still very doable for a careful beginner. The wiring is heavier and there are more connections, especially the DC-DC charger to the engine. Plan a long weekend, fuse everything, and double-check your cable sizes.