Core components
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.
Core parts and wiring examples
| 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 on Amazon |
| Battery | LiTime 12V 200Ah LiFePO4 | A 200Ah battery with a 200A BMS for this 12V example. Check its exact discharge limits, temperature protection and installation requirements. | Check Price on Amazon |
| 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 on Amazon |
| Inverter | Renogy 2000W pure sine inverter | 2000W of clean power runs a coffee maker, a microwave, or a laptop without straining. | Check Price on Amazon |
| 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 on Amazon |
| DC branch fuse block | Blue Sea Systems 5025 ST Blade 6-Circuit Fuse Block | For individually fused lights, fans and other DC branches. It does not replace the inverter main fuse. Select every fuse and conductor for its own circuit. | Check Price on Amazon |
| PV extension cable example | Renogy 20ft 10AWG Solar Extension Cable Pair | A red/black pair for compatible PV connectors. Check connector compatibility, string voltage, current and voltage drop; these are not inverter battery leads. | Check Price on Amazon |
| Battery cable example | Ancor 117502 2/0 AWG Red Battery Cable 25ft | Red tinned-copper conductor only. Confirm the gauge against the inverter manual and run length; buy the return conductor, lugs, main fuse and holder separately. | Check Price on Amazon |
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 RV solar panels, or a matched bundle from the best RV solar kits
- 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.