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Solar for RVs, trailers and camping
A completely different animal from house solar. Smaller, cheaper, mostly DIY-able, and the numbers are easy once you know what to count.
The short answer: most people massively overbuy panels and underbuy battery. Weekend campers running lights, a fan and phone charging manage fine on 100–200 watts of panel and one decent battery. The thing that decides everything is whether you want to run air conditioning — and if you do, solar is almost certainly the wrong answer.
Why RV solar is nothing like house solar
| House | RV | |
|---|---|---|
| Voltage | 120/240V AC | 12V DC, with an inverter for AC |
| Typical size | 6,000–12,000 watts | 100–800 watts |
| Cost | $20,000+ | $300–$3,000 |
| Storage | Optional, grid does it | Essential — there is no grid |
| Permits | Required | None |
| DIY | Rarely sensible | Completely normal |
That last row matters. RV solar is a genuine weekend project for someone reasonably handy, with no permit, no inspection and no utility involved.
Work out what you actually use
Everything in a camper is rated in amps at 12 volts. Multiply amps by hours to get amp-hours (Ah), which is how battery capacity is measured.
| Item | Rough draw | Per day |
|---|---|---|
| LED lights | 1–2 A | 5–10 Ah |
| Water pump | 4–6 A while running | 2–5 Ah |
| Phone and laptop charging | 2–5 A | 10–20 Ah |
| Roof vent fan | 2–4 A | 15–40 Ah |
| 12V compressor fridge | 3–5 A, cycling | 30–60 Ah |
| Furnace fan (propane heat) | 6–8 A while running | 15–40 Ah |
| Television | 3–5 A | 10–20 Ah |
Add up a realistic day. Most weekend setups land between 30 and 80 Ah. Add a fridge and you’re nearer 100–150.
Sizing it
Battery first. Aim for roughly twice your daily use, so you can survive a cloudy day without stress.
- Lead-acid batteries can only be discharged about halfway without damaging them. A 100 Ah lead-acid battery gives you 50 usable amp-hours.
- Lithium (LiFePO4) can be run down to around 10–20%. A 100 Ah lithium gives you 80–90 usable, weighs a third as much, and lasts several times longer. It costs more up front and is almost always worth it.
Then panels. A rough rule that works: every 100 watts of panel returns roughly 30 amp-hours on a decent summer day. Less in winter, less in shade, less if the panels lie flat on a roof rather than tilted at the sun.
| You use | Panels | Battery | Suits |
|---|---|---|---|
| 20–40 Ah/day | 100 W | 100 Ah | Lights, pump, phones. Weekends. |
| 50–80 Ah/day | 200 W | 200 Ah | Add a fan and a small fridge. |
| 100–150 Ah/day | 400 W | 300–400 Ah | Full-timing, fridge, laptops. |
| Air conditioning | 1,000 W+ | 600 Ah+ | See below. |
An RV air conditioner draws roughly 1,200–1,800 watts while running. Over an afternoon that’s more than most solar setups produce in two full days.
Running AC on solar means a large lithium bank, a big inverter, and a panel array bigger than most RV roofs. It’s possible and people do it, but it’s a multi-thousand-dollar build. If air conditioning is your reason for wanting solar, a generator or a campground hookup is the honest answer.
Roof-mounted or portable?
| Roof-mounted | Portable / folding | |
|---|---|---|
| Charges while driving | Yes | No |
| Needs sun on the rig | Yes — so no shady sites | No. Park in shade, put panels in sun |
| Aimed at the sun | No, flat | Yes — noticeably more output |
| Theft | Not a concern | Real concern |
| Setup each time | None | Ten minutes |
Plenty of people run both: a modest roof array for topping up while driving and parked, plus a folding panel for when they’re camped in the shade. Being able to park in shade in July and still charge is worth more than it sounds.
The other parts
- Charge controller — sits between panels and battery. Two types: PWM is cheap, MPPT gets roughly 20–30% more from the same panels. Above about 200 watts, MPPT pays for itself.
- Inverter — only needed for household AC devices. Get pure sine wave; modified sine damages some electronics and makes fans whine.
- Fuses and correct wire gauge — not optional. Twelve-volt systems run high current, and undersized wire is a genuine fire risk. This is the corner people cut and shouldn’t.
- Battery monitor — a shunt-based monitor showing true state of charge. Cheap, and turns guesswork into knowledge.
Rough costs
| Setup | Ballpark |
|---|---|
| 100 W kit with controller, lead-acid battery | $300 – $600 |
| 200 W with MPPT and 100 Ah lithium | $900 – $1,600 |
| 400 W with 200 Ah lithium and inverter | $2,000 – $3,500 |
| Professional installation, if you’d rather not | Add $500 – $1,500 |
No federal tax credit applies to any of this. The residential credit expired at the end of 2025, and RV systems generally didn’t qualify anyway unless the rig was a primary residence.