Air-conditioning is the heaviest load most rigs ever ask of their batteries. Wattonomy shows the honest numbers — the bank, solar and inverter it really takes — so you can decide before you spend.
A real Wattonomy output — an air-con-capable off-grid build
System
12 V
Battery
12.8 kWh
Solar
1000 W
Inverter
MP-II 12/3000 12
SmartSolar 150/851×
200W solar panel5×
Battery → inverter cable7×
Battery → inverter fuse1×
Wire & fuse sizes follow ABYC E-11 — each conductor carries its fuse and stays under a 3% voltage drop.
Built to ABYC standards
Gauge · fuse · volt-drop sized
Every spec sourced
Air-con is where solar dreams meet physics.
A rooftop air-con can pull more in an hour than your lights use in a day. Running it on solar means a large lithium bank, a strong inverter and serious cable — Wattonomy sizes all of it honestly, to ABYC E-11, so you see the real cost up front.
What it takes to run RV air-con
Even modest, intermittent air-con use is a big load — here’s the honest picture, and where solar alone usually isn’t enough.
The honest answer
Solar can run air-con in short bursts with a big bank, but continuous cooling usually needs shore power or a generator alongside. The tool shows your real numbers.
Daily energy
A few hours of cooling adds up fast — far more than a fridge or lights — which drives a much larger battery.
Big bank & strong inverter
Expect a large LiFePO4 bank and a 3000W-class inverter; the tool sizes both to your run hours.
Cables & fuses
Heavy conductors and the right Class-T fusing for the high current — sized to ABYC E-11.
What you walk away with — free
A system sized honestly for your air-con run hours — battery, solar, inverter
A real wiring diagram with cable gauges and fuses
Cable & fuse sizing with the voltage drop checked
A shoppable parts list, each line traceable to ABYC or Victron specs
Building it for real? Unlock the build binder.
Free gets you a safe, correctly-sized design. The build binder gets you the documents to build it right — and prove it's right.
Printable wiring diagram, yours to keep & tape inside the build
Full parts list, every line sourced
The volt-drop & fusing calculation trail — the "why" behind every spec
The build binder is a one-time unlock — no subscription, no auto-renew.
Questions
Can solar really run an RV air conditioner?
For short bursts, yes — with a large lithium bank and a strong inverter. For continuous cooling, solar alone usually isn’t enough and you’ll pair it with shore power or a generator. Wattonomy gives you the real battery, solar and inverter numbers so you can decide.
How much battery to run RV air-con?
Far more than most loads — even a few hours of cooling needs a large LiFePO4 bank. Enter your air-con’s watts and run hours and the tool sizes the exact bank, solar and inverter.
How much solar to run air-con all day?
All-day cooling on solar alone is rarely practical — it would need a very large roof and bank. The tool shows what your roof can realistically deliver versus what continuous air-con needs.
Do I need an account?
No — design free, no email. Accounts only for saving builds or the build binder.
The standards we build to
Plain version: these are the recognized rulebooks your design is sized against, so the numbers hold up to a surveyor, an inspector or an insurer.
ABYC E-11The US standard for AC & DC wiring on boats — what a surveyor or insurer actually checks.
Wattonomy applies these standards in its calculations. It is not certified, sponsored or endorsed by ABYC, ISO, NFPA or Victron — it sizes your design to meet what they require, and shows the working.
Sized and checked to ABYC E-11. Last reviewed June 2026 — see the full methodology for the exact rules behind every number and how each design is validated.
Built by anABYC Certified Master Technician