800 watts of van solar — for the power-hungry build.
800W is for vans that run more: entertainment, a fuller fridge, fast charging alongside Starlink and the essentials. Wattonomy sizes the bank, inverter and wiring for the heavier draw, and specs it all to ABYC.
A real Wattonomy output — a power-hungry van build
System
12 V
Battery
7.68 kWh
Solar
800 W
Inverter
MP 12/2000 120V
SmartSolar 150/701×
200W solar panel4×
Battery → inverter cable4×
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
Bigger arrays still need the bank and wiring to match.
More panels only help if the battery, inverter and cable keep pace — otherwise you waste the extra watts or overheat a conductor. Wattonomy balances all four to your real loads, to ABYC E-11, with the fusing and voltage-drop shown.
What 800W of van solar gets you
800W covers a heavier-use van in fair sun. Here’s how the pieces scale.
What it runs
Fridge, Starlink, entertainment, water and fast device charging — a heavier-use rig in fair sun.
Battery to match
Around 5 kWh of LiFePO4 at 12V on an honest depth-of-discharge; the tool steps the bank up if your loads grow.
When to step up to 24V
Add induction, a kettle or air-con and the tool moves you to 24V — thinner copper, less loss — and resizes everything for it.
Cables & fuses
Every gauge and fuse sized to the load and your run lengths, with the AIC checked — to ABYC E-11.
What you walk away with — free
A full 800W system sized to your appliances — battery, inverter, solar, charging
A real wiring diagram with every cable gauge and fuse
Cable & fuse sizing with the voltage drop checked for your runs
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 van
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
What can 800W of solar run in a van?
A fridge, Starlink, entertainment, water pump and fast charging in fair sun. Heavy AC loads like induction or air-con push you to a bigger bank and usually 24V — the tool flags that the moment you add them.
Is 800W overkill for a campervan?
Not if you run entertainment, a bigger fridge or work from the road in lower light. For essentials-only, 400W is plenty — Wattonomy sizes to what you actually run so you don’t overspend.
How much battery for an 800W system?
Around 5 kWh (roughly 400Ah at 12V) for a typical heavy-use van, more if your loads are large — sized from your real appliances and days of backup.
Do I need an account?
No — 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