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Free tool · Victron systems · BS 7671:2018+A4:2026

Victron system designer

Tap what you'll run. We size the whole Victron system, every cable and fuse, and give you a wiring diagram and a parts list.

1

Your build

Let's size your system. What's it going in, and where?

Checked by TomTom checked the rules and sources this tool works from. Free to use, nothing to sign up for.

What it's going in

Campervan Motorhome Cabin or tiny homeOff-grid, no mains

Battery voltage

Not sure? Leave it on Auto.

Auto 12 V 24 V 48 V

Where in the UK South EnglandMidlands and WalesNorth EnglandScotland

Plan for Summer (May to Aug)Spring and autumn tooAll year, winter included

2

12 V things

What will run straight off the battery at 12 or 24 V? Tap what you've got.

3

230 V things and sockets

Now the 230 V side. What will you plug into a socket?

230 V circuits

Each gets its own RCBO.

1 circuit2 circuits3 circuits4 circuits5 circuits6 circuits

4

How you'll charge

How will you keep the battery charged?

Days with no charging at all1 day1½ days2 days3 days4 days5 days

Solar: start with your roof

Pick your van to fill in the roof size

Make

Model and lengthChoose a make first

Or measure the clear, flat part of the roof you could cover.

Usable roof length

m

Usable roof width

m

Don't know your roof size? Tell us how many panels instead

Driving a day, on average

h

Alternator chargingOur pick (Orion XS 50 A)Orion XS 70 ANone

Hook-up (shore power)

Never Sometimes Most nightsSolar tops up

Cable runs (one way)

Our defaults suit a typical layout. Change any you've measured.

Parts you already have

5

Remote monitoring

Want to see your system from anywhere?

Remote monitoring

Yes, add itCerbo GX and touch screen. Every Victron unit on one screen and the VRM app.Recommended No, keep it simpleUse Victron's free app on your phone, plus your battery's own app.

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© 2026 Tiny Build Electrics Ltd. Proprietary tool. All rights reserved. Free to use for your own build. Copying, scraping or reusing the tool, its results or its method is not permitted. A design aid only: the plan must be checked, and the 230 V side tested and certified, by a qualified electrician.