Select your van to pre-fill sensible defaults for cable run lengths, solar capacity, and alternator output — and get model-specific design tips and electrical warnings tailored to your build.
Design tips for your van
Electrical gotchas to know
Select your van model above. The tool will:
- ›Pre-fill cable run lengths for your van's typical layout
- ›Set default B2B charger rating based on your alternator
- ›Show max solar capacity based on roof dimensions
- ›Warn you about known electrical issues for your model
- ›Give tailored design suggestions for your specific build
You can override any pre-filled value in later tabs. The van selection is just a starting point.
List every electrical device in your van. Enter the wattage (check the label or manual) and how many hours per day you expect to use it. The tool calculates your total daily energy need in Wh — this number drives every other calculation.
| Device | Watts | Hrs/day | Wh/day |
|---|
| 12V compressor fridge | 35–60W |
| LED strip lights (per m) | 5–15W |
| Laptop (charging) | 45–90W |
| Phone charging | 10–20W |
| MaxxFan / roof vent | 15–30W |
| Diesel heater fan | 10–40W |
| 12V water pump | 60–100W |
| Coffee machine (240V) | 900–1500W |
Your battery bank stores the energy you need to run through the night or on cloudy days. The key decisions are chemistry (which determines how much you can safely use), and how many days of autonomy you need without charging.
The formula is:(Daily Wh × Days) ÷ DoD% × Margin
Ah capacity assumes a 12V system. If using 24V, the Ah figure halves (but the Wh energy is the same).
Solar panels recharge your batteries using daylight — not just direct sun. The amount of energy they produce depends on panel wattage, how many hours of usable light you get, and system losses from wiring and the MPPT controller.
A B2B (battery-to-battery) charger lets your van's alternator charge your leisure battery while you drive. It protects your starter battery and delivers a proper charge profile. This is your most reliable charging source when solar is limited.
An inverter converts 12V DC battery power into 240V AC mains power for laptops, coffee machines, and other household devices. Size it for your largest expected load, with headroom for the startup surge.
Undersized cables cause voltage drop, wasted energy, and in serious cases, fires. Enter the cable run length for each key circuit and the tool calculates the minimum cable size to keep voltage drop under 3% — the accepted standard.
| Circuit | Current | Min cable | Fuse |
|---|
This tool does not replace professional electrical advice.
