Motorhome electrical control panel with switches and displays above the entry door

Electrics & Solar · 28 October 2026 · 7 min read

Campervan Electrical and Solar Setup: A Beginner's Guide

Understand campervan 12V electrics and solar in plain English: how to estimate your power use, size batteries and solar panels, and wire a safe system.

The electrical system is the heart of a modern campervan. It runs your lights, fridge, water pump, fan, phone chargers and perhaps a laptop or induction hob. It is also the part of a conversion that intimidates beginners the most, and the part where mistakes carry real risk.

This guide explains the basics in plain language so you can plan a system that suits your travel style, talk confidently with an installer, or build a simple setup yourself with care. It is not a substitute for a qualified auto electrician, especially for mains (230V/120V) wiring.

The Building Blocks

Almost every campervan system has the same main parts:

  • Leisure battery (house battery): stores energy for your living area, separate from the vehicle's starter battery.
  • Charging sources: solar panels, a DC-DC charger from the vehicle alternator, and a mains (shore power) charger at campsites.
  • Solar charge controller: sits between the panels and the battery and charges the battery safely. MPPT controllers are more efficient than older PWM types.
  • Fuse box and distribution: splits power out to the circuits, each protected by its own fuse.
  • Inverter (optional): converts 12V DC into household AC for devices that need it.
  • Battery monitor: tells you how much charge is left. A shunt-based monitor is far more accurate than a simple voltage reading.

Step 1: Do a Power Audit

Start by listing every device and estimating how long you will use it each day. Multiply the power (watts) by the hours of use to get watt-hours (Wh). For example:

Device Power (example) Hours per day Wh per day
LED lights 10 W 4 40
Compressor fridge (average) 15 W 24 (cycling) ~360
Roof fan 20 W 6 120
Phone charging 10 W 3 30
Laptop 60 W 3 180
Water pump 50 W 0.25 ~13

These are illustrative example figures only. Check the label or manual of your own devices, because actual consumption varies widely between models and with ambient temperature. A fridge, for instance, works much harder in a hot summer than in spring.

Add up your total and add a safety margin of 20 to 30 percent. That number drives every other decision.

Step 2: Choose a Battery Type and Size

The two main families are lead-acid (including AGM and gel) and lithium iron phosphate (LiFePO4).

Lead-acid / AGM

  • Lower upfront cost.
  • Heavy.
  • To keep them healthy, you should only use roughly half of the rated capacity regularly.

Lithium (LiFePO4)

  • Higher upfront cost.
  • Much lighter for the same usable energy.
  • Most of the rated capacity is usable, and they tolerate many more charge cycles.
  • Need a battery management system (BMS) and should not be charged below freezing unless they have built-in heating.

To size your battery, decide how many days you want to last without any charging, then calculate. For example, if your audit says around 900 Wh per day and you want two days of autonomy, you need about 1,800 Wh of usable energy. At 12V that is roughly 150 Ah of usable capacity, which means a lithium battery of around 150 to 200 Ah, or a much larger lead-acid bank.

Step 3: Size Your Solar

How much solar you need depends on your daily use, where you travel, and the season. In the Eastern Mediterranean, summer sun is strong and long, so a modest array goes a long way. In winter, or in northern Europe, the same panel might produce a fraction of that.

A rough rule of thumb many builders use: a panel may produce, over a full day, a few times its rated wattage in watt-hours, depending on sun hours, panel angle, heat and shading. Treat any such figure as an estimate. Heat reduces panel efficiency, so the hottest days are not always the most productive.

Practical tips:

  • Fit as much solar as your roof allows, after leaving space for the fan and any skylight.
  • Rigid panels generally last longer and run cooler than flexible ones glued flat to the roof.
  • Shading even part of a panel can reduce its output significantly.

Step 4: Add Alternator Charging

A DC-DC charger lets your vehicle's alternator charge the leisure battery while you drive. This is the perfect partner to solar, because on cloudy days or in winter, a couple of hours of driving can refill a large share of the battery. Modern vehicles with smart alternators generally need a DC-DC charger rather than a simple split-charge relay.

Step 5: Shore Power

A mains hook-up lets you plug in at campsites. It usually includes an external inlet socket, an RCD/RCBO consumer unit, a battery charger and possibly a few household sockets. Because this involves mains voltage, it should be installed by a qualified electrician and follow local regulations.

Step 6: Do You Need an Inverter?

An inverter is only needed for devices that run on household AC. Many items, such as phones, laptops (with the right adapter), lights, fans and fridges, can run directly on 12V, which is more efficient. If you do need AC:

  • A pure sine wave inverter is safer for sensitive electronics.
  • Size it for the largest device you will run, plus margin.
  • Remember that high-power devices like kettles, hair dryers and induction hobs drain a battery very quickly and need thick cables, a large battery and appropriate fuses.

Step 7: Cables and Fuses

This is where safety is won or lost.

  • Size cables for current and length. A cable that is too thin will heat up. Use online voltage-drop calculators and the manufacturer's recommendations.
  • Fuse every positive cable as close to the power source as possible. The fuse protects the cable, so it should be rated for the cable, not just the device.
  • Use a main isolator switch so you can cut all power quickly.
  • Use proper crimp terminals and a good crimping tool. Loose connections create heat.
  • Protect cables from sharp metal edges with grommets and conduit.
  • Mount batteries securely in a ventilated space, protected from impact.

A Simple Example System

To illustrate how the pieces fit together, here is an example of a modest setup for weekend and holiday use. It is not a recommendation for your specific van:

  • One lithium leisure battery of around 100 to 200 Ah.
  • One or two rigid solar panels totalling a few hundred watts.
  • An MPPT solar charge controller matched to the panels.
  • A DC-DC charger from the vehicle.
  • A 12V fuse box feeding lights, fan, pump, fridge and USB sockets.
  • A small pure sine wave inverter for occasional laptop or camera charging.
  • A shunt battery monitor.

Full-time travellers who cook on induction or work remotely on powerful equipment usually go much bigger on battery and solar.

Common Mistakes to Avoid

  1. Skipping the power audit and buying components first.
  2. Undersized cables between battery, inverter and charger.
  3. Missing fuses, or fuses too large for the cable.
  4. Mixing old and new batteries, or mixing battery chemistries.
  5. Ignoring temperature: lithium batteries need protection from charging in freezing conditions, and all electronics need ventilation in hot climates.
  6. No battery monitor, so you never really know your state of charge.

Heat Matters in the Mediterranean

In a Lebanese summer, especially on the coast and in the Bekaa, summer temperatures inside a parked van can be high. Install charge controllers, inverters and chargers where air can circulate, keep them away from heat sources, and consider a small fan for the electrical compartment. Your fridge will also draw more power in summer, so plan your audit for the hottest month you travel in.

Final Thoughts

A good campervan electrical system starts with an honest estimate of your power use. From there, battery, solar and charging choices follow logically. Keep the system as simple as your needs allow, protect every cable with the right fuse, and get professional help for anything you are unsure about, especially mains wiring. For how electrics fit into the overall build order, read our step-by-step van conversion guide.

Gear we recommend

As an Amazon Associate we earn from qualifying purchases. Learn more.