Solar Panels for Campervans: A Complete Guide

What a Solar System Actually Does

A campervan solar system lets you generate and store electricity while off-grid — without running the engine or plugging into a campsite hookup. For weekend use at campsites with electric hook-up, it may be optional. For wild camping, extended touring, or anyone who wants genuine independence, it is essential.

Understanding what you're trying to achieve is the starting point for sizing any system correctly.

Realistic UK Solar Output

Before sizing anything, set your expectations for UK conditions. Solar panels generate significantly less energy in the UK than in southern Europe. A rough rule of thumb for UK conditions:

• Summer (May–September): approximately 3–4 peak sun hours per day
• Winter (October–April): approximately 1–2 peak sun hours per day

This means a 200W panel in the UK might generate around 600–800Wh (50–65Ah at 12V) on a good summer day — and as little as 200–400Wh on a winter day. This is considerably less than many installers suggest if they quote figures from Mediterranean conditions.

Step 1: Assess Your Daily Power Consumption

Before specifying any panels or batteries, calculate how much power you actually need each day. Common loads:

• LED lighting: approximately 10Ah per day (a few hours of lights)
• Water pump: approximately 5Ah per day
• 12V compressor fridge: 40–60Ah per day (the single biggest load in most builds)
• Phone and tablet charging: approximately 5Ah per day
• Laptop charging: approximately 20–30Ah per day
• Diesel or gas heater fan: approximately 5Ah per day

A typical setup running a fridge, lights, phone charging, and a laptop uses 80–100Ah per day. This is the number to design around.

Step 2: Choose Your Battery

Choosing the battery first makes more sense than most guides suggest, because battery capacity determines how much energy you can store and therefore how long you can run without sun.

AGM (Sealed Lead Acid) batteries:

• Price: approximately £100–£200 for a 100Ah battery
• Usable capacity: only 50% of rated capacity (so a 100Ah AGM gives you 50Ah usable)
• Weight: approximately 27–30kg per 100Ah
• Cycle life: approximately 500 full cycles before significant capacity loss
• Charging: slower, needs to reach full charge regularly or sulphation damages the battery

Lithium (LiFePO4) batteries:

• Price: approximately £400–£800 for a 100Ah battery
• Usable capacity: 80–100% of rated capacity (a 100Ah lithium gives you 90–100Ah usable)
• Weight: approximately 13kg per 100Ah — roughly half the weight of AGM
• Cycle life: 2,000–3,000+ full cycles — 4–6 times longer than AGM
• Charging: accepts faster charging, no harm from partial state of charge

For anyone using their campervan regularly (more than 30 days per year), lithium is almost always worth the premium. Over the lifetime of the battery bank, lithium works out cheaper per usable Ah and per cycle than AGM. For occasional use where the van might sit for long periods, AGM is a reasonable budget choice.

Step 3: Size Your Solar Panels

With your daily consumption and battery type established, size your panels:

Rule of thumb: 1W of solar panel generates approximately 0.25–0.35Ah per day in UK summer conditions.

So to generate 80Ah per day in summer, you need approximately:

80 ÷ 0.3 = 260W of panels

In practice, oversizing is sensible to account for cloudy days, panel angle, and shading from roof bars or vents. These sizing scenarios work well for most builds:

• Weekend warrior (50Ah/day): 160W panel + 100Ah lithium (or 200Ah AGM)
• Regular touring (80Ah/day): 300W panels + 200Ah lithium
• Full-timer or off-grid (100Ah+/day): 400–600W panels + 200–300Ah lithium + inverter

Rigid monocrystalline panels are the standard choice for campervans: more efficient than polycrystalline, durable, and cost-effective. Flexible panels exist but have lower efficiency, shorter lifespan, and heat management issues on van roofs — most experienced converters avoid them.

Step 4: Choose a Charge Controller

The charge controller sits between the solar panels and the battery, regulating the charge and protecting the battery from overcharging.

There are two types:

PWM (Pulse Width Modulation): Cheaper but significantly less efficient. Acceptable only in very small, simple systems.

MPPT (Maximum Power Point Tracking): Typically 15–30% more efficient than PWM. Always worth the extra cost for any serious system.

Victron SmartSolar MPPT is the benchmark in the UK converter market. It offers Bluetooth monitoring via the VictronConnect app, excellent reliability, and is compatible with both AGM and lithium batteries. A 100/30 or 100/50 controller covers most van builds.

Step 5: Add a Battery Monitor

A battery monitor tells you exactly how much charge remains in your battery, how many amps you're drawing, and how many you're putting in via solar. Without one, you're guessing, and guessing wrong can damage batteries or leave you without power.

Victron BMV-712 is the most widely recommended unit in the UK market. It connects via Bluetooth so you can monitor battery state from your phone.

Step 6: Consider an Inverter

An inverter converts 12V DC power from your batteries into 230V AC — the same power as a household plug socket. This lets you run a standard laptop charger, a hairdryer, a kettle, or charge camera equipment.

Inverters are not essential but significantly increase the convenience and versatility of an off-grid setup. For occasional 230V use (laptop, phone charger), a 1,000–1,500W pure sine wave inverter is sufficient. For running a kettle or microwave regularly, 2,000W+ is needed — but these draw very large amounts from the battery and are only really viable with a large lithium bank.

Shore Power

If you primarily use campsites with electric hook-up, a mains charger can replenish your leisure batteries from the site's 230V supply. This works alongside solar — shore power charges fast when available, and solar tops up off-grid. Most quality converters fit a combined system.

Recommended Brands (UK Market 2026)

• Charge controllers and battery monitors: Victron Energy (the clear market leader)
• Solar panels: Renogy (good value, widely used in UK builds)
• Lithium batteries: Fogstar Drift and Battle Born are both popular in the UK; Fogstar is UK-based and competitively priced
• Inverters: Victron or Victron-compatible inverter/chargers for integrated systems

Summary

A well-sized solar system for UK use typically involves 160–400W of rigid monocrystalline panels, a Victron MPPT charge controller, lithium (LiFePO4) batteries, and a Victron BMV battery monitor. Size to your actual daily consumption, not an aspirational figure. Expect significantly lower output in winter than in summer, and plan for cloudy UK days.