Motorhome Solar Made Simple: What You Need to Know Before You Buy
Thinking About Solar Panels for Your Motorhome?
If you’re considering fitting solar panels to your motorhome, you’re definitely not alone. Solar power has quickly become one of the most popular upgrades for motorhome and caravan owners who want more freedom, reduced running costs, and the ability to stay off-grid for longer.
Whether you’re dreaming of wild camping, touring Europe, or simply keeping your leisure batteries topped up while parked, the right solar setup can make life on the road smoother and more flexible.
But with so many options out there, choosing the right setup can feel confusing. How many watts do you need? Which type of panel is best? Will it work in the UK? How much will it cost?
To make things simple, we’ve put together clear, easy-to-understand answers to the most common questions motorhome owners ask when choosing solar panels.
And if you’d like personalised help or want your system professionally installed, our team is always here to assist - just get in touch anytime.
What Size Solar Panel Should You Choose?
Choosing the right solar panel size depends entirely on how much power you use. Here’s a straightforward guide:
Minimal Use (Battery Maintenance Only)
If you only need to prevent battery self-discharge:
-
5W–10W panel
Ideal for long-term trickle charging.
Light Use (Small Daily Loads)
Perfect for LED lighting, phone charging, stereo use:
- 40W–50W panel
Medium Use (Regular Appliances)
Suitable for TVs, water pumps, non-LED bulbs:
- 80W–100W panel
Heavy Use (Electric Fridge Running 24/7)
Solar needed just for the fridge:
- 100W–150W panel
- Large or Mixed Loads
If you’re powering several appliances consistently:
- Add up all your daily consumption to calculate total wattage required.
How to Choose the Right 12V Solar Panel for Your Motorhome, Caravan, or Boat
There’s no one-size-fits-all answer. Your ideal solar setup depends on:
- What you use
- How often you use it
- How long you stay off-grid
Below, we break the process into simple steps.
1. Understand Your Average Daily Power Consumption
Before choosing a solar panel, estimate how much power your appliances use over a typical 24-hour period.
Example Usage
- 4 × 10W LED lights, used for 3 hours
- 40W 12V TV, used for 2 hours
- 20W water pump, used approx. 30 mins
Daily Consumption Calculation
- Lights: 4 × 10W × 3h = 120Wh
- TV: 40W × 2h = 80Wh
- Pump: 20W ÷ 2 = 10Wh
Total: 210Wh per day
Once you know this number, you can size your solar panel accordingly.
2. Calculating the Correct Solar Panel Size
Solar panels generate different amounts of energy depending on sunlight. For example, if you get around 5 hours of usable sun per day:
-
A 50W panel produces roughly
50W × 5h = 250Wh per day
This covers the 210Wh requirement in our example.
Don’t Forget System Losses
Solar setups naturally lose around 20% through:
- Charge controller inefficiencies
- Cables
- Battery charging losses
Always choose a panel at least 20% larger than your calculated need.
How to Choose the Right 12V Solar Panel for Your Motorhome, Caravan, or Boat
There’s no one-size-fits-all answer. Your ideal solar setup depends on:
- What you use
- How often you use it
- How long you stay off-grid
Below, we break the process into simple steps.
1. Understand Your Average Daily Power Consumption
Before choosing a solar panel, estimate how much power your appliances use over a typical 24-hour period.
Example Usage
- 4 × 10W LED lights, used for 3 hours
- 40W 12V TV, used for 2 hours
- 20W water pump, used approx. 30 mins
Daily Consumption Calculation
- Lights: 4 × 10W × 3h = 120Wh
- TV: 40W × 2h = 80Wh
- Pump: 20W ÷ 2 = 10Wh
Total: 210Wh per day
Once you know this number, you can size your solar panel accordingly.
2. Calculating the Correct Solar Panel Size
Solar panels generate different amounts of energy depending on sunlight. For example, if you get around 5 hours of usable sun per day:
-
A 50W panel produces roughly
50W × 5h = 250Wh per day
This covers the 210Wh requirement in our example.
Don’t Forget System Losses
Solar setups naturally lose around 20% through:
- Charge controller inefficiencies
- Cables
- Battery charging losses
Always choose a panel at least 20% larger than your calculated need.
Electric Fridges vs Gas Fridges
12V Electric Fridges
- High power consumers
- Usually need 100W–150W solar capacity on their own
- Must be included in your calculations
Gas Absorption Fridges
- Use very little electrical power
- Much easier to support with a small solar system
- Only require minimal wattage for control electronics and ventilation fans
Using Power Inverters: What You Need to Know
If you're running 240V appliances through a 12V–240V inverter, don’t forget:
- Inverters are 85–90% efficient
- They draw 10–15% extra power from your battery
So increase your daily usage estimate accordingly.
3. Battery Capacity and Solar Charging
Your battery size doesn’t determine your solar panel size directly, but it still matters.
Why Battery Capacity Is Important
-
Maximum Charging Rate
Many AGM/gel batteries shouldn’t charge above 20% of their Ah rating.
Example: A 50Ah battery shouldn’t exceed 10A (≈160W solar). -
Storage Limits
If your battery fills by lunchtime, the rest of the day’s solar energy is wasted.
Match your solar panel size and battery capacity so the system works efficiently together.
How Long Does It Take a Solar Panel to Charge a Leisure Battery?
Charge time depends on the amps produced by your solar panel.
Example
A 100W panel typically produces 4–5A in good sunlight.
For a 100Ah battery:
- 100Ah ÷ 5A ≈ 20–25 hours of strong sunlight from empty to full
A 50W panel takes roughly twice as long.
Need Help or Want Professional Installation?
Still unsure what you need?
Or want a system tailored to your motorhome, caravan, or boat?
We’re always happy to help.
Our team can:
- Recommend the perfect solar setup
- Supply quality panels and equipment
- Professionally install your system in our workshop
Get in touch anytime for friendly, expert advice.