A Complete Guide to Caravan Solar Panels

What Solar Panels Can I Fit on My Caravan?

There are several options for powering your caravan when it comes to solar power. You can use solar panel kits, static, flexible or freestanding ones. Each one will come with its own features, as outlined below.

Solar Panel Kits

These can be ideal panels for caravans as they are designed to be installed yourself. Solar panel kits come in a variety of sizes and power outputs, but it’s important that you have a little mechanical knowledge so they’re installed correctly. Caravan solar panels work when they’re waterproof and connected to the battery properly.

Static Panels

Perhaps the most easily envisioned panel, these sit on the roof just like they would on your home. They’re a heavier kind of installation and ideally need a profession to install them. A mounting frame would need to be fitted on the roof before you can get these caravan solar panels working.

Flexible Panels

More lightweight and able to bend around the curvature of a vehicle, flexible solar panels are the perfect solution for caravans and motorhomes. As they are a fraction of the weight of static solar equivalents, they won’t add undue stress to the vehicle.

Freestanding Solar Panels

It might be the case where you don’t want to permanently affix panels to your caravan. Freestanding cells give you the freedom to use them as and when you need to. When you’re not moving, the panel will need to be set up in the open and connected to the battery. Once finished or if you need to move, it will need to be put away again. In terms of a small system, freestanding caravan solar panels work just as well because you can angle them perfectly to the sun.

How Many Solar Panels Do I Need to Power My Caravan?

To find out how many caravan solar panels you need, you should estimate how much electricity you use. It also depends whether you’re looking to cover your entire usage with solar panels for your caravan.

A caravan or motorhome has two batteries: the vehicle battery and a leisure battery. The former is for turning the vehicle on and powering the road lights, while the latter is to power appliances when the engine isn’t running. The leisure battery works on alternating current (AC), while the vehicle battery uses direct current (DC). Solar power is generated as DC power, so it needs to be converted to AC before you can use it for appliances.

While these batteries are separate, it’s possible to discharge the vehicle battery by overusing the leisure battery. When the vehicle is in motion, the vehicle can charge the leisure battery, but depending on how much electricity you need, you can top this up by making use of caravan solar panels.

What Appliances Are You Running?

Your electricity demand will dictate how many caravan solar panels you need. Work out where your electricity is going and tally your total watt hours (Wh). This can be checked by looking at the power rating on the appliance itself. For a general guide, you can see typical wattages for various appliances in the interactive graph below.

How Much Power Are You Using?

Next, you need to estimate how many hours of use each appliance will need on a daily basis. In order to get a good idea of what kind of caravan solar panels you’ll need, it’s important to work out your usage.

Take the wattage of an appliance and multiply it by the number of hours it’s used in a day. This will give you the total amount of energy in watt hours that you’ll need to consider when choosing the right sized panel. A 1,000W kettle used for 5 minutes throughout the day would require 83Wh of electricity, for example, so adding this to all other appliances used gives a rough indication of what capacity caravan solar panels you’ll need.

The rule of thumb is to add 20% to your calculations to cover suboptimal conditions. If you’re looking for caravan solar panels that will work throughout the winter, bear in mind that they will not generate as much power as they would in the summer.

Which Caravan Solar Panels Do I Need?

Once you’ve worked out your usage per day (and added a 20% leeway), this will help you decide on the power you need from your system. It also depends on which set up you’re opting for. A freestanding panel, for example, will not be able to provide power until it’s installed outside and connected to the battery, while any fixed caravan solar panels on the roof will generate power continuously.

Think of the wattage of each unit. A 4W panel can produce anywhere between 20 and 30Wh of electricity a day, while a 150W panel is capable of producing up to 1,100Wh. For summertime use, caravan solar panels can produce anything on the top end of this. In the winter, the average watt hour is about 20% less than the total wattage of the panel, i.e., a 10W panel can produce around 8Wh of electricity per day in winter.

You can see how much power you will generate based on the size of the system you choose in the table below.

On the low end of the scale, a 4W cell will produce around 24-28Wh of electricity a day in the summer. Come wintertime, this falls to around a low 3.2Wh. A more powerful 150W cell will produce up to 1,050Wh a day in summer but only around 120Wh in the winter.

Please note, this is just a rough calculation and shouldn’t be relied upon. The weather will always affect how much power is produced by caravan solar panels, so actual figures could be even higher or lower than this. Winter power generation will always be much lower than in the summer, so it’s worth choosing a system that will consistently cover your needs year-round.

How Will You Use Your Solar Panels for Your Caravan?

Are you planning on using your caravan solar panels year-round? If so, the more wattage, the better. A 250W cell can produce a greater amount of energy throughout the winter and potentially cover your electricity usage during the summer.

Will you only use your caravan solar panels in the summer? Solar systems are at their most efficient during the summer, so a lower wattage can work in your favour. If you’re looking to cover all your energy needs throughout the day, anything from 80—150 watts could be ideal.

Do you want to use caravan solar panels to top up the leisure battery? If your usage isn’t much of an issue but you’d like to benefit from a little free electricity, a smaller 20–50 watt panel would suit you just fine.

Do Caravans Need Solar Batteries?

Leisure batteries in caravans are around 12 volts and some larger models have more than one of these installed. They’re useful for running appliances for a short period of time. If you are looking to operate additional energy-demanding appliances or need to make use of more electricity over longer periods, then a solar battery could be a good investment. Off-grid systems will need a battery with a big enough capacity to cover all your needs and ensure the energy from your caravan solar panels is captured.

Charge Controllers for Caravan Solar Panels

Perhaps one of the most underdiscussed elements of solar panels for caravans is charge controllers. Photovoltaic cells rarely charge at a consistent pace 100% of the time, which causes differing levels of charge to be supplied to the battery. A charge controller simply regulates how much charge the battery receives at any one time in order to keep it safe and prolong its life.

Small systems (5W and under) don’t suffer from this problem as they aren’t generating enough power for this to be an issue. It’s only the larger caravan solar panels that require a regulator or charge controller to ensure the power is managed effectively. Without them, you are at risk of fire or a battery that doesn’t last long enough to make use of.

If you’re installing caravan solar panels yourself, charge controllers may be included in the kit you’ve ordered. With any installation, it’s always best to check as you may need one if it’s not included. Any professional installation should have one included, but you should make sure to ask.

Power Inverters

An inverter is an essential piece of kit. This simply converts the stored battery power from DC to usable mains electricity (AC). To be able to make use of any appliances, you will need an inverter. Without it, your appliances would struggle with the higher current and become damaged. This can cause fires and is a danger to you if you ever come in contact with it.

Get the Most Out of Your Caravan Solar Panels

It always pays to look after your system as this keeps it working at its best and for many years to come. Make sure to clean them every now and again, especially if they have become dirty. Any build-up of dirt or dust can reduce the overall efficiency, limiting how much electricity they can generate.

It’s also useful to make sure you’re only using energy efficient appliances. Caravan solar panels can work more effectively when they’re powering items that don’t demand too much from them. This can also help run electricals for longer.

Similarly, be conscious of any appliances that are draining the battery too quickly. Being smart with charging and discharging can help you get the most out of your caravan solar panels.