Thinking about solar panels for your motorhome or campervan

If you’re considering installing solar panels onto your motorhome or campervan, then the Club’s Technical Manager, Martin Spencer, has some advice for you.

With the exception of the occasional daring campervan, not too long ago very few leisure vehicles had solar panels installed. In today's touring world, they seem to be almost standard on new models, but are they the best option for you?

What do you expect a solar panel to do for you? 

The truth is that the majority of solar panels are still very far from being a viable alternative to the mains hookup that we have all come to rely on at both our Club campsites and other locations. 

Here’s some advice to a few queries that you might have about solar panels on your motorhome or campervan:

I just want to keep my leisure battery topped up while in storage. 

Roof-mounted panels will typically be able to do this, but keep in mind that as we head into the winter months, the sun is quite low in the sky and the days are shorter. This means that a horizontal panel will consequently not produce nearly as much power as it would in the summer.

The solar panels' functionality can be restricted by dirt, leaves, snow, and, of course, a weather protective cover, preventing them from working properly. Some people choose to use a portable panel instead, usually one of the folding, 'briefcase' style ones because it can be adjusted to an angle towards the sun. Position your motorhome or campervan the right way and you may be able to place a panel inside one of the larger windows, although due to the window tint they will be less light coming through.

Some people like to try one of the very small, very cheap solar panels, which is normally about the size of a small book. Be warned, their output is very low and they will rarely produce enough power. Experiment with the location of your panel and make sure it’s angled towards the midday sun, this will maximise the chances of it working. Always try to fully charge the battery before storage, to give the solar panel the best chance of keeping it topped up.

I want to be able to stay off-grid a little longer and not run out of 12V power. 

There’s a big difference between 2-3 days off grid and 3-4 days off grid. A decent size solar panel of 100W or more, will certainly support a good battery. It probably won’t necessarily recharge it fully, but it will lengthen the time before it’s discharged. 

It’s perfect for that long weekend spent at a weekend rally, a trip to a festival or even on a basic Certificated Location campsite. However the performance of the solar panel will always be affected by the time of year and the climate.

I want to stay off grid for longer. 

For this, you need to consider more than just an additional solar panel but instead look at the whole power system. You’ll more than likely need:

• A more powerful battery, probably a lithium one
• A more effective motorhome charger, that can swiftly recharge the battery even during a short trip out
• A bigger solar panel, or a number of panels, especially if you want to stay in a fixed place for an extended period of time. 

Before deciding on the exact system that will suit your needs, do a lot of research into them as these systems can get quite complex and pricey.

There are good system installers and suppliers around who, for a price, can make this easy for you.  If not, the superb Caravan & Motorhome Off-Grid Group on Facebook can offer a wealth of knowledge and advice on what to buy and how to get the most out of it.

Ultimately, solar power is a fantastic resource, as long as you understand and appreciate its qualities and constraints. However, don’t compromise on the additional components that you need to connect it up, especially if you want to get the best performance. For example, to connect the panel to your battery, use a reliable charge controller, high-quality connectors and wiring. These components protect the battery from being overcharged on a really sunny day. However, if you want the best performance in our unpredictable weather conditions, choose the more advanced ‘MPPT’ kind instead of the more affordable ‘PWM’ ones, as they will maximise the efficiency of your panel.

First published in May 2023.