Guide written by:
John, DIYer & IT developer, Brighton
Depending on the power required, in kWh, for your truck, camper or boat, you can use different formulas to determine the peak kilowatts (kWp) that your solar panels will need to have to sufficiently run all the vehicle's electrical components. Solar panels are generally sold in a kit that includes an inverter and a converter.
- Calculation of peak kilowatts
- Amorphous silicon solar panel
- Polycrystalline silicon or monocrystalline silicon solar panel
- Inverter and converter
Why add solar panels to a converted vehicle?
In a truck, motorhome or boat, a service battery can power all of the electrical appliances that are required for day to day activities. Being able to power your pump is crucial if you want to transfer water from the reserve tank to enjoy a good shower, all the while leaving the refrigerator running.
When you are away at sea or on the road, there are no electric sources to supply you. While some energy is recovered from your engine, which drivesthe alternator that charges the battery, it produces relatively little. For a motorhome for example, it will only provide between 6 and 10 Ah per hour. At this rate, it will take at least 10 hours to recharge any battery over 100 Ah. Using a generator can be an alternative solution to total independence in terms of energy, but they are bulky, run on fuel and above all, are very noisy.
How much solar power is needed for your motorhome?
It is important to determine how much electricity the panels must produce in order to attain your comfort level. If they run out, it's back to the drawing board, meaning you need to find somewhere to recharge or let the engine run. That's a lot of work! On the other hand, if the solar panels generate too much power, you will never be short of electricity, which is a very positive problem to have. That being said, this type of installation tends to be quite expensive, very bulky, and will increase the weight of the vehicle considerably, which can sometimes cause issues in a tightly packed trucks.
To determine how much energy is required, you simply multiply the power of each device, expressed in watts (W), by the number of hours you expect to use it, daily. Take that number and add a margin of at least 15% to account for energy loss that may occur during battery storage and conversion of 12 V DC to 220 V AC.
Once you have arrived at an exact value, you can now start to look at the power of the actual photovoltaic panels. A solar panel's power is usually expressed in peak watts (Wc). On average, a 100 Wc photovoltaic panel will see a daily production of around 100 Wh in winter and 400 Wh in summer. If we apply this model to a 12 V system, we gets a production of anywhere between 9 and 36 Ah. This value can be increased and the panel's yield optimized if the panel is facing southernly at a 35° horizontal angle. It also helps if you live in a region where the sun shines a lot!
Contents of a solar power kit
This is the component that turns the sun's energy into electricity. There are different models available, including flexible panels, referred to as amorphous silicon, which are relatively inexpensive, but have a low yield. If the installation requires more energy, your best bet is polycrystalline silicon or monocrystalline silicon panels, they are by far the most efficient models. The cells can be independent and fixed on a flexible support, which results in a semi-flexible panel.
An electronic regulator
An electronic regulator monitors and if required, adapts the solar panel's production according to the specific batteries' characteristics, which keep it from overheating and prolongs their lifespan.
An inverter takes electricity in the form of DC current, or 12 V from the batteries and converts it to 220 V AC in order to supply your household appliances.
Why not simply adapt an regular solar panel
Solar panels for vehicles or boats are flexible or semi-flexible, in order to better conform to the support's contours. They must also be easy to transport and light. In addition, panels that are mounted on a boat deck are exposed to the elements, at risk of being in the way of passerbys. For both of these reasons, they must be tough in order to last! Buying a kit designed for these vehicles saves you the trouble, by combinging a set of panels and corresponding electronic power regular.
Installing solar panels is a big project that requires a lot of knowledge. To make sure you have everything you need, follow the links below for related accessories, advice from our editors and more helpful guides:
- How to choosey your solar panels?
- How does a solar panel work?
- How to calculate the power and size of your solar panels?
- Solar panels: efficiency and photovoltaic cells
- How to install your solar panels?
And to make sure you have all the right tools:
- How to choose your electric wires and cables?
- How to choose your drill?
- How to choose your drill accessories?
- How to choose your circular saw?
- How to choose your circular saw blade?
- How to choose your screwdriver set?
- How to choose your electric screwdriver?
- How to choose screwdriver bits?
- How to choose your screws?
- How to choose your extension cord?
- How to choose your measuring tools?
- How to choose your tape measure?
- How to choose your ladder, stepladder or scaffolding?
Guide written by:
John, DIYer & IT developer, Brighton, 70 guides
Since I was a child, I was always interested in manual and technical works. Always fascinated by woodworking, I took advantage of my first flat as a playground. On the cards: electricity (of course, safety first!) and some partition walls; but also decorating with the help of the missus, made-to-measure furniture and little tricks to optimise the space, all the while remaining as original as possible. When the little one arrived, I started building bits and pieces for him! Lacking space, I have not got a permanent workshop and certain tools I dream about but are not part of my collection. Not to worry, I already know a lot about DIY and I have a high-tech profile that I hope will guide you in your decisions!