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Campervan Solar Panels a Complete Guide:

campervan solar panel

When on the road, your campervan’s alternator should be taking care of charging the leisure battery. Connecting to a campsite’s hookup will also do the same job. However, what if you want to do some wild off-grid camping? How do you make sure there is enough power in your leisure battery? Two words – Solar power.

Fitting a solar panel to your campervan will give you power wherever you go and best of all, that power is FREE! A solar panel can also be used to keep your leisure battery charged during the winter months if the campervan is not being used.

To the uninitiated, solar power can be a little overwhelming and confusing, especially when trying to choose the correct solar set up. Well hopefully after reading through this article (if I’ve done my job correctly) you should have a clearer understanding of what size solar panel you need to charge your battery.

 

Fitting a solar panel to your campervan’s roof:

Fitting a solar panel is a job that most people with competent DIY skills can undertake. However, there are a couple of important points to outline before you get your toolbox out. Firstly, the solar panel must be securely attached to the roof. The last thing you want is it flying off halfway down the M5. The second consideration is that you’ll need to drill through your campervan’s roof to feed the cables from the solar panel, to connect to the leisure battery. This is probably going to be the most nerve-racking part of the installation process.

Tips:

  • To avoid drilling through any existing cables, use a stud finder to determine that the area where you intend to drill is free from obstructions such as cables or pipes.
  • A wardrobe is usually a good place to bring the wires through.
  • If possible, drill the cable holes close to the leisure battery or at least on the same side. This will make it easier to connect the solar controller to the battery.

After you have decided on a suitable place to drill the cable hole, drill a small (4-5mm) pilot hole (drilling from the inside of the camper). Then use a bi-metal hole saw or a step drill to open up the hole to the correct size. Using a slow drill speed and drilling from the inside out will make for a much better cleaner hole. It will also help to prevent the roof lining from splintering or ripping.

To waterproof the cable entry holes use a double cable entry gland. The gland can be attached to the roof using Sikaflex 552.

 

Fitting a conventional solar panel to a flat roof: 

The solar panel is attached to the roof of the campervan using mounting brackets. These are generally made from plastic. A set of 4 corner plastic mounting brackets will usually be sufficient. For larger solar panels (or extra peace of mind) then additional side brackets can be used. The brackets are simply screwed to each corner of the solar panel (though I would personally choose to use bolts instead of screws).

If your campervan roof is nice and flat then you can attach the solar panel using Sikaflex 552, so no additional holes will need to be drilled in the roof. Before using Sikaflex, make sure that the area on the roof where you’re going to attach the solar panel is clean, free from dirt and grease, etc. This will ensure that the Sikaflex adheres properly. (Sikaflex also makes a surface preparation product call Sika Activator 205 which is a bond-activating substance. This pre-treatment agent helps Sikaflex bond to non-porous surfaces.)

Watch this video to see the installation of a solar panel:

Recommended solar panel

 

Flexible solar panels for campervans – ideal for curved roofs:

If you cannot use a conventional rigid solar panel because the roof of your campervan is curved, then a flexible solar panel could be the way to go. A flexible solar panel will follow the contours of the roof and have the added advantage of being much lighter than a tempered glass aluminium-framed solar panel. A flexible solar panel also has a very low profile. This means less wind resistance as well as making them almost invisible to the casual observer.

 

Known problems with flexible solar panels:

Flexible solar panels are usually more expensive to buy and are not as durable as tempered glass panels. Cheaper poor quality panels can be prone to delamination and cracking. They can also suffer from a thing called cupping. This is when in warm weather the panels warp slightly causing little pockets for dust and water to collect in. This can affect the performance of the panel.

Some flexible panel can lose up to 50% of their output over a 5 years period; whereas a conventional tempered glass solar panel may lose as little as 20% over 20 years. It has also been known that some flexible solar panels can overheat in extreme temperatures due to the lack of airflow under the panel.

 

Recommended flexible solar panel:

If you do decide to go for a flexible solar panel, then stay away from cheap panels (they are usually cheap for a reason and are more prone to suffer from the problems outlined above). Choose a quality panel, like this Photonic Universe 110W flexible solar panel.

The Photonic Universe flexible panel is built from strong ETFE material. The ETFE material makes the panel very tough, you can even walk on it without damaging it. It’s also more hardwearing and less susceptible to cracking and delamination. At 3mm thick the Photonic Universe flexible solar panel is super thin and weighs in at just 2.33Kg. The panel can be bonded to the roof making for easy installation.

 

Portable folding solar panels:

Want the benefit of solar energy, but not the hassle of installing one? Then a portable folding solar panel could be for you.

Portable solar panels have a couple of unique advantages. 1. They can be moved to track the sun throughout the day, maximising its effect. 2. A portable folding solar panel can be stored when it’s not needed, so it’s not going to be subjected to the winter weather or damage from low hanging tree branches, etc.

This quality 60W 12V Photonic Universe folding solar charging kit is one of the better folding solar panels on the market and has excellent reviews. It’s a complete kit, so includes leads, charge controller and a protective carry/storage case. Using the fully waterproof solar kit couldn’t be simpler. Just unfold the panels and point them in the direction of the sun. Then attach the crocodile clips to your leisure battery and you’re good to go.


What size solar panel do you need to charge a 12v battery?

Firstly you need to know how much power is required, and how big the 12v battery you need to charge is.

Generally speaking, the size of the 12v battery is less important than the size of the solar panel. Ideally, the amount of power a solar panel generates needs to be the same as (or more than) the amount of power required per day.

If on an average day, there is say 4 hours of sun, and you are using a 100W solar panel, then the panel will produce around 400 watt-hours of electricity. However, some of this power will be lost through the solar charge controller, cables, and battery.

Charging a small capacity 12v battery using a large 100W solar panel for example, is not an efficient use of the suns rays. A small 12v battery will charge quicker than a larger one, but once the battery is fully charged any additional power produced by the solar panel will be wasted rather than stored in the battery for use later on.

So, as a rule, it’s not a good idea to use a large solar panel to charge a small battery. Another variable to consider is the batteries charging current limit. You need to check that your battery can receive the output current of the solar panel you intend to use.

 

How many solar panels do you need to charge a 12 volt battery?

This will depend on your power requirements. A single 10w solar panel will be enough to trickle charge a 12v battery. For medium to heavy loads, just one 100w solar panel will keep your campervan’s battery supplied with all the energy it needs. Note: This doesn’t include boiling an electric kettle or running a fridge. These are very power hungry appliances.

Reading through the rest of this article will give you a good understanding of solar energy basics, and help you to decide what size solar panel setup is right for you. If preferred, you can go straight to the section that best describes your needs. To do this, choose one of the scenarios below, then skip to that section by clicking the link – there you’ll find a solar panel setup tailored to that particular scenario.

 

Scenario 1:

I want a solar panel to prevent my 12v battery from going flat when it’s not being used. I just want to keep the battery topped up using a trickle charge.

Yep, that’s me – Skip to this section.


Scenario 2:

I will be using a small amount of power for approximately 2 to 3 hours a day. e.g using energy efficient led lights, charging a mobile phone, and occasional laptop use.

Yep, that’s me – Skip to this section.


Scenario 3:

I need plenty of power for running my lighting, water pump, charging my mobiles phones, frequent use of my laptop, watching TV and powering my other devices.

Yep, that’s me – Skip to this section.


How much power do you actually use per day?

To work out how much power you use in a day. You first need to know the wattage of your devices and appliances. And also how many hours a day on average, they are being used.

For example, if a 10W device is used for 4 hours, then you multiply 10 x 4 which is 40 watts. Use this method to calculate the total amount of energy consumption per day for all your devices. Then add them together, to get the total amount of energy used per day.

Example:

  • 1 x 15W water pump – used for 2 hours per day (30 watts).
  • 1 x 10W stereo – used for 1 hours per day (10 watts).
  • 3 x 10W lights – used for 3 hours per day (90 watts).
  • 1 x 40W TV – used for 2 hours per day (80 watts).
  • 1 x 25W laptop – used for 2 hours per day (50 watts).
  • 2 x 3W mobile phone charging – used for 1 hour per day (6 watts).

The total amount used per day = 266 WH (watt-hours)

The total amount of watt-hours used per day is the amount of power that is required to replenish the 12v battery.

 

How many watt-hours does my battery have?

To work out how many watt-hours a battery produces, you need to multiply the amount of AH (amp-hours) by the battery’s voltage. For example: for a 100AH 12v battery, you would multiply 100 by 12 which is 1200 watt-hours or 60WH for 20 hours. (Information source for this conversion.)

To supply the demands of Scenario 3 above, (frequent daily use of lights, water pump, laptop, mobile phone charging and watching TV, etc.) will require the use of a 100W solar panel paired with a good sized leisure battery (100AH plus). This will ensure that you’ll have plenty of stored power when you need it most.

How long does it take to charge a 12v battery with a solar panel?

This depends on a lot of factors, such as the efficiency of the solar panel, how much power is already in the battery, and how much sunlight the solar panel receives. As a general guide. On a sunny day, a 100W solar panel will produce approximately 4-5 amps per hour in full sun. This means that the solar panel would take around 18-25 hours to charge a fully discharged 100AH 12v battery. A solar panel half the size (50w) would take approximately double the amount of time to charge the same size battery.

Can you run a fridge with a solar panel?

Yes, you can. However, fridges are power-hungry appliances. If you want to use solar energy to run a fridge, then it would need a solar panel of its own: typically around 100W to 150W plus. You would also need to connect the solar panel to its own 12v battery via a solar charge controller. A compressor type fridge can work well using solar energy. However, if you have an absorption type 3-way fridge, running it on gas will usually be more efficient.


Recommended Solar Panels

We have selected three popular solar panel kits that are available on Amazon. All three kits are supplied by the UK based solar company, Photonic Universe, which have been in business since 2009. Photonic Universe only uses the highest quality solar cells in their solar panels. These cells are produced by one of the leading German solar manufacturers, SolarWorld. Their solar cells give excellent performance both on sunny days and in low light conditions. Not all solar panels are created equal so beware of cheap solar panels. As they say – buy cheap, buy twice!

10W solar panel kit for trickle charging a 12v battery:

Solar panel dimensions: 340 x 240 x 20 mm

If you’re looking for a way to keep your 12v battery charged when it’s not being used (such as the leisure battery in a campervan, caravan, boat, etc.). Then the 10W 12V Photonic Universe solar power kit with 5A charge controller is the ideal solution. The easy to install kit will supply a trickle charge to the 12v battery to prevent it from going flat. This will also prolong the life of the battery.

This 10W kit is suitable for any sealed, gel, or wet lead-acid 12V battery larger than 8Ah. The highly efficient 10W monocrystalline solar panel is designed for outdoor use and is totally waterproof. The supplied 5A solar charge controller (not waterproof) has a built-in overcharge protection function. So there is no danger of your battery being damaged due to overcharging.

The kit comes with 3m of battery cable which incorporates an inline fuse and two crocodile clips (positive & negative) to connect straight to your battery.


50W solar panel for small loads & light use:

Solar panel dimensions: 590 x 505 x 25 mm

If you use a small amount of power for approximately 2 to 3 hours a day, (e.g using energy efficient led lights, charging a mobile phone and occasional laptop use) then this 50W 12V Photonic Universe solar charging kit with 10A controller is for you.

The 50W Photonic Universe solar panel consists of 5 busbar monocrystalline high-efficiency top quality German made solar cells. These cells are able to produce more power than most other solar panels of the same size. Designed for permanent outdoor use, the solar panel has a durable sealed aluminium frame and is totally waterproof, giving many years of free electricity.

The kit includes a 10A solar charge controller which is compatible with dual or single-use sealed, gel, and wet lead-acid 12V batteries. The solar controller has an automatic cut-off function to prevent your battery from being overcharged. The solar charge controller will also prevent reverse current discharge from the battery at night.

The kit comes with a generous 5m of special solar cable. All in all this an excellent solar panel kit. It is an ideal choice for campervans, caravans, or boats, as well as many other applications where reliable solar energy is required.


100W solar panel for heavy loads & frequent use:

Solar panel dimensions: 1200 x 540 x 35 mm

For large loads and frequent use, then this 100W 12V Photonic Universe monocrystalline solar charging kit with 10A automatic solar charge controller is what you need. The 100W Photonic Universe monocrystalline solar panel will generate approximately 400 watt-hours of power with 4 hours of sunlight.

It will provide plenty of power for running lighting, regular use of a water pump, laptop, charging of mobile phones, watching TV and powering other devices. As with the Photonic Universe 50W solar panel above, this 100W panel also uses the same high-efficiency German made solar cells, which are housed in a tough aluminium waterproof frame.

The kit comes with a 10A Photonic Universe solar charge controller which incorporates an automatic cut-off feature that will protect your battery from overcharging. The controller uses Pulse Width Modulation technology to increase charge acceptance. PWM also prolongs the life of your 12v battery. The kit comes with 5m of special solar cable which has been designed to keep power loss down to a minimum.

This 100W Photonic Universe solar charging kit is the perfect choice for all off-grid applications such as campervans, caravans, and boats. It’s simple to fit, and will provide free electricity for many years to come. A great investment.


How do solar panels work?

A solar panel is much like a leaf, in that both turn sunlight into usable energy. The leaf uses the sun’s energy to create food in the form of sugars and the solar panel uses the same energy to create electricity. Solar panels are made up of photovoltaic cells which are joined together to create the panel. A photovoltaic cell is a composite of two semi-conductive materials: more often than not, this material is silicon. The cells work by allowing photons (light particles), to dislodge electrons from atoms. This process generates an electrical current.

Other chemicals like phosphorous and boron are added to the cell to impart a positive and negative charge. When these opposite charges are separated by photons (sunlight) an electrical field is created. Conductive plate around the outside of the cell directs the electrons through cables, creating a flow of electricity.

How to use a solar panel to charge a 12v battery:

To avoid overcharging the 12v battery most solar panels over 30W will need to be connected to a solar charge controller. This sounds complicated, but it isn’t. As you’ll see by watching the video below, wiring up a solar panel to a solar charge controller is really very simple.

Care and maintenance of solar panels:

There are no moving parts in a solar panel, so the only maintenance that’s required is regular cleaning. For a solar panel to work efficiently it must remain free from dust, bird droppings, leaves, etc.

The main external surface area of a conventional rigid solar panel is glass – so no fancy solar panel cleaning products are needed to clean it. Just use a soft cloth or squeegee and some clean water. To remove any stubborn residue use rubbing alcohol dissolved in water.

Avoid using anything abrasive as this could scratch the glass and reduce the amount of sunlight reaching the cells.  Some detergents can leave streaks and smudges; these can also reduce the amount of the light hitting the cells.


Our guide to campervan solar panels draws to a close:

Hopefully, this guide has given you a clear understanding of solar energy. If you do choose to fit a solar panel to your campervan, you now should have the information you need to choose the right panel for the job, and enough know-how, to fit it successfully. Solar energy is an exciting technology and is only going to get better; it offers many affordable solutions to sustainable free energy.

Let’s have three cheers for Helios… Hip… Hip…


You may also be interested in this article – Campervan Electrics DIY Guide – why you need a leisure battery

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