camper van solar panels

camper van solar panels

How do solar panels work?

Solar panels are made of photovoltaic cells, made from a material such as silicon. When particles of light (photons) reach the solar panel, they knock the electrons within the silicon free, generating electricity. Solar panels are a great choice for van life because the sun is essentially an endless source of power, making them perfect for charging your leisure batteries.

Flexible solar panels vs rigid solar panels

When deciding on what solar panels to install on your campervan, you have a choice to make. There are two main types of fixed solar panel available: flexible solar panels and rigid solar panels. The type you require will depend on both your usage and your vehicle. Portable solar panels are also available if you don’t want a solar panel permanently fixed to your vehicle.

Rigid solar panels

Rigid solar panels are typically made of either monocrystalline or polycrystalline cells. They tend to have an aluminium frame and a protective glass facade which protects them from damage and the weather. Rigid solar panels are mounted to the roof of your campervan using mounting brackets, and tend to be fairly efficient.

Flexible solar panels

Flexible solar panels are lightweight, thin and bendable, making them easy to mount to your campervan roof. They’re typically glued or taped to the roof of a van. As they have a low profile, they’re generally not visible from ground level. They can also be useful if you have an older van with an undulating or very curved roof profile that might make fitting standard panels difficult.

However, the application of glueing the panels directly to the roof can cause problems. It’s generally recommended solar panels are mounted with a gap between the panel and the roof of the van to keep the panel cool and avoid creating a heat sink, as this will prolong the life of the solar panel.

Portable solar panels

Portable solar panels are typically used to charge portable powerbanks such as the PowerOak AC50 and the Jackery 500. They can be folded open and placed in the sun when you are stationary, and stored back inside the vehicle when not in use.
rigid solar panels camper van
flexible solar panels camper van
portable solar panels camper van

Solar charge controllers

A solar charge controller is required to convert the power your solar panels absorb into usable energy for your batteries. There are two types of charge controller available: MPPT and PWM. You can learn more on our solar charge controller guidebook page.

charge controller calculator

Not sure what size charge controller you need? Use our charge controller calculator:

Solar panel performance

The performance of solar panels at different times of the year and day, and cloud coverage vary dramatically. On a hazy day where a thin film of cloud covers the sun, the efficiency will decrease to around 50%, and on a day with heavy cloud and rain, you’re unlikely to get any power from your panels. The angle of the sun on the panels will also affect the power output of the panels, meaning you’ll get less power from your solar panels in winter than you will in the summer, as the sun will be lower in the sky.

The solar panel output graph will give you an idea of solar panel efficiency throughout the day. When the sun is directly above your solar panel, you will get the highest output, whereas in the morning and afternoon when the sun is lower in the sky and hitting the panels at an angle, the output will be much lower.

solar panel performance time of day year

Wiring solar panels 

Solar panels can be wired together in series or parallel. There are pros and cons to both wiring schemes.

Wiring solar panels in parallel

When you wire solar panels in parallel, the total amps increase and the voltage stays the same. Parallel wiring keeps the panels separate from each other, so if one panel is damaged, dirty or shaded, the others are not affected. To wire your solar panels in parallel, you will need to use a solar branch connector to connect them.

Wiring solar panels in series

When you wire solar panels in series, you add together the voltage and the amps stay the same. This allows you to access a much higher voltage input, and you can also use a thinner gauge wire as the total amperage remains low. However, if one panel is damaged or shaded, the output of all of the panels will be affected. To wire your solar panels in series, you simply connect the negative of one to the positive of another.

Solar panel wiring diagram

camper van solar panels wired in series camper van solar panel wiring diagram
camper van solar panels wired in parallel camper van solar panel wiring diagram

Can I use different sized solar panels together?

Mixing solar panels with different ratings is inadvisable. When you connect different size solar panels, they’re only able to draw the current of the lowest panel in the series. This means that the power draw of the panels is severely limited and you will not be able to achieve the combined wattage of the panels.

The only way around this is to install an additional charge controller for each different set of solar panels, which would be a costly solution to an avoidable problem.

can i used different sized solar panels wired together
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How many solar panels do I need?

Once you have decided if you are opting for the flexible or rigid panels, you need to work out how many solar panels you need and what your combined wattage will be. The more solar panels you install, the more power you will be able to generate. However, taking the ‘bigger is better’ approach of filling your entire roof with solar panels can prove to be expensive and won’t be useful in bad weather! To help you decide how many solar panels you need, we have built a solar power calculator which uses your typical daily power usage to calculate how much power you will need to live off-grid without fear of the lights going out!

Solar power calculator

Our solar power calculator works differently to others available and aims to suggest a sensible solar array size based on your power usage, frequency, and the climate you will be travelling in. As solar panels are typically available in 80, 100 and 120W sizes, the calculator will suggest either one or several of a particular size. 

Typical power usage per day

power usage

Low usage

  • Charge 1-2 phones 
  • 12V lights
power usage

High usage

  • Charge 1-2 phones 
  • 12V lights
  • Small 12V fridge
  • Charge 1-2 laptops
  • 1-2 additional 12V appliances
  • 1-2 additional low power 230V appliances (e.g. camera charger, drone)

Warning! Be sure to measure how much space you have on your van roof, and leave enough space for skylights, vents, awnings and other roof-mounted equipment.

power usage

Medium usage

  • Charge 1-2 phones 
  • 12V lights
  • Small 12V fridge
  • 1-2 additional 12V appliances
power usage

Very high usage

  • Charge 1-2 phones 
  • 12V lights
  • 12V fridge
  • Charge 1-2 laptops
  • 2-3 additional 12V appliances
  • 2+ additional high power 230V appliances (e.g. hairdryer, kettle)

We would recommend not relying on a single source of power to charge your batteries. To support your solar setup, you can install a voltage sensing relay, a battery to battery charger or a shore hookup.

How long will it take to charge my batteries?

Once you know how many solar panels you need, you can calculate how long they will take to charge your batteries from 50% to 100% using the following formula:

Wh / W = h

Where Wh equals the watt hours of your batteries (half the total Ah of your batteries to get the Ah needed to recharge from 50% to 100%, and then multiply the Ah by 12 to get the total Wh), W equals the total wattage of your solar panels, and h equals the time it will take to recharge your batteries.

How much do solar panels cost?

The cost of a 100W solar panel can vary from £70 to £200. The cost of solar panels varies as to whether they are monocrystalline or polycrystalline, and if they are rigid, flexible or portable. Renogy solar panels are typically well made and affordable. You can find a large range of their solar panels on Amazon.

how much do solar panels cost

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Charge controller calculator

Climbingvan Victron solar charge controller illustration

Battery calculator

Leisure battery illustration

Inverter calculator

Climbingvan Victron inverter illustration