Solar Panels are Working for you until Dark!

Solar panels are assemblies of individual photovoltaic or solar cells.

These cells are interconnected (normally between 30 to 40 per panel) and mounted in a rigid frame to harvest the solar energy converting it into electricity. Other appellations are a photovoltaic panel or a photovoltaic module.

The typical solar panel used on RVs normally has a capacity between 80 to 120 watts.

It is very important that the panel is rated for a recreational vehicle. A lot of the less expensive ones you see advertised are not RV rated.

In size, solar panels are rectangular and usually 2 feet wide by 3 to 5 feet long.

If you intend to install multiple panels, the limitation will be the space still available on the roof of the RV (between the swamp cooler or air conditioner and other fan vents).Some smaller RVs do not have sufficient space left.

However, portable solar systems exist. You still need storage space to carry them but they can be installed on the ground beside the RV directly connected to the house batteries. You need to be careful for damage, carrying in and out all the time these portable panels.

To get the most solar energy, the panels should face south and be oriented in order to ideally have the sun's rays perpendicular to the the surface of the solar panels.Some racks with tilting brackets exist to allow to lift them at an angle to take full advantage of the sunlight.

The difference of efficiency in terms of collection of solar power for the same period of time between both systems (installed flat or on tilting brackets) would be in the order of 10 % over a year usage.

The difference would be more noticeable in the winter when the sun is low in the sky (30-50%).

Even if this loss of efficiency does not bother you, what may affect your decision to go for brackets is the ability to clean the debris accumulated underneath.

If they are installed flat, there may be build up of humidity underneath which could affect the roof overtime.

Keep in mind that you have to climb on the roof every time you tilt the panels remembering to put them down before driving away.

To give you an approximation of the best angle of tilt in winter in the northern hemisphere, use this formula : find the latitude of your location, multiply it by 0.9 and add 29 degrees.


Example: Vancouver, BC

  • latitude of 49 degrees
  • tilt angle in winter 49 X 0.9 = 44.10 + 29 = 73 degrees of tilt to get better results.


Shadows casted by objects ( branches etc...) will affect the energy output as is also the case for the surface temperature of the panel.

The output in the real world of a solar panel will be lower than the manufacturer's specs, being the results of test done at 77 F/25 C as a norm in the industry.

The surface of the panel on the roof of an RV in full sun will reach a much higher temperature and this will affect negatively its efficiency.

The purchase and installation of a solar system on your RV varies in price. For a small system having the equivalent capacity of a small 2000 watt generator, it will cost about the same, around 1000 $.

For a more robust system, it would cost a few thousands dollars ($4000 to $6000). It is not cheap and requires some planning. It would be equivalent to the purchase of a big generator without the inconveniences.

Do not forget that it can be installed in stages. You may buy a couple of panels first and add one or two more later to increase the capacity when the money is available. ( the same with the batteries).

However, the decision of installing solar panels on your RV should be well planned.

Note that you may be eligible for some kind of Energy tax credit offered by your State or Province (RV Solar power system tax credit) which will cover a percentage of your expense. It is worthwhile to check if it exists in your location.

As maintenance is concerned, solar panels only need to be wiped out of dust once in a while. Whatever you do, they always work for you and never quit until nightfall.

You can be parked along the street and go sightseeing while your solar panels are charging your batteries. You still may have a small generator (1000 or 2000 watts ) as a backup.

However, if your solar system is robust and has enough capacity, you will not really need a generator unless you want to give a final boost to charge the batteries or turn on a very energy power hungry air conditioner for a long time not wanting to discharge your batteries.

In this case, replacing the air conditioner by an evaporative cooler may be a solution.


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