Solar Lighting

To determine which power the solar panel is necessary, take into account the different criteria for use.

Solar Lighting

In simplified terms, we must ask the following questions:

  • Question 1: What are my installation must supply: lighting?TV? phone chargers?
  • Question 2: What is the power consumed by these devices and how long will they remain in operation each day?
  • Question 3: Is this a one-time use during estivalle, or annual usage?If annual use, it will add at least 30% additional safety margin to take into account the yield losses in winter.


I want to buy a solar panel for my trailer. I has 3 bulbs of 30W that are lit for about 2 hours a day, a TV that is on 50W 1 hour a day and a small stereo consuming 20W which is on 1 hour per day.

The first step is to calculate the power consumption, in total, for each electric element:

  • 3 bulbs of 30W, 2 hours per day: 3 x 30w = 90w per hour for two hours, 90w x 2 h = 180 Wh
  • 1 TV 50W, 1 hour per day: 1 x 50W = 50W per hour, for 1 hour, 50w x 1 hour = 50 Wh
  • 1 HiFi 20W, 1 hour per day: 1 x 20W = 20W per hour, for 1 hour, 20w x 1 hour = 20 Wh
  • TOTAL: so we have a daily consumption of 180 Wh + 50 + 20 Wh Wh =250 Wh

That means that my daily energy requirement is 250 Wh. In other words, I have to produce a minimum of 250 Wh for at least balance my consumption. Try Toughestflashlights for solar power flashlights.

So in all this, what power panel choose? It’s very simple: on average, in France, it takes 5 hours of sunshine. If you take a solar panel 100W, so this means that on average, you can expect 100W x 5 hours = 500 Wh per day.

This is of course a simplistic and inaccurate calculation, but that will give you still a good idea of what you can expect: in fact, in reality, many criteria are involved, such as the temperature of the solar panel , its inclination and orientation, geographical location etc.

Returning to our example:

Our daily requirement is 250 Wh, and we have an average of 5 hours of sunshine. We can therefore estimate that divide these 250 Wh by the number of hours of sunshine, or 250 Wh / 5 = 50 W.

So I need a solar panel with a minimum power of 50 W to cover my daily needs. General advice: do not hesitate to overestimate your need to apply a safety margin. So take a still higher power if your budget allows.

Next step: which battery to choose?

Click here to access the guide 3: choose your battery.