Many motorhomes are fitted with solar panels, but the vast majority are unaware of how many are needed, so we’ll tell you all about solar panels for motorhomes!
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Benefits of installing solar panels in your motorhome
The main advantages that you will experience when installing a solar kit are the following:
- You will avoid the annoying noises of generators, as with solar panels you will obtain energy in a silent way.
- You will contribute to the care of the planet by generating clean energy.
- You will reduce costs, using solar panels will reduce your consumption and you will soon see a return on your investment.
Principales características de las placas solares para autocaravanas
The most commonly sold plates are 12V monocrystalline or polycrystalline. The main difference between the two is the crystal. Monocrystalline is uniform, whereas polycrystalline is a heterogeneous mixture of crystals.
Difference in performance between monocrystalline and polycrystalline solar panels
Polycrystalline solar panels are generally less efficient than monocrystalline panels, as the incident sunlight does not pass through a completely homogeneous crystal. This means that monocrystalline panels achieve the same power output as polycrystalline panels, but use less surface area.
Aesthetic differences between monocrystalline and polycrystalline solar panels
Apart from size, another factor that can be a determining factor in the choice of solar panel is its colour. Monocrystalline panels, due to the higher purity of their crystals, tend to have darker colours, such as blacks and greys. Polycrystalline panels, on the other hand, tend to be dark blue when light hits them.
What type of solar panel should I install on my motorhome?
This decision mainly depends on the power you want and the space you have.
If you want to have a power of 150W, it doesn’t matter what type of plate, as both must be able to fit perfectly on the ceiling.
If you are looking for more than 750W, there will probably not be enough space to fit 5 normal 150W panels and you will have to opt for smaller panels that provide the same output.
How many solar panels for motorhomes should I install?
To calculate the number of panels you are going to use, start by calculating the daily power consumption, so you can determine the number of panels you need. As an extra section, we will also explain how to combine the use of solar panels with AGM batteries.
1. Calculation of W from the use of your appliances
We will start by calculating the power consumed throughout the day in our motorhome. To do this, we will estimate the power of each of the appliances we use. Before starting with the calculations, it is important to bear in mind that the W (watts) of the appliances shown by the manufacturers usually correspond to the power consumed in one hour.
- 12V Smart TV: real consumption of about 20W/h. As we spend approximately 4 hours a day in front of it, the estimated daily consumption is 204=80W.
- Dolce Gusto coffee machine: consumes about 1250W/h. We use it 5 minutes/2 times a day, which is equivalent to 1/6 of an hour. So your daily consumption will be 1250/6=210W.
- Microwave: it consumes about 1500W/h, if we use it 5 minutes/2 times a day. In total we will use it for 10 minutes, being 1/6 of an hour. Thus, the daily consumption translates into 1500/6=250W.
- Charging 4 smartphones: the battery of a mobile phone has approximately 10W, so the total consumption with its charge is 40W.
- LED lights: we use 4 LED bulbs at the same time for 5 hours. Assuming that the consumption per LED bulb is about 5W, the total consumption is 54*5=100W.
Next we will calculate the sum of all the previous consumptions, to obtain the total consumption:
80W + 210W + 250W + 40W + 10W + 100W = 690W
The previous calculation does not take into account other consumptions such as the fridge, the heating or the AACC, to make up for this we will add 10% to the previous calculation and we will have a more accurate result of the real consumption.
Total consumption = 690W*1,1 = 759W.
2. Calculation of power provided by a solar panel per day
The next step is to calculate the power output of a solar panel per day. This power will depend largely on the time of year.
Potencia generada por una placa solar en primavera-verano
The yield of a solar panel in summer is approximately 65%, and its use is approximately 5 hours a day. Therefore, a 150W panel will provide us with an approximate daily power of:
Power generated in spring-summer = 150W0,655 = 487W
Based on the calculations made, with two 150W solar panels you would have enough to meet the normal consumption of household appliances.
Power generated by a solar panel in autumn-winter
In autumn-winter the sun shines much less, therefore, the calculation will not be the same as for spring-summer.
Based on the calculations made in the previous section, obtaining the power for autumn-winter for a 150W panel is very simple. We must start from the result of power generated in spring-summer (the 487W) and divide it by 2, obtaining a result of about 250W.
Power generated in autumn-winter = 487W/2 ≈ 250W
For autumn-winter, a 150W solar panel will not be enough, but we will need at least 4 to cover the 759W consumed by the electrical appliances.
3. I don’t want to install 3 solar panels, what do I do?
With two solar panels you will have complete autonomy in summer, but not in winter. If you do not want to install four panels, what you can do is to use a backup battery.
If you consume 760W per day and your two panels generate 487W per day in winter, this means that you lose 273W per day.
W lost = 760W – 487W = 273W lost daily.
If you leave with two 100A batteries fully charged after a long trip and want to spend a few days relaxing or sightseeing in the area, how long will it take for the batteries to discharge?
Assuming the batteries are 100A AGM batteries, they will take about 70 real time. Therefore, by carrying 2 batteries you would be generating 140A. As the battery runs at 12V, the power generated will be 1680W.
Power generated by 2 AGM batteries = 12V x 140A = 1680W
If you lose 273W daily, you will have 6 days of autonomy.
Days of autonomy with the batteries = 1680W/273W = 6 days
4. Recommendations when using batteries and solar panels
- It is not recommended to use the battery until the last day. You should avoid using appliances that consume a lot of energy, such as microwave ovens.
- To recharge two very low batteries, you will have to drive the motorhome a lot, at least 7 hours.
- We recommend using a solar panel, even if you choose to use only batteries. When the batteries are discharged and are not recharged quickly (within 2 weeks at the most), they will be sulphated. Installing a solar panel will increase the life of the batteries.
Camping holidays | Alannia Resorts
Now that you know how to install solar panels on your caravan and you know all the advantages, it’s time to start your journey!
En Alannia Resorts contamos con parcelas de hasta 180 m2 y 100 % equipadas ☀️ ¡Te esperamos!