Knowing how many solar panels we need to install is very important. Not only knowing this figure will allow us to optimize the initial investment, but we will also make the most of the savings in electricity from the generation of solar energy.
Of course, the number of solar panels needed depends on a number of factors , so there is no single rule of thumb that gives us an exact figure. Taking all the variables into account, we explain how to calculate how many solar panels you need.
Factors to take into account in the number
One of the most important elements to know what is the number of photovoltaic panels that your home needs is the annual electricity consumption that you make. You can take an invoice as a reference and take a look at the statistical calculations that are provided there.
Keep in mind that electricity consumption is not the same for every month of the year, so you shouldn’t just extrapolate and multiply a random bill by 12. In case of doubt, enter your customer area of your electric company and see exactly the statistics that appear on your annual consumption in kWh .
Another factor that influences the number of plates to install is their quality and performance. Not all solar panels are the same and that is why there are some of higher quality and therefore more expensive. In case of choosing maximum performance solar panels, not only is the installation investment amortized faster, but a smaller number of panels will be required, since each one makes better use of the absorption of sunlight and is capable of producing more electricity .
There are also differences regarding the type of material, because the technology used to manufacture the cells that the photovoltaic panel contains will influence its performance, basically distinguishing three types of panels: monocrystalline, polycrystalline and amorphous .
With the sum of many of these data, you will have to calculate the power of the installation , which is the result of this formula: number of plates multiplied by the power of each panel (Wp) = Power of the installation (Wp) . It is also necessary to make a study of both the orientation of the installation surface and the geographical location of our home. In Spain, the optimal orientation of the solar panels is the south orientation.
How many solar panels to install?
You will have to take into account all the factors described above and later make the decision about the number of plates you need. According to your annual consumption, the basis to serve as a guide would be the following:
| Annual consumption | Number of solar panels | Consumption profile |
|---|---|---|
| <2000 kWh | 2 – 4 | Low |
| 2000 – 4000 kWh | 4 – 6 | medium – low |
| 4000 – 6000 kWh | 7 – 9 | Medium |
| 6,000 – 8,000 kWh | 10 – 15 | Medium – high |
| 8000 – 10000 kWh | 16 – 20 | High or tall |
Based on these indicative data calculated based on the most determining factor on the number of panels to be placed, you should make the pertinent variations as influenced by the rest of the determining factors such as the type, performance and quality of the photovoltaic panel or the location of your home and availability that you are going to have about the place of installation.
If you cannot afford a south, southeast or southwest orientation, the efficiency loss is only between 1% and 4%, which would be the second best option. If you are forced to face east and west, the drop in efficiency can be up to 20 or 30%, so it may be necessary to install more solar panels . In the case of forced north orientation, it is advisable to carry out a preliminary study because what could condition it would not be the number of panels to be installed, which obviously should be greater, but rather that it may not even be profitable for you to install solar panels.