What to consider before installing solar panels

On average, a single-family house generates almost 90% of its energy consumption by installing ten solar panels.

Rising energy prices, combined with inflation and rate increases, have led many families to consider installing self-supply systems, such as solar panels, on their homes. Government incentives and regulatory changes have accelerated the energy transition in our country. Although we have the advantage of 300 sunny days a year, until a few months ago we were lagging behind other European countries in terms of adoption of self-consumption systems.

According to data from Samara Energía, solar panels have the potential to reduce a family’s electricity bill by up to 70%, as well as mitigating the economic impacts of market fluctuations.

In fact, self-consumption installations reached a capacity of 1,203 megawatts in 2021, an increase of 101.8% compared to the 2020 record, according to the Spanish Photovoltaic Union. It is estimated that more than one million households will adopt these systems in the next three years. However, many people are still hesitant to make the decision to install them.

Assessing the household consumption profile is essential
First of all, it is essential to determine the number of panels needed for each household, which requires knowledge of the family’s consumption profile. This will help to “avoid installing too many panels, which would simply increase the cost of the installation without guaranteeing an adequate level of self-consumption”, according to Manel Pujol, co-founder of Samara.

In this sense, it is essential to consider annual electricity consumption, which defines the amount of energy that the installation must generate to cover demand. In Spain, the average consumption of a single-family house is 6,000 kWh, although the simplest way to obtain this information is to check the electricity bill.

Additionally, the distribution of consumption throughout the day and year should be analysed to calculate the proportion of electricity generated by the installation that is self-consumed at different times. The more closely the household consumption resembles the generation profile, the higher the percentage of self-consumption. It is important to note that, in general, more electricity is consumed during the day than at night.

Generally, peak electricity generation occurs at midday, suggesting that if the disparity between daytime and nighttime consumption is significant, it would be advisable to add storage batteries to the installation to maintain the level of self-consumption.

In addition, solar radiation is higher in summer than in winter, which means that seasonal differences can affect the percentage of self-consumption. After analysing these aspects together with the previous ones, it will be possible to determine the required installation power and the number of panels needed. Generally speaking, Spanish households usually need around ten solar panels on average to cover 90% of their energy consumption.

How much will it cost and what is the payback time?
When taking this step, most families wonder how much they will have to invest and how long it will take to recover the investment. Manel Pujol mentions that, on average, a single-family house usually invests between 5,000 and 8,000 euros in the installation. Although the initial cost is significant, the savings on the electricity bill are immediate, so it usually takes between four and seven years to recover the investment. This is attractive considering that the lifetime of solar panels is almost four times longer.

However, if we are looking to optimise the power generation of the panels, it is crucial to consider the geographical location of the house, as this can influence the generation capacity, as well as the type of solar panel we choose, as each has a different efficiency. Finally, we must take into account the orientation and inclination of both the roof and the panels, as this affects how the solar radiation hits them.