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How many solar panels do I need for my house?

Determining the size of a photovoltaic installation starts with a simple question: how many solar panels do I need?

How many solar panels do I need for my house?

The potential offered by natural resources and renewable and clean energies, not only in terms of creating more sustainable environments around us, but also to reduce the cost of our electricity bill, is the first motivator for deciding to incorporate a self-consumption installation in your home.

Sustainability and savings. How do we start?

There are many factors to determine to achieve an approximate estimate, but in this article we will try to guide you in those aspects that are most relevant to answer the question of how many solar panels you will need in your home.

Factors that affect the number of panels to use

Energy consumption of your home

Perhaps one of the most difficult aspects of sizing a solar panel system is estimating your home’s annual energy use. The first thing to look at are the devices and appliances you use on a daily basis, which are what dictate your kilowatt-hour needs and therefore can have a big impact on how many solar panels you will need. For example, do you have air conditioning or a heated pool at home? There are many extras in your home that can cause consumption to skyrocket or go off average. Depending on your consumption habits, the energy you are going to need could change drastically.

Available surface on your roof

The amount of energy (kWh) that your solar panel installation will be able to produce depends on the space you have for its location and how much exposure to sunlight it receives. The amount of sunlight you get in a year depends on where you are and how it fluctuates with the seasons. But the good news is that almost anywhere it is possible to produce enough energy to cover your energy needs. The Canary Islands, for example, is the region of Europe with the most hours of sunshine per year, with a figure that amounts to 4,800 hours per year, so the installation of solar panels is very simple. In case you live in an area that receives less sun, you will only need to have a larger solar panel installation.

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Orientation of your roof

Depending on the direction your house is facing, whether it is facing north, south, east or west, you will have more or less sunlight available to convert into solar energy. The other determining factor is the amount of shade your home receives. Shadows or spaces that lose the impact of the sun are one of the biggest enemies that we can find when installing solar panels.

The existence of shadows on part of a photovoltaic panel causes the so-called “Bypass” diodes of the connection box to come into operation and this gives rise to steps in its curve, that is, its production is reduced. Why is this happening? When a group of photovoltaic cells is shaded, it goes from producing electricity to consuming it, which can cause overheating and even the destruction of the cells, known as Hot Spot , which is why there are “Bypass” diodes that act as bridging from the electrical current to prevent this from happening.

Hours of light in your area

The most important thing at this point is to know approximately how many hours of sunshine we enjoy in the place where we plan to install the self-consumption installation, knowing your location or, more technically, its Latitude and Longitude .

We all know that the insolation or amount of sun received increases from north to south, although not constantly.

In the case of the Canary Islands, the amount of solar radiation received is variable due to the cloudiness produced by the trade winds. For example, according to the average measurements recorded by the National Geographic Institute , the southern part of the island of Tenerife reaches 3,000 hours of sunlight.

Data to take into account about the solar panels to use



Domestic consumption represents approximately 25% of the total electricity consumption in our country. The amount of energy consumed in a home varies greatly depending on the size and type of home, its location, and the number of occupants. On average, according to the Red Eléctrica de España , the average electricity consumption of a Spanish home is 9 kWh per day, 3,272 kWh annually.

If you want to make a rough estimate of your home’s electricity consumption, we recommend that you find out how many kilowatt hours (kWh) of electricity you use in a year.

  • To give a general perspective, one kWh is equal to 1,000 watts of power used in one hour. So if you have 20 lights in your home and they all use 50-watt bulbs, having all the lights in your house on for one hour would consume 1 kWh of electricity.
  • Take a look at your bills. Your electricity supplier provides you with the total energy consumption for the last twelve months on your monthly bill.


The location and orientation of the photovoltaic panels is just as important as what type of solar panel is used in a given location. A solar panel will harness the greatest amount of energy when the sun’s rays strike its surface perpendicularly. Thus:

  • Make sure your solar panels are facing the right direction to ensure they produce the maximum power when exposed to the highest intensity of sunlight for the longest period of time.
  • Regarding the direction, in the northern hemisphere, the general rule for the placement of solar panels is that they must be oriented towards the south. In general, as we say, this is the best direction because the photovoltaic solar panels will receive direct light throughout the day. However, there is a difference between magnetic south and true south that needs to be considered. Magnetic south is the “south” shown when using a compass, and this south points to the magnetic south pole of the Earth. The solar panels, however, must face geographic or solar south, which is the direction toward the South Pole.
  •  The angle or tilt of a solar panel is also an important consideration. The angle at which a solar panel should be placed to produce the most power is determined by geographic latitude. A general rule of thumb for optimal annual energy production that meets your electrical usage is to set the tilt angle of the solar panel equal to the geographic latitude. For example, if the solar panel location is at 50° latitude, the optimal tilt angle is also 50°. Essentially, the closer a solar panel is located to the equator, as is the case with the Canary Islands, the more the panel should point upwards.


As we saw in the article How do solar panels work?   and more in detail in What is the efficiency of solar panels? To maximize the amount of energy and performance of photovoltaic solar panels, technology is vital. At EAVE Canarias we are committed to Mono PERC technology, which consists of placing a reflective layer (Dielectric Layer) to make the most of radiation. Or in other words, it is based on the process of adding an additional layer to the back of the solar panel that allows part of the photons that pass through it to be reflected back towards the photovoltaic cells, thus increasing the total efficiency of the solar panels.

How many solar panels do I need to install?

Finally, we invite you to discover in a simple way how many solar panels you need for your home through our website. In our SELF-CONSUMPTION section we have an area calculator that will allow you, in an approximate way, to answer the number of solar panels that your home requires according to the available space.



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