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How many solar panels do I need for a country house?

Many clients ask us  how many plates do I need for a country house? . If it is important to plan photovoltaic self-consumption, it is even more so when we seek to have an installation isolated from the network so as not to fall short or make an oversized installation.

Since being disconnected, everything will depend on our ability to produce electricity with our solar panels and accumulate it in the  solar batteries.

Our advice is to contact a team of professionals with extensive experience in these types of installations, which seem the same as those for self-consumption, but whose installation and dimensioning have a series of peculiarities that mean that not all installers have enough experience to carry them out.

At Cambio Energético we have more than 10 years of experience in all types of solar panel installations and we can advise you and make you a sizing, design and installation adjusting to your energy needs.

But if what you want to know is more or less what type of solar panel installation you need for a country house, in this article we will tell you the necessary steps with which you can  estimate the number of solar panels  you need for your country house. countryside.

The easiest way to know how many solar panels you need for a country house

If you don’t want to get complicated, the easiest way to find out how many panels you need for your country house is to use our  search filters  for solar kits for isolated houses on our website:

On our website, you can search according to the  type of use  you are going to make of the photovoltaic installation in your country house, either to use it as a habitual residence or as a second residence for vacations or weekends.

It is also very important to select the  consumptions  that you are going to make; that is, the electrical devices that you will need to use in your country house. And a last filter that you can use is the one referring to the  components  that you want to install in case you already have a rough idea of ​​what you want.

It is a very intuitive tool and in a few seconds you will have the answer to what you are looking for to get an idea of ​​the needs you have.

But if you want to know the  steps to take to estimate how many solar panels  you need to install in your country house, keep reading.

How to calculate the energy needs of an isolated house to install solar panels

The first thing we need to know in order to estimate the photovoltaic installation you need is  how much electricity you need .

And here it is very important that you quantify not only the  kWh you consume throughout the day  but also the  hours where you have those consumptions . Why? Because  you will also have to know the electricity that you are going to consume in the hours when you do not have enough solar production . In this way, you can calculate the capacity of the  solar batteries  that you will have to install.

But  how to calculate your consumption of an isolated house without connection to the electricity grid?

If you are going to have a need for electricity similar to what you have in your usual home, you can look at your  electricity bill  to find out the monthly and annual electricity consumption. If you have a smart meter, you can also register on the  digital platform of your marketer  and check your consumption.

Now, if the consumption you plan to have in your isolated installation is going to be different from that of your usual home, it is appropriate to make an estimate of it.

As you know, your consumption consists of the  sum of the energy needed by all the appliances and electronic devices  you use in a period of time (specifically in one hour). So, what you will have to do is list the electronic devices that you plan to use throughout the day, the power that each one has and the number of hours that you will use them.

You can use the following table model that we present to you with an example as a reference.

Apparatus Units Power (W) hours / day Total (Wh/day)
Led light 4 7 8 224
Laptop two 65 8 1,040
TV A + 1 31 6 186
Blender 1 750 0.30 225
Microwave oven 1 800 0.20 160
Fridge A++ 1 32 24 778
mobile charger two 13 4 104

According to this example, the daily consumption would be 2,717 Wh per day. Over a month (30 days), it would be 81,510 Wh, which is equivalent to 81.5 kWh per month and 978 kWh per year, approximately.

If the country house is your habitual residence, you will have to make a more exact calculation, bearing in mind that it is always better to have too much energy than to fall short, and you must also bear in mind that the consumption you may have in the future is greater , so we always recommend that once the calculations have been made, we oversize the installation a little so as not to fall short in the short or medium term.

If it is a second residence, you do not have to be so thorough in the calculation, although our recommendation is that you never adjust to the exact calculation, but leave an upward margin to avoid falling short at a certain time.

What photovoltaic production do I need with solar panels for a country house or isolated house

Once you have estimated your consumption, you need to know how much photovoltaic energy you are going to require to satisfy said consumption. And for this, we must take into account different issues:

  • On the one hand, the  power that each solar panel can generate . Depending on the manufacturer, you can find different powers, as well as the number and size of photovoltaic cells.
  • On the other hand, the  efficiency of the system . Generally, in the process of converting direct current into alternating current, around 10% of solar energy is usually lost. Therefore, to make the calculations, you must dimension the installation taking into account a production of 90%.
  • Thirdly, the  hours of sunlight  that the country house has where you plan to make the photovoltaic installation. Depending on whether the installation is in Galicia or Andalusia, you can find differences of up to 25%.

In the following table you can find examples of provinces with their  Peak Solar Hour  (HSP). We can understand this as the sum of annual hours in which the solar panels are supposed to work at maximum performance. You can also see the estimated energy in kWh per year for each square meter of solar panel.

Province Peak Solar Time kWh / year
A Coruna 1,170 2,047
Barcelona 1,370 2,477
Madrid 1,560 2,723
Caceres 1,680 2,698
Cadiz 1,670 2,773
grenade 1,670 2,831
Almeria 1,710 3,052

The Photovoltaic Geographic Information System of the European Union may also be useful to you. Through this platform you can estimate the solar production of a photovoltaic installation in your location.

To  calculate the kWh generated per year by a solar panel , you can apply the following formula:

Formula to calculate the kWh generated per year by a solar panel

Let’s say that we have a 450 W solar panel and that our country house is in Granada, with an annual average of 1,670 hours of light at full capacity. To estimate the kWh that panel generates per year, it will be necessary to perform the following calculation:

Result of applying the formula to calculate the kWh generated per year by a solar panel

If we want to know the monthly or daily average, we only have to divide the 676.35 kWh by 12 (56.36 kWh per month) or by 365 (1.85 kWh per day), but be careful, keep in mind that the daily production will not be the same in the summer months as in the winter months.

What area do I need to install solar panels in a country house or isolated house

Another element to take into account is the  surface you have  for the solar panels, as well as its  characteristics  (orientation, inclination, shadows).

For example, if you choose to install 450Wp monocrystalline solar panels, you should know that their size is 2108 x1048 x40 mm (just over 2 m2 ) . If you have an area of ​​26 m 2 , you can install a maximum of approximately 12 of this type of photovoltaic panels. This will also depend on how they are installed (in pairs or trios, horizontally or vertically, etc.).

However, to calculate the surface you must  discount the obstacles  that you can find. These can be  physical  (chimney, ventilation or window elements in the attic) and that directly prevent the placement of the plates; or in the form of  shadows  that can limit the power of the affected solar panel and the rest of the panels in the same chain connected in series (for example a tree).

You should also take into account two other fundamental elements. One, the  orientation , the South orientation (South-East, South-West) being recommended, as it is the one that receives the greatest solar radiation in the Northern Hemisphere. However, there may be times when we are interested in other types of orientations.

On the other hand, the  inclination  of our solar panels. Although the angle of incidence of the sun varies throughout the year, given the complication caused by the change in inclination, it is advisable to study the most optimal global inclination, but always bearing in mind that in most cases the most indicated, if they are going to be installed on a sloping roof, it is done with an installation coplanar to it. In this way we will save on materials, we will reduce the visual impact of the plates with a better architectural integration of the same and we will prevent them from creating a sail effect.

In the event that you do not have enough space on the roof for the photovoltaic installation that you had in mind, you can choose to install them in solar parking lots, on a pergola, etc.

Calculate the number of solar panels you need

To roughly calculate the number of solar panels you will need, you can apply the following formula:

formula to calculate the number of solar panels needed for an isolated photovoltaic installation

Unlike a self-consumption installation connected to the grid, in an  isolated photovoltaic installation  you will need to generate more energy than you consume at the moment. The reason is simple, you must ensure that you have electricity when the solar panels do not produce enough. And for this reason, solar kits for isolated housing include a storage system in the form of  solar batteries .

Therefore, to calculate the number of solar panels for a country house, you need to take into account the  hours at which you make consumption . If the greatest consumption falls during the day, you will need to store less energy for the night. On the other hand, if the greatest consumption is made in the hours with less solar radiation or directly without it, you will need more electricity storage capacity.

In turn, it is important  to take as a reference  the calculation of the energy you need in  the months of lower photovoltaic production . These months are the winter months, when the estimated production may be 50% less than in the summer.

According to this, if we have a daily consumption of 10 kWh in winter and the production that we previously calculated for each solar panel (1.85 kWh) must be reduced by half, the calculation to be carried out would be as follows:

results for the calculation of an isolated photovoltaic installation

In other words, to satisfy 100% of consumption, we should install at least 11 solar panels.

However, we must take into account that in the summer we would produce twice as much electricity. Therefore, if we do not want to oversize the installation for the summer months, you can install 8 or 10 solar panels and use a backup generator for the months of December and January.