Calculate the solar panels needed for a house

While a few years ago I had to persuade my clients to install solar panels, now that the news has spread, they are the ones who demand that their new homes should have a solar system installed.

 

Local companies say that they are being overwhelmed with demand after a government decree eliminated bureaucratic red tape and installation prices dropped dramatically.

Last year, 235 megawatts (MW) of new photovoltaic power were added in Spain, and this year the industry expects to see an installed capacity of 400 MW.

It is true, however, that most of this extra power is being demanded by small and medium-sized businesses and by the industrial sector, which stand to benefit the most because they can produce and consume energy simultaneously.

For now, households, which typically have 3kW solar power systems, account for around 10% of self-generation of solar energy, but it is expected that the figure will rise throughout the year.

 

Solar systems has fallen in cost by nearly 80%

Now that self-generation is legal and makes economic sense, companies are working round the clock to meet the demand. Gone are the bureaucratic hurdles kept in place for years by the right-wing Popular Party (PP) governments. The price of installing solar systems has dropped by nearly 80% in just one decade. Even some local authorities are incentivising self-production with lower property taxes for homes with solar systems.

The company[dd1]  expects to have installed 1,500 systems by the end of the year, and 5,000 by 2021. These are mostly home systems for detached houses and other installations that do not feed excess production back into the grid.

All this encourages people to install a solar energy system, although it can be somewhat complicated to know how to calculate the solar panels needed for one’s house.

 

How to do it…simply.

In this article we will explain how to calculate the number of solar panels we need for our home in an approximate way.

It is important to know that if you have any shadow cast on the panels this may invalidate the exercise. A 10% shadow may turn off the whole system so please take into account chimneys, aerials etc.

First of all, we must know that the PV power that we can install on a roof that is well oriented i.e. south-facing could provide us with 150Wp / m2. Thus, the two standard panel formats that are found in most firms are those of 72 cells: they measure 2x1m and provide an output of about 320Wp, while an installation with 60 cells measures 1.6x1m and provides about 280Wp. The truth is that the smaller modules can more easily take advantage of the available space.

So let’s say that you require about 5.5KW in your home. You will therefore require about

17 panels of 320 Wp or about 20 panels of 280Wp or about 34m2 of roof space for the first example and 32 m2 for the second one. Taking into consideration circulation spacers around the panels etc., you would require about 40m2 of roof or terrace space for the panels installation.

 

A good reason to install solar panels.

Solar panels will reduce the energy you consume and thereby you will pay less on your electricity or gas bills. All this to counteract the rising charges that we have faced in recent years. As we mentioned earlier, with a view to being more respectful of the environment, homeowners and communities of residents are increasingly receiving greater financial support to install them.

Another advantage to take into account once we have learned how to calculate the photovoltaic solar panels we need, is based on the fact that we will be increasing the value of our house considerably. What’s more, the sun has the advantage of reaching everywhere[dd1]  and therefore, it is very useful for rural areas or farmhouses that do not have access to electricity.

 Now that we know how to calculate the necessary solar panels and what advantages there are in investing in solar energy, the time has come to install a PV system in our home to enjoy a cleaner world and make considerable energy savings.

 [dd1]Not if you are in a valley, for instance

 

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