Simple estimation of the power and the number of panels required for our PV system

Nov 13, 2015. | By: Adriana Sánchez and Ana Morales

Using as an example the case of Spain and by a simple simulation, we are going to estimate how much power and the number of panels required for our PV system. All this will depend on factors such as hours of sunshine received per year, the region we are living in, the correct orientation of the solar panels … According to the National Geographic Institute, Spain receives around 2,600 and 2,800 hours of sunshine a year. This information is important for not to fall short during the months of lowest solar radiation, which tends to increase the electricity consumption, since there are fewer daylight hours, colder temperature and we spend more time at home.

Once we have determined the proper installation place, we must decide how many batteries we’ll use depending on our consumption. Keep in mind that when sizing batteries, these should not be downloaded below 50% capacity. So when we think of the capacity of the batteries, we should think in the worst: a cold and rainy winter day. In a standard housing in such a day it could be spent 15kWh, which resulted in amps battery is 625Ah 24V (15.000W / 24). So to spend a day “eating” batteries, need a 1.250Ah and 24V, in two days of rain, one of 2.500Ah etc.

We have reached the point of deciding how many solar panels we need to install. It is fundamental the space available for the installation and the place where we are going to settle the batteries. Assuming that we can orientate our panels efficiently and considering that we must seek the combination of the worst month of sunlight on our worst month of consumption, weĺl have to face an energetic necessity where we have to produce 3000 kWh per year with panels producing 250W each hour. Performing the relevant calculations, in a city like Granada, we conclude that we only need four of these panels to produce such amount of energy (0.25kW x 3000 hours x 4 panels = 3.000kWh)

As for the amortization for such facilities it is estimated to be completed in 4 or 5 years, considering that the life of the plates RSP250P Rekoser is about 25 years.

Finally, the installation must be performed by a qualified technician that can always provide solutions to our photovoltaic isolated system and connected to the network.

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