How many panels do we need to produce 1 kW of energy: cost and sample calculations

These are the next questions in a series of questions you probably ask yourself when you start thinking about setting up your own PV installation, because without knowing this topic it is simply impossible to determine how many panels you need to meet your home’s electricity demand.

Most importantly, remember that the power of the panels specified on the nameplate is the value obtained under standardized test conditions, allowing for an accurate comparison of the performance of individual types of solar batteries.

The Nominal Power value is an indication of the amount of energy produced per hour of operation under maximum exposure to the sun and in undisturbed conditions. It is most often assumed to be 1000 W per m2 in relation to the instantaneous solar radiation power, and the test takes place at a temperature of 25oC and a wind speed not exceeding 1 m/s.

In natural conditions, the generating potential of our installation is of course variable, so the amount of energy produced varies on a daily and yearly basis and depends, among other things, on the type of panels we use, but also on the angle of the roof, the degree of its shading, or weather conditions, as we mentioned earlier.

Photovoltaic panels currently available on the market generate on average from 290 to 400 W of energy. To illustrate the topic, let’s assume that we will use the most popular option, i.e. a 330 W panel that, working for an hour at maximum power, will generate 330 Wh of energy.

Similarly, for our yields from a photovoltaic installation to be approximately 1 kWh, we need three panels working simultaneously.

Additionally, it is assumed that a family of four consumes between 4,500 kWh and even 6,000 kWh annually in a house with an area of ​​approximately 100 m2. Differences in the demand for electricity in each household result, of course, from their equipment, as well as the idea of ​​what part of the consumed energy we want to obtain from our own PV installation and what part from the general grid or whether we decide to install an off-type installation. -grid, i.e. complete disconnection from external power sources.

Taking the lowest value, it means that using our example panels, we need 14 panels to completely meet the energy demand in one hour of maximum operation (4500 / 330 @ 14).

In practice, these numbers mean that to meet the annual electricity demand used in our example, we need a photovoltaic installation with a peak power value of approximately 4.5 kW. Calculating on this basis, the result is the same, namely:

4.5 kW x 3 panels per 1 kW @ 14

Taking into account that the dimensions of all panels are similar and it is approximately 110×180 cm, so one module needs an area of ​​1.98 m2, using 14 modules we need almost 28 m2 of roof, which should be allocated for the installation.

If for some reason there is not enough space on the roof – the modules can be placed on the ground, which in turn gives much greater possibilities of manipulating the angle of inclination and makes it much easier to optimize the operation of our installation compared to the one placed on the roof, but of course it requires devoting an additional part of the plot to installing panels, which does not work in the case of small properties.

• For a photovoltaic installation with a peak power of 5 kW, we will need about 15 of our model panels (cost about PLN 16,000).
• 6 kW means 18 panels and costs PLN 18,000.
• The 7 kW installation will consist of 21 panels and will cost approximately PLN 20,000.
• Similarly, for a 10 kW installation, you will need to use as many as 30 panels, which costs just under PLN 40,000.
• The prices given are sample prices from our store for self-assembly kits covered by the promotion.

We would like to remind you that the choice of the appropriate installation power and the method of its use always depends on the individual needs of each user, so we encourage you to familiarize yourself with our offer and consult with our specialists. We will help you adjust all parameters and complete the installation notification procedure with your supplier and obtain funding of PLN 5,000.