Photovoltaic panels are usually made from polycrystalline silicon cells. There are at least a dozen or so in one panel. They are used for the construction of solar installations, in which there are 60 or 72. Then the device has a size of approximately 1 * 1.7 m and a peak power of 240-290 W. The required power of the entire installation is ensured by the appropriate number of panels.
Suppose that we are interested in an installation with a capacity of 5 kW, from which household consumers of electricity must be powered. Panels with a peak power of about 250W are currently sold for about UAH 2,500. We need 20, so we will pay UAH 50,000. To this should be added at least UAH 30,000. to the inverter, providing a change in the current parameters from panels to those required by home receivers (AC, 230 V, 50 Hz), and a couple of thousand more for fasteners, structures, special wires (with a cross section of 4 mm², that is, much thicker than in the installation 230 B), accessories and assembly of the whole installation. Therefore, if you want to have a solar power plant with a peak power of 5 kW / s, you need to prepare for spending -82 thousand hryvnia. If we are interested in a lower power, then in terms of 1 kW the price will be slightly higher .. The estimated price of a system with a peak power of 3 kW is about 60,000 UAH.
Solar radiation reaching the earth's surface in our geographic location rarely reaches 1000 W / m², for which manufacturers report the parameters of photovoltaic panels. Therefore, a parameter called peak power says little about the benefits of using them. To calculate how much you can save using a photovoltaic installation, you need to know how much energy it provides, and this depends not only on solar energy, but also on the location of the panels (angle of incidence of the rays), ambient temperature, shading and other factors. Therefore, the amount of energy should be determined based on the tests of the device in the given situation.
To roughly estimate the profitability of purchasing photovoltaic energy, we have to rely on information from manufacturers, who usually estimate it on the basis of theoretical calculations. They show that a 5 kW peak plant built with panels like the ones described above can provide an average of 4,200 kWh of electricity per year. In Ukraine, the so-called expected annual energy production is estimated at 110-150 kWh per 1 m² of a typical solar module. If we optimistically assume that it will be fully utilized, we will get a very attractive return on investment. Since 1 kWh of energy is consumed for electricity about UAH 1.68 (average tariff), thanks to a photovoltaic system with a capacity of 5 kW / h, about 7000 UAH are saved annually. Estimated above UAH 85,000. spent on the purchase will pay off in about 11-12 years, and then start to make a profit. Although the efficiency of photovoltaics decreases over time, manufacturers guarantee that panels made from polycrystalline silicon cells will deliver at least 90% of their rated power after 12 years, and after 25 years they will work, and their power will not drop below 80%. Thus, it looks like a photovoltaic installation is a smart investment.
However, it is still necessary to take into account the fact that the amount of energy generated by the installation provided by the manufacturers is approximate, since it is even influenced by the weather (mostly cloudy), which no one predicts. The information on the amount of energy generated by the panels is based on statistics for each type of system. Therefore, you need to consider the difference between theory and practice. Energy losses should also be taken into account - about 3% on the wires and from 3 to 15% on the inverter.
Of course, this depends on the price of the installation and the price of electricity - the more expensive it is, the more profitable will be the operation of the photo-generating system, which provides it for free. But not everyone pays attention to the fact that not all photovoltaic energy can be used, and the degree of its use has a huge impact on the profitability of their purchase. For this reason, investing in a large capacity installation is not a good idea, even if the higher it is, the lower the unit cost (per kilowatt of capacity). If solar cells provide energy with a large surplus, the payback period will be long. By choosing a unit with a reasonable (moderate) power, you can count on the fact that without storing energy, you will be able to use it for your own household needs on the 30%. And this means that the payback period is three times longer than if it was fully used. This is why it is very important to be able to supply excess energy to the grid. But that is another story.