# How to calculate solar panels

Solar panels are an excellent alternative to traditional energy sources, they are environmentally friendly and economical. But in order for solar installations to give the desired result, to work smoothly, trouble-free and productively, it is very important to correctly calculate solar panels for a house or apartment. To do this, take into account many indicators that affect the performance of solar panels.

Usually, the calculation of a solar battery or a power plant is an individual matter. Much depends on the needs, location, climatic conditions. Specialists for calculating solar panels for the home use special algorithms and calculator programs, take into account meteorological conditions (solar insolation, temperature, wind speed, etc.). There is no single approach to the calculation of various solar panels, but there are general principles on how to do this, taking into account certain parameters. Below we will consider the main ones and try to figure out how to correctly calculate solar panels.

## What to consider when calculating solar panels

Before calculating solar panels for a house or apartment, you need to decide on the task. Namely, whether solar panels will be used only for backup power, as an additional source of energy, or should they fully meet the needs of the facility for electrical energy. Then you need to determine the total power of devices that need a stable and uninterrupted supply of electricity generated by solar panels. It is important to remember that there is a directly proportional relationship between the output power consumed by the devices and the duration of their operation with an increase in the capacity of the battery array, the power of the inverters and, ultimately, the cost of the entire solar plant.

In addition, the calculation of solar panels will depend on whether it is planned to provide uninterrupted solar energy to all appliances and equipment in the house / apartment, or it is planned to provide only certain appliances, for example, boilers, pumps, heating system automation, lighting in common and most frequent places. use. In the first case, the consumer may not limit himself in comfort, because the system will work smoothly in full. But such pleasure will cost much more. In the second case, after determining the priority of devices, solar panels can be added, based on the possibilities, funds already spent and the feasibility obtained. It is also important to decide on the type of batteries, the area they will occupy, and their power. Knowing all these data, you can start the calculations.

• We calculate the power of the devices required by the consumer.

First you need to calculate the exact number of devices that need to be provided with electricity, taking into account the energy consumption of each of them. This may include household appliances (refrigerator, TV, washing machine, microwave, iron, electric kettle and other small household appliances), computers, lighting systems, boilers, boilers, pumps, lawn mowers, snow removal equipment, etc. To do this, we either analyze and average the average daily performance of the electric meter, or simply add up all the power of the devices that will work with solar panels . This can be done according to the instructions on the devices or find information on the average values of technology in specialized literature or on the Internet.

If you decide to install solar panels, when calculating the power of all devices, you must take into account losses, which are approximately 20%. For example, if the consumed daily power of devices is 5 kW / h, then the total average daily consumption, taking into account losses, will be: 5 x 1.2 \u003d 6 (kW / h). We will need such a supply of energy per day for the smooth operation of all devices.

• We calculate the required battery capacity of solar panels.

This can be represented by such a simplified formula with symbols: E \u003d M / N, where E is the capacity of the battery of solar panels, M is the power consumed by the devices, H is the mains voltage. In our example, at a voltage of 12V, we get:

E \u003d 6kW / 12V \u003d 500 (A / h).

• We find out the insolation coefficient or the monthly level of radiation , which depends on the region / city of residence. This is open information that is easy to find on the Internet and reference books. For example, in Kharkov, the average annual radiation level coefficient is 3.49 kW/h/m 2 , its minimum value in December is 0.93 kW/h/m 2 /day, and the maximum in June is 5.89 kW/h/ m 2 / day. And in Odessa, the average annual figure is 3.41 kW / h / m 2 , minimum in December – 0.87 kW / h / m 2 / day, maximum in July – 6.39 kW / h / m 2 / day.
• We calculate the daily performance of the selected solar battery.

To calculate how many solar panels are needed for a house or apartment, we use the formula: P \u003d K x S x efficiency, where P is the performance of one battery, K is the insolation coefficient (radiation level), S is the area of \u200b\u200bone battery, Efficiency is the battery efficiency in percent. Let’s consider in practice. For example, for a battery with a power of 250 W, an area of 2 m 2 and with an efficiency (COP) of 15%, we get:

Average daily productivity, Kharkiv:

annual: 3.49 kW / h / m 2 x 2m 2 x 0.15 \u003d 1.047 kW;

max: 5.89 kW / h / m 2 x 2m 2 x 0.15 \u003d 1.767 kW;

min: 0.93 kW / h / m 2 x 2m 2 x 0.15 \u003d 0.279 kW.

Average daily productivity, Odessa:

annual: 3.41 kW / h / m 2 x 2m 2 x 0.15 \u003d 1.023 kW;

max: 6.39 kW / h / m 2 x 2m 2 x 0.15 \u003d 1.917 kW;

min: 0.87 kWh/m 2 x 2m 2 x 0.15 = 0.261 kW.

• We calculate the required number of solar panels.

This can be done using the following formula: C \u003d M / P, C is the required number of solar panels, M is the power consumed by the devices (we have already determined it above), and P is the performance of one solar battery.

In our examples we get:

For Kharkov:

max: 6 kWh / 1.767 kW = 3 batteries

min: 6 kWh / 0.279 kW = 22 batteries

For Odessa:

max: 6 kWh / 1.917 kW = 3 batteries

min: 6 kWh / 0.261 kW = 23 batteries

## What else to consider when calculating solar panels

The value of the radiation level coefficient, which you will rely on when calculating solar panels for a home, affects their performance. For example, if you take the minimum value, then in general you will always have enough energy produced, except for long periods of bad / cloudy weather. If you start from the maximum, then you will certainly have overproduction and excess electricity in some months during the year.

Also keep in mind that the above algorithms are an approximate version that gives a general understanding of how to calculate solar panels for a home. More detailed calculations take into account other specifying coefficients, the angle of inclination of the batteries, their location, etc. In addition, you must remember that the calculated power can be adjusted by you depending on the needs – if they grow, the amount of electricity can easily be increased by adding Nth number of solar panels. But only after appropriate calculations, which are preferably clarified with specialists.

And one moment. At the stage of preparation for the calculation of a solar installation, it is necessary to know the electricity needs of a particular consumer, technical standards and legal requirements, the current project of a house, apartment or facility where a solar system is planned to be installed. If you plan to use the energy generated by solar panels not only for your own needs of a household/company, but also for the sale of surplus electricity, consider the requirements for solar installations according to the Feed-in Tariff and the electricity supplier agreement (RES).