1. What is photovoltaics?

Photovoltaics (PV) – a field of science and technology dealing with the conversion of sunlight into electricity, or in other words, the generation of electricity from sunlight using the photovoltaic phenomenon.

2. What can I power with a home photovoltaic system?

All single-phase and three-phase consumers. For example, a 4kWp installation that covers an area of 24 sqm per year will produce about 4000kWh of electricity, which is the amount consumed by most households annually.

3. What are the types of photovoltaic panels?

The main photovoltaic technologies are monocrystalline, polycrystalline and thin-film panels. The three types differ in appearance and production method, as well as efficiency.

Monocrystalline panels are made of monocrystalline silicon as their name suggests. They are traditional solar panels. Their efficiency is higher than polycrystalline panels.

Polycrystalline panels are made up of many smaller crystals. They are minimally less efficient however they are cheaper to produce than monocrystalline panels.

So-called thin-film panels are the least efficient. Due to the very thin silicon layer, they require a large surface area to achieve a certain power. In addition, they require a more expensive mounting system, which altogether makes them much less commonly used today.

A broader breakdown:

  • selenium
  • silicon
    • monocrystalline
    • polycrystalline
    • thin-film (amorphous silicon)
  • dye (under research)
  • polymeric (3rd generation, under research)

Photovoltaic cell 

Photovoltaic cells, also known as solar cells, are made from the same types of semiconductor materials (such as silicon) as those used in microelectronics. It is a semiconductor material in which solar radiation is converted into electrical energy. The photovoltaic effect was first observed by A.C. Becquerel in 1839. A photovoltaic cell is shown in the picture below:

JA Solar ogniwo PV1

Below is a photo of a polycrystalline photovoltaic module – consisting of 60 cells.

How is a photovoltaic panel built?

Below is a cross-section showing us the different layers: aluminum frame, gasket, glass, EVA film, cells. The quality of each of these individual components determines the performance and durability of the entire module and the entire installation.

4. What is an inverter?


Solar panels produce direct current. The Polish electric grid is designed for 230V/50Hz AC current. An inverter is needed to convert the direct current produced by the solar panels into alternating current with parameters compatible with the public grid. Usually inverters, in addition to the function of converting DC to AC, perform other functions like:

  • Control of grid parameters
  • Monitoring of operation
  • Recording of data
  • Optimization of PV generator operation

There are different types of inverters – by technology: transformer, transformerless, as well as microinverters and string central.

Modern inverters have a very high efficiency of up to 98%. The inverter is crucial to the overall efficiency of the system and should be matched with the other components.

5. Does the photovoltaic kit include batteries?

Depending on the selected system, for example grid-connected systems do not need batteries to store energy. The type of system and system of energy use is selected at the design stage.

In the case of domestic photovoltaic systems, our solutions are so advanced that the life of batteries is up to 20 years. A system with storage means, in addition to its own energy, independence and even greater savings in the long term.

Autonomous systems make it possible to supply energy, in addition to use for domestic and commercial needs, wherever there is no access to the public grid – especially in Third World countries, shelters, cottages, hospitals, fire stations or schools.

Autonomous systems are also used for garden lighting, parking meters or ticket vending machines.

6. Can photovoltaics be used to heat water?

Solar energy used to heat hot water is often confused with photovoltaics. Unlike photovoltaics, solar thermal panels use the sun’s rays to produce heat, not electricity. In individual homes, solar thermal energy can be used to heat water. Photovoltaic systems such as SOLSUM’s innovative solutions combined with a heater or heat pump can heat water all year round, and much more efficiently than collector energy.

7. Is there enough sunshine in Poland to produce electricity?


Poland receives an average of 1,100 watts of solar energy per square meter, enough to economically operate installations as small as 10 square meters. The sun doesn’t always have to shine for the system to work. Under overcast conditions, modern panels can convert solar radiation into electricity, and the differences in production over the course of a year for different locations in our country are not significant (about 5%), so it is worth using a photovoltaic system anywhere in Poland.

8. How much electricity will my system generate during the winter?

Undoubtedly, the summer months are the most energetic, due to longer days and more radiation per square meter. However, the energy produced by a photovoltaic power plant is generated all year round, even in winter. For Polish conditions, PERC technology modules are recommended, which achieve high efficiencies even in harsh weather conditions.

9. Is my roof suitable for a photovoltaic system?

If you have more than 15 square meters of roof or lot area then it is worth investing in a photovoltaic system. The orientation and pitch of the roof are also important factors to consider at the design stage to maximize the entire system. As a rule of thumb, in Poland the roof should be oriented between southeast and southwest, with a slope of 25 to 40 degrees.

10. What is the SOLSUM warranty like?

The performance warranty is 25 to 30 years depending on the equipment used.

A well-designed system has a lifespan of min. 30 years. There are systems that have been in operation for more than 30 years despite the fact that they were made at a time when photovoltaics were not as developed as they are today.

11. Is it worth it to produce energy for our own consumption?

It certainly is. The more solar energy you use, the less you will have to buy from the energy supplier, plus you can switch to a lower tariff to draw from the public grid at night at an even lower price. And since energy prices are likely to rise in the future, your savings will also increase.

12. How long is the payback period for a photovoltaic system?

This depends on a number of factors, you can calculate the estimated payback period in Polish conditions here: https://solsum.eu/klient-indywidualny/kalkulator-fotowoltaiczny/

13. Will the energy operator buy back the surplus from me?

Yes, a change in regulations already allows the sale of surplus energy to the public grid and the replacement of the meter for domestic installations up to 40kWp is done free of charge.


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