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Curious to know how the solar panel works? Know your specifics and learn how to choose

Have you ever thought of a more sustainable way to get energy? A renewable energy source that has been growing and gaining more and more space among Brazilians is solar. Brazil is an excellent market for this energy sector, as the average solar radiation that falls on the country's surface is up to 2300 kilowatt-hours per square meter (kWh/m²), according to Cepel's Solarimetric Atlas.

Despite the incentives to use the solar energy (important as it allows for a reduction in concerns regarding the reservoirs of hydroelectric plants, which in recent years have suffered from the lack of rain and excessive sunshine), some doubts can still be observed among consumers and those interested in applying this type of obtaining energy in their homes. How the system works? How much does it cost to install it? Is the financial return beneficial? The questions are many. Well, let's get to the answers!

A photovoltaic solar energy system (or just “solar energy system” or even “photovoltaic system”) is a system capable of generating electrical energy through solar radiation. The energy produced can then be used to supply the electricity grid on a large scale, as in solar plants, but it can also be generated on smaller, residential scales (residential solar energy), serving to supply the residence where the system was installed.

These systems have some basic components, grouped into three different blocks: the generator block, the power conditioning block and the storage block. Each group is made up of components with specific functions.

• Generator block: solar panels; cables; support structure.
• Power conditioning block: inverters; charge controllers.
• Storage block: batteries.

Solar panels are considered the heart of photovoltaic systems and are part of the first block, that of energy generation. Its specific function is to convert solar energy into electricity. The number of panels needed depends on the energy demand of the home.

How do they work?

Solar panels generate electricity from the sun in a very simple way. In addition to being environmentally friendly as they don't generate waste, they also don't need maintenance. One solar panel is formed by a set of photovoltaic cells that have electrons (negatively charged particles that rotate around the nuclei of atoms) and these, in turn, when hit by solar radiation, move generating an electric current.

Size and lifespan

The sizes and weights of solar panels are quite variable. There are many types and variations, but a panel is, on average, approximately one square meter, and weighs just over 10 kilos. A panel of these proportions has about 36 photovoltaic cells, being capable of producing around 17 volts, and a power of up to 140 Watts.

Existing models generally range from 5 to 300 Watts of maximum power, depending on the purpose of their use, and the technology adopted. In addition, several photovoltaic panels can be installed, which can be arranged in different ways, allowing you to work with many variations of solar systems. A solar panel has a useful life of approximately 25 years, being very practical as it does not need maintenance (remembering that other components of the system can have a longer or shorter lifespan). The payback time for the investment in the photovoltaic system can vary from eight to ten years, when the energy bill no longer needs to be paid.

There are three basic types of photovoltaic solar panels:

• Monocrystalline solar panels

  They are more efficient and made of silicon monocrystalline cells, that is, each cell is formed by a single crystal of this element. The manufacturing process of these panels is complex, as it requires the production of single crystals of high purity silicon for each photovoltaic cell.

• Polycrystalline solar panels

  With less efficiency than the previous panel, in polycrystalline cells the cells are formed by several crystals, and not just one. The end result is a photovoltaic cell that looks like broken glass.

• Thin Film Panels

  The photovoltaic material is deposited directly on a surface (which can be metal or glass) to form the panel. Despite being cheaper, they have a much lower efficiency, making it necessary a much larger area to compensate.

How to choose?

The choice of the type and number of panels to be installed depends on several aspects, such as:

• Energy demand;
• Purpose of energy use;
• System installation location;
• Available space.

Where to install?

Residential solar panels are usually installed on roofs (rooftop), however, you should be aware of some recommendations:

• The generation of electricity by solar panels can be harmed by winds, shadows and reflective surfaces, which interfere, reducing the efficiency of the process.
• It is important that there is good air circulation in the place so that the cells do not overheat.
• The roof must be resistant to the weight of the panels.
• The tilt and orientation of the panels can also interfere with their efficiency. In the case of Brazil, located in the Earth's southern hemisphere, the solar panel installed in your home must have the face oriented to true north (which is not the same north as given by the compass). For northern hemisphere countries, the solar panel must be facing true south. Magnetic north, where a standard compass points, is aligned with the Earth's poles and is constantly moving, albeit light. True north is what you see on a paper map: it's constant.

See more about installing solar energy in your home by clicking here.

Unfortunately, there are still few incentives and financing lines for this type of energy in Brazil, which are still difficult to access and have little applicability. It is expected that, with the increase in consumer demand for photovoltaic energy systems, new, more applicable and accessible incentives will emerge.