Solar energy has been gaining ground as one of the main alternatives for those looking to reduce their electricity bills, invest in sustainability and achieve greater energy independence. But how does solar energy work?
In short, the system captures sunlight through solar s and transforms it into electrical energy that can be used in homes, businesses and industries.
This process involves specific technologies, such as photovoltaic modules and inverters, and depends on a series of conditions to guarantee efficiency and safety.
In this guide, we will explain in a practical way how photovoltaic solar energy works, the types of technologies available, the care required to keep the system in operation, and the main advantages of this investment.
Also understand how solar energy generation works in different situations, such as at night and on rainy days!
How does photovoltaic solar energy work?
Photovoltaic solar energy works by directly converting sunlight into electricity. This process occurs through photovoltaic solar s, which are generally made up of silicon cells, a semiconductor material that reacts to solar radiation.
When sunlight hits these cells, it generates a flow of electrons, producing a direct current (DC) electric current. This current, however, is not yet suitable for powering conventional electrical devices, which run on alternating current (AC).
This is where the solar inverter, a fundamental piece of equipment in the system. Its function is to convert direct current into alternating current, compatible with the electrical grid and with the equipment in the home or business.
So what seems simple on the surface involves an efficient energy conversion chain, integrating electricity capture, transformation and utilization.
How the photovoltaic solar energy system works in general :
- Capture: solar s capture solar radiation;
- Conversion: the inverter transforms direct current into alternating current;
- Distribution: the energy is used directly in the property's electrical equipment;
- Compensation: If there is excess generation, it is sent to the electricity grid, generating credits that can be used later.
It is important to that small energy losses occur at each of these stages. For example, during capture, there are losses due to dirt or light reflection; during conversion, the inverter is not 100% efficient (losing about 1 to 3% of the energy); and during distribution, there are losses in the cables due to electrical resistance.
A well-dimensioned and maintained project minimizes these effects and ensures high system efficiency.
In systems connected to the public grid (grid-tie), the consumer can take advantage of both the energy generated during the day and the energy from the grid at times of low solar production, such as at night or on rainy days.
Now that you know how photovoltaic solar energy works, let's detail the step-by-step process of generating solar energy and what happens in specific situations, such as periods without sunlight!
How does solar thermal energy work?
Solar thermal energy uses the sun's radiation not to generate electricity, but to heat fluids or environments. Its operation is relatively simple and quite efficient for residential, commercial and industrial applications.
The process takes place through solar thermal collectors, which are generally installed on roofs. These collectors absorb heat from solar radiation and transfer it to water (or another fluid) that circulates in internal pipes.
This heated liquid is then stored in thermal boilers (thermal reservoirs) and distributed for use in baths, swimming pools, industrial processes or building heating systems.
How does heliothermal solar energy work?
Heliothermal solar energy (or concentrated solar energy, also called CSP – Concentrated Solar Power) is a more complex technology, used mainly in large power generation plants.
The principle is as follows:
- Large arrays of mirrors or lenses are used to concentrate sunlight onto a single point, such as a tower or receiving tube.
- This concentration raises the temperature of a thermal fluid (such as special oil or molten salts) to very high temperatures, above 500°C.
- The heat generated is used to produce steam, which drives turbines and generates electricity, similar to traditional thermal power plants.
One of the advantages of solar thermal technology is that the heat accumulated in the fluids can be stored, allowing electricity to be generated even at night or during periods of lower solar radiation.
How does solar energy work at night?
A common question among those who are learning about the technology is understanding how solar energy works at night, when there is no sunlight available.
The answer is simple: at night, the photovoltaic system does not generate energy, because it depends on solar radiation to activate the photovoltaic cells. Since there is no generation, the property starts to consume energy directly from the public electricity grid.
In network-connected systems (on-grid), this transition happens automatically and imperceptibly for the . The energy consumed during the night can be offset by the energy credits accumulated during the day, if the system has generated a surplus.
In systems with energy storage (off-grid ou hybrid), the energy generated during the day is stored in solar batteries. Thus, during the night, the necessary electricity is supplied by the batteries, ensuring total autonomy.
How does solar energy work on rainy days?
Another important point is to understand how solar energy works on rainy days. After all, the weather can directly impact electricity generation.
On rainy days, the solar radiation that reaches the s is reduced, but does not disappear completely.
Clouds filter some of the light, but still allow diffuse radiation to through, enough to generate some energy production, although at a lower intensity.
The efficiency of the system depends on factors such as:
- Cloud density;
- Duration of rain;
- Solar technology (some more modern models perform better in low light).
Just like at night, if generation is insufficient, the property automatically starts consuming energy from the electricity grid, with the possibility of compensation via credits.
In fact, rain, despite reducing generation, also brings benefits. It helps to naturally clean solar s, removing dust and dirt that could hinder light capture on sunny days.
After all, how can you use solar energy safely?
The safe use of solar energy begins at the planning and installation stage of the system. To ensure proper functioning and protection of the property and people, some precautions are essential:
- Well-dimensioned project: the system must be sized according to the property's consumption profile and local solar radiation conditions;
- Certified equipment: choose modules, inverters and components that meet Brazilian and international technical standards;
- Professional installation: the system must be assembled by professionals or specialized companies, who follow ABNT standards (such as NBR 16690);
- Electrical protection: surge protection systems (DPS), adequate grounding and circuit breakers prevent the risk of short circuits and lightning strikes;
- Monitoring and maintenance: Monitoring system performance allows you to quickly detect problems and ensure ongoing security.
With these precautions, the photovoltaic solar system operates safely, efficiently and with excellent longevity.
What happens when not all the energy produced is used?
In systems connected to the public grid (grid-tie), when solar energy production exceeds the property's consumption, the excess is automatically injected into the electricity grid.
This surplus generates energy credits, which are ed with the distributor. The consumer can use these credits to reduce consumption at times when they generate less energy than they consume — such as at night, on rainy days or in months with less sunlight.
According to the rules of the compensation system, these credits are valid for up to 60 months (5 years). If they are not used within this period, they expire.
This mechanism is what makes solar energy even more advantageous, as it allows excess production to be fully utilized over time, maximizing the return on investment.
How does solar energy system maintenance work?
Maintaining solar energy systems is simple, but essential to ensure their durability and efficiency.
The main maintenance practices are:
- Cleaning of the photovoltaic modules: dust, pollution, bird droppings and leaves can reduce the efficiency of the s. Cleaning should be done with water and a soft cloth or special equipment. It is recommended to consult the manufacturer's installation manual;
- Regular visual inspections: check cables, connectors and fastening structures to identify possible damage or wear;
- Performance analysis: monitoring generation data through the inverter or monitoring system allows detecting drops in performance or inverter alarms that indicate the need for intervention;
- Annual preventive maintenance: an annual review carried out by a specialized company or professional is recommended, which may include electrical tests, retightening connections and updating firmware.
With regular maintenance, photovoltaic solar systems can have a useful life of over 25 years, with high performance throughout this period.
What are the precautions for the solar energy system?
Although photovoltaic systems are robust and designed to withstand different weather conditions, some simple precautions help to preserve their efficiency and extend their useful life:
- Monitor energy generation: regularly monitoring the system's performance is essential to identify any outages or anomalies;
- Keep s clean: cleaning must be done carefully, avoiding the use of chemical products or abrasive materials that could damage the glass of the modules;
- Protect against shadows: prevent new construction, tree growth or dirt accumulation from causing shading on the s, which impairs efficiency and can reduce the useful life of the diodes present in the modules or damage the cells due to overheating;
- Check the fastening system: strong winds, rain and the weather itself can affect the structures of the modules. Periodic reviews help to ensure the safety of the installation;
- Upgrade the inverter if necessary: Since the inverter has a shorter lifespan than the s (about 10 to 15 years), it may need to be replaced or upgraded during the system's lifecycle.
Small preventive measures ensure that the system maintains high performance over decades.
Advantages of solar energy
Investing in photovoltaic solar energy offers a series of practical, economic and environmental advantages. The main one is the possibility of drastically reducing the electricity bill, depending on the size of the system and the consumption profile.
Another important factor is the increase in property value. Properties equipped with solar systems are more attractive to buyers and tenants, increasing their market value.
Solar energy also contributes directly to sustainability, as its operation does not emit polluting gases, reducing s' carbon footprint.
In the global context, solar energy continues to grow at a rapid pace. By 2023, global renewable energy capacity additions will increase by approximately 36% to reach 473 GW — a new record set for the 22nd consecutive year.
In 2024, solar energy ed for 6,9% of global electricity generation after record growth of 29%, equivalent to 474 TWh, a volume sufficient to supply all of India's electricity demand. This data reinforces the growing role of solar energy in the global energy matrix.
In addition to the financial and environmental benefits, investing in solar energy provides greater autonomy in relation to public energy tariffs and greater predictability in costs over the years.
After all, is it worth investing in solar energy?
Given the current energy scenario, investing in solar energy is a strategic decision for both residential consumers and businesses. The technology offers significant savings, stability in energy costs and equity gains by increasing the value of properties equipped with photovoltaic systems.
The moment is especially favorable in Brazil. In 2024, the country reached 55 GW of installed capacity in photovoltaic solar energy, with 37,4 GW coming from distributed generation — such as residential and commercial systems — and 17,6 GW from centralized generation in large plants.
Solar energy was the source that grew the most in the national electricity matrix, adding 14,3 GW of new capacity, an increase of almost 40% compared to the previous year.
These numbers confirm not only the expansion of the market, but also the maturity of technology and the supply chain in the country.
Furthermore, the steady growth of solar energy globally shows that this is an irreversible trend.
The Brazilian regulatory environment, which still offers significant advantages for those who install solar systems, combined with financing options and technological advances that have made the equipment more accessible and efficient, reinforces the excellent moment to invest.
If you want to continue learning about how solar energy can transform your consumption and your future, access our guide on everything you need to know about solar energy and delve even deeper!
