A solar energy has been gaining prominence as an economical and sustainable option for Brazilians. In May 2024, the country reached more than 3.7 million homes benefiting from photovoltaic solar energy, according to data from the Brazilian Photovoltaic Solar Energy Association (Absolar).
This growth reflects both the search for savings on electricity bills and increased environmental awareness among consumers.
If you too are thinking of investing in solar energy for your home, knowing how to choose the ideal system power is essential. Understanding how the power of the solar panels impacts the system's performance is an important step towards an efficient and economical installation.
Read on and find out how to set the right power for your solar system!
What does the power of a solar panel mean?
The power of a solar panel refers to the capacity of a photovoltaic module to generate electricity, expressed in watts (W). In practical terms, this means that the higher the power of a solar panel, the more electricity it can produce.
This potential is mainly determined by the quantity and quality of the photovoltaic cells that make up the panel, which can be made from different semiconductor materials and incorporated into technologies aimed at optimizing efficiency.
Solar panels come in a wide range of power ratings, from 305 W to 590 W, depending on the intended application. Most of the models available on the market offer an 80% guarantee of their original power for up to 25 years.
However, it is essential that this guarantee is provided by a recognized entity in Brazil, in order to ensure that consumer rights are protected in the event of failures in the panel's performance before the end of the coverage period.
How do you determine the ideal power for your solar system?
The power to be chosen for a solar system is unique to each project, reflecting the specific needs and conditions of the user. As such, there is no standard value applicable to all cases.
To better understand the factors that must be taken into account when selecting the power of your solar system, see below:
1) Identify the property's energy consumption
For homes, it is important to assess total energy consumption, taking into account the number of residents and their usage habits. In the case of companies, you should consider the number of employees and the daily activities that consume energy.
This analysis of energy demand is essential for determining the capacity of the solar system to be installed. Once the total consumption has been identified, it is possible to calculate the number of solar panels needed to meet this demand.
Remember: each panel has a specific power generation capacity!
2) Consider solar incidence
As a tropical country, Brazil enjoys a significant natural advantage. Exposure to the sun is intense over most of the territory, but the incidence varies by region, with some areas receiving more solar radiation throughout the year than others.
When planning the installation of solar panels, it is important to take these regional variations into account. TecMundo has already highlighted the best Brazilian states for implementing solar energy.
3) Analyze the space for installing the solar system
A detailed examination of the site conditions will make it possible to develop an efficient project that meets the expectations of the chosen solar energy solution.
Although most installations take place on roofs, it is also possible to opt for ground installation. Regardless of the choice, it is essential to carry out a technical assessment to ensure that the panels are positioned in such a way as to avoid shading, which can compromise the efficiency of energy generation.
In addition, knowing the dimensions and orientation of the available area helps determine how many panels can be installed and, consequently, what the ideal system power will be.
Understand the power values of solar panels.
The power values of a solar panel reveal the performance you can expect from your system. The main indicators include the Maximum Power (Pmax) in STC, the Maximum Power (Pmax) in NOCT/NMOT and the Power Output Tolerance. Check out the explanation of each one below!
Maximum power (Pmax) under standard test conditions (STC)
Maximum Power (Pmax), measured under Standard Test Conditions (STC), represents the maximum electrical generation that a module can achieve under ideal conditions: cell temperature of 25°C, solar irradiation of 1000 W/mÂČ and air mass of 1.5.
Although this measurement is an important reference, these conditions do not reflect the reality in which the panel will be installed. In practice, the power generated tends to be slightly lower than Pmax, taking into account the climatic and environmental variations of the installation site.
Maximum Power (Pmax) in NOCT/NMOT
The Maximum Power (Pmax) at NOCT (Nominal Cell Operating Temperature) or NMOT (Nominal Module Operating Temperature) is a value that represents the solar panel's capacity to generate electricity under conditions that are closer to reality.
The tests carried out in laboratories simulate an ambient temperature of 20°C, irradiance of 800 W/mÂČ (less sunlight than in STC conditions) and a wind speed of 1 m/s.
These conditions are more similar to those that solar panels will face on a day-to-day basis, such as on a typical roof, where sunlight may not be ideal and temperatures may be higher.
Thus, the actual power of the panel tends to be around 25% lower than the power recorded under STC conditions (ideal test standards).
Power Output Tolerance
The power tolerance is information provided by solar panel manufacturers to indicate the variation in performance that a panel can show in relation to its maximum power (Pmax) under standard test conditions (STC).
This value is expressed as a percentage and defines the limits within which energy production can fluctuate during actual operation.
For example, if a solar panel has a Pmax STC of 400 W and the power tolerance is +5%/-5%, this means that energy production can vary between 380 W and 420 W during operation. In ideal conditions, production can reach 420 W, but in less favorable situations, it can drop to 380 W.
This means that, depending on the conditions, the panel can operate below or above its rated power.
Today, many manufacturers offer solar panels with a negative tolerance of 0%, which guarantees that the panel will never produce less than the indicated Pmax value, but can operate above it in ideal conditions. This feature gives the system more reliability, ensuring stable and predictable performance.
Selecting the ideal solar panel power is a process that requires consideration of various factors, such as energy consumption, solar incidence in the region, the space available for installation and variations in panel power.
In addition, it is essential to check the quality of the panels and ensure that they are certified, guaranteeing the efficiency and safety of the system. By evaluating these aspects carefully, you will be better prepared to make the best decision for your solar energy project!
Nubank informs its customers about the closure of the service on December 31, 2024.
Conclusion
Choosing the ideal power for a solar system is a crucial step in ensuring its efficiency and economic viability. By considering factors such as energy consumption, solar incidence, available space and the quality of the panels, you can make an informed decision that meets your specific needs. In addition, understanding power indicators such as Maximum Power at STC and NOCT/NMOT, as well as Power Tolerance, gives you a clear picture of the system's expected performance. With the right preparation and careful planning, you'll be ready to invest in solar energy effectively and sustainably.
FAQ
- What is maximum power (Pmax) in a solar panel?
Maximum power (Pmax) is the amount of energy a solar panel can generate under ideal conditions, usually measured in watts (W). - How is solar panel power measured under standard test conditions (STC)?
Pmax at STC is measured with a cell temperature of 25°C, solar irradiation of 1000 W/mÂČ and an air mass of 1.5. - What is Power Tolerance?
The Power Tolerance indicates the variation that the panel's performance can have in relation to its Pmax, expressed as a percentage. - How does Maximum Power in NOCT/NMOT differ from Pmax in STC?
The Pmax in NOCT/NMOT is measured under more realistic conditions, such as an ambient temperature of 20°C and an irradiance of 800 W/mÂČ, resulting in lower power values. - Why is it important to check the quality of solar panels?
Guaranteeing the quality and certification of solar panels is essential to ensure the efficiency and safety of the energy system. - What factors should I consider when choosing the power of my solar system?
You need to consider energy consumption, solar incidence in your area, the space available for installation and the characteristics of the panels. - How important is solar incidence when choosing a system?
Solar incidence affects the amount of energy the panel can generate; regions with higher solar radiation are more advantageous for installing solar systems. - How do I calculate my home's energy consumption?
Energy consumption can be calculated by adding up electricity bills and analyzing the household's consumption habits. - Are solar panels guaranteed?
Most solar panels come with a power guarantee, usually Pmax's 80% for up to 25 years, depending on the manufacturer. - Can I install solar panels on the ground instead of the roof?
Yes, ground installation is a viable option, but it must be carried out with a technical assessment to ensure efficiency and avoid shading.