Instituto de Mestrado em Fotovoltaica
How to Properly Connect Photovoltaic Panels?
Photovoltaic panels usually require creating a durable connection between individual cells, which on one hand increases the system’s efficiency, and on the other reduces the risk of failure. Installers have two methods for connecting photovoltaic panels at their disposal – series connection and parallel connection. Each has its own advantages and disadvantages, as despite some similarities, their operational characteristics differ significantly. Let’s take a closer look at all the solutions!
Parallel Connection of Photovoltaic Panels
Parallel connection of photovoltaic panels is a method in which all the positive terminals of the panels are connected together, just like all the negative terminals. This type of connection is mainly used in small off-grid systems or micro-inverters. This connection results in maintaining the same voltage on each panel, which is characteristic of a single module, but the current in the entire system increases by summing the currents from individual panels. This is particularly useful in systems where higher current efficiency is required, such as in installations that power large loads or are designed for fast battery charging (DC off-grid systems). Parallel connection is also beneficial in situations where panels are installed under varying sunlight conditions.
Advantages of Parallel Connection of Photovoltaic Panels
1. Greater resistance to shading of individual panels
In a parallel connection, each panel operates independently, which means that shading or damage to one of them does not significantly affect the performance of the entire installation.
2. Flexible system expansion
Parallel connection of panels allows for the easy addition of new modules to an existing system without the need to redesign the entire installation. This enables a gradual increase in the system’s power, adjusting it to growing energy needs.
3. Voltage stability
Since the voltage in a parallel system remains constant and equal to the voltage of a single panel, it is easier to manage and control the entire system. Stable voltage also facilitates compatibility with home energy systems and prevents issues that may arise from higher voltage.
Disadvantages of Parallel Connection of Photovoltaic Panels
1. Increased risk of power losses
In parallel systems where the current from each panel is summed, higher current intensities can lead to greater energy losses, especially in installations with longer cables of insufficient thickness.
2. The need for additional protections
In parallel systems, it is important to use appropriate fuses and current limiters to protect each panel from overload and potential damage.
3. Complications with panel diversity
If you want to connect different photovoltaic panels in parallel, you must consider the complexity of this process. Although, in theory, each panel operates independently, differences in characteristics can affect the overall performance and efficiency of the system.
Series Connection of Photovoltaic Panels
Series connection of photovoltaic panels is the most commonly used connection in residential installations. In a series connection, the modules are connected in such a way that the positive terminal of one panel is connected to the negative terminal of the next. This way, the voltage adds up, while the current remains at the level of a single panel. This solution is especially beneficial when higher voltage is required, such as in installations with a single inverter or those that need to transmit energy over long distances. With higher voltage, it is possible to minimize energy losses that could occur with lower voltage and higher current.
Advantages of Series Connection of Photovoltaic Panels
1. Higher system efficiency
In series systems, the voltage in each circuit is increased, which raises the overall efficiency of the installation. A string inverter receives DC voltage in the range of several hundred volts, allowing for more efficient conversion to AC voltage of 230 V, used in home installations.
2. Reduced energy losses
In series connections, energy losses associated with transmission are smaller, as smaller cable cross-sections are used. Long cables, often needed in larger installations, generate fewer energy losses at higher voltage.
3. Lower inverter costs
In series systems, a single inverter can manage multiple modules, making it more economical. There is no need for expensive microinverters for each module, significantly reducing the overall cost of the installation.
Disadvantages of Series Connection of Photovoltaic Panel
1. Reduced efficiency under shading
In series systems, the performance of one module affects the efficiency of the entire string. If one panel is shaded, dirty, or damaged, the performance of the entire installation decreases, leading to significant energy losses.
2. Increased risk of electrical arcing
Higher DC voltage in series installations increases the risk of electrical arcing, especially in case of installation errors, such as improper use of MC4 connectors from different manufacturers or physical damage to cables.
Series-Parallel Connection of Photovoltaic Panels
Sometimes, to meet specific energy installation requirements, a series-parallel connection is used. Individual groups of panels are first connected in series to increase the voltage, and then connected in parallel, which increases the current in the system and eliminates problems with shading in certain areas. This type of connection is particularly useful when it is necessary to adjust electrical parameters to the inverter’s requirements and when the installation needs higher flexibility due to varying sunlight conditions across different parts of the system.
Photovoltaic Panel Wiring Diagram – Is It Possible to Connect Devices with Different Power and Parameters?
The wiring diagram of photovoltaic panels must take into account many technical factors, including the power and electrical parameters of individual panels. Generally, connecting panels with different power and parameters is not recommended, as it can lead to efficiency problems and potential system damage.
In the case of a series connection of panels with different current parameters, the current flow may become suboptimal, reducing overall efficiency and accelerating component wear. Parallel connection of panels with different voltages is also risky, as it may cause improper voltage distribution.
However, there is an exception to this rule with the use of microinverters, which are installed individually on each panel or for the connection of two panels. This solution minimizes the negative effects of performance differences between panels, ensuring optimal operation of each module regardless of the others.
Conclusão
As we can see, both parallel and series connections of photovoltaic panels have their pros and cons. Despite some differences and similarities, both solutions facilitate the creation of solar panel systems. If, despite the above information, you are still wondering whether a parallel connection of photovoltaic panels would be better than series connection, be sure to contact specialists. They will certainly explain both methods of connecting photovoltaic panels and clarify their characteristics in your specific case.
FAQ:
1. How to connect photovoltaic panels?
Photovoltaic panels can be connected in a series, parallel, or series-parallel configuration, depending on the voltage and current requirements of the installation.
2. What is the series connection of photovoltaic panels?
Series connection of photovoltaic panels involves connecting the positive terminal of one panel to the negative terminal of the next, which increases the system’s voltage while maintaining constant current.
3. What is the parallel connection of photovoltaic panels?
Parallel connection of photovoltaic panels involves connecting all positive terminals together and all negative terminals together, which increases the current while maintaining constant voltage.