Two types of connecting solar modules: do you really know why?
Solar system usually consists of one or more rows of solar modules connected together. The voltage and current reaching the inverter depends greatly on how the individual solar panels are connected.
With this in mind, PV modules can be connected in two ways :
- Parallel Connection
- Series Connection
The type of connection you choose depends on your accessories, such as inverters or batteries. However, you should also consider the expansion plans or operating conditions of your solar system.In this article, we will explain the difference between parallel and series connections using batteries, wires, and light bulbs as examples.
That is to say, multiple solar panels positive pole and negative pole connected together in sequence, the current is unchanged, the voltage is added, the total voltage is equal to the sum of the voltage of the panels added together. Series connection can increase the total voltage, suitable for long distance transmission of electricity.
Series connection is explained more generally using the example of a string of lights on a Christmas tree. In this setup, each light bulb is connected in a sequential manner on a single wire. Current can only flow in one direction through the wire. If one bulb goes out, it breaks the circuit, and the entire string of lights stops working. To avoid this, it is necessary to check each bulb individually before using the Christmas tree.
Applying this concept to solar panels, wiring them in a similar series fashion can have drawbacks. If one solar panel goes out or is shaded, it significantly reduces the output of the entire system. This is because the current passing through the series-connected panels is affected by the weakest link, causing a drop in overall performance. Therefore, proper assessment of shading and regular maintenance is important to ensure optimal functioning of the solar panel system.
Series connection of solar panels is a common option and is typically used for large-scale photovoltaic power plants.
Solar panels in series: pros and cons
- Reduce transmission losses: By increasing the voltage, the current required to deliver the same power can be reduced, thus reducing the resistance losses in the wires and cables.
- Increase power output: In a series connection, since the panels draw equal current, it helps ensure that the panels operate at the same operating point, maximizing the total power output of the system.
- Reduce costs: Series connections enable high-voltage system designs that reduce cable count and equipment costs.
- Wide impact: In a series connection, if one panel fails or is obscured by shadows, the performance of the entire series circuit is affected.
- Complex system design: Factors such as voltage equalization, line capacity and current distribution need to be taken into account, and series connections require more complex circuit design and wiring in power station wiring.
It is important to note that in large PV power plants, panels are typically divided into combinations of multiple cell banks connected in series and parallel to achieve the proper system voltage and power output. Such a design combines the advantages of series and parallel connections to meet the specific requirements of large PV plants.
That is to say, multiple solar photovoltaic panels are connected to the positive pole, the negative pole is connected, the voltage is unchanged, the current is added, and the total current is equal to the sum of the current of each panel.
In parallel connections, which are commonly used in homes, each circuit or set of appliances is connected independently. For example, kitchen appliances may be connected in one circuit, hall appliances in another circuit, and room appliances in a separate circuit. These circuits are then connected in parallel at the end. If a light bulb in the kitchen circuit goes out, it doesn’t impact the lighting in the hall or the room.
Applying this concept to solar panels, connecting them in parallel means that each solar panel operates independently. If one panel malfunctions or experiences a decrease in performance, it won’t affect the overall performance of the other panels. For example, if you have five solar panels rated at 12V and 5A, connecting them in parallel would still provide 12V output, but the current capacity would increase, resulting in a combined output of 25V.
Parallel Connection of solar panels is a common option and is typically used for residential solar systems.
Solar panels in parallel: pros and cons
Series connections may be used in special circumstances, such as in specific commercial or industrial applications, or when specific voltage requirements need to be met. However, in most residential solar systems, it is common and effective practice to utilize parallel connections for higher generation capacity and system reliability.
- Increase total power: Each panel is capable of independently generating power and contributing it to the overall system, thus increasing the total power generation capacity.
- Reduced shadowing effects: Due to the parallel connection, even if one panel is affected by shadowing or malfunctioning, the other panels will still function normally. This reduces the energy loss of the system due to partial shadowing or failure.
- Flexibility: Parallel connection makes the system more flexible. The number of panels can be increased or decreased as needed to accommodate different power generation requirements.
- Energy Loss: Parallel connections may result in some energy loss. Due to the presence of current branches in the circuit, there is some current wastage, which reduces the overall energy efficiency.
The main thing to remember is that wiring in series will increase your voltage while wiring in parallel will increase your amperage. Generally parallel wiring uses thicker wires because there is more current, and conversely, series wiring has less current and uses smaller wires. Both voltage and amperage need to be considered when designing your system!
In practical applications, series-parallel connection combinations are generally used to enable solar PV modules to fully utilize the characteristics of practical application scenarios. For example, large-scale photovoltaic power stations are generally connected in series to fully increase the output voltage and reduce line losses, while distributed and household photovoltaic systems are more likely to be connected in parallel to meet the daily demand for electricity.