Introduction
With the widespread adoption of solar technology, efficiently connecting solar panels has become an important issue. Solar panels can be connected in series or parallel, each having unique advantages and suitable scenarios. This article will detail the concepts, selection methods, and application scenarios of series and parallel solar panel connections, helping you better understand and choose the appropriate connection method.
What Is a Series Solar Panel Connection?
When you connect the positive terminal of one solar panel to the negative terminal of another, you create a series connection. Connecting two or more solar panels this way forms a photovoltaic source circuit. Series solar panels increase the overall system voltage while keeping the current unchanged, suitable for systems that require high voltage.
When solar panels are connected in series, the voltage of the panels adds up while the current remains the same. Increasing the voltage of the solar array is essential because photovoltaic systems need to operate at a certain voltage for the inverter to function properly. Therefore, you can connect solar panels in series to meet the inverter's operating voltage window requirements.
What Is a Parallel Solar Panel Connection?
In a parallel connection, the positive terminals of two solar panels are connected together, and the negative terminals are also connected together. The positive wire connects to the positive connector in a combiner box, and the negative wire connects to the negative connector. When multiple solar panels are connected in parallel, it forms a photovoltaic output circuit.
Parallel solar panels increase the overall system current while keeping the voltage unchanged, suitable for systems that require higher current. Parallel connections increase the current but maintain the voltage. This wiring allows for more solar panels without exceeding the inverter's operating voltage limits. Inverters also have current limits, which can be met by paralleling solar panels.
Differences Between Series and Parallel Solar Panel Connections
Series-connected solar panels add system voltage, keeping current unchanged, while parallel-connected solar panels add system current, keeping voltage unchanged.
Series Connection Explanation:
If you need to connect solar panels in series, you can follow the diagram below. After connecting in series, the system voltage adds up, and the current remains the same. For instance, connecting three solar panels with a rated voltage of 20V and a rated current of 5A will output 60V 5A into the solar controller. Ensure the circuit output voltage is below the controller's maximum allowable input voltage.
The charge controller is a decisive factor in solar panel wiring. A Maximum Power Point Tracking (MPPT) charge controller is used for series connections, while a Pulse Width Modulation (PWM) charge controller is used for parallel connections.
Series connections work similarly to how solar panels function. If one solar panel in a series circuit has a problem, the entire circuit will fail. However, in a parallel circuit, a faulty panel or loose wire won't affect the production of the other panels. The wiring method depends on the type of inverter used.
Parallel Connection Explanation:
For parallel connections, connect all positive terminals to the photovoltaic branch connector, and all negative terminals to another branch connector. After connecting in parallel, the system current adds up, and the voltage remains unchanged. For example, connecting three solar panels with a rated voltage of 20V and a rated current of 5A will output 20V 15A into the solar controller. Ensure the circuit's maximum current is within the controller's acceptable range and that the output voltage meets the controller's minimum startup voltage without exceeding its maximum allowable input voltage.
Parallel circuits require thicker wiring due to voltage limits, and using a PWM charge controller is more suitable for parallel connections.
Example with 2 Panels:
For two 100W, 12V rigid panels:
- In series, the total power is 200W, and the open-circuit voltage will be 12V × 2 = 24V.
- In parallel, the total power is 200W, voltage remains 12V, and current increases.
How to Choose Between Series and Parallel Solar Panel Connections?
The choice between series and parallel connections depends on various factors, including voltage and current requirements, power output needs, available space, and component compatibility.
Series Advantages:
- Better performance in low light conditions.
- Less wiring needed, cost-effective.
- Higher voltage output reduces power loss over long distances.
Series Disadvantages:
- A single panel's shading can affect the whole system.
- Requires a high-voltage inverter.
Parallel Advantages:
- Less affected by shading, more stable.
- Lower voltage output reduces the risk of hazardous electrical conditions.
Parallel Disadvantages:
- More wiring and complex installation.
- Different panels might affect efficiency.
Summary of Series and Parallel Connections:
If your installation environment has good lighting with minimal shading, series connections can save on wiring costs. However, if the environment is unstable with frequent shading, parallel connections provide more stability as the circuit is less affected by local issues. For optimal performance, consider a hybrid connection combining series and parallel methods to balance voltage and current outputs, tailored to specific application requirements.
Example: OKEPS All-in-One System Installation Suggestion
For the OKEPS All-in-One System with a maximum photovoltaic input voltage of 120V and power of 1500W, we recommend using six 20V, 5A flexible photovoltaic panels in series. For higher power needs, you can connect up to 12 panels in parallel. Please inform us during consultation for an additional Photovoltaic Panel Parallel Connection Harness.
Hybrid Setup:
In addition to a single series and parallel connection, there is also a connection that combines the two, known as a hybrid setup. Hybrid setups and series-parallel connections can achieve a balance between voltage and current outputs to meet the voltage and current requirements of a particular application. It should be noted that hybrid setups can only be composed of an even number of solar panels.
Taking the application of marine vessels as an example, assuming that there are four solar panels, we can arrange two solar panels on the port side of the ship, and the other two are arranged on the starboard side of the ship, connect the solar panels on the left and right sides in series, and then connect the two series circuits in series and parallel for the hybrid setup. This way of connecting solar panels is very suitable for sailing boats.
What are the advantages and disadvantages of connecting solar panels in series and parallel?
Solar panels connected in series can save wire costs, but it should be noted that once the solar panels are connected in series, the overall power generation of the system will be affected if there is localized shading.
Solar panels connected in parallel will increase the current, need more wires than series connection, but after the parallel connection of solar panels, if one of the panels is damaged and loses the ability to generate electricity, it will not affect the overall power generation system, and the solar panels installed in the other branches will also be able to operate normally.
Can solar panels of different sizes be connected in series or parallel?
Yes, as long as the open-circuit voltage after series connection does not exceed the maximum value of the controller at low temperature.
However, OKEPS does not recommend that you connect solar panels of different specifications in series or in parallel. When solar panels of different specifications are connected in series, the current of the whole circuit will be close to that of the solar panel with the smallest current; and when solar panels of different specifications are connected in parallel, the voltage of the whole circuit will tend to be that of the solar panel with the smallest voltage. This is a loss for the larger power solar panels in the circuit.
Conclusion
No matter which connection method is chosen, solar panels with the same specifications should be used as much as possible to ensure that the solar panels have a uniform rated voltage and rated current, in order to prevent different solar panels from being matched with each other to reduce the efficiency of the system or to damage the panels. At the same time, the connection of solar panels should be connected to the appropriate controller and wire to ensure that the system can operate safely and reliably. Each connection method has certain advantages, in the actual connection process, you can choose according to their own needs and system requirements.