Solar Panels Series vs Parallel: What’s Best for Your System?

Solar panels comprise multiple solar cells that assist convert sunlight into DC (Direct Current) through the photovoltaic (PV) effect, and the inverter further helps convert it into usable AC (Alternating Current) that is widely used in appliances.

Proper wiring configuration is necessary for the optimal performance of a solar power system as it ensures greater efficiency, and higher energy output and prevents safety threats or hazards.

The major difference between these two types is the connecting pattern where in series, the panels are connected end-to-end, and in parallel, the panels are connected side-by-side.

Both series and parallel connections can differently influence the effect of voltage and current on solar panels. Before choosing the type of wiring connections for your solar panels, in series or parallel, it is important to consider certain factors, as both methods have their pros and cons. Let’s dive deeper to find out whether you can combine the series and parallel connections.

Series Connections in Solar Panels

Linking multiple solar panels together in an end-to-end pattern is known as a series connection, in which the positive terminal of one panel is connected to the negative terminal of the next panel.

Solar panels are connected in a single string, and this configuration increases the voltage while constantly maintaining the same current level.

For example: If you are connecting three 300-watt solar panels where each panel has a voltage of 36V and an amperage of 10A, the total voltage will be 108V (36V + 36V + 36V), but the current level (in amperage) will remain at 10A.

The series configuration is very beneficial, especially when the solar array has to be connected to a larger voltage system that operates at a higher voltage level, such as a grid-tied inverter or a battery bank.

Pros of Series Connection

There are several advantages of series connection in solar panels, especially for residential and commercial installations.

1. Higher Voltage Output

Whenever the solar panels are connected end-to-end in a series configuration, the voltage of each panel gets added up. And, this results in a higher total voltage output, which could be very advantageous for systems that demand higher voltage for operating efficiently. Also, it meets the specific voltage requirements of inverters or charge controllers.

2. Less and Simple Wiring

Compared to parallel connections, series configurations use very little wiring, which simplifies the installation process. Moreover, with fewer connections to manage, it reduces the cost of materials and the risk of wiring errors.

3. Better Low-light Performance

In a series configuration, the entire string keeps functioning and producing energy even if any panel is damaged or does not function well. This is because the series connection is adaptable to partial shading, where only the shaded panels do not function while other panels do.

4. Greater Efficiency with MPPT Charge Controllers

Series configurations are generally well-compatible with MPPT (Maximum Power Point Tracking) charge controllers, which optimize energy output and make the system highly efficient.

5. Easy integration with Inverters

Most of the solar inverters are designed in such a way that they work flawlessly with increased voltage inputs by connecting panels in series. And, with this configuration, you will be able to match the voltage requirements of the inverter and enhance the overall efficiency of the solar power system.

Cons of Series Connection

Connecting solar panels in a series-type configuration can be an excellent way of increasing voltage output, but it also comes with many potential issues and risks.

1. Shading or Shadowing Effects

In a series configuration, even if one of the panels is underperforming due to shading, it tends to reduce the overall output of the entire string of panels. The current flows in a series pattern and through the weakest panel, which restricts the current and reflects an efficiency drop.

2. Risks associated with Higher Voltage

Generally, the series connection increases the voltage of the system and this demands to have inverters and charge controllers that are capable of tolerating such large amounts of voltage. Firstly, these components would be expensive and difficult to install. And, then comes risk related to safety as these higher voltages could be dangerous to handle, so strong safety measures must be followed during installation.

3. Limited Flexibility

Compared to the Parallel connections, the series configuration is less flexible, so once the installation is complete, it becomes difficult to modify the system. If you are willing to add or remove panels, it will be tougher to do so without affecting the entire system.

4. Troubleshooting Complexities

In a series configuration, it is very difficult to identify the problem because all panels are connected in a string pattern. If any one of the panels is underperforming, the entire string of panels has to be tested one by one to find the faulty one.

5. Damages due to Overvoltage

There is a possibility that your solar panels can get damaged in a series of connections. It can be due to a lighting storm or unexpected power surge that causes overvoltage and damages the panel or associated equipment.

Parallel Connections in Solar Panels

Linking multiple solar panels together in a side-by-side pattern is known as a parallel connection, in which all panels’ positive terminals are connected to the negative terminal.

Solar panels are connected in a parallel pattern, and this configuration increases the current (in amps) while constantly maintaining the same voltage level (in volts). Especially, it is suitable for applications that require system expansion.

For example: If you install six 100-watt solar panels, each rated at 12V and 5A, the total current will be 30A (5A+5A+5A+5A+5A+5A), but the voltage will remain the same at 12V.

The parallel setup operates using a heavier wire to handle a larger current of 30 amps (based on the above example) which is advantageous for off-grid system owners to fulfill their battery power requirements.

Pros of Parallel Connection

Here are the main advantages of parallel connection in solar panels you need to know:

1. Easier Expansion

Compared to the series configuration, you can easily include extra panels to expand the system in a parallel setup.

2. Higher Current Output

The overall current can be calculated from the sum of currents from each panel connected parallelly, which is beneficial for systems with higher power output.

3. Cost Efficient Controllers

The parallel connections use PWM (Pulse Width Modulation) charge controllers that come with an affordable price than MPPT controllers.

4. Minimized Shading Effect

One of the major benefits of using the parallel connection is that the current production on other panels isn’t affected, even if one panel is prone to shading due to the independent operation of the solar panels. This ensures a consistent power output.

5. Increased Safety

Lower voltage levels in parallel connections increase the safety levels during the maintenance process, which minimizes the risk of severe electrical shocks.

Cons of Parallel Connection

Connecting solar panels in parallel type configuration can be the best way to increase current output, but there are certain disadvantages you should consider:

1. Complicated Wirings

The installation process becomes costlier and increasingly complicated as parallel connections require more wiring and expensive cables.

2. Heavier cables

As the current levels are higher (in terms of amps) in parallel connection, you might require heavier cables that are costlier. Most often, the higher amps in parallel wirings require heavier and highly expensive cables.

3. Less Distance

Due to less voltage in parallel connections, there could be a voltage drop if longer cables are used, and limiting the distance between panels and inverter is the only solution for effective performance.

4. Extra Components Requirements

If solar panels are wired parallelly, then you might require extra components such as branch connectors and fuses, which can increase your overall budget.

Choosing Between Series and Parallel Connection

While selecting between series and parallel connections, you need to consider these important factors:

1. Voltage and Current Requirements

Series connection is suitable for applications that require high voltage by keeping the current constant. Contrarily, parallel wiring is applicable for devices requiring huge currents by adding current from each panel by keeping the voltage constant.

2. System Size

If you have large-sized systems, then the series connection is the best option rather than a parallel to reduce the complex wiring process and voltage drop.

3. Shading Issues

Parallel connections are recommended to overcome shading issues and reduce efficiency losses.

4. Complexity in Wiring

If you have a smaller system installed within a limited space, then parallel connections might be more useful.

5. Installation Cost

Compared to parallel connections, the series configurations with less complicated wiring require few labors for installation and cut down excess investment.

6. Connector Compatibility

Considering the stability of the connectors, series connections require connectors to handle higher voltages, whereas parallel connections need basic types of connectors. Most importantly, you should go with the connectors that safely handle the voltage or current requirements of your system setup.

Can you combine Series and Parallel Connections?

Yes, Combining solar panels with series and parallel connections is possible through a method called series-parallel configuration. Through this combination, both voltage and current are increased by ensuring all panels possess the same electrical characteristics to avoid errors and maximize performance.

Let’s consider a scenario where a combination of series and parallel connections is possible:

Imagine that you are willing to install a solar array, and it consists of multiple solar panels. This configuration is used to maximize energy production, and you can be 100% assured of reliability. In this setup, you can connect two groups of solar panels in series to increase the voltage output.

For example, each panel that you have produces 300 watts at 36 volts and if you are connecting three panels in series, you will be able to yield a total of 900 watts at 108 volts. So, you benefit from the higher voltage and can reduce current losses occurring due to long distances up to the inverter.

However, you will have to eliminate the shading impact and improve the overall performance of your solar system. And, this can be done when you connect multiple series strings in parallel.

For example, if you are having 2 strings consisting of 3 panels in each, and these are connected in series, then you can connect these 2 strings in parallel. By this configuration, you are allowing each string to function independently. So even if any one of those strings gets affected by partial shading, still the other panels will be able to produce output to the fullest. As a result, this configuration would ultimately improve the overall efficiency of the solar array.

NOTE: It is recommended to consult a professional who is an expert in designing the best series-parallel configuration for your solar system.

Conclusion

Both the series and parallel have their unique advantages and limitations in the solar energy system. A Series Connection is beneficial, especially when you require voltage output to be maximized. And, this can indeed be advantageous in a few situations that need higher voltage. However, the limitation of series configuration occurs when even one panel is shaded and leads to limiting the entire string’s performance.

Whereas, Parallel Connection delivers better and more consistent performance because here every single panel functions independently. Even if one panel is shaded or underperforming, the others would still be operational. However, one limitation faced is that this configuration will require very thick wiring to handle the increased current. And, considering the cost factor, these additional requirements could sum up to a significant part of the installation costs.