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Series, parallel, combo: How to connect solar panels together

Lots of solar power means multiple solar panels. How do you join them? In this article, we’ll talk about how to connect solar panels together, look at three wiring methods and explain which one is the best for you.

High voltage: Series connection

Series connection is the most popular configuration for home grid-tie systems. When you connect solar panels in series, their voltages add up. The current is as low as a single panel in an array provides.

Pros and cons: For large systems that are ov, say, 4 kilowatts, the series connection is the most natural choice. Series connection is also great when solar panels and the inverter are far away from each other. High voltage connection reduces power loss along the cables. 

The biggest enemy of solar panels connected in series is shading. The entire series string performs as well as its weakest link, therefore when one panel gets shaded, then the performance of others drops as well. 

How to connect multiple solar panels together in series: Connect the positive (+) cable of one panel to the negative (-) one of the next panel. The female MC4 connector marks a positive cable and the male MC4 is the negative. Continue so until all panels are connected. The positive cable of the first panel and the negative one of the last panel remain loose so you can connect them to the inverter or charge controller. Check out our article on series connection with step-by-step instructions.

Positive cable is usually red and the negative should be black. If your cables aren’t colored, mark them using duct tape

High current: Parallel connection

Parallel connection is common in small off-grid systems, such as RV and boat systems. With panels wired in parallel, their currents add up while the voltage in the system remains low.

Pros and cons: In this configuration, solar panels are independent of one another. When one panel is shaded or malfunctions, it doesn’t affect the performance of others. Since the voltage in a system is low, you can often add a cheap PWM controller instead of a more expensive MPPT one.

Wiring panels in parallel requires thick wires that can carry high currents. You’ll also need addons, such as branch connectors and combiner boxes. In a large system, using parallel configuration becomes costly and complicated.

How to connect solar panels together in parallel: Join the positive (+) cables of all the panels into a single one, then do the same with all the negative (-) cables. For this, you will need branch connectors or a combiner box. If the array needs fuses, add them in between the positive cables from panels and a branch connector. Branch connectors or cables from the combiner box usually go into a charge controller in an off-grid system. Check out our article on parallel connection with step-by-step instructions. 

Full control: Series-parallel connection

Series-parallel connection is common in small to medium-sized off-grid systems for RVs, boats or tiny houses where there are at least four panels. This configuration gives you more control over voltage in the system. For example, you can create two strings of panels with high voltage but then wire them in parallel to combine their amperage.

Pros and cons: Wiring panels in series parallel is adjusting volts and amperes in the system to your needs. For example, it can be good if you don’t want to exceed the maximum input voltage of a charge controller and at the same time don’t want to have too much current so that the system requires a thick wire.

The configuration is more complicated than a simple series or parallel connection. The number of panels in a system has to be even. The strings that you want to wire in parallel have to match. You’ll require addons such as branch connectors or a combiner box.

How to connect solar panels in series-parallel: Let’s say you wonder how to connect six solar panels together. There are two ways: you could create two strings with three panels in each or three strings with two panels in each.

First wire solar panels in series. Each string will have a loose positive cable and a loose negative cable. Then join the loose negative cables from strings together and positive ones with branch connectors or a combiner box. If the array needs fuses, add them in between the positive cables from strings and a branch connector. A combiner box usually has built-in fuses. Use a multimeter to check volts and amperes in the system.

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Andrey Gorichenski
Senior Editor

Andrey had been a news editor and freelance writer for a number of medias before joining A1SolarStore team. Climate change and its impact on people's lives has always been among his interests and it partially explains his degree in Philosophy and Ethics.

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