Parallel VS Series – Wiring 12V Solar Panels

In this informational guide, let’s cover the difference between Parallel VS Series for wiring 12V solar panels.

There is a lot of technical information regarding solar panels, sometimes it can be overwhelming if you don’t have experience in electrical engineering or anything electrical-related.

So does it matter?

Let’s learn about it here.

How Does It Affect Your Setup

Parallel Vs Series affect the type of inverter you can use and it impacts the overall solar system performance.

Parallel setup uses PWM charge controller (Pulse Width Modulation)

Series setup uses MPPTcharge controller (Maximum Power Point Tracking)

They also affect the cost.

In theory, Parallel wiring is better because it allows for continuous operation if one of the panels is not working. However, it doesn’t always meet certain voltage requirement in order for the inverter to operate.

Typically, a good solar panel setup has the balance between voltage and amperage to perform at its best. Therefore it will be a hybrid of both series and parallel connections.

Let’s go in depth below:

Wiring Solar Panels In Parallel

Connecting solar panels in parallel will increase the amps and keep the voltage the same. (Electrical Engineering 101 basic knowledge). This helps solar panels to produce more energy without exceeding the voltage limits of your inverter.

Each solar panel must have an identical voltage rating, and your solar charge controller must be able to accommodate total system amperage. This type of wiring is common for multiple 12V systems, which allows 12V charging capabilities.

Pros

  • Increase amps & same voltage
  • Like Christmas tree light configuration
  • Continue to work if one 12V solar panel in the middle fails
  • Better solar panel charge activity under partially shaded conditions

Cons:

  • Require thicker, shorter wires equipped to handle heavier amp loads
  • Costly for large coverage projects
  • Use multiple wires to connect to the grid

Wiring Solar Panels In Series

When connecting two or more solar panels in a series, the amp charge is stable, while your voltage multiplies just like battery terminals.

Connect positive terminal of one panel to the negative terminal of another in a series connection is exactly what we are talking about here.

For example: If you have two 12V solar panels each rated at 5 amps, you will retain the 5 amps but would get a 24-volt charge.  In other words, an MPPT solar charge controller is required and configured to “step down” voltage in cases where you are only charging a single 12-volt battery. 

Pros:

  • Less voltage drop during a cycle
  • Most efficient
  • Single wire to connect to the grid
  • Less concern over lost energy efficiency
  • Make inverter work properly by meeting requirement

Cons:

  • One breaks everything breaks
  • Shade sensitive

Common FAQ

Can You Have Both?

Wiring in series increases voltage and parallel increases amperage. Both systems need to be considered when designing a system for particular use. For the most part, solar installers will mix them together to peak the voltage performance without overworking the inverter

Does Microinverter / Optimizer Change How Solar Panels Are Wired?

The use of microinverter or optimizer can expand the inverter size limitation that string inverters have. When each panel is connected to its own microinverter, the system can expand one at a time.

Ying Xu

Graduated from the University of Kansas with an Aerospace Engineering degree & served 4 years as an US Air Force officer. Experienced with basic survival skills, weapon system security,  technical disaster recovery, and system troubleshooting

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