​Should I wire my panels in parallel or in series?

renogys blog Feb 1st 2017

By George Lone

To answer this question, I would start by asking what charge controller do you have or plan on using?

If you have a  PWM charge controller, and plan to charge a 12v battery bank, you must connect your panels in parallel.

Parallel Connection 2x RNG-100D (100 W Mono)

If you have an  MPPT charge controller, you have the option to wire your panels in series or parallel. To determine which set-up is better, we would answers to a few questions:

  • 1.What is the distance you will have between your solar panels and charge controller?
  • 2.Are your panels going to experience any type of constant shading throughout the day?
  • 3.What type of battery bank do you want to charge: 12V or 24V?

1. If your answer to this questions is longer than 20 -25 feet, we would recommend connecting your panels in series. When your panels are connected in series, the operational voltage of the panels is added together. If you are connecting two 100 Watt panels in series, and each panel has an output of 18.9 volts, you will end up with 200W (37.8 Volts and 5.29 amps under optimum conditions). The higher voltage helps with the voltage drop caused by the large distance and allows the amperage to reach the controller efficiently.

2. If you answered yes to this question, we would recommend connecting your solar panels in parallel. When your panels are connected in parallel, you add the amperage together, but the voltage stays the same. For example, if you have two RNG-100D 100 Watt panels, each panel will produce about 5.29 amps. Connecting these panels in parallel will produce 200 Watts (18.9V and 10.58 amps under optimum conditions).

3. If you answered this question “I would like to charge a 24-volt battery bank,” you would have to connect your panels in series to be able to achieve the necessary charging voltage to charge a 24 Volt battery bank.

Series Connection 2x RNG-100D (100 W Mono)

I hope that this information helps inform your wiring decision. If you need any additional information please contact our technical support department at 800-330-8678 or techsupport@renogy.com.

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