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Wiring solar panels in series for a 24V system

Since off-grid solar panels are usually setup for 12 volt charging system, if you have a 24 volt battery system, you will need to wire two panels in series, or get a single high voltage solar panel, in order to generate enough voltage to charge a 24V battery. 

To wire two panels in series: 

  • Connect the positive terminal of one solar panel (let's call it Panel A) to the negative terminal of the other panel (let's call it Panel B). TIP: There is usually an embossed '+' and '-' symbol on the Junction box near these cables on the back of the solar panel.
  • Grab the remaining negative (from Panel A) and positive terminal (from Panel B), and connect to their corresponding terminals in the input of the solar regulator. 
  • Your solar regulator should detect the solar panels and in sunlight will begin to charge your battery

The alternative is to get a single solar panel with a high enough voltage to charge the higher 24V battery voltage by itself. Any Large Solar Panel has an open circuit voltage of >30 Voc which would achieve this, but in the winter it may struggle to reach a high enough voltage. Aim for >45 Voc, like our Perlight 200W Delta Monocrystalline Solar Panel that has an incredible 50.97 Voc !

You do of course have to make sure that your regulator is rated for 24 volts. Basic PWM regulators are generally only available in 12 volt versions, or they will have a low input voltage range which will not be suitable for larger solar panels. MPPT regulators can charge both 12 or 24V systems, such as the Victron Energy SmartSolar MPPT controller range, can be configured to run on either 12, 24 or 48 volt systems, and have automatic battery voltage recognition (12/24V).

two panels seriessolar wiring diagram - series
Two 12V solar panels wired in series to charge a 24V battery bank


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