This is my first project ever, I'm running into some problems with the power supply stage, I hope you could help! I want to power a solenoid (12v/2A), which will get its voltage from a battery (12V/3000mAh) connected to a Solar Panel (12V/430mA – 5.2Watt). I would really appreciate it if you could show me a schematic design to this simple circuit. To sum my idea up [solar panel >> battery>> solenoid]. Thanks in advance!

components used: Solar panel: Mini Solar Panel 12V/430mA – 5.2Watt, Solenoid: JF-0826B Push Action Type Electric Linear Solenoid 12Vdc, Battery: Lithium-ion Super Rechargeable Battery Pack (12V, 3000mAh)

I would like to connect the solar panel directly to the battery: Can you please explain why it is a bad idea to connect the solar panel directly to the battery ?

  • \$\begingroup\$ You need a (solar) Li-ion charger configured for your battery pack (3S?) between your solar panel and the battery; just connecting the panel to the battery is asking for trouble. \$\endgroup\$
    – ocrdu
    Oct 8, 2020 at 12:44

1 Answer 1


A battery connected directly to the solar panel isn't a good idea because the battery could be overcharge (overvoltage) or the panel may not supply enough voltage or current to charge the battery. At minimum a regulator is needed (you could trickle charge the battery), but this will be inefficient. An MPPT tracker is needed to regulate the voltage at the maximum point of power from the solar cell. The battery needs a charger to charge the battery at the right voltage. A solar charge controller does both. Find a solar charge controller, connect it to the panel and your load (solenoid). You may also need a capacitor on the load, make sure the solar charge controller has the same voltage output that the solenoid requires and it can source enough current for the solenoid.

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Source: https://zhcsolar.com/solar-panel-charge-controller-wiring-diagram/


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