Technically, all you need to charge a 12v battery is a solar panel with a 12v rating. This can be any solar panel, although the bigger it’s, the quicker your battery will charge. Anything under 5–10 watts is not enough, as these will only “trickle charge” your battery very slowly.
If you purchase a 12v solar panel you should pair it with a 12v battery (a 12 volt lithium battery will work best with the 12 volt solar panels), a 12v inverter, and at least a 12v charge controller. A 24v solar panel should be used with a 24v battery bank, 24v inverter, and at least a 24v charge controller.
The same battery compatibility rules should apply to inverters and charge controllers with 12V and 24 V solar panels. So a 12V solar panel should operate with a 12V battery, a 12V inverter, and a 12V charger. Same for 24V solar panels. Here are some common questions about 12V and 24V solar panels.
In our example: 185Wh x 3 = 555Wh or 46Ah for a 12V system. Select appropriate solar panel wattage: As a rule of thumb, your solar panel wattage should be at least 1.3 times your daily energy usage. In our example: 185Wh x 1.3 = 240W of solar panels. As your energy needs grow, you can easily expand your 12V solar system.
Solar panels can generate up to 20v, much higher than the 12v required by a 12v battery. This can lead to overcharging, permanently damaging your battery. The best action is using a charge controller or regulator between the panel and battery, which regulates the charge current and keeps your battery healthy.
As you can see, utilizing 12 volt solar panels are a great way to become more energy independent, save money on utility costs, eliminate the need for gas-powered generators, and ensure reliable access to energy when you need it.