I just bought a 200ah Latium 12v battery and 2 x 130w solar panels with a 12/24v charge controller. HOWEVER, now I see that the 2 panels are 36 volts. I am about 800 kilometers from where I bought the stuff so it is difficult to go back and exchange.
A company called Genasun makes boost charger controllers for golf carts that can charge a 36 volt battery from a panel with lower than 36 volt output. I have a similar need, charging a 36v golf cart out of solar power. I found in my garage 3 old panels that seem to be in good shape. My tester shows 12.3 Volts (open circuit).
Can You Charge A 12V Battery With 24V? A 12V battery can be charged with a 24V solar panel. For current to flow, there must be a difference between the source voltage, in this case, solar panels, and the destination voltage, in this case, batteries.
For a 24 volt system the panel at max power rating needs to be 32 to 36 volts. Roughly 16 to 18 volts for every 12 volts of battery. However that rule only applies if you are using a standard PWM or shunt regulator. Using that type of regulator you will loose 30% minimum of the power from the panels.
How does a 24 volt Solar System work?
A 24 volt solar system uses multiple solar panels wired in series to produce a higher DC voltage output around 24V. This 24V DC electricity is stored in batteries and converted by inverters to power 24V appliances and equipment. Installing a solar power system can be a confusing process, especially when dealing with higher 24V systems.
How do I set up a 24V Solar System?
Setting up a fully functioning 24V solar system requires these key components: 340-500W polycrystalline or monocrystalline panels in 24V or 48V nominal voltage ratings. Number of panels depends on your power needs. Wire in series to reach desired system voltage.
Moreover, you can power up the DC load directly connected to the DC output terminals in the solar charge controller. To wire two or more solar panels and batteries in series, simply connect the positive terminal of solar panel or battery to the negative terminal of solar panel or battery and vise versa (respectively) as shown in the fig below.