When solar panels are connected in the system, the way they are connected plays an important role in the voltage or amperage sent from the panels for charging and energy purposes. The three main ways of connecting solar panels are series, parallel, and series-parallel.

Series Connection:

When connecting panels in series, connect the positive wire of one panel to the negative wire of the next panel, and so on. The voltage value of each panel is added together, the current value will not add up, no matter how many solar panels you connect in series, the current value remains the same.

Solar Panel Series Connection

Parallel Connection:

When connecting panels in parallel, connect the positive or negative wire of one panel to the positive or negative wire of the next panel, and so on. In a parallel connection, you connect wires with the same sign between panels. You may also need a branch connector to complete the parallel connection of the solar panel wires. When connecting panels in parallel, no matter how many panels are connected in parallel, the voltage value will not add up and remain unchanged, and the ampere value of each panel will be added together.

Solar Panel Parallel Connection

Series-parallel Connection:

When connecting panels in series-parallel, the panels are connected in series to form a panel string. After that, the panel strings connected in series are connected in parallel with each other. It causes the voltage of each battery panel to be added and the ampere value of the battery panel in the connected battery panel string remains unchanged, but after each battery string is connected in parallel, the ampere value of each battery panel string is also changed Add up. The number of times the ampere values from the strings are added depends on the number of panel strings connected in parallel.

For example:

12 pieces of 18V 100W solar panels charge a 24V battery, how to connect 12 pieces of solar panels in a series-parallel?

Please note that the battery voltage needs to be considered for the connection of the solar panel, and the input voltage of the solar panel should be about 1.2 times the battery voltage as much as possible.

Then we connect 12 solar panels in series and parallel according to the following 4 points.

(1) The voltage of this solar panel system needs to be higher than 24V, at least 24V x 1.2 = 28.8V

(2) After the two solar panels are connected in series, the output currents are equal. If the voltages are added together, the voltage after the series connection is 36V, which is sufficient.

(3) We connect every two solar panels in series, so 12 solar panels can form 6 parts in series.

(4) We connect these 6 series parts in parallel.

Solar Panel Series-parallel Connection
PWM Charge Controller:

For a system with a PWM charge controller, it is best to connect all panels in parallel. The PWM charge controller reduces the operating voltage of the solar panel to the required level to charge the battery pack and does not adjust the operating current of the solar panel. Therefore, when multiple panels are connected in series, the voltage value of each panel is added together, the ampere value does not add up and remains the same, which will lead to low efficiency because the PWM charge controller will reduce the voltage value of the entire solar panel system and The ampere value is still only equal to a battery panel. And please make sure that the voltage value of the entire solar panel system is higher than the battery pack voltage.

MPPT Charge Controller:

For systems using MPPT charge controllers, only when the voltage value of the solar panel system is higher than the battery pack voltage, the series, parallel, or series-parallel connection of solar panels is preferred.