How to Wire Batteries in Parallel to a Solar Panel and UPS?

Electrical Technology

Parallel Connection of Batteries to the PV Panel

In our previous solar panel wiring installation tutorials, we showed how to wire solar panels and batteries in series, parallel and combination of series-parallel configuration according to our system needs and design. In today’s post, we will learn how to wire two or more batteries in series to the solar panel and other related appliances such as an inverter, charge controller and load points etc.

Suppose, we have a 12V system and we have to connect a 12V, 180W photovoltaic panel to the two 12V, 100Ah batteries. The only possible solution is that we will connect the two batteries in series and connect to the charge controller.

The storage energy in the batteries can be used later in night/shading to the direct DC load or AC load via UPS/Inverter. During the sunshine/day, The PV panel can be used to charge the batteries as well as power up both AC and DC load. The solar panel rating should be according to the load rating and proper design to prevent the overload condition as well as reduce the charging time of batteries.

To connect the two batteries in parallel, you will have to connect the negative terminal of the first battery to the negative terminal of the second battery and vice versa as shown in fig. In other words, same terminals of batteries should be connected for parallel connection

Note that the parallel connection of batteries will only increase the current capacity of batteries as voltage remains the same in parallel connection.

Batteries Current in Parallel

I₁ + I₂ …… + I_n

i.e.

100Ah + 100Ah = 200Ah

It shows that two 12V, 100Ah batteries connected in parallel will increase the Ampere-hour rating i.e. battery capacity while the voltage level is the same as for single battery i.e. 12V.

Batteries Voltage in Parallel

The voltage of batteries in parallel.

V₁ = V₂ …… = V_n

i.e.

12V = 12V = Total 12V

It shows that two 12V batteries connected in parallel will remain the same i.e. 12V.

The following solar panel and battery wiring diagram shows how to wire a 12 V Solar Panel to two 100Ah, 12V batteries in parallel with an automatic UPS system.

Good to know:

Current is additive in parallel connection of batteries.
Voltage is the same in parallel connection of batteries.
To connect batteries in series or parallel, the voltage rating must be the same.
A 12V battery can only be connected in series or parallel with another battery having the same level of voltage i.e. 12V.
Do not connect a 12V battery in series or parallel connection to a 6V, 9V or 24V battery.

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