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

Electrical Technology

Series Connection of Batteries to the PV Panel

We know that solar panels and batteries can be wired either in series, parallel or combination of series-parallel connection depending on the system voltage, backup capacity, load rating etc.

Let’s suppose we have a 24V, 350W solar panel. We will have to connect them with two 12V batteries connected in series or a direct connection through the 24V charge controller to the single unit of 24V battery (rarely used).

To do this connection, We will have to connect both 12V, 100Ah batteries in series by connecting the Negative terminal of the 1st battery to the Positive Terminal of the second battery and vice versa. In short, the two batteries are connected in series by connecting their first pair of negative and positive terminals (the interconnecting wire is shown by blue color) and the rest terminals are connected to the charge controller.

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

The terminals connected to the battery have been also connected to the Automatic UPS/Inverter as input (120 or 230V AC). The inverter supplies the PV panel power (during day/sunshine) and battery backup power (during night/shading) to the connected AC loads. The DC load can be directly connected to the charge controller.

Keep in mind that:

Connecting batteries in series will only increase the level of voltage (current is same in series while voltage is additive).

Batteries Voltage in Series

V₁ + V₂ …… + V_n

i.e.

12V + 12V = 24V

It shows that two 12V batteries connected in series will add up the level of voltage to the 24V.

Batteries Current in Series

The amperage rating of batteries in series.

I₁ = I₂ …… = I_n

i.e.

100Ah = 100Ah = Total 100Ah

It shows that two 100Ah batteries connected in series will not increase the Ah rating i.e. battery capacity remains same.

The following solar panel and battery wiring diagram shows how to wire a 24 V Solar Panel to Two, 12V batteries in series with an Automatic UPS System.

Good to know:

Voltage is additive in series connection of batteries.
Current is the same in series connection of batteries.
Only same voltage rated batteries can be connected in series or parallel connection.
A 12V battery should only be connected in series or parallel with 12V battery.
A 12V battery should not be connected in series or parallel with a 9V, 6V or 24V battery.

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