Series Connection of Solar Panels and Batteries with Automatic UPS System – 24V Installation
In this solar panel wiring installation tutorial, we will show how to wire two solar panels and batteries in series with automatic UPS/Inverter for 120V-230V AC load, battery charging and direct DC load from the charge controller.
PV panels and batteries are available in the range of 12-23-36V etc. The most common is the 12V system. Obviously, the series connection is less common for solar panel and batteries installation as the system will only increase the level of voltage (from 12VDC to 24VDC) which is only applicable in a 24V inverter system. In other words, additional load can’t be fed up by this system as well as the battery charging process will be slow as compared to the parallel connection. This is due to the same amperage capacity in series connection for both batteries and PV panels.
Most solar panels and batteries come in 2/24/36V etc. If you want to add extra capacity to the system, you will have to wire the system in parallel configuration. Suppose a single battery powers up a ceiling fan for 6 hours. The same fan can be powered up for 12 (almost double) hours by two batteries (having the same capacity) connected in parallel. In addition, The two parallel connected solar panels will charge the batteries quickly and power up extra load.
This setup is needed in case of a 24V inverter system. For this reason, we have to wire the PV panels and 12V batteries in series to obtain the desired voltage level. Keep in mind that you can wire multiple solar panels and batteries in series, parallel or series parallel for 12V, 24V, 36V or 48V DC systems.
We know that the current in series connection is same while the voltage level is different i.e voltage are additive in series connection. This way, the voltage level of both solar panels and batteries would add up. In other words, the 12VDC from solar panel and batteries (in series) would have:
V1 + V2 + V3 ……+ Vn
12V + 12V = 24V.
While the Ampere hour (Ah) of battery as well as current in solar panels remains same (series connection)
I1 = I2 = I3 ……In
5A = 5A = 5A … (Solar Panels)
100Ah = 100Ah = 100Ah … (Batteries)
Note: The amperes hour capacity (Ah) of batteries (as well as voltage level of solar panels) must be the same for all batteries while connecting them in series or parallel.
This way, we get the required 24V DC for our 24V DC inverter system. The inverter output (120 or 230VAC) is directly connected to the AC load (i.e. fans, light bulbs etc.). 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.
The following wiring diagram shows that the solar panel will charge the battery as well as power up the AC load through batteries and inverter. During shading/night (when there is no generating power from solar panels) the battery will be used as a backup power and it will power up the AC load via inverter. This whole process is automatically done through UPS i.e. no manual action or changeover/ATS switch is needed to switch ON/OFF multiple loads.
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