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How to Wire Solar Panel & Batteries in Parallel for 12V System

Parallel Connection of Solar Panels and Batteries with Automatic UPS System – 12V Installation

12V is the most common solar panel wiring connection with batteries. Generally, to achieve the 12VDC to 120/230VAC system, both PV panels and batteries are connected in parallel. To do so, let’s see how to wire two or more solar panels and batteries in parallel with solar charge controller and automatic Inverter/UPS for 120-230V AC load, battery charging and direct load i.e. DC operated appliance.

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 parallel wiring configuration is needed in case of 12V system i.e. 12V charge controller and inverter system. For this reason, two or more solar panels as well as batteries (each of 12VDC) are connected in parallel.

Note that we may also wire multiple solar panels and batteries in series, parallel or series parallel for 12V, 24V, 36V or 48V DC systems depending on our requirements.

We know that Voltage in parallel connection is the same while current is different. i.e. currents are additive in parallel connection. In other words, The voltage level of both solar panels and batteries remains the same while current capacity (Ah = Ampere-hour in case of battery) would add up (increases). In simple words, two parallel connected solar panels or batters each of 12VDC, 120W, 10A would have:

10A + 10A = 20A.

Same is the case for batteries, i.e. we can increase the ampere hour (Ah) capacity of batteries when connected in parallel.

100Ah + 100Ah = 200Ah

While the voltage level of battery as well as solar panel remains same (Parallel connection)

V1 = V2 = V3 ……Vn

i.e. 12V for both 12V solar panels and 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.

In this parallel configuration, the voltage level from both batteries and PV panels remains 12V while higher amperage capacity. We can connect the power generating (PV Panel) and energy storage as backup power (in batteries) with the 12V UPS/inverter and solar charge controller.

The DC to AC inverter is fed up by the direct solar panels (during normal sunshine / day) and batteries (in case of shading or night). The inverter inverts the 12VDC to 120VAC (US) or 230VAC (UK & EU) depending on our local AC voltage levels and power up the AC loads i.e. light bulbs and fan etc. In addition, DC operated devices can be directly connected to the charge controller (DC load terminals only).

To wire two or more solar panels and batteries in parallel, simply connect the positive terminal of solar panel or battery to the positive terminal of solar panel or battery and vise versa (respectively) as shown in the fig below.

The following wiring diagram shows that the two 12V, 10A, 120W solar panels connected in parallel will charge the two 12V, 100Ah parallel connected batteries as well as power up the AC load through batteries and inverter during the day in normal sunshine. During shading/night (when there is no generating power from solar panels) the battery stored energy 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. it is hassle free and no manual action or changeover/ATS switch is needed to switch ON/OFF the electrical appliances and breakers.

How to Wire Solar Panel & Batteries in Parallel for 12V System
Series Connection of Solar Panels and Batteries with Automatic UPS System – 12V Installation

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  1. Most Solar panels come in 12/24/36 etc volts.If you are using a 12V system and want to add extra capacity to your system you will wire your batteries in parallel. Sunnyvale solar panel.

    1. Why is charge controller being used with inverter during solar connection. But when connecting with main power supply only inverter is been used without charge controller.

  2. If you use 5 Amps x 24h in a 120Ah battery bank, you’re killing this bank. The max use of a battery bank, to increase its life, its 25%. So, that 120 / 4 (25%) = 30, and 30 / 5 Amps = 6 hours.

  3. According to your calculations on determining the panel size,are the 4hrs assumed or standard…& While you advise…a great day.

  4. Good Day,
    Kindly advise if you have in stock and available to supply the items below
    Sealed lead acid Battery or AGM battery12v /100AH to 200AH
    Or rather let us know if you have ultimate item that similar to our request
    Scott George
    Galp Ventures
    981 Auraria Pkwy #15
    Denver, CO 80204

  5. just wondering if I have two separate solar panel systems (folding type used for camping) and running my two batteries as a parallel system can i use both separate solar system to charge the batteries at the same time.

  6. Sir, I have a solar system installed with inverter 1000W, solar panels 600w, 12w solar inverter hybrid 12v, battery one12v 150ah, please advise /help may I add in parallel one more battery 12v 150 ah, to increase back up, NO harm to inverter and home appliances of 220 v, like mixer, fan, led bulbs, etc. please advise help thanks and regards.

    1. I would like to buy solar panel and battery for my laptop and one fan LED light how much that is cost is all the things

  7. I would like to run a garage fan 12/24 v or 240. Only to run when ther is enough light to generate power. No battery. Can it be done? And what would I need?

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