Questions About Solar Installation

John sent GreenJoyment an email and asked the question below.  If you can help John answer his question, please post a comment in the notes below.

Thank-you!

GreenJoyment

Name: john
Subject: 12volt batteries in a series.
Message: I’m planning on making some solar panels, with a charge controller and four 12 volt deep cycle batteries going to a 1000 watt grid tie inverter, plugged into a g.f.i outlet on a 900 sq ft mobile home. and i’m not sure on how to wire the batteries in a series or the best way for my needs? we don’t use alot of power, t.v, p.c. lights, coffee maker,frig. really need some better information thats easy to understand! thanks..

9 Comments

  1. Tommy

    Hi John,

    It depends on the output of the solar panels. If the output of the panel is 18 volts, that will charge the 12 volt battery with a charge controller. You want the solar panel to be 1.5 times the voltage of the battery. If your inverter is Allen rated for 12 volts, hook your batteries in parallel. This is accomplished with jumper cables from positive to positive and negative to negative. DO NOT HOOK POSITIVE TO NEGATIVE IN THIS CASE. You will see sparks in this case. With 12 volt batteries, you can have a 12, 24, 36, or 48 volt system if you have up to 4 batteries. You need to make everything match voltage-wise on your DC side or it will not work properly.

  2. Yves

    connecting batteries in series is really simple.
    +++batt1—+++batt2—+++batt3—+++batt4—
    So you will have 48 volts (in fact it will be a bit more than 50 volts DC) between + side of battery 1 and – side of battery 4.

    note: you have to check what is the minimum voltage require by your inverter to produce 110VAC

    • Going Green

      Yves, would you be able to draw a picture and email it to me so I can post it alongside this article (about how/why to connect batteries in series)?

      Please let me know at your convenience. Email Green [at] greenjoyment.com and ask Lindsey to forward your email to me. Thanks Yves!

  3. Gregory

    There are many options you can take in the design of your system John .
    But I would suggest if your not confident to handle the wiring yourself
    maybe get some help .It sounds to me like you could fit about 1kw of panels on your MH .Great now your charge controller must be able to handle this amount of power for prolonged time .And the best type by far is a MPPT(maximium power point tracking) type.These regulators can squeeze up to 20% more from your panels than a conventional float regulator .But you can’t decide your system voltage until you have found out some more info on your inverter.
    Higher voltage means less current to deal with , smaller wiring ,smaller switches and fuses. Also MPPT regulators are most efficient when run at a higher input voltage , so putting the panels in series /paralell and running them as a 48 v(actual OCV is about 84v) array is more likely.Then the MPPT outputs a regulated voltage to your battery bank . Which could be 12,24 or 48 volt. Depending on the needs of your inverter .But again it’s probably better to design your system with a higher voltage like 24 volts as there is a lot more off the shelf equipment like like large fuses and large DC isolators .Hope this helps

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