Author Topic: Question: Connecting solar panels, charge controller and batteries  (Read 4474 times)

david210166

  • Newbie
  • *
  • Posts: 2
I have 4 x 90W 5Amp Solar panels, 1 x TES 15Amp 12V controller, 2 x 12V 100AH batteries.

Can I connect the four solar panels in (series and parallel) to give me 24V 10Amp to my controller, and connect my 2 batteries in parallel to give me 12V 200AH?

Does it matter whether the input of the solar panels are 12V or 24V as long as they don't exceed 15Amp?

What does the 12V description of the charge controller mean? 12V panels or 12 V batteries?


kibi

  • Full Member
  • ***
  • Posts: 121
Re: Question: Connecting solar panels, charge controller and batteries
« Reply #1 on: April 21, 2013, 04:25:03 AM »
Howsit David, welcome to the forum.

The voltage of the charge controller usually refers to the battery voltage and the current is usually the charging current into the battery.
You'll be fine connecting your two batteries in parallel to give you a 12V system, but you will also have to connect all your PV panels in parallel for a nominal 12V array. This is because your charge controller is not an MPPT type, so your PV panel voltage needs to be as close to your battery voltage as possible. The next thing you will need to do is ensure that each of your PV panels has a 10A fuse in line with it before the junction where they all join together in parallel.
Ideally you should build a combiner box with the fuses in it. The fuses will prevent fires if one panel fails and the others try to back feed into it. Blocking diodes may not be installed in your panels, so it would also be a good idea to have one in series with each panel too.
I built a combiner box a few weeks ago, I'll update my thread with some pictures later on.

MPPT controllers are a lot more expensive, but they can support PV voltages many times higher than the battery voltage. I have one that supports 150V PV input and it will be charging a 12V battery bank.

david210166

  • Newbie
  • *
  • Posts: 2
Re: Question: Connecting solar panels, charge controller and batteries
« Reply #2 on: April 21, 2013, 03:34:11 PM »
Thanks for the response KIBI. Another question.

If I wanted to add on to my system one day, and I bought a Steca 20Amp 12V/24V PWM charge controller, would I be able to connect, lets say, 8 x 90W 5Amp panels in series and parallel to give me 24V 20Amp panel array and have a 12 Volt battery system? Or would I have to buy a 20Amp MPPT controller with max 50 Voc to do this?

Thanks for the tip about the 10Amp fuses!

kibi

  • Full Member
  • ***
  • Posts: 121
Re: Question: Connecting solar panels, charge controller and batteries
« Reply #3 on: April 22, 2013, 02:56:05 AM »
No, the Steca PWM controller will have the same issue.

Another important thing that I overlooked in my previous response was the power of the TES charge controller. It is 180W maximum, (12V x 15A).
This means that you will only be able to run two of your 90W panels in parallel into it. Four panels is 360W, so the TES would blow up on a lekker sunshiny day.
The Steca PR2020 is 240W on a 12V system (12V x 20A = 240W), so it would also die with a 360W PV array.
However, the Steca PR2020 would be able to transfer 480W on a 24V battery bank (24V x 20A = 480W) with your panels set up in a 2 parallel, 2 series configuration. This will obviously be a problem if you need a 12V battery bank. In this case a Steca PR3030 30A controller would just about do it for you (12V x 30A = 360W) and your panels set up with all four in parallel.

I have this problem too, my inverter is 12V, so I need a 12V battery bank. This limits the power of my Midnite Classic 150 charge controller to about 1KW, but if I had a 48V battery bank I could charge at nearly 5KW with the same charge controller if I had enough space to install a 5KW array.
It's all to do with the maximum current capability of your charge controller and the battery voltage up to the limit of the charge controller.
I hope this makes sense.