Which side do I connect the charge controller

Dailypix

This is a newbie question. I am learning about solar on an off grid cabin in Northern Ontario. I have 12 deep cycle batteries and 12 100watt panels. I am using 3 MPPT charge controllers. I incorrectly just wired up all of the batteries in a line, positive to positive, negative to negative with the invertor on one end and the charge controllers on the other end. I gather that this causes an imbalanced load and will soon wear out the last battery that is connected to the load. Now I am wiring the batteries according to a guide so that the load is balanced.

My question is do I connect the charge controllers to where the load is drawn to the invertor or at the other end far away from the load? It might be obvious but I cannot seem to find clear instructions and I was worried that at full sunlight I might be overloading my invertor and the batteries could act as a buffer.

BB.

Stop!

What brand/model/AH/voltage rating of batteries do you have? Placing 10 batteries in series will generally not give you a "standard" voltage for most inverters--And if these are 12 volt storage batteries, that will give you 120 VDC nominal voltage--There are a few inverters that can use that voltage, but mostly UPS type computer backup power systems. And these become very difficult to charge (few, if any, solar charge controllers can charge a 120 VDC bank).

Tells us a bit more of your system components (batteries, charge controllers, inverter, etc.).

-Bill

Dailypix

Bill I hooked them up so that the end voltage is still 12 volts. It is a parallel set up not series.

vtmaps

Dailypix said:

My question is do I connect the charge controllers to where the load is drawn to the invertor or at the other end far away from the load? It might be obvious but I cannot seem to find clear instructions and I was worried that at full sunlight I might be overloading my invertor and the batteries could act as a buffer.

Having 12 batteries in parallel is going to be a disaster.  Parallel battery banks are unstable... when charging them the current will not divide up equally among them.

But to answer your question, you need bus bars.  One bus bar would be for the positive and one for negative.   The positive cable from each battery goes (via a fuse) to the positive bus bar.  The positives from the inverter and controller also connect to the positive bus bar (via fuses).  The negative bus bar receives the negative cable from each battery as well as the inverter and controller.

You will go to a lot of trouble and expense to hook up those batteries correctly and safely, but for what?  12 batteries in parallel is an unworkable scheme.  You will not get satisfactory results no matter what you do.

--vtMaps

inetdog

And just to complete the guidelines, bypassing the problem of massively parallel batteries:
Whether you use a bus bar or a wiring harness you should connect the CC and the inverter to the same points. (Making sure that you have a separate fuse for each.)

BB.

To understand how best to connect parallel batteries to equalize resistance (and current flow):

http://smartgauge.co.uk/smartgauge.html

However, as talked about above--12x 12 volt batteries in parallel is going to be a pain. You can get a DC current clamp type DMM so you can measure current flow during charging/discharging (find weak batteries, shorted cell, bad wiring connections).

-Bill

Dailypix

Thank you for the comments. If I understand correctly even if I create two separate 6 battery banks connected in series to give me a 24 volt system I am still running 2 sets of 6 batteries in parallel no?  Jut two banks of 6 rather than one long bank of 12. At what point does hooking everything up in parallel become a disaster? I believe that my inverter only goes up to 24 volts.

But my question of where I hook up the charge controller was answered. Thank you. I created a well insulated bus bar for the positive and negative sides and connected each of the batteries with the same length of #1 gauge wire. At around the middle I connected  very thick welder cable to the invertor with a good DC fuse close to the batteries. 

vtmaps

Dailypix said:

 if I create two separate 6 battery banks connected in series to give me a 24 volt system I am still running 2 sets of 6 batteries in parallel no?  Jut two banks of 6 rather than one long bank of 12. At what point does hooking everything up in parallel become a disaster? I believe that my inverter only goes up to 24 volts.

Most sources (textbooks, Home Power Magazine, etc) consider that a single string is optimal and 2 strings is acceptable.  Sources are split on whether 3 strings is acceptable.

Going to 24 volts will reduce the parallelness of your bank, but it is still too parallel.

In order to get to a 24 volt system, you are suggesting that you make a big 12 volt battery out of six little 12 volt batteries in parallel, and then take two of those big 12 volt batteries and put them in series to make a big 24 volt battery.  That will work, but you can do better.   It is better to put two of your little 12 volt batteries in series to make a little 24 volt battery.  Then take six of those little 24 volt batteries and put them in parallel to make a big 24 volt battery.

--vtMaps

Joebar17

Why does my battery drain when I attach it to my solar panel?

Aguarancher

Joebar17 said:

Why does my battery drain when I attach it to my solar panel?

It's hard to tell with the limited info you provided, but you might have a bad diode in your panel.

inetdog

Aguarancher said:

Joebar17 said:

Why does my battery drain when I attach it to my solar panel?

It's hard to tell with the limited info you provided, but you might have a bad diode in your panel.

These days solar panels do not have series (blocking) diodes. That function is assumed to be provided by the Charge Controller (CC) that is connected between the panel(s) and the battery.
The only panels I know of with a built-in blocking diode are the small portable "battery maintainer" panels that are designed to be connected without a CC.
You panel may have diodes inside its terminal box, but they are in parallel with sub-sections of the panel and are used to keep the panel safe when it is used where it will be partially shaded at some times during the day. They are called bypass diodes.

BB.

The amount of reverse current into a 12 volt panel from a 12 volt battery bank is usually so small of current, that nobody worries about it.

And pretty much all of the present solar charge controllers will prevent reverse current flow into the panels at night.

Only very small systems, or systems with a small solar panel/array use to "float" batteries during storage (without any charge controller) would reverse current flow possibly be a problem.

Of course, if you connect a solar panel "backwards" to the battery bank, you will have a dead short through the panel and probably the excessive current flow will ruin the solar panel.

-Bill

Aguarancher

With the limited amount of information provided, it's hard to tell what his set-up is.

Skippy

A picture is worth a thousand words...