The Rainbow Connection

The solar battery bank can be so confusing.

Five o’clock this afternoon, we get home in overcast weather and I, as usual, check the status of our new solar power system.

To my dismay, the voltage is only showing 11.9. Definitely not any sort of a charge. In fact, that’s about a 40 percent state of charge (SAC) of the batteries. Great big sigh. We thought we had everything up and running smoothly as of the other day; but not so fast.

Unless you have a professional or someone who’s experienced in solar technology do the job for you, be prepared for an onslaught of information in setting up your battery bank.

The battery bank or array is the place where all of that free energy will be stored until you use it. If it isn’t working properly, all of that sunshine is going somewhere besides your refrigerator. Setting it up and diagnosing problems can be overwhelming and confusing.

In my quest for guidance online, I’ve learned that the most talked about and hotly debated subject is the battery bank or array. I think it’s the Achilles Heel of most systems.

There is an overwhelming list of variables to consider and possible issues that may come up such as:

  • How to wire the batteries correctly
  • How many solar panels at how many watts are needed to recharge the bank in a day?
  • How many batteries will you need to meet your power needs?
  • How to calculate your power needs
  • How to equalize the batteries in your array or does your controller do that for you?
  • What type of battery is best and how much of it’s charge can you use to prevent rendering it useless?
  • How to tell if it’s useless (If even one battery is toast, you’ll have to go out and buy another four or eight, or however many all at once because they need to be put into commission at roughly the same time)
  • The energy losses inherent in the system also need to be factored in when either calculating your usage or production of electricity.
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Photo by John Daines on Unsplash

Try browsing any forum with a question and you’ll most likely discover that for every one asked you’ll find multiple answers from varying personality types such as:

  • The guy with the overly scientific approach who posts mathematical formulas broken down into several categories depending on the type battery, panel, geographical location and whether or not you like peanuts
  • The guy who just slams in a one-liner that “your batteries are dead, done, depleted, sulfated” (death sentence for a battery).

Which answer is right?

Since it appears we aren’t able to maintain a charge once we plug in, our next step is to check the batteries themselves to see if they are only carrying a surface charge. That is a temporary false state of charge that quickly diminishes after either a pull is introduced or it just sits for an hour at which point a second reading reveals a significant drop in voltage.

We’ve had batteries tested at various dealers while still carrying a surface charge and were told the battery was good. Then, upon asking for them to be retested later, they were found to be bad.

A properly working battery bank is crucial to a solar power system. They hold the juice until you need it but they can be complicated. Learn all you can about them and how to take care of them if you want to get the most efficient use of your solar setup.

Where does the rainbow connection come in? An old RV repairman recently barked at me after I asked how him how to do the wiring on a water pump. He snapped “red is red and black is black”. My ass it’s that simple. Electrical wiring might as well be rainbow colored.

 

 

 

Author: ldinlove

I am a 55 year old woman with one husband and one child living on raw land we bought in eastern Washington state. I am not normal. I am eccentric. Our whole family is, for that matter.

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