Off Grid Power: Charge Controllers

| 9/20/2013 9:08:00 AM

The Off-Grid Power: Charge Controllers

In the last two posts we looked at energy conservation and the importance of solar panels getting full sunlight. In this post we’ll look at charge controllers.

Charge Controllers: Their Function and Purpose

The only reason charge controllers exist is to make your batteries last longer and perform at their maximum capacity so we need to understand a few things about batteries before we go farther.

Batteries consist of a series of "plates" that change chemical composition during their charge/discharge cycles. When they discharge they do so more quickly on the outer surfaces. The charge in the inner part of the plate takes longer to leach out to the surface where it too, is siphoned off as electrical energy. That's why you can run the battery of your vehicle down trying to start it then let is sit for a few minutes; and when you try to start it again the battery will once more spin the starter (but not for long!).

When you recharge the battery(ies) the process is reversed. The outer parts of the plates charge first (called a "surface charge") then the inside of the plates slowly catch up. The better charge controllers are programmed to recharge your batteries in the most efficient way possible.

9/27/2013 11:11:36 PM

Dave: The panels have tempered glass and it is tough stuff. I've seen panels blown off the top of a motorhome and hit the ground hard yet they didn't have a scratch on them. Our array is on a rotating pedestal (we turn it manually during the day to keep it in direct sunlight) so if we're home we turn it 90 degrees away from oncoming storms. That's more to keep the wind from blowing it apart than to protect from hail damage. Of course there's no guarantee but they should take some pretty impressive hail without harm.

9/24/2013 8:38:33 PM

Steven, good to see you and your electrical knowledge back on GRIT blogging. Your understanding of the working of low voltage electrical systems boggles my mind. If I were ever to consider being off the grid, this information would be priceless in value. My only concern would be how do the panels hold up to hail. We have hail storms in my area at least once or twice a year. One of those storms totaled my mother in law's car this year. A broken panel doesn't put out much voltage. :0) Thanks for always breaking down the working of solar power so even a un informed lad like me can understand it. Have a great off the grid day.

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