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post #1 of 27 Old 07-17-2013 Thread Starter
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Solar charge controller question

It seems my solar panels are not charging the batteries (again!) and I suspect I may have to replace my controller. The panels check out OK and the batteries are fine. I'm going to try a last attempt to troubleshoot it, but the controller is more than 20 years old and perhaps on its last legs...

I started shopping for controllers and I came across some reasonably-priced ones that are not marketed as "marine" solar controllers. It seems the big market here is telecommunications and signaling (think of those posts with a panel, battery and controller mounted on top). I have found a "smart" controller that is rated 10 amp and can handle up to 130w of solar panels. My electrical system is simple- two 65w panels on the hard dodger and one big house battery (160amp). I don't think I need a lot of bells and whistles; just something to regulate the charge going to the battery so I don't overcharge it. Would I be a fool going with one of these controllers? Bear in mind that these are usually mounted outdoors in plastic boxes, so I don't think they are especially delicate. Is there something special about the so-called "marine" ones? I'm in Brazil so don't tell me about all the great deals at West Marine! I have to either mail order one from the US or find something local.


Thanks in advance.

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post #3 of 27 Old 07-17-2013
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Re: Solar charge controller question

Well this was timely. I just replaced the controller in my solar panel setup, which is similar to yours. I had an old flexcharge controller and the system was never able to fully charge my batteries. While kicking around the web I came across one of Maine Sail's latest tutorial type posts on his website, relating to solar panel installations. It can be found here: Installing A Small Marine Solar System Photo Gallery by Compass Marine at pbase.com

I have a LinkLite monitor installed, so I can see relatively accurately what is going on with my batteries. Since installing the new controller (I went with a Genasun) it is like night and day. Before, my 300 amp bank was always at least 30 amps short of being fully charged. Last night, it was 0.5 amps short.

So I can't answer your question about whether the marine ones are different, but I can tell you that going with an MPPT type controller made a huge difference. The Genasun ones weren't that expensive either.

Maine Sail: Thanks again for sharing. The amount of excellent information you have made available has been just tremendous.
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post #4 of 27 Old 07-17-2013 Thread Starter
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Re: Solar charge controller question

Yes, Mainesail is a saint for sharing his knowledge. I often consult his web pages for information. Hopefully he'll chime in here to set me straight on this controller.

Thanks for the reply Plumbean. I don't think I can find a Genasun controller here in Brazil, but I'll have a look.

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post #5 of 27 Old 07-17-2013
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Re: Solar charge controller question

A true "marine" controller will differ only in that it will be protected further from moisture damage and salt air corrosion. That could mean a conformal coating (wax or plastic sprayed on everything) or different parts (no bare aluminum on junction blocks, etc.) or a variety of things. Sometimes it just means someone put an extra coat of paint on the case so it wouldn't rust as quickly. So the 'marine' label is hard to judge.

"I have found a "smart" controller that is rated 10 amp and can handle up to 130w of solar panels" Run away from that one. 10 amps at a nominal 12 volts is 120 watts, so a controller rated for 10A is already overloaded with a 130W panel. Since a 12v panel may put out 17-22 volts in full sunlight, you want a controller that is rated beyond that maximum watt rating of the panel. Depending on how conservative you are, you might want a rating 10-50% higher than the panels' maximum output.

If your panels are giving you more power than you need, a plain cheap controller may be fine. If you could use more power, do look at MPPT because they can give you 10-20% more effective charging power out of the same old panels, and that can be worth the extra cost. There have been some reports of no-name "MPPT" controllers being sold that actually are not MPPT at all, so the usual caveat emptor about real bargains applies.
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Re: Solar charge controller question

Thanks Hellosailor. Good advice. I got the rating for up to 130w panels from the specs provided by the manufacturer. I'll see about getting a 20amp controller. I'm a bit reluctant to spend too much on this controller as I intend to get a better one on my next trip to Canada. In the mean time, I have to find something available here or order from abroad, doubling the price when the taxes are applied in Brazil

The place my current controller is mounted is very secure and dry so I'm not too worried about corrosion.

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Re: Solar charge controller question

You might want to check eBay for Morningstar PWM and MPPT solar controllers.

The 15A PWM can be had for less than $100.

The 15A MPPT model is just over $200.

I have tested and installed the Sunsaver MPPT model, as well as larger Morningstar controllers, and like them very much.

They are very well made and supported by Morningstar in PA.

Bill

Last edited by btrayfors; 07-17-2013 at 07:06 PM.
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Re: Solar charge controller question

bill-
If Brazil is like some other countries (offhand, I think Equador) there may be a 100% import tariff on electronic goods, so a $100 controller becomes $200 and a $200 controller becomes $400, and that's before international shipping and a possible brokerage free get tacked on.
We have similarly insane trade policies here in the US. Mercedes was building the Sprinter vans overseas and then taking the tops off, to be re-assembled in the US because it was cheaper overall than paying the tariff on a completed vehicle. Toyota was installing air conditioning "at the port" in the US because it was cheaper than shipping in cars with AC factory-installed overseas. All kinds of lunacy from the consumer point of view.
Ignoring the questions of whether China and South Korea actually subsidize the export of electronics to the US below cost.
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Re: Solar charge controller question

Exactly, Hellosailor. I'm looking at an 80% import tax and other fees. It doubles the cost when I bring it in. For this reason I try to do my shopping abroad. I was hoping to find a cheap controller to tide me over until I get a good one in Canada.

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Re: Solar charge controller question

Quote:
Originally Posted by btrayfors View Post
You might want to check eBay for Morningstar PWM and MPPT solar controllers.

The 15A PWM can be had for less than $100.

The 15A MPPT model is just over $200.

I have tested and installed the Sunsaver MPPT model, as well as larger Morningstar controllers, and like them very much.

They are very well made and supported by Morningstar in PA.

Bill
Bill, I found these models in Brazil. Are any of them the models you refer to above? Thanks in advance.

http://minhacasasolar.lojavirtualfc....48,morningstar

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