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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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