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Old 09-12-2015, 16:55   #1
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Dumb solar install question

Hey folks just received my new Arch from Atlantic Tower and are about to order my solar components. Here is my super dumb question, we are going with a single 300 watt 24 volt panel a Midnite Marine MPPT controller to feed our 600ish amp/hr house bank, how do we actually connect the controller to the bank? Directly, at the switch, at the DC electrical panel. Searched but couldn't find the exact answer.

Thanks in advance

Will
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Old 09-12-2015, 17:04   #2
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Re: Dumb solar install question

If you disconnect the controller from the batteries wile the solar panels are connected you can burn out the controller. Mine has a 100a fuse (40a controller) between it and direct to batteries. I also want to install a circuit breaker close to it going to the solar panels. I highly recommend you talk to midnight marine
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Old 09-12-2015, 17:42   #3
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Re: Dumb solar install question

Quote:
Originally Posted by Clipper4730 View Post
how do we actually connect the controller to the bank? Directly, at the switch, at the DC electrical panel.
Your question is a bit confusing. Do you mean where do you locate the controller box?
I put mine where I can easily see its display. That's in the galley.

The wires want to be as short as possible from your panels to your battery, but you don't have to go too stupid about it. The easy location is more important.

No it doesn't need to be wired through your big electrical panel.

Hope this helps. If it doesn't then please re-write your question
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Old 09-12-2015, 18:10   #4
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Re: Dumb solar install question

Installing A Small Marine Solar System Photo Gallery by Compass Marine How To at pbase.com
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Old 09-12-2015, 18:12   #5
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Re: Dumb solar install question

Since there will be higher current OUT of the controller keep it closer to the batteries. That will save on wire cost.

Fuse near the batteries to protect the wire run to the controller, in case of a short.

Wired correctly, the panels should not be able to overload the wires, since they are the power producer and can only create so much power.

My controller output is connected to a battery switch, wired to my bank with 2/0 gauge wires.

The controller is a 60 amp output and has, as recomended by the manufacture, a 80 amp breaker.
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Old 09-12-2015, 18:16   #6
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Re: Dumb solar install question

The only dumb question is the one you don't ask...

Putting a switch (or circuit breaker) between the panel(s) & the MPPT controller inputs will let you turn the panels off when you want to use your SSB. The MPPT uses a DC/DC converter that often creates RF noise. We connected our MPPT outputs directly to the shunts that measure current to/from our batteries, but putting a fuse in there also has value. But you want the voltage sense leads to go directly from the batteries (or shunts) to the MPPT, to minimize connection losses. Also, a good MPPT will use your shunt to decide when it's supposed to switch to Float mode, which is very useful. The MPPT will have it's own shunts to measure current through the MPPT, but for correct Float mode transition it wants to know current in/out of the batteries, so it can go into Float even when your fridge or other DC loads are active. We opted for an external display, so we could mount our MPPT close to the batteries & still see what's going on. We have a page on installing solar panels that might help with other questions. Good Luck!
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Old 09-12-2015, 19:41   #7
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Re: Dumb solar install question

There is some good info in this forum about solar. If you don't have interference (EMI) with electronics you don't need a circuit breaker between the panel and the controller because they are current limited, but as been stated DON'T EVER CONNECT A CONTROLLER TO A SOLAR PANEL WITHOUT A BATTERY CONNECTED. So it's a nice feature to have. The controller to batteries needs a fuse on the positive side and most go straight to the battery bank. The negative lead from the controller should go to the negative bus shunt so your boat's amp meter will work. It's pretty easy stuff in its basic setup, but you can get pretty fancy.
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Old 10-12-2015, 21:39   #8
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Re: Dumb solar install question

Quote:
Originally Posted by puffcard View Post
There is some good info in this forum about solar. If you don't have interference (EMI) with electronics you don't need a circuit breaker between the panel and the controller because they are current limited, but as been stated DON'T EVER CONNECT A CONTROLLER TO A SOLAR PANEL WITHOUT A BATTERY CONNECTED. So it's a nice feature to have. The controller to batteries needs a fuse on the positive side and most go straight to the battery bank. The negative lead from the controller should go to the negative bus shunt so your boat's amp meter will work. It's pretty easy stuff in its basic setup, but you can get pretty fancy.
+1 here, but remember to disconnect the solar to the controller if you disconnect the battery for any reason...or put a breaker betwixt the solar and controller for ease of maintenance...ie...cleaning Battery terminals or replacing batteries and/or cables
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Old 10-12-2015, 22:52   #9
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Re: Dumb solar install question

Fuse the wire from the battery to controller, and size that wire correctly. I do not fuse the panel wiring. ('cause if the fuse is rated for something around Imp, and it shorts, all your gonna get is Imp anyway and the fuse won't blow)

I feed my solar into my panel through a breaker in the panel. Was the easiest way to do it. But I've only got 160W of solar on the boat. And my panel is 3 feet from my batteries.

I've got the 30A Midnight kid in my motorhome and it's a fantastic solar controller. The MPPT tracks great, the battery charge profile is perfect, etc.... Too bad I've got a crap PWM in the boat.

Interesting all the don't hook up panels without the battery comments. I'll bet dollars to doughnuts that a Midnight Solar controller won't blow up without a battery connected. After all, what happens if the fuse blows? My cheap PWM controller gets switched off all the time. It hasn't blown up either. If I designed a buck converter circuit that would fry itself in that situation (input but no load)... well... I don't know.. But I wouldn't be proud of it.
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