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Old 10-10-2021, 15:41   #1
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Where to connect solar controller output

About the only place I can mount this behemoth of a 60A MPPT controller on my dinky little boat is under the nav station seat.

But, happy day, its actually a jolly good location. That spot is the nexus of all things electrical on the boat.

So now I have some options.

I have separate disconnect for the house and start batteries with a parallel charge circuit. There's even a blank hole for a breaker.

I'm planning on coming off the Common side of the On/Off switch for the house battery, to a 70A breaker in the empty spot (currently labeled 'Winch'), and then over the controller for a total run of maybe 18" of 6AWG cable.

Does that sound like a good plan with this setup?
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Old 10-10-2021, 15:54   #2
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Re: Where to connect solar controller output

You can connect the output of the controller wherever it suits you. I just want to draw your attention that the controller will be damaged if the 12V battery connection is interrupted while the panels are still supplying their current to the controller. Always cut off panels to controller before breaking the controller to battery connection.
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Old 10-10-2021, 16:17   #3
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Re: Where to connect solar controller output

My understanding is that solar controllers should be connected direct to the batteries, within six inches and individually fused with the manufacturer recommended size fuse.
The only items that I have direct connected are the controller and the auto bilge pump. Has worked flawlessly for 9 years now.
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Old 10-10-2021, 17:19   #4
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Re: Where to connect solar controller output

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Originally Posted by sailormed View Post
I just want to draw your attention that the controller will be damaged if the 12V battery connection is interrupted while the panels are still supplying their current to the controller.
Thanks

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Originally Posted by Uncle Bob View Post
My understanding is that solar controllers should be connected direct to the batteries, within six inches and individually fused with the manufacturer recommended size fuse.
I have two, possibly soon to be three house batteries in parallel connected with 2/0 AWG cable. Electrically there s/b no difference connecting the negative of the output to the big ol' grounding buss bar where the 2/0 AWG battery negative connects, and somewhere on the panel electrically equivalent to where the 2/0 AWG battery positive connects than to the pos/neg of the battery than direct to battery posts.

Wiring into the panel gives me options in terms of whether I want to connect where the alternator output connects, for example, or whether I want the solar dedicated to house only, and whether I want the output to be switchable or not.

That's really what I'm asking for input on. In this setup is one option glaringly better than others? I'm ok at moving electrons around, but new to boat electrical systems.

The fuse in my case will be a breaker, with a 3" run to the post on the switch.
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Old 10-10-2021, 18:46   #5
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Re: Where to connect solar controller output

Hi..

I have a breaker from controller to the house batteries and I did not connect to the alternator. You want that connection as close to the batteries as possible.
I also put an on off switch between the panels and the controller so I can turn them off completely if I want to.
I never turn the house batteries off...I can't because my bilge pumps are connected through the panel, unlike most boats that bypasses the panel and switch and is connected directly to the batteries....that is the way Jeanneau does things.
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Old 10-10-2021, 20:45   #6
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Re: Where to connect solar controller output

Quote:
Originally Posted by flightlead404 View Post
Thanks



I have two, possibly soon to be three house batteries in parallel connected with 2/0 AWG cable. Electrically there s/b no difference connecting the negative of the output to the big ol' grounding buss bar where the 2/0 AWG battery negative connects, and somewhere on the panel electrically equivalent to where the 2/0 AWG battery positive connects than to the pos/neg of the battery than direct to battery posts.

Wiring into the panel gives me options in terms of whether I want to connect where the alternator output connects, for example, or whether I want the solar dedicated to house only, and whether I want the output to be switchable or not.

That's really what I'm asking for input on. In this setup is one option glaringly better than others? I'm ok at moving electrons around, but new to boat electrical systems.

The fuse in my case will be a breaker, with a 3" run to the post on the switch.

Just listen to Uncle Bob. You don't want to be switching them. You don't want them on an obvious breaker that someone will turn off. A fuse is fine and will last a long, long time, since there is no common overload scenario.

Keep it simple and interaction-free. You will reap more benefit that way. The only gadget that I see as useful is an output current meter, which may be in the MPPT.
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Old 11-10-2021, 13:48   #7
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Re: Where to connect solar controller output

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Originally Posted by flightlead404 View Post
Thanks

or whether I want the solar dedicated to house only, and whether I want the output to be switchable or not.
Reread SailerMed and Uncle Bob's posts!

The solar controller will likely become toast during the time the solar controller is receiving power from the panels but is not connected to either battery. Read its manual.

You need to disconnect the panels before, during, and until just after switching batteries. Unless this is automatically enforced, sooner or later you'll forget and ruin the solar controller.
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Old 11-10-2021, 14:29   #8
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Re: Where to connect solar controller output

Make sure you have some airflow for cooling.....
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Old 12-10-2021, 19:34   #9
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Re: Where to connect solar controller output

FWIW...We run 3 "house batteries(each=2 T-105s)", all connected together via a batt busbar. And our solar controller connects to that batt busbar, as does the windgen controller and the main eng alternator; our 3-legged batt charger is connected to each (house) batt directly. I wired a "Bilge Busbar", fed directly from the house battery busbar, and then feed each of my 2 staggered bilge pumps and a hi water alarm off the Bilge Busbar. By the way, we wired it so that each "house batt" has an on/off sw, and then the combined batt busbar has a on/off sw before the power goes to a "house fuse", and then the DC dist. system....that allows me to isolate any house batt from the system, or to cut off all DC-except the bilge bus- to the house should some type of electrical malfunction occur. I built and installed the system about 15 years ago, and it has worked perfectly ever since!
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Old 12-10-2021, 20:45   #10
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Re: Where to connect solar controller output

Quote:
Originally Posted by flightlead404 View Post
Thanks

I have two, possibly soon to be three house batteries in parallel connected with 2/0 AWG cable. Electrically there s/b no difference connecting the negative of the output to the big ol' grounding buss bar where the 2/0 AWG battery negative connects, and somewhere on the panel electrically equivalent to where the 2/0 AWG battery positive connects than to the pos/neg of the battery than direct to battery posts.

Wiring into the panel gives me options in terms of whether I want to connect where the alternator output connects, for example, or whether I want the solar dedicated to house only, and whether I want the output to be switchable or not.

That's really what I'm asking for input on. In this setup is one option glaringly better than others? I'm ok at moving electrons around, but new to boat electrical systems.

The fuse in my case will be a breaker, with a 3" run to the post on the switch.
You are going to get some opinions on this one, including, I guess, mine.

I feed the output of the Solar Controller through a breaker and then to the house side of the battery switch. Since I have two batteries I can direct the solar charging amps to either battery. There is a meter on this line (with internal shunt) to allow measurement of the solar output.

I also feed the Alternator output to that same house side of the battery switch. I can direct the alternator output to either battery or both. I have to be careful not to switch that battery to OFF while the alternator is running, this could be expected to blow the alternator diodes. The alternator output goes through a shunt to allow me to measure the alternator output.

I also feed the Battery Charger to the the house side of the Battery swich (though a breaker). The output of the battery charger can be directed to either battery or both. The battery charger has it's own control panel which also shows the battery voltage and amps going into the batteries.

There is a meter with an internal shunt between the battery switch and the house load panel to show the house draw.

Every load on the boat goes through the battery switch including engine start and windlass, but these two items do not go through the house amp meter in order to keep the meter scale large for easy observation of normally small amounts of current.

There are no cables, connections, or electric items on the battery terminals except the 1-0 cables to the battery switch.

Confusing? Sorry. If you want I can do a diagram.
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Old 12-10-2021, 21:01   #11
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Re: Where to connect solar controller output

Quote:
Originally Posted by ikanode View Post
Reread SailerMed and Uncle Bob's posts!

The solar controller will likely become toast during the time the solar controller is receiving power from the panels but is not connected to either battery. Read its manual.

You need to disconnect the panels before, during, and until just after switching batteries. Unless this is automatically enforced, sooner or later you'll forget and ruin the solar controller.
It is not a given that sooner or later the OP will "forget" and switch off the battery, thereby ruining the solar controller.

We have been wired that way for 35 years and we have never "forgot" and switched off the battery. By the way, the alternator is also wired this way (through the battery switch). If the house battery is selected the solar and alternator feed the house battery. If the start battery is selected the solar and alternator feed the start battery.The battery charger is also wired this way. The battery charger feeds which ever battery (or both) that is selected on the battery switch. It is all simple and clear. Everyone unfthe engine was running. But we don't, have never done, that.

Since ALL electric devices, including the bilge pumps, are wired to the house panel, the house battery, or the engine battery, or both, are always selected. always.

There is no isolator, no acs, no combiner, no DC-DC charger. Nothing. Simple, controllable, and direct. If we screw up, we screw up, but so far, we haven't.

BTW, there is a simple breaker on the solar panel output between the solar control and the battery switch. It allows you to cut off solar. Switching it to "off" does not blow the solar controller.
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Old 13-10-2021, 00:28   #12
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Re: Where to connect solar controller output

Certainly Victron mppt controllers have no stipulation that you canít disconnect them from the batteries with the PV array still connected.
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Old 13-10-2021, 00:30   #13
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Re: Where to connect solar controller output

My own wiring is simple , all charge sources go directly to the domestic bank , no splitters or combiners etc. A dc dc battery charger keeps the starter topped up. Very simple wiring , high efficiency
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Old 13-10-2021, 01:53   #14
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Re: Where to connect solar controller output

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Certainly Victron mppt controllers have no stipulation that you canít disconnect them from the batteries with the PV array still connected.
You can frequently get away with switching the battery connection off without damaging anything even with the solar panels charging, but it is not a good idea.

Also note that on some installations the solar output can keep the systems energised with the main battery switch off. Not only does this defeat the purpose of turning the battery switch off, but without a battery in the system the voltage will fluctuate dramatically and can easily reach voltages that will damage equipment. If your systemis wired like this you have to be particularly careful.

Victron does specify connecting the battery before the solar panels and warns.

"Connections must always be made in the sequence described in the Installation [9] chapter of this manual. "

Also note that there are some very unusual controllers that require the battery to be disconected before the solar panels, so check the manual.
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Old 13-10-2021, 02:33   #15
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Re: Where to connect solar controller output

I read the above posts, and there is some confusion it seems, at least in my mind.

A few people have said to disconnect the panels before disconnecting the controller form the battery(bank), otherwise controller will (or may?) be damaged. I get that and I have seen it some manuals.
At the same time some (?same people?) say to insert a fuse between controller and battery. I also understand that. But if that fuse blows and the panels are providing current to the controller, then the controller will be damaged?!
That is the confusing part, for me.
Or is it that if the fuse blows, something is already awry in a big way? And a damaged controller is the least of the worries?

Since I started playing with solar some 25 years ago, I have yet to damage a controller, and yes at times I disconnected the controller from the batteries, while the panels remain connected. Or is only certain type or brand that is susceptible to damage, when disconnected from the battery?
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