Where to connect solar controller output

[Wotname]

And to complicate matters further, my mate's 375W LG panel specificity warns against connecting or disconnecting the panel while under load. I haven't researched why yet. However this suggests to me that the panel be covered before connecting/disconnecting panel wiring or doing the work at night.

[goboatingnow]

Originally Posted by noelex 77

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.

Sorry how can disconnecting an mppt controller cause “ damage “ or high voltage

And Victron manual about “ sequence “ has nothing to say about disconnecting the battery side

I know some old pwm controllers tended to be powered by the battery and couldn’t handle an unloaded PV panel. But there’s no reason today this should be an issue

[thomm225]

Originally Posted by ikanode

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.

I doubt that as there will probably be no current flow through the controller.

I actually disconnect one of my controllers (PWM) from it's panel when not sailing and it just reads the battery voltage.........I still have my other controller connected.

Other times I disconnect the panels from both controllers. Sometimes I leave the panels connected and disconnect from the batteries at which time the controller voltage just bounces around wherever never staying on any certain voltage.

[flightlead404]

Originally Posted by Scubaseas

Make sure you have some airflow for cooling.....

its a good point. There are already some 2" vent holes at the bottom of the seat. I was planning on using a hole saw to cut a couple at the top and stick one or two cheapie muffin fans in there

[flightlead404]

Originally Posted by wingssail

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.

Essentially what I'm planning although your setup sounds more complicated and I have an ACR.

Your diag would be useful.

[flightlead404]

Originally Posted by wingssail

It is not a given that sooner or later the OP will "forget" and switch off the battery, thereby ruining the solar controller.

The OP is a reasonably intelligent person lol

Anyway, breaker/switch panel is behind a cover and I can make a placard that says "Solar Controller - Do Not Interrupt Before First Disconnecting Panels"

There will be a 30A ANL between panel and controller that is easy enough to disconnect if necessary.

[flightlead404]

Originally Posted by HankOnthewater

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?

This is my reasoning. The fuse (breaker in my plan) is there to prevent the wire from overheating and starting a fire in the case of something like chafe leading to a short to ground.

It is not there to protect the controller.

In the unlikely event I have an issue like that I'm willing to sacrifice a few hundred dollar controller to save a much more expensive boat (and potentially life).

[Wotname]

What make / model is your 60A MPPT solar charge regulator?

[wingssail]

Originally Posted by flightlead404

Essentially what I'm planning although your setup sounds more complicated and I have an ACR.

Your diag would be useful.

This is future (currently I do not have all the heavy duty fuses in place) and the windlass and bilge pump connections are not shown and some liberties taken with exact equipment items

Not shown:
The bilge pump is switched at the DC panel.
The windlass connects same as the engine starter
The solar panel is 280 watt
The AC side is not shown

[noelex 77]

Originally Posted by Wotname

And to complicate matters further, my mate's 375W LG panel specificity warns against connecting or disconnecting the panel while under load. I haven't researched why yet. However this suggests to me that the panel be covered before connecting/disconnecting panel wiring or doing the work at night.

This is good advice with high voltage panels. Modern panels are sometimes over 60v DC. DC systems do not cycle through a 0 voltage point like AC systems. This makes breaking the connection difficult. An arc will be formed as the contacts separate. This arc damages and pits the contact surfaces over time, leading to increased resistance.

High voltage DC switches and circuit breakers incorporate mechanisms to minimise these issues such as silver plated contacts and even magnets that will quell the arc.

On lower DC voltages such as 12v this not much of an issue, but at 60v+ pulling apart a MC4 connection risks some pitting of the contact surfaces. Over time this will gradually increase the resistance of the plug.

[Wotname]

Originally Posted by noelex 77

This is good advice with high voltage panels. Modern panels are sometimes over 60v DC. DC systems do not cycle through a 0 voltage point like AC systems. This makes breaking the connection difficult. An arc will be formed as the contacts separate. This arc damages and pits the contact surfaces over time, leading to increased resistance.

High voltage DC switches and circuit breakers incorporate mechanisms to minimise these issues such as silver plated contacts and even magnets that will quell the arc.

On lower DC voltages such as 12v this not much of an issue, but at 60v+ pulling apart a MC4 connection risks some pitting of the contact surfaces. Over time this will gradually increase the resistance of the plug.

If that is the only issue, I can live with it!

I was wondering if the problem was some voltage spike which may have caused damage to any diodes (or the PV cells themselves) but I couldn't see enough inductance (or current) in the circuit to create a significant spike.

[flightlead404]

Originally Posted by Wotname

What make / model is your 60A MPPT solar charge regulator?

Its the Epever AN series with a remote MT50 display

Originally Posted by Wotname

If that is the only issue, I can live with it!

I was wondering if the problem was some voltage spike which may have caused damage to any diodes (or the PV cells themselves) but I couldn't see enough inductance (or current) in the circuit to create a significant spike.

Which way around are the isolation diodes on the panel? Would they act as a quenching diode?

[thomm225]

Originally Posted by flightlead404

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?

You didn't mention the amount of watts worth of panels you have? To charge just two 12 volt batteries in parallel.

[flightlead404]

Originally Posted by thomm225

You didn't mention the amount of watts worth of panels you have? To charge just two 12 volt batteries in parallel.

3x210W, 420 ahr AGM, probably adding an additional 210 ahr.

[thomm225]

Originally Posted by flightlead404

3x210W, 420 ahr AGM, probably adding an additional 210 ahr.

420 ahr AGM. Nice. What brand are they?

I couldn’t find any normal size 12 volt batteries with over 200ah so bought 220 ah 6 volt golf cart batteries