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Old 16-05-2024, 04:39   #1
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Solar Disconnect & Alternator Interference

Calling all EE’s.
I plan to install 2 Renogy 250W bifacial panels on our davits. Intend to wire parallel into single Victron 100 / 50 controller. Each panel is 22.4V open circuit and 13.49A max current. We have five 225 Ah gel mat batteries in the stern cabin wired parallel. Four of the batteries are located together at the foot of master bunk and the last one is 6’ to stern and much closer to solar panels. I will wire with 10 gauge tin plated copper using mp4 connectors to controller even though charts say smaller gauge is ok for 20’ at my 27A total.

Is there any concern connecting solar to the
battery located to stern and away from the main bank? My thought is no problem.

I plan to install a Renogy 30A in line fuse on positive leg of cable running from panels to controller and another in line fuse rated at 40A on the positive leg after controller right before battery connection.

I have read some folks have issue with charging their battery bank with engine alternator if solar panels are connected and charging. Others say no problem.

Do I need disconnects or battery switch in the solar system? For this issue or for any other reason? Where?

Thanks for your input. I’m hoping to do this right the first time.
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Old 16-05-2024, 05:28   #2
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Re: Solar Disconnect & Alternator Interference

I'm not an "expert" on d.c electrical systems, but here's my 2 cents worth on some of your questions/plans:
1) You say all the 5 batteries are wired together in parallel and you plan to connect the panels to a single solar controller which will be directly connected to the aft battery. I don't see a problem there.

2) Victron says do NOT put any switches or fuses between the controller and the battery (you will find this warning in the manual). If you disconnect the controller from the battery for any reason while the panels are producing any output, you will damage the controller beyond any repair. If you need to disconnect the controller from the battery, you must disconnect it from the panels first. So your wiring from controller to battery needs to be done very carefully with no chance of it coming loose at either end or shorting out. If you feel you must put a fuse in that positive wire from controller to battery, remember that if it blows or fails while the panels are producing any output, you'll destroy the controller. I speak from experience. Of course, if you got a dead short in that wiring without a fuse and the wire melted, the controller would be toast anyway.

3) Yes, good idea to have a fuse in the pos line from controller to panels to protect that wiring.
4) Solar charging and alternator: Depending on the way your alternator is regulated and how it senses battery voltage, the solar input could affect the output of the alternator. (and vice versa). If you have an external regulator (say a Balmar 614) with a sense wire going directly to the battery bank and you have substantial input from the panels (say 20A), the regulator will sense the elevated voltage and cut back the charge current. That's not really an "issue" as I see it since the batteries don't really care where their charge current comes from.
What exactly were the "issues" you heard about? And exactly what were all the parameters of the affected systems?
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Old 16-05-2024, 07:01   #3
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Re: Solar Disconnect & Alternator Interference

Thanks for your experience and discussion of not cutting connection from controller to battery while panels supply any current to controller.

Sounds like any disconnect in the system must be between the panels and the controller. Disconnect there then do any work needed to controller or batteries. Sounds like the way to do initial install also.

The alternator discussion described high voltage low current coming from solar controller providing low charge but ‘turning off’ charging from alternator with external control. I have external Xantrex alternator control.

Any thoughts on this are would be appreciated.
Thanks.
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Old 16-05-2024, 07:11   #4
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Re: Solar Disconnect & Alternator Interference

Your parallel connections are arranged in about the worst set up you can make for the health of your batteries.

You might want to read this for details:

Battery connections
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Old 16-05-2024, 07:16   #5
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Re: Solar Disconnect & Alternator Interference

My 2c, put the panels in series, not parallel. Your panels have bypass diodes so shading is not a problem, in series, the panels will start producing sooner and produce longer.

Joe
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Old 16-05-2024, 10:38   #6
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Re: Solar Disconnect & Alternator Interference

SailingHarmony thanks for the connection on battery banks and connection strategy. I will be on the boat this weekend and will verify but I’m pretty sure the boat and batteries we bought is wired in the worst case for parallel. The single battery off by itself is its own worst enemy it would seem. Will check and get back with you.
Thanks
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Old 16-05-2024, 10:43   #7
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Re: Solar Disconnect & Alternator Interference

Joe,
I get what you are saying about series. I sized the Victron so it could go parallel or series thinking I would run my own test once operational. So many cruisers answer parallel works best but I also read the Victron White Paper. AND I am buying 16 buss bar panels with diodes. Either way I will run the big wire.
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Old 16-05-2024, 10:45   #8
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Re: Solar Disconnect & Alternator Interference

Any comment based on experience on installing breaker switches on panel cables before controller? Good idea? Waste? Thanks.
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Old 16-05-2024, 13:39   #9
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Lightbulb Re: Solar Disconnect & Alternator Interference

Quote:
Originally Posted by Gone Gypsy View Post
Any comment based on experience on installing breaker switches on panel cables before controller? Good idea? Waste? Thanks.
you don't need any fuse between solar panel and solar controller.
why because solar panel have max Amperage know and by calculation you pick cable . Again fuse in any circle protect only cable from fire .

now is good put between solar to solar controler breaker with overvoltage protection. this call somewhere combiner box but be careful 100-thousant fire start in combiner bo special if this outside.

best 2 poll MCCB and solar surge protection

but i usually use mcb + DC surge protection.

for example dis is low voltage
spd https://www.aliexpress.com/item/1005...Cquery_from%3A
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Old 16-05-2024, 14:07   #10
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Re: Solar Disconnect & Alternator Interference

Quote:
Originally Posted by Gone Gypsy View Post
Thanks for your experience and discussion of not cutting connection from controller to battery while panels supply any current to controller.

Sounds like any disconnect in the system must be between the panels and the controller. Disconnect there then do any work needed to controller or batteries. Sounds like the way to do initial install also.

The alternator discussion described high voltage low current coming from solar controller providing low charge but ‘turning off’ charging from alternator with external control. I have external Xantrex alternator control.

Any thoughts on this are would be appreciated.
Thanks.
I also believe that the solar interferes with the charging from by 120amp Balmar. My solar can be turned off via my Bluetooth Victron controller app which is what I do when running my engine and wanting max charge. I also have a Victron shorepower charger that recognizes the Victron solar controller and coordinates charging with it.
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Old 16-05-2024, 14:14   #11
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Re: Solar Disconnect & Alternator Interference

yesterday 24 transient yacht burn ,everything start from new splash boat.
100% you must look how you pull new cable from solar to battery.
if you can use 2 conduit 1 for + one for -nobody need for boat under 20 meter
1-2 AC plug,shut off inverter when leave boat or go sleep. not charge overnight eletronic. when you leave boat main switch off except frige and bilge pump


this guy and his property is in deep ****.insurance dont cover all this,maybe cleaning what is priority. couple boat is over 1 000 000€
cleaning this is lot money,lose of marina is huge.
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Old 17-05-2024, 07:16   #12
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Re: Solar Disconnect & Alternator Interference

@nuku34 #2:
Quote:
2) Victron says do NOT put any switches or fuses between the controller and the battery (you will find this warning in the manual). If you disconnect the controller from the battery for any reason while the panels are producing any output, you will damage the controller beyond any repair
I cannot find this limitation in the Victron documentation. Can you provide a citation?
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Old 18-05-2024, 08:52   #13
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Re: Solar Disconnect & Alternator Interference

Hey CharlieJ.
Nuku34said he had personally experienced controller failure by disconnecting between controller and battery when panels are connected to the controller and producing.
I have heard others talk of shorting the system during install if panels are generating current. I plan to put 30A breaker disconnects on each leg, positive and negative, between the panels and the controller. This allows me to isolate the panels for install and any downstream work later. Make sense. Cheap. It would be easy to short something out doing work without isolation.
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Old 18-05-2024, 09:15   #14
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Re: Solar Disconnect & Alternator Interference

@Gone_Gypsy #13:
I was only questioning his assertion that Victron prohibited an OCPD in the conductor between the PV panel(s) and the Victron solar controller. A quick look at the techdoc for a Victron MMPT controller shows a fuse in this service. Since my review was not exhaustive, I asked for the citation.

I absolutely agree that a means of isolating the PV panel(s) from the controller is a necessity. I generally use a DIN mounted circuit breaker in a separate box for this.
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Old 18-05-2024, 10:38   #15
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Re: Solar Disconnect & Alternator Interference

I always put fuses between the controller and the battery, and I have blown them more than once. I also put a circuit breaker between the panels and the controller, so I can easily cut off the panels so that I can test the battery system or disconnect the controller from the battery without damage.

I would rather replace a solar controller than replace the boat. I have damaged some small controllers that were connected to the battery by a cigarette lighter plug that got loose. These controllers showed signs of over heating with 100 watts of solar, so it is possible to cause a fire with 500 watts of solar. I would size your connection to the battery for 50 amps to be on the conservative side

As far as interference between the alternator controller and the solar controller, they are both designed to limit the total charging current based on battery voltage. The charge acceptance rate of your battery bank will determine how quickly it gets charged.
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