Shut off for solar panels to batteries

[50ST8R]

I am getting ready to start laying out my solar and I have a quick question for the experts here. I have fuses both between the panels and MPPT (30amp) and MPPT and batteries (100amp). I had planned a shut off between MPPT and batteries but is it better to place that before the MPPT to isolate the panels?

[howson]

I am getting ready to start laying out my solar and I have a quick question for the experts here. I have fuses both between the panels and MPPT (30amp) and MPPT and batteries (100amp). I had planned a shut off between MPPT and batteries but is it better to place that before the MPPT to isolate the panels?

On my Victron it is mandatory to apply battery power to the controller BEFORE applying PV (power from the panels) to the controller. Having a shut off is the easiest way to ensure this is possible.

This AMSolar diagram reflects exactly how I have my system configured. Shutoff between the MPPT and panels, circuit breaker between the MPPT and batteries.

[50ST8R]

This AMSolar diagram reflects exactly how I have my system configured. Shutoff between the MPPT and panels, circuit breaker between the MPPT and batteries.

Howard, so instead of fusing between batteries and MPPT you used a circuit breaker. That would resolve the shut off issue between the batteries and controller. I think part of my confusion was seeing different diagrams between your 315 diagrams and the “all about RVs diagram that’s I have used a a template mostly for mine. Will try to draw it out on paper and place here to get feedback while I am still planning with 4 inches of snow on the roof now.

[mpking]

50ST8R, Usually people use resetable Circuit breakers. The larger one's usually have a "test" button (as depicted on howson 's diagram between the battery and the MPPT150|100. Many people use this as a disconnect switch as well. So between an actual switch for the Solar panel, and the Breaker for the battery, you should be good.

Nobody should be using Fuses for this.

howson , would it be bad to use a circuit breaker between the Solar Panel and the MPPT? I realize a switch is all that is necessary, but I have more Circuit breakers than switches on hand.

[50ST8R]

50ST8R, Usually people use resetable Circuit breakers. The larger one's usually have a "test" button (as depicted on howson 's diagram between the battery and the MPPT150|100. Many people use this as a disconnect switch as well. So between an actual switch for the Solar panel, and the Breaker for the battery, you should be good.

Nobody should be using Fuses for this.

howson , would it be bad to use a circuit breaker between the Solar Panel and the MPPT? I realize a switch is all that is necessary, but I have more Circuit breakers than switches on hand.

Howard, thanks, I have the same controller as you’re just less panels. Starting with 4 175 watt Renogy panels so 700 watts with room to add 2 more later. Will run 2 in series then parallel to the controller. Panels arrived this week so even though I would have to shovel the roof, I am looking to get my extra pieces in place so I can simply install the panels with the controller already complete.

[ncitro]

I have mine wired up the same as howson and it works great. Shut off for the panels and breaker for the batteries.

mpking It would probably work, but generally breakers make bad expensive switches. They are only rated to trip so many times. Eventually when used as an on off switch it will not turn back on. I work on medical x-ray equipment and a few of the units we service use breakers as the main on/off switch. They usually last a few years before failure. That said they are probably turned on and off daily. For your use you would probably never have an issue.

[howson]

Yoda -- tagging you as this is good info for you, too.

[TucsonJim]

Personally, I recommend a fuse/breaker and switch for both the panel to controller side and the controller to battery side.

Jim

[Yoda]

Yoda -- tagging you as this is good info for you, too.

There you go again -More $$$ And I just placed an order with Continuous Resources. My 190 watt panels will be at say 50V/10amp rounded up. And the SmartSolar 100/20 has a max output of 20 amps at 12V. So to install correctly I need a 25 amp circuit breaker and a switch for 50V/10 amp or go up one size? 50V/20A. Any recommendations?

Also Jim is indicating I need both (switch and circuit breaker) on both legs. I am not running that much power and the 10 awg PV cable is very capable of handling the short circuit amperage from the panels, so I am a bit confused as my current install has none of this?. I was going to run 4 gauge to my battery's from the MPPT



Thanks for tagging me
Keith

[howson]

There you go again -More $$$ And I just placed an order with Continuous Resources. My 190 watt panels will be at say 50V/10amp rounded up. And the SmartSolar 100/20 has a max output of 20 amps at 12V. So to install correctly I need a 25 amp circuit breaker and a switch for 50V/10 amp or go up one size? 50V/20A. Any recommendations?

Also Jim is indicating I need both (switch and circuit breaker) on both legs. I am not running that much power and the 10 awg PV cable is very capable of handling the short circuit amperage from the panels, so I am a bit confused as my current install has none of this?. I was going to run 4 gauge to my battery's from the MPPT



Thanks for tagging me
Keith

Keith,
An excellent resource is AMSolar's diagrams. Go to https://amsolar.com/rv-solar/support Scroll down the page and you'll see links to a Wiring Diagram Library and Kit Wiring Diagrams. There are many, many examples to peruse that show what AMSolar provides/recommends in a given circumstance. My assumption is you'll be able to find something similar to what you're putting together and substitute as appropriate.

Howard

Snip from AMSolar's website...

[Yoda]

howson
I found a diagram that was close for a 100/15 controller - they used a 20amp breaker. I could find nothing on the switch specifications - maybe I missed it.

TucsonJim ncitro mpking

50ST8R I'm trying not to hijack your thread, but I am embarking on a similar install (Sorry), so I will pose the question generally. Folks - How do you properly choose/size a switch (voltage/amp ) based on panel configuration and output? In my case its 50v/10amp (48.18V / 9.98A actual) going to the controller from the panels. Many of the Blues sea switches have only a 48V max rating.

Second, how do you properly size the circuit breaker for a Victron SmartSolar MPPT unit going to the battery or from the pannels. I noticed in Howard's set up per AMSolar's diagram its 20A over his controller max output. So for my 100/20 I would go with a 25 amp circuit breaker? I also want a breaker between my battery's and the trailer original 12V bus bar. Trailer is a 30 amp AC service - not sure of the 12V rating but I think it more like 50 - 55 amp, but not sure how to tell.

Today SWMBO put me on a strict budget (No MultiPlus) . I want to do this only once ( safely). BTW Continuous Resources has some good prices on the circuit breakers compared to others. https://www.continuousresources.com/...e+Sea+Systems+

Thanks
Keith

[50ST8R]

howson
I found a diagram that was close for a 100/15 controller - they used a 20amp breaker. I could find nothing on the switch specifications - maybe I missed it.

TucsonJim ncitro mpking

50ST8R I'm trying not to hijack your thread, but I am embarking on a similar install (Sorry), so I will pose the question generally. Folks - How do you properly choose/size a switch (voltage/amp ) based on panel configuration and output? In my case its 50v/10amp (48.18V / 9.98A actual) going to the controller from the panels. Many of the Blues sea switches have only a 48V max rating.

Second, how do you properly size the circuit breaker for a Victron SmartSolar MPPT unit going to the battery or from the pannels. I noticed in Howard's set up per AMSolar's diagram its 20A over his controller max output. So for my 100/20 I would go with a 25 amp circuit breaker? I also want a breaker between my battery's and the trailer original 12V bus bar. Trailer is a 30 amp AC service - not sure of the 12V rating but I think it more like 50 - 55 amp, but not sure how to tell.

Today SWMBO put me on a strict budget (No MultiPlus) . I want to do this only once ( safely). BTW Continuous Resources has some good prices on the circuit breakers compared to others. https://www.continuousresources.com/...e+Sea+Systems+

Thanks
Keith

Yoda,

not a problem. From past posts I think we both have very similar questions as we are planning our systems. I have found this grotto typically has answers I am more comfortable with than some of the other GD groups on Facebook and GD4life.

[ncitro]

Yoda

I only put two panels in series (in three sets), so I did not exceed 48V and used the Blue Sea switch. Personally I think it would probably be fine, but I would check with your dealer, or maybe Howard or Jim have a thought. I suppose you could always use a smaller rated switch and a contactor or relay but that seems excessive IMO.

I checked the site for the manual on your SmartSolar but all they had was the 100/30. That unit states the max draw is 35 amp, so I would wait until you get your unit and check the manual. You will go up to the next size available from there. If yours is a max draw of 25 amps (pure guess here), I would get a 30 or 40 amp, as long as your wire size covers it (I think you said 4AWG which should be good well above that).

Sad news on the MultiPlus. Thats what the next months credit card bill is for lol.

[50ST8R]

Personally, I recommend a fuse/breaker and switch for both the panel to controller side and the controller to battery side.

Jim

@Jim, I was kind of leaning that way just thinking of needing to isolate for any reason, you need to make sure neither source can get to the MPPT and I am always reluctant to use breakers as switches.

[John L]

From past posts I think we both have very similar questions as we are planning our systems. I have found this grotto typically has answers I am more comfortable with than some of the other GD groups on Facebook and GD4life.

Hi everyone I'm not asking many questions but I am taking a lots of notes. Thanks to everyone howson TucsonJim ncitro 50ST8R mpking Yoda for all the info in these various post. It is extremely helpful. I'll be placing my order next week for all my stuff and ready to start as soon as the snow melts.