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cc5084 avatar image
cc5084 asked

Breakers/Disconnects for MPPT

mppt-disconnects.pngI was browsing the system diagrams for victron components and came across the Automotive Van drawing. In this diagram, they show two mppt solar controllers. I noticed that the controllers had some sort of breaker or disconnect connected to the PV side for both positive and ground (seen in the attached image circled in red). Can anyone inform me as to what exactly is being used there, and if possible a brand or part number?

MPPT SmartSolar
mppt-disconnects.png (66.3 KiB)
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cardy01 avatar image
cardy01 answered ·

https://community.victronenergy.com/questions/16654/fusecircuit-breaker-between-panel-and-controller-d.html

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outsourcedguru answered ·

Here is what I usually include for my solar designs:

  • One single-pole disconnect from the negative side of the batteries to the battery monitor shunt. Turning this OFF will remove the batteries from the system.
  • One single-pole disconnect on the positive side of the batteries to the inverter's input. Turning this OFF will remove the power to the inverter.
  • One single-pole disconnect on the positive side of the batteries to the charge controller's output. Turning this OFF will remove the charge controller's output to the batteries.
  • One double-pole disconnect on positive/negative lines from the solar panels to the charge controller's input. Turning this OFF will remove the solar panels from the system.

If you have other charging systems (alternator, generator, grid power) then add another single-pole disconnect for the alternator or another double-pole disconnect for the other two input types.

This probably seems like overkill but I assure you that the power involved in these types of systems is dangerous to life and limb.

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cc5084 avatar image cc5084 commented ·
@OutsourcedGuru Thank you for the feedback, do you have a brand or part number that I can take a look into for those single and double pole disconnects?
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outsourcedguru avatar image outsourcedguru cc5084 commented ·

You'll want to review the voltage/current in each of those areas of your installation. (One of my clients added four more 12VDC lithium batteries in parallel—adding at least another 400A of current—and managed to burn out his own inline disconnect since it was now underrated.)

  • Here is a good example of a single-pole, wall-mounted inline breaker & service disconnect that would work for my bullet points two and three above, noting that you'd want to add about 25% to the expected current rating to get the right model. Look for similar products within that brand to see the other current ratings available. Note also that this one is rated for 48V so this isn't necessarily what you need; it's just an example of the Bussman brand and format.
  • Here is a good example of a double-pole, wall-mounted inline service disconnect that would work for my fourth bullet point above. Again, they make several in this line, brand and format so you'd want to match it up with your specifications. You can always call the phone number of that website, ask to speak to a salesperson, read them the specifications for that portion of your installation and ask for the best service disconnect. Note that if you intend to add panels to your system, it's a good idea to forecast the upgraded voltage/current requirements on a piece like this.
  • Here is a good example of a single-pole, wall-mounted inline breaker & service disconnect that would work for my first bullet point above. I call this the "big red switch" and educate my clients as to its usefulness in safety.
  • I didn't mention it before but in some installations I also add inline fuses within the quick-disconnects of the solar panel arrays. Here is an example but again, there are different versions.


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