Residential solar question

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bark

Member
Location
Washington
We are residing our house this spring/summer. A couple yers ago we had solar panels installed with a wall mounted inverter, conduits etc. In order to properly side the wall, I'll have to pull loose the conduits to slide the siding behind them and also remove the inverted to side behind it. I plan to disconnect the power feeding the inverter, then start the removal. But here's the question. When power is shut down for the converter, does that also shut down the solar panels? I was told that there are relays at the panels that open when the power is lost, thus no backfeed when the utility goes down. If so, how does the solar panels know the power is off. My worry is that there will still be DC voltage at the inverter with the relay at that point to open when the power is off. Of course I'll check the DC at the inverter before proceeding, but would like to know before hand. I've been in the trade for over 40 years but never have I had the opportunity to work on a solar project. I'm thinking a pretty simple disconnect, remove AC and DC conductors from the terminals, remove inverter then side the wall them replace the inverter and terminate the wires.

Thanks

Bark
 

romex jockey

Senior Member
Location
Vermont
Occupation
electrician
I think (?) you'd want to review your inverter for RSD (rapid shut down), and/or anti-islanding Bark.....~RJ~
 

victor.cherkashi

Senior Member
Location
NYC, NY
Solar panels have different equipment on them. Take a picture of label on the panel. Google it and see what specification says.

Sent from my ONEPLUS A6013 using Tapatalk
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
We are residing our house this spring/summer. A couple yers ago we had solar panels installed with a wall mounted inverter, conduits etc. In order to properly side the wall, I'll have to pull loose the conduits to slide the siding behind them and also remove the inverted to side behind it. I plan to disconnect the power feeding the inverter, then start the removal. But here's the question. When power is shut down for the converter, does that also shut down the solar panels? I was told that there are relays at the panels that open when the power is lost, thus no backfeed when the utility goes down. If so, how does the solar panels know the power is off. My worry is that there will still be DC voltage at the inverter with the relay at that point to open when the power is off. Of course I'll check the DC at the inverter before proceeding, but would like to know before hand. I've been in the trade for over 40 years but never have I had the opportunity to work on a solar project. I'm thinking a pretty simple disconnect, remove AC and DC conductors from the terminals, remove inverter then side the wall them replace the inverter and terminate the wires.

Thanks

Bark
Chances are your system was installed before rapid shutdown was being enforced, so when power is cut to the inverter the DC conductors to the inverter are still energized. If your inverter is a SolarEdge, the voltage will be only 1V per module in a string but with any other make of inverter the voltage could be as high as 600V with 10A or more available short circuit current per conductor pair. Is there a DC disconnect on the roof? If so, turn it off and you are good to go.

If you don't have a rooftop DC disco, what you should do is turn the inverter off and then at the array unplug the home run conductors for every string. That, or put tarps or blankets over the modules.
 
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