Auto Transfer Switch for Battery Back up

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The ATS in the oneline only has one source.
If that is represented correctly, then you should use a contactor with a voltage sensing relay to island the solar / battery source. Since this wouldn't be a NRTL listed system (the contactor / protective relay actuating the island mode), it would be interesting to see if an AHJ would bust your chops.
 
ron said:
The ATS in the oneline only has one source.
If that is represented correctly, then you should use a contactor with a voltage sensing relay to island the solar / battery source. Since this wouldn't be a NRTL listed system (the contactor / protective relay actuating the island mode), it would be interesting to see if an AHJ would bust your chops.
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Yeah, that’s my concern. Not only getting an engineer to sign off, but also getting passed by AHJ. We have a meeting with battery company tomorrow to discuss the ATS situation. I’ll update everyone when I have more info.
 
If the ATS only has one source, it will never transfer away to disconnect when that one source is absent. The 2nd source has to be considered "good" for the ATS to transfer, so the switch will stay connected to the Normal contacts, even if it is de-energized, making it not islanded.
 
SJKLLC877 said:
Im very skeptical as well, but I figure we could give it a try. It's one of the other owners house that we are planning to test it out on.
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instead of doing it to a house, why not set up a test j
SJKLLC877 said:
Yeah, that’s my concern. Not only getting an engineer to sign off, but also getting passed by AHJ. We have a meeting with battery company tomorrow to discuss the ATS situation. I’ll update everyone when I have more info.
Click to expand...


Does the battery company have a physical footprint? Their website (if I got the right one) shows only a phone number and even their domain has a private registration. Are the battery units listed? Does the company carry product liability insurance? Is this a china direct to consumer type operation?
 
ron said:
The ATS in the oneline only has one source.
If that is represented correctly, then you should use a contactor with a voltage sensing relay to island the solar / battery source. Since this wouldn't be a NRTL listed system (the contactor / protective relay actuating the island mode), it would be interesting to see if an AHJ would bust your chops.
Click to expand...

Yup. See 705.170 in the 2017 NEC or 705.70 in the 2020. (I believe the addition of 'evaluated in the latter would make it more stringent.)

If the ATS only has one source, it will never transfer away to disconnect when that one source is absent. The 2nd source has to be considered "good" for the ATS to transfer, so the switch will stay connected to the Normal contacts, even if it is de-energized, making it not islanded.
Click to expand...

Yup, again. And as I'm thinking about it, I don't think there is any multi-mode battery inverter that would provide a 'good' 2nd source if it didn't have it's own redundant (and more amperage limited) isolating switch inside. The solar would definitely turn off and not provide a 2nd source without the battery inverter.
 
This whole thread is proof of the advantage of buying an integrated system, instead of trying to patch battery A with inverter B and controller C and so forth. If you go Tesla Powerwall, it comes with its own gateway which is the transfer switch, the charge controller, the panel controller and the brains of the system. Our installer prescribed Enphase microinverters, one for each panel, so they tie nicely into the Enphase Envoy on our system. The Envoy allows you to inspect each panel's output and other parameters, continuously, or at any given time of the day. If you have a weak panel or inverter, you'll spot it right away. I think our installer was considering making the Envoy a standard part of a Tesla-PV system.
 
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