Replacing Generac ATS with Grid BOSS

[diso12]

Part of my solar install project would be replacing Generac Auto Transfer Switch with EG4 Grid BOSS. I have two romex wires coming into ATS labelles "AC" and "DC". I _think_ Generac wiring is described here, but not sure what wire does what exactly. Here's whet they look like inside ATS:




Generator is a whole-house propane 16kW Generac with remote auto-start.

Presuming a "typical" installation, what would I need to do to swap the ATS to GridBOSS, without loss of functionality? Specifically, I'm concerned with having generator battery charged, so that it can start when necessary. I understand Grid BOSS has a generator start/stop feature as shown here:

 

[DIYrich]

The wires in your pictures looks like the control wires for an HVAC system. Not the power lines. You need to play with the wires that go into the breaker on the right side of the picture.

 

[TechRider]

You'll want to look up your control board on your generator to make sure it supports 2 wire start. I was hoping, like you, that I could control it with the ATS wires but it doesn't work that way. For mine, I had to install 2 wires in the factory connectors at the generator then enter the programming mode and enable 2 wire start. After that, whenever the wires are touched together, the generator starts. I then have those wired to my Sol-Ark 15k so it controls my generator. (Similar to what the gridboss should do.) The kit to do it was around $30 I believe.

If you get rid of the controller, you'll need at least a 120v line out to the generator to run the charger, heater, etc. In your case, it's the blue/black wire combo on the right side of the board. T1/00 Neutral

 

[diso12]

@TechRider the blue-black wires are from the generac ATC, they are not generator wires. My generator control board has following schematics:

 

[diso12]

Linking thread at EG4 forums

 

[TechRider]

@diso12 That's not the control board unfortunately, it's the board where the display is. If it's supported, you have to remove a large molex style connector and insert 2 more pins and connect the 2-wire start wires there.

It's something like this depending on the model of generator you have: https://www.nationwidegenerators.co...QvMufgB0iOu_RdC3JafBwUDWT6ZAZgjFwjnsUjD4nPAbM

 

[Oldphile]

Generac 2 wire start instructions.

 

[diso12]

Remote start aside, as far as the N1, N2, and T1, can someone give me a sanity check?

Generac writes:

• "The N1 and N2 wires are responsible for sensing utility power dropout and pickup. These wires originate in the switch and must have 120VAC each (240VAC between them)."
• "The T1 wire powers the generator's battery charger and originates in the switch. It provides the 120VAC required to operate the internal battery charger."

Since GridBOSS will be triggering generator to run, the N1 and N2 should be always sensing power, otherwise generator would auto-start on grid power loss, and I don't want that to happen, since there's going to be battery backing up the system. So... do I just splice them directly into the "back-up loads"? This is what goes to the main panel. And then T1 should also be spliced into one of the phases, so that it charges the battery.

I'm wondering where does current return in that setting. T1 is charging battery, but what about neutral? There's no way it is using common ground for that purpose. Does it use the neutral connected to D?

 

[Oldphile]

Besides rewiring the Generac for 2 wire start, you must reprogram the controller. That will probably make N1 and N2 nonfunctional.

 

[diso12]

Besides rewiring the Generac for 2 wire start, you must reprogram the controller. That will probably make N1 and N2 nonfunctional.

I'm not sure what you meant to say, but when there is no power on utility sense wires, the generator always auto-starts, and the only way to prevent that from happening is to turn it in off position. Regardless of anything else as far as I can tell, generator does it by itself. Are you saying this feature can be turned off in generator settings?

 

[Oldphile]

I'm not sure what you meant to say, but when there is no power on utility sense wires, the generator always auto-starts, and the only way to prevent that from happening is to turn it in off position. Regardless of anything else as far as I can tell, generator does it by itself. Are you saying this feature can be turned off in generator settings?

You need to reprogram the Generac controller to change the start/stop function to respond to the 2 wire start and not care about power on N1/N2.

 

[diso12]

You need to reprogram the Generac controller to change the start/stop function to respond to the 2 wire start and not care about power on N1/N2.

I was looking to get rid of controller altogether... Do I need it anymore? I thought gridboss will replace its functionality

 

[Oldphile]

I was looking to get rid of controller altogether... Do I need it anymore? I thought gridboss will replace its functionality

I mean the generator controller, not The ATS.

 

[diso12]

I mean the generator controller, not The ATS.

Oh, nice, I didn't know it was possible! How does one go about it, is there a new firmware to download or something?

 

[TechRider]

The guide that was posted has the instructions on how to do it. That's where 2-wire start is needed. If you look closely at the gridboss diagram, it shows the 2-wire start lines. Otherwise, the power would have to go out for the generator to start and you wouldn't be able to use it as supplemental power.

I still have my ATS in place but my Sol-Ark controls my generator now. (Generator is grid-tied.) The ATS just gives me a nice little grid isolation when the generator is running.

 

[diso12]

Ah, this procedure both enables 2-wire start AND disables the utility sense!!!



Amazing, perfect, that's exactly what I am looking for. I would still need to connect the T1 wire though, right? To charge the battery

 

[TechRider]

That is correct. My guess is the neutral will probably have to stay as well.

 

[diso12]

That is correct. My guess is the neutral will probably have to stay as well.

Weirdly, my harness has no neutral:



There's neutral as in: generator neutral. My theory is that this is the 2nd wire for T1 supply, but I'm not sure.

 

[TechRider]

It has one big Neutral, it has to use that is my guess.

 

[diso12]

Do I understand correctly that the whole 0/194/23 set of contacts will not be used anymore once I switched generator into a 2-wire mode? Just disconnect it and terminate the wires?

 

[TechRider]

I'm not sure, I left my ats connected.

 

[Oldphile]

Do I understand correctly that the whole 0/194/23 set of contacts will not be used anymore once I switched generator into a 2-wire mode? Just disconnect it and terminate the wires?

Correct. 0 is battery -ve, 194 is battery +ve, 23 is a relay contact that closes to battery -ve to activate the ATS.

 

[diso12]

@diso12 That's not the control board unfortunately, it's the board where the display is. If it's supported, you have to remove a large molex style connector and insert 2 more pins and connect the 2-wire start wires there.

It's something like this depending on the model of generator you have: https://www.nationwidegenerators.co...QvMufgB0iOu_RdC3JafBwUDWT6ZAZgjFwjnsUjD4nPAbM

View attachment 262709

The manual provided by @Oldphile specifies different set of wires:



Both seem to be for evolution controller. Is that either/or, doesn't matter; or is there different wires for different evolution controllers and I do need to figure out which set of wires to use?

 

[TechRider]

The directions should indicate which sets of wires to use. I think when I looked at my plug, I thought it was one and it turned out to be the other. IE: J1-5 already had a wire in it but the corresponding point for the other version didn't. I connected them and tested it and it worked so I didn't worry about it too much.

 

[diso12]

Ok, in my case, as-documented in the PDF worked, e.g: J1-5, J2-11. The spaces were empty, I populated them and now when I short the wires, generator starts, and once I disconnect them, it stops.

I disconnected the ATS wires and will reuse them for gridboss connection.

I shall update the thread once I test the gridboss generator failover.