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EG4 GridBOSS Deep Dive

Thanks for the info! I guess it looks like I'll be running another conduit for the control cable :\. Not horrible just a PITA.

So I assume that if I need to run the Tigo TAP power back from the critical loads panel I can run those wires through the disconnect and meter without a problem.
 
OK, I'm pretty confused by this TIGO TAP speak. In my mind the CCA is next to your inverter, so it can react easily to a shutdown. And then you use CL2 wire to carry the power and signal to all TAPs in the system. This naturally would follow the DC path.

The AC disconnect and combiner speak is weird b/c that path has no natural correlation to the TIGO's business. And I would argue that it really stretches the idea of a functionally associated circuit since it's on the DC side, granted the DC side is non-isolated from the AC side and it's related to the inverter being connected to on the AC side so you could maybe rules lawyer your way in.

A picture would help.

Previously I assumed you were talking about CT comms cable (either digital or analog). That makes sense because it needs to go far from the inverter.
 
Sorry I was thinking I was going to have to power my Tigo off an AC circuit from my sub panel, after your comment I went back and looked at the Flexboss21 again and see that they provide a 1A DC connection that I can use to power the CCA.

Double checked the Tigo site and it seems that I can run 2 TAPs w/ a CCA getting 1A DC. (Label P - DC power for customer use, max. 1A)

Next up on the design is figuring out how / where to mount the CCA box w/ the inverter so I can have the TAP cable running up the w/ the DC wires.
 
I'm in the process of planning a grid-tied solar system with net metering and would appreciate some advice. Here’s my setup:

Service: 400A

Meter Location: About 200 ft from the house

Generator: 45kW Generac, located near the meter, with two ATS (automatic transfer switches) for two separate 200A lines feeding two 200A breaker panels in the house.

Planned Solar Array: Ground-mounted, 30kW, near the meter/generator.

I’m considering using EG4 Gridboss and EG4 Flexboss inverters for the system. For now, I’m not planning to include batteries, but I might add them in the future.

What would be the ideal way to configure this setup? I know I need multiple inverters but do I also need two GridBoss units as well? Where would they tie in with the Generac and do I get rid of two ATS?

Thanks!
 
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I'm in the process of planning a grid-tied solar system with net metering and would appreciate some advice. Here’s my setup:

Service: 400A

Meter Location: About 200 ft from the house

Generator: 45kW Generac, located near the meter, with two ATS (automatic transfer switches) for two separate 200A lines feeding two 200A breaker panels in the house.

Planned Solar Array: Ground-mounted, 30kW, near the meter/generator.

I’m considering using EG4 Gridboss and EG4 Flexboss inverters for the system. For now, I’m not planning to include batteries, but I might add them in the future.

What would be the ideal way to configure this setup? I know I need multiple inverters but do I also need two GridBoss units as well? Where would they tie in with the Generac and do I get rid of two ATS?

Thanks!
Figure out the total kW that you need from the inverters.
Gridboss is good if 200a passthrough is enough, but you need more inverter than 12kW.
two 18kpv's in parallel will give you 400a passthrough with 24kW of inverter.
If you need more than 24kW of inverter, then you need to decide if you want to parallel more 18kpv's, or parallel two Gridboss (to get 400a passthrough), and attach a bunch of Flexboss21's. Note: Don't know if you can parallel Gridboss.
 
Figure out the total kW that you need from the inverters.
Gridboss is good if 200a passthrough is enough, but you need more inverter than 12kW.
two 18kpv's in parallel will give you 400a passthrough with 24kW of inverter.
If you need more than 24kW of inverter, then you need to decide if you want to parallel more 18kpv's, or parallel two Gridboss (to get 400a passthrough), and attach a bunch of Flexboss21's. Note: Don't know if you can parallel Gridboss.
24kW of inverter (via two 18kpv's) is plenty for what I have in mind. But you're thinking of the standard generator setup where you tap in before the two ATS's, right? That would shut off my solar when the service goes down and generator fires up. I was hoping that with Gridboss I'd have the best of two worlds - ie. on grid setup, but still be able to use solar when the grid goes down (and if I run out of propane for the generator).
 
24kW of inverter (via two 18kpv's) is plenty for what I have in mind. But you're thinking of the standard generator setup where you tap in before the two ATS's, right? That would shut off my solar when the service goes down and generator fires up. I was hoping that with Gridboss I'd have the best of two worlds - ie. on grid setup, but still be able to use solar when the grid goes down (and if I run out of propane for the generator).
80% of 45kW is 36kW (max continous for generator). You can bring that in through the Gen Port of the 18kpv if they are in parallel. 24kW to charge batteries, and rest to load.
 
Buying UL9540 inverters is a really expensive way to get grid tie solar. I guess maybe there’s an argument as a hedge against tariffs
Agreed! However, I’m not sure if there’s a significantly more economical solution. I’m trying to maximize my municipality’s limit of 25kW AC output, which can be achieved with two 18kPV systems in parallel, as suggested above by @DIYrich. Are there other viable alternatives? For example, Growatt (which seems to be quite popular here) offers a 10kW grid-tie inverter, but I’d need three of them to meet my target output. While this option could save some (around $2,500 based on retail prices), I’m curious if anyone has insights or recommendations on better setups.

 
Maybe two growatts and some microinverters (like HoyMiles HMS2000). The microinverters will help you get on 25KW on the dot, since you can be so precise with sizing
Something like:
12.5*$500 =$6,250.00

Assuming the micros + their specific balance of system are $500 per 2kW
 
Agreed! However, I’m not sure if there’s a significantly more economical solution. I’m trying to maximize my municipality’s limit of 25kW AC output, which can be achieved with two 18kPV systems in parallel, as suggested above by @DIYrich. Are there other viable alternatives? For example, Growatt (which seems to be quite popular here) offers a 10kW grid-tie inverter, but I’d need three of them to meet my target output. While this option could save some (around $2,500 based on retail prices), I’m curious if anyone has insights or recommendations on better setups.


Which Growatt are we talking? The 48V All in one, or any of the straight grid tie inverters?
 
Thought to pass on what I have had confirmed regarding the GridBoss (prior to purchase) direct from Signature Solar and watching EG4 videos/live stream. To be clear I do not yet own this unit so cannot independently confirm but as EG4 and Signature Solar confirm, that's as good as I can get prior to purchase.

Service Entrance Disconnect (optional Eaton 200A breaker)
Standalone function of grid connection with no connection to functioning of Manual Bypass breaker.

Firmware Updates
You need to engage the manual bypass while doing GridBoss firmware updates, to keep the power on to the house (via the Backup Loads Panel). Once updated you switch back the manual bypass for normal operation.

Manual Bypass
Direct copper switch path to the Backup Loads Panel.

There are no relays or circuitry involved so if the GridBoss relays get stuck (open or closed) or a circuit board dies or the GridBoss firmware/software isn't working correctly, you still can power you house while seeking a solution/replacement unit, without needing a bypass switch installed upstream of the GridBoss to fully isolate the unit. In this wiring setup, to replace the GridBoss without an upstream bypass switch you would need to pull the meter.

I really wanted clarity before purchasing the GridBoss, to know if I had to do an upstream manual bypass if the GridBoss died on me to keep the power on to the house. If I can live without putting in this upstream bypass switch then I am happy to just pull the meter if the unit needs replacing and save on the wiring cost and complexity.

If this bypass functionality wasn't isolated from potential stuck relays, circuit board failure or the PCS (Power Control System) software then I would definitely put in an upstream bypass switch as backup to keep the lights on in case of unit failure.

Aly
 
There are no relays or circuitry involved so if the GridBoss relays get stuck (open or closed) or a circuit board dies or the GridBoss firmware/software isn't working correctly, you still can power you house while seeking a solution/replacement unit, without needing a bypass switch installed upstream of the GridBoss to fully isolate the unit. In this wiring setup, to replace the GridBoss without an upstream bypass switch you would need to pull the meter.

There has to be "relays or circuitry involved" for the Gridboss to island from the grid.

The questions is: Are there failure modes where:
1) the Gridboss fails disconnected from the grid, and you can't get it to reconnect to the grid
2) Gridboss is connected to the grid, but is messing up your power, and can't disconnect from the power path
 
There has to be "relays or circuitry involved" for the Gridboss to island from the grid.

The questions is: Are there failure modes where:
1) the Gridboss fails disconnected from the grid, and you can't get it to reconnect to the grid
2) Gridboss is connected to the grid, but is messing up your power, and can't disconnect from the power path
OK...I give up trying to find this answer, if EG4 and Signature Solar don't know then only someone with the unit can tell us for sure after testing.
 
EG4 James has been reiterating this in a few interviews lately. Here's one from two days ago, starts at 17:38:
"this bypass interlock ... is a direct copper bypass ... there is nothing electronic about it ... it will always work."

 
I don't remember where, but I have seen a diagram of the internals of the gridboss. And there are no electronics involved in the manual bypass function. It a physical switch (or breaker, maybe) that performs the operation.
The only downside is that it's also inside the gridboss. So you will be without power during a gridboss replacement.
 
I don't remember where, but I have seen a diagram of the internals of the gridboss. And there are no electronics involved in the manual bypass function. It a physical switch (or breaker, maybe) that performs the operation.
The only downside is that it's also inside the gridboss. So you will be without power during a gridboss replacement.
"Sumthin to be said" for a plain old manual bypass switch, or an ATS with a manual bypass. Anything can fail, but the reliability of a bypass switch is going to be seriously better than anything else.
 
Isn’t that physical bypass in the Gridboss basically making it an ATS with manual bypass?
Yes, albeit controlled with integrated electronics. Thus it's a device that contains an ATS such that should the electronics fail, you have to knock everything down somewhere to replace it. Not as complex as an AIO, might be OK. So if you can work on your Gridboss (replace a dead control board for example) and mechanically force / default it in bypass, it might be a win. I haven't looked at the manual, but I'm not sure it's worth having one more control system unless you are scaling way up. Interesting device.

I should have said mechanical bypass or ATS. 18Kpv has a relay as well, but if you need to replace the thing or work on it again you have no power while you do. OTOH, I can go out to my ATS, turn the key, and the handle and change the source of the power to my panel. Then I can fiddle around with my solar gear without constant disruptions. When I'm done, turn the key, and it clicks back over to solar. No software or firmware is involved, just some coils and relays.
 
I don't remember where, but I have seen a diagram of the internals of the gridboss. And there are no electronics involved in the manual bypass function. It a physical switch (or breaker, maybe) that performs the operation.
Its in the manual on page 40 which can be found here https://eg4electronics.com/wp-content/uploads/2024/07/EG4-Grid-BOSS-User-Manual.pdf, only downside I see is anything on the smart port won't get power which would normally be hot water heater or ev charger and maybe HVAC:

Gridboss bypass.png
 
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