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Flexboss/Gridboss versus 18kpv

tonyandjill

Newish member
Joined
Nov 13, 2023
Messages
115
Location
Cartersville, GA
Hey there!

I have already purchased the 18kpv for my system (not installed yet) but i'm considering exchanging it with the the Flexboss 21 and gridboss.

EG4 claims to be able to eliminate some of the typical components by adding the grid boss. I would need it anyway in order to get the 200A pass through.

Is there anyone familiar enough with these components or solar systems in general to explain to me exactly what I would be able to eliminate by switching to the FB/GB?

I have attached my single line drawing for my planned system but it comes directly from the 18kpv manual.

I appreciate the help!
 

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The appeal for me was the configurable smart ports, load shedding, and the ability to place the inverter and battery in another room with better heat. Also super easy to add second or third inverter. The Gridboss can replace the main disconnect and manual transfer switch among other things. These videos may help.


 
from what I recall (not my area of expertise) The 18kpv has the 200A bypass... the issue is that if something goes wrong with the 18kpv the question is amount of downtime while replacing it (all of these hybrid inverters are more likely to have a lifespan like a natural gas hot water heater than a main load center breaker). So, best practice is to have a transfer/bypass switch separate from hybrid inverter to enable bypass (regardless), enable easier system maintenance, etc. Such switches are NOT cheap. And then there are those (often in southeast with multiple AC units where a single 18kpv isn't enough output... the GridBOSS/FlexBOSS can be cheaper in some install circumstances, or at least more flexible). On the other hand, the GridBoss may be subject to similar lifespan, and if you plan to wire in a bypass switch regardless (not a bad idea)... then you really aren't eliminating anything

For a single hybrid inverter, the GridBOSS/FlexBOSS may (probably), or may not, be more expensive, depending on how you do your wiring. And even if more expensive, the added smart load mgmt features may may it worth it to you.
 
There's a recent discussion on here that perhaps the Gridboss doesn't provide a true 200A pass through the way the 18K does. Gridboss pass-through from the grid port to the backup load port may only be 90A. If you're intending to do a whole-house backup and place your entire main panel on the 18Kpv Load port, then the Gridboss isn't the same.

<EDIT>
This seems to be a very wrong conclusion. Please ignore the above statement.
 
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The appeal for me was the configurable smart ports, load shedding, and the ability to place the inverter and battery in another room with better heat. Also super easy to add second or third inverter. The Gridboss can replace the main disconnect and manual transfer switch among other things. These videos may help.


A perfect summary.
 
The appeal for me was the configurable smart ports, load shedding, and the ability to place the inverter and battery in another room with better heat. Also super easy to add second or third inverter. The Gridboss can replace the main disconnect and manual transfer switch among other things. These videos may help.


This is what I was hoping to hear. I plan to use at least one of the smart ports for an ev charger.
 
There's a recent discussion on here that perhaps the Gridboss doesn't provide a true 200A pass through the way the 18K does. Gridboss pass-through from the grid port to the backup load port may only be 90A. If you're intending to do a whole-house backup and place your entire main panel on the 18Kpv Load port, then the Gridboss isn't the same.
At the moment my plan is to do whole home backup. I’m not sure it would be possible, without rewiring half the house, to install a sub panel for the non back up loads.

Do you have a link to that thread?
 
from what I recall (not my area of expertise) The 18kpv has the 200A bypass... the issue is that if something goes wrong with the 18kpv the question is amount of downtime while replacing it (all of these hybrid inverters are more likely to have a lifespan like a natural gas hot water heater than a main load center breaker). So, best practice is to have a transfer/bypass switch separate from hybrid inverter to enable bypass (regardless), enable easier system maintenance, etc. Such switches are NOT cheap. And then there are those (often in southeast with multiple AC units where a single 18kpv isn't enough output... the GridBOSS/FlexBOSS can be cheaper in some install circumstances, or at least more flexible). On the other hand, the GridBoss may be subject to similar lifespan, and if you plan to wire in a bypass switch regardless (not a bad idea)... then you really aren't eliminating anything

For a single hybrid inverter, the GridBOSS/FlexBOSS may (probably), or may not, be more expensive, depending on how you do your wiring. And even if more expensive, the added smart load mgmt features may may it worth it to you.
Yeah the 18kpv would be plenty of power 95% of time I think. But with 2 EV’s and 4 hvac units, I like the idea of easy expansion and higher output, higher solar input with the boss combo.
 
At the moment my plan is to do whole home backup. I’m not sure it would be possible, without rewiring half the house, to install a sub panel for the non back up loads.

Do you have a link to that thread?
Here's the thread. I have an 18K. After studying the Gridboss manual, to me it looks like if all you want to do is pass through and backup your entire main, then the 18K would be a much simpler solution. I can't find anything in the Gridboss manual that confirms it can pass through 200A like the 18K does.

 
There's a recent discussion on here that perhaps the Gridboss doesn't provide a true 200A pass through the way the 18K does. Gridboss pass-through from the grid port to the backup load port may only be 90A. If you're intending to do a whole-house backup and place your entire main panel on the 18Kpv Load port, then the Gridboss isn't the same.
Where are you getting these numbers from? is it in the doc or through testing?
 
I suspect a misunderstanding. I looked at the wiring diagram and it passes 200A to backed up loads attached to the grid boss.

90A corresponds to attempting to use bypass through one of the attached hybrids, which is not explicitly called out as working on the grid boss wiring diagram. At best the bypass capacity is however big the biggest breaker GridBoss can hold.
 
It was probably a configuration issue, the Grisboss has a direct connection from it's grid to the non backup loads and a single 200A relay to the backup loads.
For some reason, it did not switch when the load was greater than what the inverters could handle.

The EG4
GridBOSS is a service entrance rated intelligent power distribution device that utilizes
software, relays, and programmable smart ports to direct power to where and when it’s needed. There
are four possible sources of AC input to support various system design needs: the grid, up to three
hybrid inverters, a generator, and AC coupling ports. The system can output power to the backup loads
port, smart ports, and the non-backup loads port. Common uses for smart ports include power
shedding for various loads such as electric vehicles, water heaters, and HVAC units. Smart ports are
also used for attaching AC coupled PV, which provides another source of power. The unit supports an
AC pass-through current of up to 200 amps,
providing end users with intelligent distribution solutions.
Common application scenarios are shown in the image below, with the configuration steps shown in
section 6.
 
I suspect a misunderstanding. I looked at the wiring diagram and it passes 200A to backed up loads attached to the grid boss.

90A corresponds to attempting to use bypass through one of the attached hybrids, which is not explicitly called out as working on the grid boss wiring diagram. At best the bypass capacity is however big the biggest breaker GridBoss can hold.
It appears I got this very wrong. I've gone back through that entire thread and studied the GB manual trying to recreate my thought sequence that lead me to this conclusion, and I honestly don't know why I felt the need to write that. On the GB wiring diagram there's clearly a path from the Grid port to the Backup port limited only by 200A breakers. I wasn't drunk, and the post was too late in the morning to have needed more coffee. I had a brain fart and shouldn't have written it down. I'd like to delete that post and go hide under a rock.
 
Pulled the trigger.

$5553.97 for flexboss and gridboss, shipped.

After the tax credit they will end up being $23 cheaper than the refurbished 18kpv, which does not qualify for the tax credit. I will also be returning the manual transfer switch and safety shut off. So that will be additional savings. Thanks guys.
 
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I’m reading the manual for the grid boss and it says not to use anything but copper wire when connecting to it. This is a bit of an issue since I was planning to leave the 40’ section of 2/0 aluminum from the main disconnect to the main breaker panel that runs up and over my garage ceiling. I was going to just move the wire from the disconnect to the load terminals on the grid boss.

What would be the best way to fix this without blowing the remaining budget on copper?

I was thinking I could just install another main disconnect breaker between the aluminum wire and the grid boss. On the other side of the disconnect I could have a short section of copper going into the grid boss.
 
I was thinking I could just install another main disconnect breaker between the aluminum wire and the grid boss. On the other side of the disconnect I could have a short section of copper going into the grid boss.
If your that paranoid or if the lugs are not rated, blah blah, any kind of a rated transition bus bar arrangement a few feet ffrom the unit should meet code and be sufficient.
 
Polaris connectors are rated for both Cu and Al, so you can use them to splice the dissimilar cables together as suggested above. I did that in my 18K install.
 
I’m reading the manual for the grid boss and it says not to use anything but copper wire when connecting to it. This is a bit of an issue since I was planning to leave the 40’ section of 2/0 aluminum from the main disconnect to the main breaker panel that runs up and over my garage ceiling. I was going to just move the wire from the disconnect to the load terminals on the grid boss.

What would be the best way to fix this without blowing the remaining budget on copper?

I was thinking I could just install another main disconnect breaker between the aluminum wire and the grid boss. On the other side of the disconnect I could have a short section of copper going into the grid boss.


Yep you can run the Aluminum URD into the wire boxes (outside of structure) and polaris connect to stranded Copper. The disconnect and transfer switch lugs are dual rated so as long as nolox etc. is used no problem. In the Interview with James of EG 4 he said they are in process of getting the approval for Aluminum terminations for GridBoss IIANM.

At least it is working well for my new set up.

Pretty amazed with the power transfer efficiency When the sun is out.

Ran #6 Aluminum urd over 370 feet and have seen as high as 16370 watts peak to the inverter from the 14.4 KW array at the 48th Parallel. Love the Bifacial panels and tilt array!
Impressed that the EG 4 hybrid made use of all of it simultaneously- 11.5KW to the batteries and the rest went to lower the Grid usage.

Only been running a little over a month now but looking Good.

Used 250 Kcmil URD between the outdoor boxes transfer and disconnect to 3/0 Copper and again polaris style connectors for the 18kPV. My main worry actually was putting to much pressure on the terminations in the cold with the non flexible wire.

ps. Please post up your experience with the Grid and Flexboss Combo.
 
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Not paranoid, the manual says using anything but copper could cause damage. Just following directions!
Hi tonyandjill,

If you want to bring in aluminium wire for the grid connection on the gridboss (and follow the manual), you can install the eaton 200A breaker. It is rated for both Cu and Al.

The Gridboss is supposed to pass 200A, like the 18kV. Currently it does not, but they are improving the firmware around the OCP logic. You can follow the progress on the thread about the 21kW pass through.
 
Hi tonyandjill,

If you want to bring in aluminium wire for the grid connection on the gridboss (and follow the manual), you can install the eaton 200A breaker. It is rated for both Cu and Al.

The Gridboss is supposed to pass 200A, like the 18kV. Currently it does not, but they are improving the firmware around the OCP logic. You can follow the progress on the thread about the 21kW pass through.
Since we’re on the subject, the main breaker for my house is only 150A. So I will have the main breaker after the meter and I also want another one in the grid boss. I don’t think it will be a problem but I want to ask, is it ok to install a 150A, not 200A in the grid boss pass through?

Also, I will need to have EG4 lock the grid export limit to 10kw. I know they could do this remotely with the 18kpv. Hopefully this is an option with the flex boss since the city requires it.
 

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