going_commando
Solar Enthusiast
Yup, breaker box= panelboard or load center. The Grid boss is neither of those things, it's a microgrid interconnection device.
FlexBoss21 / GridBoss Issue List
- Thread starter skimandan
- Start date
Yup, breaker box= panelboard or load center. The Grid boss is neither of those things, it's a microgrid interconnection device.
RCinFLA
Solar Wizard
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Good luck arguing that with an inspector.
going_commando
Solar Enthusiast
It wouldn't be hard, the definitions are right in the code book. I'll snap some pics from my 2023 NEC when I go to the shop this weekend for you.
jharrell
Solar Enthusiast
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Did they add language to 2023? Looks like it has come up before and there was talk on adding specific language:
skimandan
New guy
Here is my inverter outputting 12kW to Grid even though I have set the Force Discharge to 12kW and I have 5,723 kW of PV this morning. Force discharge appears to be limited to 7774 W to not exceed 12kW Export to grid. Always limited to 12kW for some reason.
I have no interest in force discharge of 12kW on the weekends so I ran it for 10 minutes:
Seriously, I am not interested in more gaslighting or unpaid beta testing for EG4. Please let me know if this can be fixed in software near term or do we need to talk about other solutions?
going_commando
Solar Enthusiast
I was just able to get my NFPA link account working, and got the free access version of the NEC, so let me directly copy the wording from 705.12(B), which is Load side source connections: Busbars (load side of service disconnect):
705.12(b): For power source connections to distribution equipment with no specific listing and instructions for combining multiple sources, one of the following methods shall be used to determine the required ampere rating of busbars.
1) The sum of 125 percent of the power source(s) output circuit current and the rating of the overcurrent device protecting the busbar shall not exceed the busbar ampere rating.
2) Where two sources, one a primary power source and the other another power source, are located at opposite ends of a busbar that contain loads, the sum of 125 percent of the power-source(s) output circuit current and the rating of the overcurrent device protecting the busbar shall not exceed 120 percent of the busbar ampere rating. The busbar shall be sized for the loads connected in accordance with Article 220. A permanent wiring label shall be applied to the distribution equipment adjacent to the back-fed breaker from the power source that displays the following or equivalent wording: (skipping this part)
It goes on and on and im sick of typing them out, but these are the pertinent parts. Note the red in the main part of the article that says "With no specific listing and instructions for combining multiple sources". The Gridboss is a microgrid interconnection device, and is listed and has instructions on how to combine multiple sources of power (PV, generator, grid, etc), therefore the options given in (1) through (6) do not apply, of which the 120% rule is one. It's not a load center or panelboard NOT listed for connection of multiple sources of electricity.
Hopefully this clears that up. You can make an account with the NFPA, and google how to get free access to code books, and then go to Chapter 7, and flip through pages until you get to the pertinent parts, or now you can buy a copy of the NEC online for around $50. My copy was $140 since I had to get it in 2023 so I could take my 15 hours of state mandated code update class.
705.12(b): For power source connections to distribution equipment with no specific listing and instructions for combining multiple sources, one of the following methods shall be used to determine the required ampere rating of busbars.
1) The sum of 125 percent of the power source(s) output circuit current and the rating of the overcurrent device protecting the busbar shall not exceed the busbar ampere rating.
2) Where two sources, one a primary power source and the other another power source, are located at opposite ends of a busbar that contain loads, the sum of 125 percent of the power-source(s) output circuit current and the rating of the overcurrent device protecting the busbar shall not exceed 120 percent of the busbar ampere rating. The busbar shall be sized for the loads connected in accordance with Article 220. A permanent wiring label shall be applied to the distribution equipment adjacent to the back-fed breaker from the power source that displays the following or equivalent wording: (skipping this part)
It goes on and on and im sick of typing them out, but these are the pertinent parts. Note the red in the main part of the article that says "With no specific listing and instructions for combining multiple sources". The Gridboss is a microgrid interconnection device, and is listed and has instructions on how to combine multiple sources of power (PV, generator, grid, etc), therefore the options given in (1) through (6) do not apply, of which the 120% rule is one. It's not a load center or panelboard NOT listed for connection of multiple sources of electricity.
Hopefully this clears that up. You can make an account with the NFPA, and google how to get free access to code books, and then go to Chapter 7, and flip through pages until you get to the pertinent parts, or now you can buy a copy of the NEC online for around $50. My copy was $140 since I had to get it in 2023 so I could take my 15 hours of state mandated code update class.
In reality, the 120% rule is actually not based in engineering. The rule was apparently just to put something in the code that sounded "about right".
There is no way to overload a bus bar if it is fed from both ends with breakers that are below bus bar rating.
Say we had a 200 amp main grid breaker, a 200 amp inverter back feed breaker, and a 200 amp load breaker. This is about as worst case as it gets., a "200% rule" if you like. Now tell me how you get more than 200 amps in the bus bar at ANY point given all three breakers are 200 amp.
You can't.
Even if you put a large number of 200 amp load breakers between the grid and inverter breakers, there is still no point on the bus bar over 200 amps. You could have 400 amps flowing into the panel, but that never occurs at any point on the bus bar.
The code isn't necessarily based on the actual engineering involved, sometimes it is just to make rules that sound "reasonable".
Mike C.
skimandan
New guy
@EG4TechSolutionsTeam
Hi, I decided to let it run today at 12kW Force Discharge until hitting my 30% SOC cutoff. It really is interesting to watch the loads and sources balance throughout the day. The only real constant is the 12kW Export to Grid limit.
From 11:00 to 12:00 it was only serving my 1kW local loads and Export to Grid which is set to 16kW but only achieves 12kW.
It will service 16kW AC if 4kW are local loads. My EV charger pulls 4kW so I let it run around 12:00.
I ran out of battery around 13:35.
May I run any more tests for you?
Are we still blaming clouds or my PV?
Hi, I decided to let it run today at 12kW Force Discharge until hitting my 30% SOC cutoff. It really is interesting to watch the loads and sources balance throughout the day. The only real constant is the 12kW Export to Grid limit.
From 11:00 to 12:00 it was only serving my 1kW local loads and Export to Grid which is set to 16kW but only achieves 12kW.
It will service 16kW AC if 4kW are local loads. My EV charger pulls 4kW so I let it run around 12:00.
I ran out of battery around 13:35.
May I run any more tests for you?
Are we still blaming clouds or my PV?
Brucey
Velcro Man
So the flexboss 21 can push 16kW to the grid while the 18kpv is limited to 12kW... pretty big difference.
NC_hydro
Solar Wizard
Or so the claim is. Or is it 12kw
Brucey
Velcro Man
If both of them can invert 12 kW from DC to AC...I must be missing something.Or so the claim is. Or is it 12kw
SunDave
Solar Wizard
Hi Brucey,
You are not a fan of Sol-Ark though huh? I push 14kW to the grid while running loads. Wish I had more panels to see what the true max is.
Hopefully the EG4 early adopter trouble is short lived. Competition is always a good thing price wise.
There is often a difference in the inverter's capability, and how much it can invert from battery. The battery being at a lower voltage than PV input is what I would suspect causes the difference. Just an uneducated guess.
Brucey
Velcro Man
Not a fan of either but good to have truth in advertising. I would have thought the 18kpv could export 18kW until James corrected me.
Quattrohead
Emperor Of Solar
Yeah that was one of the improvements for the Flexboss 21.
jharrell
Solar Enthusiast
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Then you would assume the Flexboss 21 would do 21kw, no EG4 names them based on MPPT capability which can then be split between Battery DC-DC and Inverter output. Battery DC-DC is 12kw and inverter is 16kw according specs which is why it can only do 12kw on battery but supposedly 16kw with solar:
Sol-Ark has 19.5kw MPPTs and a 15kw inverter with 12kw DC-DC and they named it after the inverter instead of MPPTs
Quattrohead
Emperor Of Solar
18kPV as in it can harvest 18kw of PV.
12kw can go towards AC out, the other 6kw goes to the battery.
The name is quite clear, the specification sheet makes it extremely clear. Tim finally got me calling it the right name, thanks 18kpv Tim.
The Sol-ark 15k can actually do 22.5kW from PV now. They should rename it to one-up the flexboss21.
robby
Electronic Engineer
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I have heard some stories of 19kw I have not seen a screen shot of it doing 22.5Kw
jharrell
Solar Enthusiast
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21.4kW today
robby
Electronic Engineer
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Very cool 
So it's now the Sol-Ark 22Kpv.
If any of you guys get an LCD shot of it taking full advantage of this please DM me it.
I would suspect that most 15K owners are going to have to put up some more panels to take full advantage.
That's a nice problem to have.
So it's now the Sol-Ark 22Kpv.
If any of you guys get an LCD shot of it taking full advantage of this please DM me it.
I would suspect that most 15K owners are going to have to put up some more panels to take full advantage.
That's a nice problem to have.
skimandan
New guy
Gentlemen, please stay on topic. That fine looking Sol-Ark is not a FlexBoss21 / Gridboss Issue.
James Showalter
CEO, EG4 Electronics, Signature Solar founder
It is 16kw to the grid, but PV has to be present over 4kW to supply that. you can't export 16kw to the grid from just batteries as we also say that batteries are maxed out at 12kw.
I believe this was confirmed multiple times before launch, as well as in person recently again. will post results
the mppt "issue" is a non-issue. if you skim the bottom of the range you will not be happy, no matter who you buy from, not interested in "fixing" this, IMO get a book on solar please. can't "fix" an industry
Sure, what book says that the MPPT works like this? I will buy it right now. I've read most of the most popular ones.
I think if the working voltage range is higher than the minimum voltage rating of the MPPT, It should be able to produce good power.
Do you disagree with the points in this video:
James Showalter
CEO, EG4 Electronics, Signature Solar founder
Irradiance and temperature coefficients on the PV make them a very unsolid basis to hit the minimum windo without a 20% buffer at least. I think Ryan Mayfield's book was what showed me this back in 2014, I hated it, even wired up a 6kw system for a friend at 130v on a solis grid tie with the same window, had to go back out and run it in strings of 6 instead of 3. the hope had been that battery chargers were at 150v max at the time and I could swap between the units for a hybrid experience.
Not meant personally, but if people just read spec sheets they need to understand that electronics are solid and panels are not, their voltage collapses under use and irradiance has a secondary effect as well as temperature
This is something I did a couple days ago:
Not VOC, but working voltage of six panels was 187V. I connected it to the flex boss MPPT. Spec sheet states the lowest voltage is 120. I figured 187V working (and 220VOC) would be enough. But unfortunately the performance was awful. I can show you multiple other products that are specd properly, and I can show you the solar panels I was using. And I even show this in multiple videos in the past.
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