FlexBoss21 / GridBoss Issue List

[Brucey]

Please let me know if I should make a new thread, but this was highly relevant to the MPPT voltage conversation here.

It sounds like the actually optimal voltage input per string on the Flexboss21 is 250-360V.

If I were to use these panels (https://signaturesolar.com/runergy-400w-bifacial-solar-panel-black-up-to-500w-with-bifacial-gain/), does that mean I would need a string of at minimum 7 panels (37.07V/panel) to hit 250V at Voc? It looks like according to the spec sheet I'd actually need at least 9 (29.82V/panel in power generating conditions) in series to approach the efficient range.

Unfortunately, I don't have the roof space (~35ft length) to fit 9 solar panels in a row. Would this mean that the Flexboss21 is an infeasible inverter for my setup? The 5 string capacity seemed extremely useful for my space-limited setup, but it seems like the panel/string minimum is quite a bit too large for my use case. The only way I could make it fit is if one string connected to panels both on the south and west sides of my roof, which as far as I can tell doesn't sound ideal.

Are there suggestions for high-voltage panels that could make the setup work? On Signature Solar there is exactly one set of high-voltage panels (https://signaturesolar.com/philadelphia-solar-550w-bifacial-solar-panel-ps-m144-hcbf-550w/) that could work with only 6 at maximum power voltage (42.19V), but I do not have a loading dock to receive the shipment.

It seems odd that the Flexboss21 has such a narrow range of acceptable string lengths. Would you suggest just going with a microinverter setup if I cannot fit 9-12 panels per string?

You could consider something like an additional Victron 250/85 SCC connected to your power bus. Voltwge max is 250V, with five panels in the 40V range thats perfect. That has a minimum startup voltage of 5V over battery voltage, i.e 63V if battery at a high 58V. May or maybe not be approved by your ahj as it doesnt have arc fault or ground fault protection.

 

[Quattrohead]

5 panels may work, 6+ definitely will.
I have Panasonic 330 watt panels that are 70 voc, can you find something similar? I got mine on Facebook marketplace.
How many of the average size panel can you fit on each roof?

 

[dotjpg]

You could consider something like an additional Victron 250/85 SCC connected to your power bus. Voltwge max is 250V, with five panels in the 40V range thats perfect. That has a minimum startup voltage of 5V over battery voltage, i.e 63V if battery at a high 58V. May or maybe not be approved by your ahj as it doesnt have arc fault or ground fault protection.

If I'm adding additional MPPTs into my system, does that mean I have redundancy with the built in MPPTs in the Flexboss21? If I'm understanding correctly I might as well skip the Flexboss as an inverter if I'm not using half of its functionality. Or would that only be for my smallest string, if I could keep the others in the 9-12 range?

Also, should we be considering Voc or maximum operating voltage when calculating whether or not the string fits into the Flexboss21's ideal range?

5 panels may work, 6+ definitely will.
I have Panasonic 330 watt panels that are 70 voc, can you find something similar? I got mine on Facebook marketplace.
How many of the average size panel can you fit on each roof?

I have to go up and do measurements today, as I've got a relatively square roof (so it's cut into triangles / rhombus and isn't obvious from the aerial view). My house is about ~32' long on the south side, so I'm hopefully looking to fit at least 8*2 lengthwise but I might be limited to 6 or 7 depending on the angle.

I'll definitely look for 70V panels if I need them

 

[Brucey]

The victron was just a possible suggestion for your smallest string as it won't be at optimum voltage for full output on the fb21

 

[dotjpg]

The victron was just a possible suggestion for your smallest string as it won't be at optimum voltage for full output on the fb21

That makes sense, thank you. Since the Flexboss21's PV input points are (I presume) controlled by the internal MPPT, would that string get "double controlled"? Would I deactivate the MPPT on the Flexboss21 side? Or are there different input ports?

 

[obsoletion]

I am struggling with an issue on my Flexboss setup. When using closed communications, whenever I have the system export to grid from the batteries, it has a communication error (W000) and stops working for 5 minutes. It then clears the comm error and resumes for some random amout of time, 10 mins to 90mins, then repeats with the error and reset. It only happen when discharging to the grid. It may also when just operating on the batteries when the grid is down, but i have not tested that. Signature solar has checked it and the only solution at this point is to set it to Lead Acid. Hoping its a firmware issue that gets resolved.

Well I have got an update on this issue. I have 12 Basen Green 314ah packs. They are paralleled together and connected to the Flexboss master via CAN bus. I narrowed my communication issue down to this odd situation. When i connect up to 10 packs in parallel, every thing works perfect. As soon as i add the 11th pack, the comm errors start with the inverters. I am 99.99% sure this is a firmware issue with the JBD BMS in the packs as solar assist will only see 10 packs at once as well. It is running version 1.0.0 and i have a newer version though i am hesitant to update them in case it adds a new issue. It is working as is and im thinking of just leaving it. Any one got thoughts or see something i am missing?

Thanks as always for feedback!

 

[skimandan]

Please let me know if I should make a new thread, but this was highly relevant to the MPPT voltage conversation here.

It sounds like the actually optimal voltage input per string on the Flexboss21 is 250-360V.

If I were to use these panels (https://signaturesolar.com/runergy-400w-bifacial-solar-panel-black-up-to-500w-with-bifacial-gain/), does that mean I would need a string of at minimum 7 panels (37.07V/panel) to hit 250V at Voc? It looks like according to the spec sheet I'd actually need at least 9 (29.82V/panel in power generating conditions) in series to approach the efficient range.

Unfortunately, I don't have the roof space (~35ft length) to fit 9 solar panels in a row. Would this mean that the Flexboss21 is an infeasible inverter for my setup? The 5 string capacity seemed extremely useful for my space-limited setup, but it seems like the panel/string minimum is quite a bit too large for my use case. The only way I could make it fit is if one string connected to panels both on the south and west sides of my roof, which as far as I can tell doesn't sound ideal.

Are there suggestions for high-voltage panels that could make the setup work? On Signature Solar there is exactly one set of high-voltage panels (https://signaturesolar.com/philadelphia-solar-550w-bifacial-solar-panel-ps-m144-hcbf-550w/) that could work with only 6 at maximum power voltage (42.19V), but it looks like...it'll only ship to customers who have business-sized loading docks?

It seems odd that the Flexboss21 has such a narrow range of acceptable string lengths. Would you suggest just going with a microinverter setup if I cannot fit 9-12 panels per string?

You might get better feedback if you create your own thread. It's a public forum so you do you!

Here is where this is discussed more:
https://diysolarforum.com/threads/flexboss21-error.98378/

 

[AlyGreen]

@skimandan

Thanks for pointing out the MPPT voltage range spec sheet versus manual documentation discrepancy.

This has helped me avoid a panel in series configuration mistake and given me thought on an array redesign. I am a beginner designer and thought 6 panels in series would give me what I needed in terms of voltage (based on the spec sheet numbers) but now I see that it may not be enough voltage on a north facing roof. I had allowed for lower radience and shading but still thought the MPPT would function to some low but still worthwhile degree at 120V.

This is how you learn by reading and carefully researching from other's experiences and I appreciate you pointing it out.

Aly

 

[42OhmsPA]

north facing roof

Hello Neighbor.
The portion I quoted worries me, I really don't think you will be happy at all; based off my experience in PA since my addiction started a few years ago.

Do you have a thread with your plans?
You should create one if you don't.

 

[AlyGreen]

@42OhmsPA

Thanks for the concern.

I had a thread but since creating it have eaten some considerable humble design pie and been reconsidering my plans for a while, these designs have changed considerably, as I watch how the GridBoss / FlexBoss new devices play out in the field and I improve my knowledge of string / parallel design factors.

The north facing roofs are solely to maximize my home's generation capacity, understanding that generation in the winter would be very, very low but still these roofs do receive direct sunlight in the summer months and the calcs I was doing via https://pvwatts.nrel.gov and double-checked against Signature Solar's design team radiation software confirming the figures (nearly exactly amazingly) looked like it made things worth while.

Most generation is coming from my south facing roofs. I hestitate to put the revised design out there until I get better educated and am still reworking them. Can send you a private link if you wish but not public again, just yet... too many errors.

 

[doityourself2021]

@skimandan

Thanks for pointing out the MPPT voltage range spec sheet versus manual documentation discrepancy.

This has helped me avoid a panel in series configuration mistake and given me thought on an array redesign. I am a beginner designer and thought 6 panels in series would give me what I needed in terms of voltage (based on the spec sheet numbers) but now I see that it may not be enough voltage on a north facing roof. I had allowed for lower radience and shading but still thought the MPPT would function to some low but still worthwhile degree at 120V.

This is how you learn by reading and carefully researching from other's experiences and I appreciate you pointing it out.

Aly

Aly, in reading your message... try to stay away from as much shading as you can. You would be shocked to see how much reduction even a small amount of shading on a PV panel reduces output.. its serious..

Ric

 

[skimandan]

@skimandan

Thanks for pointing out the MPPT voltage range spec sheet versus manual documentation discrepancy.

This has helped me avoid a panel in series configuration mistake and given me thought on an array redesign. I am a beginner designer and thought 6 panels in series would give me what I needed in terms of voltage (based on the spec sheet numbers) but now I see that it may not be enough voltage on a north facing roof. I had allowed for lower radience and shading but still thought the MPPT would function to some low but still worthwhile degree at 120V.

This is how you learn by reading and carefully researching from other's experiences and I appreciate you pointing it out.

Aly

This is why I’ve spent effort documenting my issues,
I do think “imperfect” strings are absolutely fine as long as they contribute something greater than zero. ROI is for you to determine.
Maybe move to this thread for panel discussion?

S

Thread 'FlexBoss21 - Error with 4 PV Panels?'

Jan 22, 2025

Hello All,

I used the EG4 Solar Panel String Sizer tool to create my strings for my Flexboss21 back in December and printed out the result for my reference. https://eg4electronics.com/wp-content/themes/hello-elementor/eg4-solar-panel-string-sizer/
It showed that I might have some clipping on string 1 due to it being 0.16A high, and the rest was fine. I ran the same report today and it showed string 3 may not have enough voltage on hot days. Today was cold.

I installed the 36 ZNShine 450W panels, Flexboss, Gridboss, 2 indoor wallmount batteries and had my first day of self...

• skimandan
• Replies: 33
• Forum: DIY Solar General Discussion

 

[OffGridForGood]

may not be enough voltage on a north facing roof. I had allowed for lower radience and shading

Ditto what @doityourself2021 said. If you have shading (at all) you will lose an astonishing amount of energy.
When you say "North facing roof" do you mean at a shallow angle or a significant pitch?
This is a dual edged sword - shallow pitch will be better angle to the sun, but will also collect snow. If you don't clear it, snow will kill production.

I plugged in Philly PA for a reference here using noon today - the max elevation for the sun was 35-degrees. So imagine if you have a 5:12 (23-degrees) pitch north roof, the solar is grazing the panels at just 12-degrees from parallel to the PV surface., and only for an hour as the sun rises and then dips again before and after local noon. It will do far better during summer, but this is the reality during winter months.

I found my West shop roof - which is 4:12 pitch and faces due West - was usable by installing rows of panels that tilt south on that roof. I had to space my rows 12 feet apart to avoid each row shading the next, but it added a good array area since the roof is pretty large. In summer I lay the array down close to the roof angle to get late afternoon West sunlight directly on those panels. A win-win for me.

I guess I am saying you need to spend some time analyzing your options before you spend money and build stuff. It is low cost to push numbers around on a spreadsheet compared with building a roof top array only to be disapointed with it's performance.

 

[skimandan]

Dear @EG4TechSolutionsTeam ,

Any thoughts as to when some fixes may be in place? Primary concerns are being able to set a 120V starting voltage for PV and TOU scheduling allowing weekend settings.

Yours truly,
@skimandan

 

[mciholas]

Primary concerns are being able to set a 120V starting voltage for PV

That's likely a hardware limitation so I would assume this won't get changed.

Mike C.

 

[AlyGreen]

@doityourself2021
@OffGridForGood

Thanks for the shading advice, all valid points, north facing roofs give really poor ROI agreed. Just trying to squeeze out the last pssible kWh as I can on all available roof space. Here are the numbers for each of the north facing arrays.

Shallow pitch is fair, steeper pitch is only good in summer but end of day they still give me something to try and reach my net zero goal. Without them I can't produce enough. One option is wait for higher efficiency panels to come out maybe next year bumping the 430W to 460W with any luck for the same panel size. That would help alot.

The six panels in series likely won't give enough voltage as per the point of this thread except in the summer on the steeper pitched roofs. Don't really want to put microinverters on these roofs and complicate the build. Anyway I appreciate the reality check from you guys, still thinking about the design and playing with spreadsheets.

Shallow Pitch 14 Degrees


Steeper Pitch 39 Degrees

 

[StephenV]

Anyone running a Flexbox 21 at 8000ft? Or above the rated >2000m ? I saw mention of the 12 & 18Kpv’s being de-rated which is fantastic. Wondering if the same can be done for the these bad boys?

 

[RARankin]

echoing what @skimandan has said about documentation and explanations within the webapp... and some other items I wouldn't mind seeing:

- A better "disable when grid offline" option for smart ports.
- Allow us to use the extra relay in the GB for something.
- Ability to turn off or dim the lights on the front of the GB (mine are unplugged due to how bright they are.)
- The phone apps don't seem to support the GB/FB setup very well. Web app isn't awesome either, but in generally functions.
- It would be great to get a protocol mapping table document for the modbus interfaces on both of them.
- monitor.eg4electronics.com release notes as you update it would be helpful.
- Allow me to disable the bluetooth and wifi AP once the dongle is connected to the internet.
- Allow more than one GB per station.

 

[skimandan]

echoing what @skimandan has said about documentation and explanations within the webapp... and some other items I wouldn't mind seeing:

- A better "disable when grid offline" option for smart ports.
- Allow us to use the extra relay in the GB for something.
- Ability to turn off or dim the lights on the front of the GB (mine are unplugged due to how bright they are.)
- The phone apps don't seem to support the GB/FB setup very well. Web app isn't awesome either, but in generally functions.
- It would be great to get a protocol mapping table document for the modbus interfaces on both of them.
- monitor.eg4electronics.com release notes as you update it would be helpful.
- Allow me to disable the bluetooth and wifi AP once the dongle is connected to the internet.
- Allow more than one GB per station.

@RARankin
Maybe it's your turn to start and run the FlexBoss / GridBoss "wish" list. I bet that would be fun to manage!

- A better "disable when grid offline" option for smart ports.

This.

 

[RARankin]

Tired of managing it already!?

What are you setting the "Smart load based on N" too for that to work?

I just want an enable/disable... like a human would use.

 

[skimandan]

Tired of managing it already!?

What are you setting the "Smart load based on N" too for that to work?

I just want an enable/disable... like a human would use.

Oh jeez this poor documentation is so tiring.
My guess is that is whatever the default starting position is for "N", but I've changed all of my settings trying to figure out my own config. I didn't record the settings I didn't need, so it's now your job to test various settings and report back to the group what you found.
I have a separate thread documenting my Smart Load journey. Its still in progress.
https://diysolarforum.com/threads/gridboss-smart-loads.98598/

 

[RCinFLA]

Has anyone 'crossed swords' with an inspector over 120 rule on GridBoss?

Diagram looks like a 120-rule violation.

 

[zanydroid]

Isn’t this an engineered system so exempt from 705.12? You can’t even see where the busses are on this diagram (it’s a schematic), so if inspector really cares they would ask to open and inspect the internal.

Which loops back to this being engineered already

 

[niktak11]

Has anyone 'crossed swords' with an inspector over 120 rule on GridBoss?

Diagram looks like a 120-rule violation.

View attachment 280954

Where? The internal bus is rated for 350A.

 

[RCinFLA]

Where? The internal bus is dated for 350A.

GT PV inverter(s) AC coupled inputs to Smart ports + Hybrid inverter PV export inputs to Hybrid ports + Grid sourcing input, supplying power to Backup panel loads + Smart port load can exceed 120% of 350 amps.

Most inspectors are going to just sum the goes into breakers and if they exceed 120% of internal bus 350A rating they will fail inspection.

Maybe challenging to convince inspector that computer firmware controlling Smart and Grid port relays will manage this.

According to block diagram, hybrid inverter ports only have manual breakers with no CT sensors so GridBoss would have to rely on hybrid inverters reporting their export current via networking comm. If you sum the Grid input, backup load current, and all the smart port net currents you could mathematically deduce the total Hybrid Inverter ports current. Throw in split phase loading imbalance and possible power factors and this is a nightmare to compute.