EG4 FlexBOSS 21 Discussion.

[FilterGuy]

The new EG4 FlexBOSS 21 offers a lot of power and functionality at a very competitive price, this thread is to start a discussion about what it is and how to use it.
The top line spec is that it can generate 12KW from battery and 16KW with battery and solar.

Let’s start with an overview of the ports:

 

[FilterGuy]

The simplest use case for the FlexBos 21 would be a totally off-grid system with just PV Battery and generator.
(Configure for ‘Microgrid in order to use the generator on the Grid Port)

This is a higher power Off Grid system than the 18Kpv at a lower price

 

[Cheap 4-life]

The 90 amp seems so much more practical to me. I almost never use more than 90amps. Could easily make sure to not use over 90.

 

[FilterGuy]

The FlexBOSS 21 is also a great partner to the GridBoss for doing whole Home backup

 

[AntronX]

Power	Efficiency (peak)
12 kW battery to AC 16 kW PV+batt to AC 21 kW PV to batt+AC	PV to AC = 97% Batt to AC = 94% PV to batt = 94.5%

Idle power = 80W
Weight = 88 lbs or 52 Kg <<< mistake in data sheet
Batt voltage = 40 - 60V

 

[timselectric]

Can the flexboss accept AC coupling on the loads port?

 

[FilterGuy]

Can the flexboss accept AC coupling on the loads port?

I saw James say that in the Signature Solar Video, but I am 99% sure that does not work. It can be a load port but not an AC Couple port. In addition, the Gen port on the 18Kpv and 12Kpv is disabled when used with the GridBOSS.

I have suggested that enabling the load port to be a great big smart port would be a great feature. (same thing on the Gen port for the 18Kpv and 12Kpv)

 

[spiker611]

The FlexBOSS21 manual has these recommendations for breaker sizing (below)

Does this mean that each MPPT string input can handle at most 20A? Or can a string providing 26A (as your diagram shows) be connected to one or both (with a bridge) MPPT inputs?

 

[740GLE]

I’m waiting 6mo for when they announce FlexEmperor26.

 

[FilterGuy]

The FlexBOSS21 manual has these recommendations for breaker sizing (below)

Does this mean that each MPPT string input can handle at most 20A? Or can a string providing 26A (as your diagram shows) be connected to one or both (with a bridge) MPPT inputs?

View attachment 255743

Wow, I missed that chart in the manual. I am pretty sure the chart is wrong. I will send a note to EG4 to confirm.

Having said that.
1) when properly wired, 1 or two parallel strings on an MPPT does not need over current protection devices.
2) I do not like using breakers for PV disconnect. I much prefer a switch that is designed for PV disconnect (Like the IMO switches).
3) In many places there is no code that will require an additional PC disconnect. The built in one will satisfy the code. However, it is nice to have an external switch in order to de-energize the PV wires wile working in the inverter wire box.

 

[spiker611]

Wow, I missed that chart in the manual. I am pretty sure the chart is wrong. I will send a note to EG4 to confirm.

Having said that.
1) when properly wired, 1 or two parallel strings on an MPPT does not need over current protection devices.
2) I do not like using breakers for PV disconnect. I much prefer a switch that is designed for PV disconnect (Like the IMP switches).
3) In many places there is no code that will require an additional PC disconnect. The built in one will satisfy the code. However, it is nice to have an external switch in order to de-energize the PV wires wile working in the inverter wire box.

Thanks for the reply. I sent eg4 this question but haven't gotten a response yet.



Here's the three scenarios i'm considering. I'd prefer to use a combiner to save on cabling costs (compared to the first one). Can I put ~24A into the MPPT1-1 input (second from top) or can I put a bridge in (third from the top)?

I'm not sure what the current rating for the MPPT string inputs each are.

Regarding disconnects/breakers, is a breaker necessary if you want to use a SPD? MY understanding is that a SPD will shunt current to ground long enough for a breaker to trip.

 

[wpns]

So while it's more powerful than the 18Kpv, if I wanted to boost my peak grid power (currently 100A) I'd need either an 18Kpv _or_ the FB21 _and_ the GridBoss?

 

[FilterGuy]

Here's the three scenarios i'm considering.

This works as long as the Isc does not exceed spec. If Imp exceeds the usable current it will still work but clip.



This works as long as the combined Isc does not exceed spec for MPPT1. If the combined Imp exceeds the usable current it will still work but clip.


This is not supported.

 

[wispitgood]

The FlexBOSS 21 is also a great partner to the GridBoss for doing whole Home backup

View attachment 255713

This is pretty much what I am about to pull trigger on by Friday with 16.5kW panels. With one caveat. I have 400 amp service with two 200 amp breaker boxes. Can one FlexBox21 handle that, or do I need two? I installed 400 amp meter box that has dual ports, one set for each 200 amp box.

 

[FilterGuy]

This is pretty much what I am about to pull trigger on by Friday with 16.5kW panels. With one caveat. I have 400 amp service with two 200 amp breaker boxes. Can one FlexBox21 handle that, or do I need two? I installed 400 amp meter box that has dual ports, one set for each 200 amp box.

You need two systems..... or one system stays with one panel and the other panel is not backed up.

 

[Singlehanded]

How many power pro batteries can be connected to flex boss?
How many Eg4 server rack batteries can be connected to flex boss?
Are all certifications shown for flex boss and grid boss complete? For me that would be California.

 

[DIYrich]

How many power pro batteries can be connected to flex boss?

64 with communications. Unlimited without communications.

How many Eg4 server rack batteries can be connected to flex boss?

64 lifepower4 v2 with communications. Unlimited without communications.

When in communication mode, you are limited by the number of ID's the batteries can have. You can put 64 in communication mode, and the rest without communications.

BTW: To max out the inverter with no sun, you would need ~22 powerpro batteries per day of run time.

 

[wpns]

How many power pro batteries can be connected to flex boss?
How many Eg4 server rack batteries can be connected to flex boss?
Are all certifications shown for flex boss and grid boss complete? For me that would be California.

As @DIYrich said, there's no real theoretical limit, though there may be code (to the limit that Lux/EG4/SS have tested and certified to UL9540, for instance) and practical (even with closed-loop comms, 64*$3300 is over $200K, but I bet you could get a discount and free shipping 8*) limits.

And of course (stop me if you've heard this refrain) your AHJ has the final word, and they may restrict you to some limit on KWHR or placement or impose silly restrictions (battery disconnects on the exterior of the building or the like).

 

[Singlehanded]

As @DIYrich said, there's no real theoretical limit, though there may be code (to the limit that Lux/EG4/SS have tested and certified to UL9540, for instance) and practical (even with closed-loop comms, 64*$3300 is over $200K, but I bet you could get a discount and free shipping 8*) limits.

And of course (stop me if you've heard this refrain) your AHJ has the final word, and they may restrict you to some limit on KWHR or placement or impose silly restrictions (battery disconnects on the exterior of the building or the like).

I was referring to code limit.

WPNS you brought up an example of 450’ distance from grid boss to flex boss. What is the limit of separation for the 2 ? I know with enphase I had communication issues with around 300’. I really like this system. Just want to sort out how far I can separate them without issues.

 

[FilterGuy]

I saw James say that in the Signature Solar Video, but I am 99% sure that does not work. It can be a load port but not an AC Couple port. In addition, the Gen port on the 18Kpv and 12Kpv is disabled when used with the GridBOSS.

I have suggested that enabling the load port to be a great big smart port would be a great feature. (same thing on the Gen port for the 18Kpv and 12Kpv)

If you have not seen it yet, you may want to watch this interview:

They talk a lot about the FlexBOSS and the GridBOSS

James clarified that the AC couple capability is still in Beta.

 

[timselectric]

James clarified that the AC couple capability is still in Beta.

Just on the load port of the flexboss.
It's an interesting option. But it would also be limited by the 70a (or whatever it is) total output to the Gridboss.

 

[timselectric]

Also, if they turn that port on for AC coupling. There's nothing to stop someone from connecting loads to it.

 

[FilterGuy]

Just on the load port of the flexboss.
It's an interesting option. But it would also be limited by the 70a (or whatever it is) total output to the Gridboss.

It would be limited to the 90A Pass through capability of the flex boss.

There all sorts of wild things that could be attempted with AC coupling, but the big driving demand is for the person who already has a grid-coupled system without batteries and wants to upgrade to batteries. The vast majority of these systems are limited by the 120% rule to 32A.

 

[timselectric]

It would be limited to the 90A Pass through capability of the flex boss.

There all sorts of wild things that could be attempted with AC coupling, but the big driving demand is for the person who already has a grid-coupled system without batteries and wants to upgrade to batteries. The vast majority of these systems are limited by the 120% rule to 32A.

Right, but that's what the extra ports are for on the Gridboss. What's still in beta is for the load port of the flexboss. (To solve the dark start issue)

 

[FilterGuy]

Right, but that's what the extra ports are for on the Gridboss. What's still in beta is for the load port of the flexboss. (To solve the black start issue)

Correct. The gridboss already supports AC Couple on the smart ports.

What is being proposed is that by making the Flexboss Load Port a 'smart' AC coupled port, they will be better able to deal with low battery situations when the PV is AC coupled and at risk of having a dark start issue. When the batteries get to a near-empty level and no Grid or PV power is coming in, the system will cut off all the loads and only keep the AC coupled port alive. That way when the sun comes up, the AC-coupled inverters will still be on and will be able to start charging the batteries. Once the batteries get to a high enough SOC, the loads will be turned back on.

Note that for DC coupled PC, this is not an issue.

Also, if they turn that port on for AC coupling. There's nothing to stop someone from connecting loads to it.

If they put loads on the port while it is configured for AC couple, it will either slow down or prevent the dark-start recovery.