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EG4 18kPV vs 12000XP vs FlexBOSS21

mciholas said:
59 volts is 2.46 volts per cell which is way high for lead acid. You shouldn't need to go that high. I'd recommend you stay at 2.4 volts per cell or less (57.6 volts). High voltages lead to out gassing. Lead acid will equalize with long term float charging at about 2.30 volts per cell.

The "60 volt" limit is a general limit for "safe" low voltages. This is why Power over Ethernet stops at 57 volts, for example, and why you don't see 96 volt inverter battery systems (once you go that high, might as well be ~400 volts for efficiency).

Mike C.
Click to expand...

Dunno, as both the current and previous lead acid 48v battery systems (Trojan and Rolls) had that high of charging and of course higher equalizing. I made a specific thread about that with some documentation of the Trojan and Rolls manuals:

ddxv

Thread '12000XP not compatible with 48v lead acid batteries? Unable to set absorb or equalize above 59v'

Previously I thought the issue was just some settings, but after calling Signature Solar they told me that 59v is a hard limit set by NEC standards.

This causes an issue because the 48v lead acid battery manufacturer states the default absorb charge should be 60 and more importantly the equalize is 63v.

59v is ok for the charge, but it seems we've lost the ability to equalize our battery bank.

Does this sound correct? Is the work around to look into changing battery bank to 24v?

I get the feeling EG4 is not very compatible with lead acid batteries.
 
ddxv said:
Dunno, as both the current and previous lead acid 48v battery systems (Trojan and Rolls) had that high of charging and of course higher equalizing. I made a specific thread about that with some documentation of the Trojan and Rolls manuals:

ddxv

Thread '12000XP not compatible with 48v lead acid batteries? Unable to set absorb or equalize above 59v'

Previously I thought the issue was just some settings, but after calling Signature Solar they told me that 59v is a hard limit set by NEC standards.

This causes an issue because the 48v lead acid battery manufacturer states the default absorb charge should be 60 and more importantly the equalize is 63v.

59v is ok for the charge, but it seems we've lost the ability to equalize our battery bank.

Does this sound correct? Is the work around to look into changing battery bank to 24v?

I get the feeling EG4 is not very compatible with lead acid batteries.
Click to expand...
@ddxv @mciholas

EG4's 60V upper limit reference *(in effect, 59V) is due to Article 706 of the NEC. You can see examples of the NEC Article 706 here and in some states, e.g.: CA or here (NY) and others, where it states that "...706.1 Scope. This article applies to all permanently installed energy storage systems (ESS) operating at over 50 volts ac or 60 volts dc that may be stand-alone or interactive with other electric power production sources."

It then goes on to state that UL9540 (not 9540A) certification is required for ESS exceeding 60V DC. Being an onerous requirement, many battery and inverter manufacturers avoid exceeding this limit. The EG4 18kPV has specific UL9540 certifications with three battery configs, because previously the NEC stated that it was for any system that exceeded 1kWh (regardless of what voltage it ran at, e.g.: see NEC 706.1 adopted by VA (here). EG4 decided to avoid this for other inverters given that the updated NEC codes now states that the requirement is above 60V.

Solution
ForLead Acid batteries (12.6V nominal) based ESS used with EG4 can simply move from 5S configs (12.6x5 = 63V) to 4S configs (12.6 x 4 = 50.4V) which would fall in EG4's battery operating voltage range (40-60V) as per their manual specs (12000XP, 12kPV, 18kPV, FlexBoss21).
 
NEC isn’t the only governing code that defines ESS/UL9540. So I wouldn’t extrapolate from that to, it’s OK in California to install a non-9540 ESS.

(Another two are NFPA 855 and international residential code)

Also, it’s not clear whether the voltages apply to only battery side, or both battery and inverter side. The inverter side obviously operates above 50VAC
 
Also I checked the NEC 2017, 2020, and 2023. The 60V limit was not present in the 2020 and 2023 codes I looked at, via clicking on up codes for states that adopted without amendments
 
ddxv said:
Do you have a link for that?
Click to expand...
I didn’t save them since I was satisfied with the due diligence of looking it up once

On upcodes You can navigate from Electrical code -> year of code -> adopted without amendments list

If you can’t figure it out ping the thread and I can look it up tonight
 
zanydroid said:
NEC isn’t the only governing code that defines ESS/UL9540. So I wouldn’t extrapolate from that to, it’s OK in California to install a non-9540 ESS.

(Another two are NFPA 855 and international residential code)

Also, it’s not clear whether the voltages apply to only battery side, or both battery and inverter side. The inverter side obviously operates above 50VAC
Click to expand...
Non-PoCo speaking, e.g.: AHJ (Building Permits), in California, NON-Interactive (i.e.: one that does not feed back to the grid) Inverters are governed by CEC, Chapter 1-4 & in some jurisdictions 5-7 (e.g.: San Jose, CA, where I live, require that CEC 5-7 be also satisfied). As a consequence, inverters only require to be UL1741 certified for AHJ (Building Permits) purposes.

Here's the excerpt from San Jose CA's permit requirements that are relevant: Chapter 6 - Section 690.1-690.4. Note: UL9741 is only required for INTERACTIVE inverters (Definition under CEC CHapter 1 here, --> Requirements in Chapter 6 Section 625.48 here.

Since the 12000XP is a non-interactive inverter and is UL1741 certified, it is allowed by San Jose, CA (under the non-interactive inverter category).

_____________

In my case, PoCo certification requirements are different from local city/county AHJ requirements. For my case include: CPUC Rule 21 (Phase I, II and III) ONLY IF feeding back (i.e.: interactive inverter). IF NOT FEEDING BACK, i.e.: ZERO EXPORT but grid is still connected to inverter (e.g.: 12000XP), it is PoCo specific and PGE has indicated they require the following from EG4. Note: UL3141 is an emerging standard which is why PGE refers to it as well as the latest UL PCS standard. Since costs are typically $5k+, it is unlikely that EG4 will satisfy this. As such, I will have to rely on a generator without a grid connection as a backup for power sources. That's why I went with 64kWh of batteries.

1737073728955.png

1737073692414.jpeg
 
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No-one-&-Not-Important said:
Electrically speaking, in California, Inverters are governed Chapter 1-4 of CEC, and only require to be UL1741.
Click to expand...
Do you have installer experience backing this up? Because your conclusions are not what I've seen elsewhere in many conversations, and if true would be highly disruptive and of broad interest.

What is your counter argument to my long held position that R328.1 does not apply? https://up.codes/viewer/california/ca-residential-code-2022/chapter/3/building-planning#R328.1
 
No-one-&-Not-Important said:
EG4's 60V upper limit reference *(in effect, 59V) is due to Article 706 of the NEC. You can see examples of the NEC Article 706 here and in some states, e.g.: CA or here (NY) and others, where it states that "...706.1 Scope. This article applies to all permanently installed energy storage systems (ESS) operating at over 50 volts ac or 60 volts dc that may be stand-alone or interactive with other electric power production sources."
Click to expand...

I don't see this text in CEC 2022 706.1


It is in CEC 2019 706.1, but, that was superceded in Jan 1, 2023

 
In any case, if you can convince SJ to give you a building permit with 12000XP (+ battery explicitly specified), more power to you. I wouldn't recommend ordering neither the battery nor the inverter until you have that permit in hand.
 
Thanks @zanydroid. I've definitely learned from this forum not to order until permit is in hand.

To respond to your question:
1. I have ZERO solar installer experience. I am learning from the codes.
2. I've learned that if I make categorical statements, some, yourself included will respond and highlight the problems with my statements.
So I've resorted to this style of statement making to help me more quickly navigate the knowledge base found in this forum. Instead, when I solicited help (as I did in my other thread, see here, and highlighted certain users seeing their experience), I got nothing.


zanydroid said:
I don't see this text in CEC 2022 706.1


It is in CEC 2019 706.1, but, that was superceded in Jan 1, 2023

Click to expand...
Not all states adopted NEC2023; For e.g.: NY is still on 2017. e.g.: https://up.codes/viewer/new_york/ (has not been amended yet). California has been amended as you pointed out and now the regulations apply to anything over 1kWh regardless of Voltage; however, for batteries in California that were grandfathered in before Jan 1, 2023, UL9540 certification is not required.

For new installations that use EG4, this mens only this & this EG4 battery are allowed in California & ONLY then with 18kPV, i.e.: not with FB21, not 12000XP and not with any other inverter. All the other batteries are not UL9540 approved. In fact, I only know of one other battery, the RiuXu 16kWh that is being UL9540 approved. Know of others? I am installing the EG4 Life4Power v2 (UL9540 approved) to ensure I am permit compliant.

zanydroid said:
Do you have installer experience backing this up? Because your conclusions are not what I've seen elsewhere in many conversations, and if true would be highly disruptive and of broad interest.

What is your counter argument to my long held position that R328.1 does not apply? https://up.codes/viewer/california/ca-residential-code-2022/chapter/3/building-planning#R328.1
Click to expand...
I am not stating this does not apply. I read this as apply to batteries, not inverters. Can you explain how it applies to inverters? As before, this is consistent with a battery having to be UL9540 certified. Given that California's requirements are onerous, and I am learning on a daily basis just how onerous they are, I will not buy anything until the permit is in hand.


BTW, if you found other UL9540 approved batteries please do share. I think I've counted 2x EG4s and that's it. Any other brands?
 
No-one-&-Not-Important said:
So I've resorted to this style of statement making to help me more quickly navigate the knowledge base found in this forum. Instead, when I solicited help (as I did in my other thread, see here, and highlighted certain users seeing their experience), I got nothing.
Click to expand...
Got it, standard Internet rule of saying something slightly wrong to get faster answers :laugh:

No-one-&-Not-Important said:
Not all states adopted NEC2023; For e.g.: NY is still on 2017. e.g.: https://up.codes/viewer/new_york/ (has not been amended yet). California has been amended as you pointed out and now the regulations apply to anything over 1kWh regardless of Voltage; however, for batteries in California that were grandfathered in before Jan 1, 2023, UL9540 certification is not required.
Click to expand...

R328 covers Energy Storage Systems, which is a bit of a tricky definition (https://www.nfpa.org/education-and-research/electrical/energy-storage-systems). An inverter + a battery is an Energy Storage System. There also a definition of ESS in UL9540, that is battery only (DC ESS, I have a thread on that here https://diysolarforum.com/threads/finally-found-a-ul9540-dc-ess-simpliphi-6-6.83761/page-2). I believe UPSes are in a bit of a gray area as to whether it's an ESS.

The problem with whether UL9540 was not required, is that there are multiple codes governing them, which may be adopted/amended at different times. It's quite possible it was not needed earlier, since some of the codes enforce ESS only on larger systems. I have a hard time keeping track of them.

No-one-&-Not-Important said:
For new installations that use EG4, this mens only this & this EG4 battery are allowed in California & ONLY then with 18kPV, i.e.: not with FB21, not 12000XP and not with any other inverter. All the other batteries are not UL9540 approved. In fact, I only know of one other battery, the RiuXu 16kWh that is being UL9540 approved. Know of others? I am installing the EG4 Life4Power v2 (UL9540 approved) to ensure I am permit compliant.

I am not stating this does not apply. I read this as apply to batteries, not inverters. Can you explain how it applies to inverters? As before, this is consistent with a battery having to be UL9540 certified. Given that California's requirements are onerous, and I am learning on a daily basis just how onerous they are, I will not buy anything until the permit is in hand.
Click to expand...
UL9540 is generally a paired listing between inverter and battery. DC ESS allows only the battery to be listed, and any 1741 to be combined (modulo some caveats around the DC ESS's instructions saying how that inverter is to be integrated safely. it is possible for a 1741 inverter to not have a compatible installation with a DC ESS, EG, if the DC ESS mandates communications and they don't speak the same protocol) with a DC ESS, to form a 9540 system. However, DC ESS batteries are more expensive.

Here is an OK article I've read before explaining AC vs DC ESS https://solarbuildermag.com/news/energy-storage-system-buyers-guide/:

"
AC and DC ESS: Under UL 9540, Ed. 3 there is also modification for battery systems to have AC or DC ESS certification. An AC ESS is inclusive of named/specific inverters. For DC ESS, the battery does not rely on the inverter to perform safety functions under UL 9540A, and that it can stand alone to perform all of the requirements. This allows the DC ESS to be installed with any inverter that has met its own safety certifications such as UL 1741.”
"
 
FWIW there are a ton of 3rd party batteries that are UL9540 with Sol-Ark. Not sure which other inverters have this amount of 3rd party support.

I think Ruixu is targeting 9540 for their own inverter. Don't remember exactly.
 
zanydroid said:
FWIW there are a ton of 3rd party batteries that are UL9540 with Sol-Ark. Not sure which other inverters have this amount of 3rd party support.
Click to expand...
Thanks. I did review Solark's Battery Partners. Here's my quick analysis:
  • Briggs & Stratton: UL9540 battery requires use of an installer, no DIY, Price likely >>2x EG4/kWh.
  • Discover Energy: 1.5x $EG4/kWh. Requires AES rack-mount to be UL9540 certified --> makes it 2x price $EG4/kWh)
  • Pytes: Same price as $EG4/kWh; Requires rack to wall mounted --> Price = >2x $EG4/kWh
  • Storz Power: Certified for UL9540 but only with SolArk, 1.5x $EG4/kWh
  • Renon Power: 2.5x $EG4/kWh for UL9540 wall mounted solution
  • EndurEnergy: 2x $EG4/kWh for UL9540 wall mount + wall attached rack
  • Volthium: 2.5x $EG4/kWh for UL9540 rackmount + wall attached rack.
And finally, found Riuxu. It's UL9540A; not UL9540.

When I started this journey back in late Nov, I was interested in an EG4 and SolArk based solution. Now, it's clear the entire ecosystem is designed for maximum extraction, leaving little room for practical solutions. I'm beyond frustrated with PGE and the city of San Jose's positioning; EG4 & SolArk's tactics are not much better either. I know the true costs of these systems; for instance, I can source fire-suppression-enabled (FirePro-based, NOT the small Pellet based in the EG4), heated JK BMS based 16S1P 280Ah EVE Grade A batteries for $1,400 delivered (DDP, i.e.: after taxes and duties are paid, delivered to my doorstep); Furthermore, UL9540 certification costs just $100 per battery for 1,000 units (total cost for UL9540 is $100,000) —yet pricing is not meant to facilitate volume. But this is not my main line of work & my ethos goes against buying these systems, even though I can afford it. I would just be lending my support for it. I have to find another solution.

It's truly disgusting; what we've devolved to...
 
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Yeah, UL9540 niche is a bitch. You missed bitching about how much AES upcharges, presumably as among the only DC ESS. Somehow the extra volume from NEM3 requiring battery hasn’t helped much

I believe California still has the recycled EV battery exemption, but it requires separation from buildings and other annoying stuff. And I strongly suspect this is actually a bigger safety risk than a solid non 9540 battery
 
zanydroid said:
NEC isn’t the only governing code that defines ESS/UL9540. So I wouldn’t extrapolate from that to, it’s OK in California to install a non-9540 ESS.

(Another two are NFPA 855 and international residential code)

Also, it’s not clear whether the voltages apply to only battery side, or both battery and inverter side. The inverter side obviously operates above 50VAC
Click to expand...
Might be some confusion there on the lead acid and ni-cad battery exceptions for communication utilities:

Screenshot_20250117_001740_Gallery.jpg
 
I'm thinking of installing a DIY system on a detached garage with 5K of solar panels. I am thinking about using the following equipment:

  1. 14 x SilFab 410-HC panels
  2. EG4 Flexboss 21 (future integration with GridBoss)
  3. 1 x 16kwh Ruin wall mount battery
Now comes the questions:

  1. Who has successfully permitted one of these systems recently in the bay area
  2. Will the AHJ ask for UL9450 or ??? for off-grid, detached garage install?
  3. Do you still need RSD for detached garage installs?
  4. Any other things I should know for off-grid, completely isolated from grid installs?

@zanydroid any advice you have here?
 
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