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3x battery racks (92kw) in residential?

begna112

begna112

New Member
Joined
Oct 16, 2024
Messages
10
Location
Dallas Texas, USA
So I'm working on a system currently for solar + whole home battery. Specifically, trying to take advantage of Texas's Free Nights plans by charging a massive bank of batteries overnight and then using them + solar during the day and selling back anything I don't use.

To do this, I need 3 racks of batteries for a total of 92.16 kwh. (EG4 Lifepower4 V2)

The installer I'm working with mentioned there might be a problem with that large of an installation, so I got to digging. I found this in Dallas City Codes, which seems to mostly match IFC. https://up.codes/viewer/dallas/ifc-2021/chapter/12/energy-systems#1207.11.4

Individual ESS units shall have a maximum rating of 20 kWh. The aggregate rating structure shall not exceed:​
  • 40 kWh within utility closets and storage or utility spaces.
  • 80 kWh in attached or detached garages and detached accessory structures.
  • 80 kWh on exterior walls.
  • 80 kWh outdoors on the ground.
So I'm trying to figure out how this works... I know my installer has done eg4 racks before because they quoted me one. And obviously these systems are super popular. But it seems like they exceed the 20kw limit.

So how are people doing this? Just call to get the city inspector to allow it? How likely is it I can get my 92kwh system approved?

If anyone has any experience with large battery systems at home within city limits where normal building codes apply, I'd really appreciate any advice or experiences you've had.
 
begna112 said:
Individual ESS units shall have a maximum rating of 20 kWh. The aggregate rating structure shall not exceed:
  • 40 kWh within utility closets and storage or utility spaces.
  • 80 kWh in attached or detached garages and detached accessory structures.
  • 80 kWh on exterior walls.
  • 80 kWh outdoors on the ground.
Click to expand...
Is your answer.
 
begna112 said:
So I'm working on a system currently for solar + whole home battery. Specifically, trying to take advantage of Texas's Free Nights plans by charging a massive bank of batteries overnight and then using them + solar during the day and selling back anything I don't use.

To do this, I need 3 racks of batteries for a total of 92.16 kwh. (EG4 Lifepower4 V2)

The installer I'm working with mentioned there might be a problem with that large of an installation, so I got to digging. I found this in Dallas City Codes, which seems to mostly match IFC. https://up.codes/viewer/dallas/ifc-2021/chapter/12/energy-systems#1207.11.4

Individual ESS units shall have a maximum rating of 20 kWh. The aggregate rating structure shall not exceed:​
  • 40 kWh within utility closets and storage or utility spaces.
  • 80 kWh in attached or detached garages and detached accessory structures.
  • 80 kWh on exterior walls.
  • 80 kWh outdoors on the ground.
So I'm trying to figure out how this works... I know my installer has done eg4 racks before because they quoted me one. And obviously these systems are super popular. But it seems like they exceed the 20kw limit.

So how are people doing this? Just call to get the city inspector to allow it? How likely is it I can get my 92kwh system approved?

If anyone has any experience with large battery systems at home within city limits where normal building codes apply, I'd really appreciate any advice or experiences you've had.
Click to expand...
Are you going to use an 18kpv or two? Based on this document it's an approved UL9540 configuration when you are using up to two stacks of 30kWh (12 in total) with one or two 18kpvs. I believe this unit testing of inverter and batteries together is exempt from the regular ESS limits (after all that's 60kWh presumably in a dwelling), but you'd want to get approval from the inspector for the design before spending any money.


What would be ideal is if eg4 tested with two full racks of batteries giving you a max of 120 kWh, maybe that's in the works.
 
> Is your answer.
I mean, clearly it isn't if installers are installing these racks within code. So there must be some nuance to the situation.
 
Brucey said:
Are you going to use an 18kpv or two? Based on this document it's an approved UL9540 configuration when you are using up to two stacks of 30kWh (12 in total) with one or two 18kpvs. I believe this unit testing of inverter and batteries together is exempt from the regular ESS limits (after all that's 60kWh presumably in a dwelling), but you'd want to get approval from the inspector for the design before spending any money.


What would be ideal is if eg4 tested with two full racks of batteries giving you a max of 120 kWh, maybe that's in the works.
Click to expand...
I planned to only use one 18kpv with a victron lynx busbar to link the batteries.

What leads you to it being exempt?
 
begna112 said:
I planned to only use one 18kpv with a victron lynx busbar to link the batteries.

What leads you to it being exempt?
Click to expand...
Because that's giving you a 60kWh solution that is larger than the 40kWh limit in your code. But that's why you have to verify if your code guy will accept the design.

In the 2024 icc code the limit is increased to 600kWh (with 50kWh stacks and three feet seperation.

Looks like there is some leeway, if you can provide the ul9540 config and paperwork and he signs off:

"4.The fire code official is authorized to approve larger capacities or smaller separation distances based on large-scale fire testing complying with Section 1207.1.5.

Digital Codes

ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures.
codes.iccsafe.org codes.iccsafe.org

And this:

"ESS installation codes contain size and separation requirements designed to prevent a fire originating in one ESS unit from propagating to adjacent ESS units or adjacent battery room walls and exposures. The size requirements limit the maximum electrical storage capacity of nonresidential individual ESS units to 50 KWh while the spacing requirements define the minimum separation between adjacent ESS units and adjacent walls as at least three feet. Exceptions in the codes allow the code authority to approve installations with larger energy capacities and smaller separation distances based on large-scale fire testing conducted in accordance with UL 9540A, the Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems Standard."

www.ul.com

UL 9540A Test Method for Battery Energy Storage Systems (BESS)

Learn how UL Solutions’ innovative testing under the UL 9540A test method can help accelerate compliance and enhance safety.
www.ul.com www.ul.com

I read that as 9540 compliant "can" be excepted by your code officer.
 
Here's another related thread:

Screenshot_20241023_074037_Samsung Notes.jpg

T

Thread 'Stacking Multiple Energy Storage Systems'

I am attempting to build an off-grid energy system consisting of 13 kW of solar and around 45 kWh of battery capacity. My area requires NEC 2020, therefore UL 9540.

UL 9540 limits residential energy storage systems to 20 kWh or less. Does anybody know if that means one can simply add "systems" spaced out 3 feet or more and remain compliant while increasing total battery capacity?

For context I will probably be using KiloVault HAB batteries and Schneider XW Inverters and chargers. Because the ESS is listed as a "system" would I need to space the inverters out 3 feet as well? I would much...
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Looks like the code official has leeway on separation and capacity of each unit based on 9540a testing.
 
I mean, it’s always an option to add more battery capacity after the inspection is completed, if that’s something you’re comfortable with.
 
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