Stacking Multiple Energy Storage Systems

[topyardman]

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 prefer to keep them together and just space out the groups of batteries.

Any insight would be appreciated. I've tried contacting my AHJ many times and have never heard back. I'd like a sanity check that my system will be compliant before dropping a year's salary on it....

Thanks!

Edit: This is a link to a UL document indicating 3 ft seperation is acceptable. But they also imply that the inverters and batteries are in the same housing, which is obviously not always the case.

https://code-authorities.ul.com/wp-...sidential-Requirements-002_TLrev_09302021.pdf

 

[pvgirl]

You may get some help be reaching out to KiloVault, or one their resellers like altestore for details and help on getting a listed system.

 

[Hedges]

So ridiculous:

"80 kWh max. aggregate in attached or detached garages and detached accessory structures; on exterior walls; or outdoors on the ground"

Totally arbitrary limit, with no basis in providing safety.
Meanwhile, you park a Tesla with 90 kWh of "explody" chemistry in garage under bedroom.

Well, one way out:

"Except where larger kWh ratings are documented based on UL 9540A Test Report."

 

[rodrick]

Government regulations are more for control than safety

 

[topyardman]

You may get some help be reaching out to KiloVault, or one their resellers like altestore for details and help on getting a listed system.

Thanks. I did talk to KiloVault, who just directed me to ask my AHJ, and I also spoke with Alt-e but they seemed to be unaware of any system capacity limits. I wish there were more examples of UL 9540 compliant systems out there for DIY, as most places are going to require it if they don't already, but the knowledge base doesn't seem to be there yet.

If somebody had a compact but scalable UL 9540 system out there I'd buy it immediately. The KiloVault HABs are really inefficient space-wise for a large system, but they may still be my best bet. Wish I could find a listed server rack system that isn't insanely expensive.

 

[400bird]

Any insight would be appreciated. I've tried contacting my AHJ many times and have never heard back. I'd like a sanity check that my system will be compliant before dropping a year's salary on it....

Draw up and submit the permit before you spend money on the components. Only purchase once it's approved by the AHJ

 

[topyardman]

Draw up and submit the permit before you spend money on the components. Only purchase once it's approved by the AHJ

Maybe I misunderstand the permit process. Is that how its normally done? With previous permitted work I've done, I just did the work and when it was ready paid my fee and they came to inspect it. No drawings or approval process except the inspection.

Granted that was for less complex projects.

 

[400bird]

Maybe it depends on where you live, that's how it's done here (California) means I know the components I purchased are approved and can't be failed by the inspector.

 

[timselectric]

The purpose of the permit is to get approval to begin working. Once the work is completed. The inspector verifies that the work performed matches the permit and meets code.
That said, small towns may be lax in the procedure.

 

[topyardman]

Looking at the website for my electrical authority, they state:

"Homeowners and anyone excluded from requirements below: Do not submit drawings for review or preapproval. Rules prohibit us from consulting on your electrical system design. If you have a code question, contact your local office.

In L&I jurisdiction, rules require electrical plan review for all new or altered electrical projects in educational, institutional, or health care occupancies defined in WAC 296-46B-900(1) when not excluded by WAC 296-46B-900(3)(a)."

So it looks like a plan review is not in the cards. Shame really, thats exactly what I am wanting. BTW contacting my "local office" has yielded no productive results.

While I am supposed to buy the permit before starting work, it looks like the first indication that the system does not meet approval is at the final inspection. Not a big deal for most work, but could be really expensive in this case.

 

[DIYrich]

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?

The limit is 20kWh per rack, and each rack must be separated by 3 feet.

The limit for one location is 40kWh. With location being indoors, garage, and outside. In theory uou can have 120kWh at any house.

Note: most rack batteries are 5.12kWh, so you can have a max of 3 in a rack, and 7 in a location.

I believe UL9540 also requires a fire rated room.

 

[timselectric]

The simple solution is to get through the inspection with minimal batteries installed. And add the rest, after.

 

[67King]

The limit is 20kWh per rack, and each rack must be separated by 3 feet.

The limit for one location is 40kWh. With location being indoors, garage, and outside. In theory uou can have 120kWh at any house.

Note: most rack batteries are 5.12kWh, so you can have a max of 3 in a rack, and 7 in a location.

I believe UL9540 also requires a fire rated room.

I hadn't come across this listing before seeing this thread. Interesting in that all the racking systems I've seen have racks that are over 20KWh. The EG4's are 30, the SOK's are 25.6.

 

[DIYrich]

I hadn't come across this listing before seeing this thread. Interesting in that all the racking systems I've seen have racks that are over 20KWh. The EG4's are 30, the SOK's are 25.6.

Designed before UL9540

 

[GSXR1000]

Maybe I misunderstand the permit process. Is that how its normally done? With previous permitted work I've done, I just did the work and when it was ready paid my fee and they came to inspect it. No drawings or approval process except the inspection.

Granted that was for less complex projects.

legally your are supposed to pull permits before work starts. they do have exceptions like weekends for emergencies.... that's where red tag stop work tags come from people that didn't

 

[glandpuck]

My latest info for California says:

New Residential Energy Storage Code Requirements - Sustainable Energy Action Committee

Find out about options for residential energy storage system siting, size limits, fire detection options, and vehicle impact protections.

sustainableenergyaction.org

You have four options for siting ESS in a residential setting: an enclosed utility closet, basement, storage or utility space within a dwelling unit with finished or noncombustible walls or ceilings; inside a garage or accessory structure; on the exterior wall of the home; and on ground mounts.

Inside dwelling units, ESS shall not be installed in sleeping rooms, or closets or spaces opening directly into sleeping rooms or in habitable spaces of dwelling units. Systems in these locations are also limited to 40 kilowatt-hours (kWh) of storage capacity.

In all other locations noted above, the size limit is 80 kWh.

On the exterior walls of the home, it’s important to note that systems cannot go within 3 feet of doors or windows leading directly into the home.

And as we will soon discuss, code compliance for ESS in an attached garage can be much more complicated than systems in a detached garage.

The California State Fire Marshal has stated in an information bulletin that the locations can be combined for a cumulative total of 280 kWh of ESS capacity.

 

[timselectric]

That's not bad.
But, still not enough. lol

 

[prometheanfire]

going to have to finish a single room in the basement just for some batteries...

 

[400bird]

going to have to finish a single room in the basement just for some batteries...

This is California, sadly we don't do basements very much. I'd love to have one, but I didn't build this house.

 

[timselectric]

A basement is a great place to hide from a tornado.
Not so much, for a hurricane.