[HN Gopher] Fire risk assessment of battery home storage compare...
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Fire risk assessment of battery home storage compared to general
house fires
Author : gnabgib
Score : 56 points
Date : 2024-12-09 19:33 UTC (3 hours ago)
(HTM) web link (papers.ssrn.com)
(TXT) w3m dump (papers.ssrn.com)
| kelnos wrote:
| To save others the clicking and scrolling (if you're mainly
| interested in the conclusion, as I was), the summary at the end
| says that the risk of fire starting in your battery energy
| storage (or in your EV) is lower than that of your average house
| fire (or in your ICE car). They liken the risk of a fire starting
| in the battery storage to that of fire starting in a clothes
| dryer. But, depending on the placement of your batteries
| in/around your home, the severity of a fire, if one should
| happen, could end up being worse than a fire that starts in some
| other household appliance.
|
| I was pleased to read that the risk of fire is reasonable and
| low; I wasn't sure what to expect, but was afraid the conclusion
| would be that they're higher-risk. I suppose I expected to see
| the result that a fire that included large batteries could be a
| much worse fire. Li ion battery fires can be pretty bad, and
| those batteries are much larger than what you'd find in your
| phone or other small electronics.
|
| I still would like to add rooftop solar to my house (even though
| California's metering system is all kinds of anti-rooftop-solar
| now). When I last looked into it a couple years ago, battery
| storage seemed like it was a little too pricey to be worth it,
| but it seems like that's been changing.
| Sayrus wrote:
| > The fires in HSS in Germany were determined using web
| crawling for the year 2023 because no other data was available.
| All other probabilities were calculated using researched data.
|
| HSS may also be underrepresented in the scrapped data due to
| the method used. The document sections Discussion and
| Limitations and Outlook touch about this. The authors highlight
| a lack of common categorization of fires types and count as
| well as the need for a standardized reporting framework.
|
| Another warning made by the author is that their document
| investigates the number of fires but not how much damage was
| done.
| mindslight wrote:
| Note that the research is centered on Germany, where there is a
| bit more of a default-deny approach to electrical safety.
|
| Here in the US, some of the pictures I've seen of sample
| finished installations that the installer is proud of have been
| downright scary. Like giant wall of 2V batteries with terminals
| coming out horizontally, open bus bars tying them all in series
| to make 48V, and then the leads going to the inverter just
| draped over the entrance to a wiring trough with a rough edge!
| There was probably a fuse as part of the inverter itself, but
| no protection for the batteries themselves.
|
| I'm guessing it has to be a case of code inspectors not
| particularly caring or knowing about the DC side? Although with
| that kind of current capacity, perhaps the wiring itself is
| considered a fuse...
| gottorf wrote:
| > I'm guessing it has to be a case of code inspectors not
| particularly caring or knowing about the DC side?
|
| I don't know what you saw, but it could have been a
| "homeowner's special", or some kind of proof-of-concept?
| Professionals are certainly capable of hackjobs, but I have a
| hard time thinking that a client would be satisfied enough to
| pay for what you describe. You don't have to be an
| electrician to know that some stuff just looks dangerous and
| poorly done!
| mindslight wrote:
| No. It was a Faceboot page of a solar installation company
| advertising their completed works. There could have been
| some anti-abrasion thing I couldn't see in the picture, but
| the lack of fusing was still concerning. (And FWIW I did
| check the battery datasheets to make sure there weren't
| internal fuses)
| neither_color wrote:
| >I'm guessing it has to be a case of code inspectors not
| particularly caring or knowing about the DC side?
|
| I'm inclined to agree with this. US electrical code,
| especially in recent years, is pretty robust and has gotten
| to the point where people groan about excessive safety
| features(tamper resistant outlets required in all new
| dwelling spaces, arc fault circuit breakers, whole home surge
| protection all make wiring a house significantly more
| expensive than 15 years ago). Inspectors are pretty good at
| catching grounding and other issues. That said we don't yet
| have generational knowledge of PV and battery systems. A lot
| of installers are still learning by doing, it feels.
|
| Are you sure it wasn't just DIY un-permitted work, though?
| devjab wrote:
| It will be interesting to see what it does for fire fighting if
| we start adopting batteries on large scale in our homes. EVs
| already pose a significant challenge in European cities. Easy
| enough for electric cars which can be put into some sort of
| container to handle the fire, less easy with electric busses.
| I'm not sure we have a good strategy in place yet here in my
| city. So far the strategy seems to be "well, it was lucky it
| caught fire outside the main streets".
|
| I imagine it'll be wild if a fire breaks out in a line of town
| houses with battery storages. If it's as difficulty to put out
| as EV's then you're probably going to have a hard time
| containing it to just a few houses.
| WalterBright wrote:
| I'd prefer to have the battery outside the house, with a
| concrete wall between it and the house. Or just have it 10 feet
| away, like where you'd put a generator.
| 1970-01-01 wrote:
| Most generators are installed within 4ft of the exterior
| house wall.
| philjohn wrote:
| Mine's in my garage, which is breezeblock construction, and
| the garage doors are insulated, so it keeps it away from
| temperature extremes - which will cause issues with an
| outside battery dependending on local climate minimas and
| maximas.
|
| The SolarEdge battery has a built in fire suppression system
| that triggers if thermal runaway is detected, which should be
| enough time to evacuate (in the UK it's also mandatory to
| have a smoke alarm fitted in your solar "plant room").
| carimura wrote:
| We put a 15 kWh battery storage system in our garage and had to
| build a fire-rated room around it with a 60-minute fire-rated
| door to maintain code -- which is a pretty heavy weight steel
| door. It wasn't easy. All to maintain county code. The funny part
| is by the time we got the inspection, the fire department had a
| new inspector and he said "wow, you did all of this for the
| battery?"
| kelnos wrote:
| How much did that cost, as a percent of the total cost of the
| system you built? My feeling is that a requirement like that
| could make the project financially infeasible for a lot of
| people.
| cf100clunk wrote:
| Consider the U.S. insurance industry and their desire/need to
| refuse payouts when possible. If a fire occurs and the
| location contravenes just about any code their staff can
| find, they will likely refuse payout and it will be time for
| you to lawyer up. So, in that case, the expense of that
| special room might be seen as a bargain in the long run.
| Vecr wrote:
| A lot of people probably don't follow the law.
| ipython wrote:
| Wow. And you can park a car that has a battery with 5x the
| potential energy in my garage without any additional
| requirements? Somewhere or another the code doesn't add up.
| trhway wrote:
| Typically the code requires 60-min firewalling of the garage.
| floatrock wrote:
| For an EV?
|
| I think the op is pointing out that some building codes put
| huge restrictions on building isolation with stationary
| storage like powerwalls, but as soon as those batteries are
| on wheels then regulating cars is someone else's
| department.
| trhway wrote:
| >For an EV?
|
| For a 20 gallon tank of gasoline on wheels.
| ipython wrote:
| Also a good point. If each gallon of gasoline is
| equivalent to about 33kWh of energy, I could have 1.3MWh
| stored in two ICE powered cars. I guess it's harder to
| put out a battery fire than a gas fire?
| numpad0 wrote:
| 5x more _usable_ energy. Energy density of Li-ion cells
| improve by couple digits or so? if set on fire in expendable
| mode, if I 'm skimming this[1] right.
|
| 1: https://www.sciencedirect.com/science/article/pii/S0378775
| 32...
| mvkel wrote:
| Isn't there some recency bias in this, considering home battery
| backups are relatively new tech (at scale), and the other
| measures of fire risk are millennia old?
| debacle wrote:
| We had a home near us in the last decade where the propane tank
| exploded. I don't know the details, there are a lot of things
| that go into something like that happening, but one of the things
| found during the investigation was that, per the building code,
| the propane tank was too close to the house.
|
| The news went on to say that some non-trivial percentage of
| residential propane tanks were positioned in a way that wasn't up
| to code. Because most manufactured homes don't have traditional
| financing, they aren't subject to the same code inspections,
| yadda yadda, house goes boom.
|
| The risk of a fire with a home battery system might be lower, but
| the outcome is an unknown. I've had engines and stoves and fryers
| and furnaces and chimneys start on fire on me. I know how to deal
| with those things, even if they are scary. A battery fire, I have
| no idea how to deal with. Coupled with code standards that are
| probably not as mature as they should be, and may not see the
| enforcement they should, and I am content to wait.
| ZYbCRq22HbJ2y7 wrote:
| For above ground tanks, minimum distance from structure
| according to NFPA 58:
|
| No restriction for tanks < 125 gallons
|
| 10 feet for tanks 125 - 500 gallons
|
| 25 feet for tanks 1,000 - 2,000 gallons
|
| A summary here: https://www.cfins.com/wp-
| content/uploads/2021/11/Propane-Con...
|
| > A battery fire, I have no idea how to deal with
|
| If its a small battery, like any other fire.
| bsder wrote:
| But you also need a _generator_ to go with that propane tank.
| And that generator has quite a few code restrictions, too.
| reverius42 wrote:
| You've had 5+ separate spontaneous house fires? That sounds
| very unlucky.
| nativeit wrote:
| Does anyone know what they're referring to when citing the risk
| of fire as similar to that of "tumblers"? Is this a euphemism for
| clothes driers? My first thought was rock tumblers, but surely
| they're not common enough to be statistically significant in
| determining risks for house fires....
| chrisandchris wrote:
| I would assume so. Tumblers are known for causing fires (hot
| air and dust due to not good cleaning by owners).
| lowbloodsugar wrote:
| Many years ago I got to see a neighbor's tumble dryer on fire.
| He'd dragged it out onto his driveway and let it burn. No fire
| extinguisher apparently. Had this been a battery fixed to his
| wall, he'd have lost his house.
| pretendgeneer wrote:
| > HSS share roughly the same probability of catching fire as
| tumblers
|
| Does "tumblers" in this context mean tumbler dryer? I've only
| ever heard tumbler meaning the type of cup.
| Animats wrote:
| This is Germany. Here's a summary of the safety regulations.[1]
| Safety testing by an "accredited laboratory" is required.[2]
|
| The New York City Fire Department reports that lithium-ion
| battery fires are a leading cause of fires and fire deaths in
| NYC.[3] NYFD got the city to require UL or equivalent testing for
| lithium battery fires.[4] This is working for sales within NYC
| but Amazon is still selling batteries with fake UL stickers.
|
| NYC's big problem is e-bikes and scooters being charged in
| apartments and stores. Several hundred of those a year now, and
| they tend to be severe fires. Entire e-bike stores have blown up.
| Those things need to be lithium-iron phosphate until solid state
| batteries become affordable.
|
| (A good political move would be to get the incoming
| administration to require UL or better certification for anything
| imported that has a lithium-ion battery or a wall plug.)
|
| [1]
| https://www.batterietechnikum.kit.edu/downloads/Safety_Guide...
|
| [2] https://www.tuvsud.com/en-us/resource-
| centre/blogs/mobility-...
|
| [3] https://www.nyc.gov/site/fdny/news/Y40203/fdny-warns-
| lithium...
|
| [4] https://www.msn.com/en-us/news/us/fdny-is-trying-to-curb-
| lit...
| metacritic12 wrote:
| The incoming administration doesn't seem to really be pro
| upregulating anything. In fact core members of their team
| believe the firefighters have had way too much political power
| already in building requirements, etc.
| Syonyk wrote:
| They don't have to add regulations. They just have to suggest
| that Amazon actually enforce the regulations on the books,
| instead of allowing fake UL/ETL listings to be accepted as
| seems Amazon's common practice.
| RcouF1uZ4gsC wrote:
| Just tell them that enforcing these regulations will hurt
| Bezos who owns the Washington Post.
| Syonyk wrote:
| There shouldn't have to be any political reasons at all
| to enforce safety testing listings, and I would actively
| discourage anyone from taking that path regardless of
| their views on any given administration.
|
| Far too many Chinese vendors just treat the "UL circle"
| as a required marking to forge, along with everything
| else they're forging on the items.
| http://www.righto.com/2016/03/counterfeit-macbook-
| charger-te... is a good teardown that highlights the
| problems with the fakes.
|
| Amazon has had more than enough chances to solve this
| problem somehow or another, and it's clear they _do not
| care_ about it at this point. They cannot claim ignorance
| after a decade of people highlighting the problems to
| them. As much as I don 't like Walmart, I'd go to Walmart
| over Amazon for anything electronic (realistically, I'll
| buy NewEgg or B&H Photo for most things), because I have
| somewhat more faith in Walmart's supply chains to
| actually get me the thing I'm buying, vs "binned product
| fraud" that seems to be Amazon's bread and butter these
| days.
|
| "Fraudulent markings on poorly designed, unsafe
| electronics that lack all the safety systems that the
| markings indicate exist" isn't a political problem. It's
| a basic consumer safety problem.
| aaomidi wrote:
| It's time to enforce these on state and state compact levels
| tbh.
| floatrock wrote:
| It's important to differentiate a "Battery Home Storage" system
| like a powerwall, an EV, or even a bunch of stackable ecoflow's
| sold at Costco from small-enough-to-be-hackable e-bikes and
| scooters. Asphalt and gasoline are both "petroleum products",
| but completely different worlds.
|
| The NYC problems are caused largely by stores and race-to-the-
| bottom retailers doing DIY spot-welding, homebrew extending of
| battery packs with the cheapest cells found off aliexpress (and
| skipping the engineerey-bits like cell testing and cell
| balancing), and going for the cheapest chargers that skip
| things like a BMS or any regulator circuitry because it shaves
| a few bucks in power ICs.
|
| You'll see these things in the $100-1000 battery market.
|
| Your powerwalls and EV's are expensive enough that they
| probably didn't have to cut those corners. Plus the
| installation should be permitted and installed.
|
| I'd love to have Amazon require UL certification for anything
| with burn-the-house-down risk, but this defeats the whole
| purpose of the cheap-off-the-boat business model of Amazon so
| that won't happen. "We're just a marketplace, sellers should be
| able to sell whatever they want." Besides the outright fraud on
| there, there's also subtle fakery like "UL Certified"
| electronics where if you take the time to lookup the
| certification number, you see all that's actually certified is
| the steel box meets UL "steel box" box standards, nothing about
| what's actually inside.
| nanomonkey wrote:
| Shouldn't home batteries be lithium iron phosphate and not
| lithium ion, and thus almost a zero fire hazard? At least as far
| as cell chemistry goes...electricity is always a fire hazard if
| discharged incorrectly.
| philjohn wrote:
| They should, but quite a few are still NMC chemistry.
| numpad0 wrote:
| [delayed]
| danans wrote:
| Unless I missed it, the paper didn't indicate what the battery
| chemistry breakdown of the data set was. If it is heavily
| weighted for Sonnen (German home backup battery manufacturer)
| batteries, then those have always used Lithium Iron Phosphate
| (LFP) chemistry, which has much lower thermal risk.
|
| In contrast, most historical home backup batteries sold in the US
| have been early generation Tesla Powerwalls, which are Lithium
| ion batteries and thus inherently more thermally risky (they must
| have active cooling systems [1] inherited from Tesla's cars).
|
| Most home batteries currently sold (Enphase, Tesla, etc) now use
| LFP, so the thermal risk going forward for new installations
| should be significantly lower.
|
| 1. https://wanakasolar.com/knowledge-hub-posts/tesla-
| powerwall-...
| lolc wrote:
| I can't really relate to per-year risk percentage numbers. But
| the inverse is quite illustrative I find. Here is the expected
| time between events for each category according to the paper:
|
| General house fire: 360 years
|
| ICE fire: 1100 years
|
| EV fire: 4200 years
|
| Battery storage fire: 20'000 years
|
| Tumble dryer fire: 27'000 years
|
| PV system fire: 71'000 years
|
| This way I can understand that while I might see my house burn,
| the battery storage is very unlikely to pop in my lifetime.
| Because these numbers are not very accurate anyway, I've rounded
| to two digits. The authors note that the number for battery
| storage in particular are very unreliable.
|
| On the other hand: just looking at probabilities of events does
| not tell you how lethal or destructive the event will be. And
| lithium fires are very bad in both categories. Comparing to
| tumble dryers is not very useful when you factor in the
| properties of the fire. Quite possibly the danger to life is
| higher with an EV compared to an ICE, even if the ICE is assumed
| to catch fire at four times the rate of the EV. In addition, the
| wear-out failure rate of EV is to be discovered yet, because the
| fleet is so young. The EV rate may still climb. Or maybe battery
| manufacturers improve and the danger will be reduced? Some things
| do get better after all!
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