The advent of rooftop solar power generation was a huge step forward for renewable energy. No longer was generating electricity the sole preserve of governments and major commercial providers; now just about any homeowner could start putting juice into the grid for a few thousand dollars. Since then, we’ve seen the rise of the home battery, which both promises to make individual homes more self sufficient, whilst also allowing them to make more money selling energy to the grid where needed.
Home batteries are becoming increasingly popular, but as with any new home utility, there come risks. After all, a large capacity battery can present great danger if not installed or used correctly. In the face of these dangers, authorities in jurisdictions around the world have been working to ensure home batteries are installed with due regard for the safety of the occupants of the average home.
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Home batteries exist for one reason—to store electrical energy for later use. Currently, this is most effectively achieved with the use of lots of lithium-ion cells. While the dangers of lithium-ion cells are often overstated and dramatized, they do nonetheless pose a safety risk when things go wrong. There is of course, the electrical danger, however adherence to proper wiring standards and such typically manages that problem. The greater concern when it comes to home battery installations is around fire. If a large bank of lithium cells catches alight, either through its own malfunction or an external cause, the resultant blaze can be fierce, and incredibly difficult to extinguish. It is for this reason that authorities have developed extensive regulations around home battery installations. The aim is generally to avoid the likelihood of ignition or fire wherever possible, and limit the possible harms if such a thing should occur.
Basically, you don’t want a massive lithium battery fire to overwhelm you with smoke and flames, trap you in your home, or otherwise cause great injury. Thus, most jurisdictions post strict regulations about where a battery may be installed in a typical home. For example, in the US, NFPA rules mandate that residential batteries can only be installed in garages, on exterior walls or outdoors at least three feet away from windows, or in utility closets and storage spaces. Regulations in other jurisdictions are similarly strict; Australian rules ban installations under stairs or ventilation ducts, for example, along with any installations in ceilings or wall cavities. It might feel convenient to tuck batteries away where they can’t be seen, but the risks are considered too great. It’s just generally considered a bad idea to pack your walls or roof full of highly-combustible material.
Often, many jurisdictions also require some level of non-combustible barrier to protect nearby structures that are made of combustible material. For example, if installing a battery near a wooden part of a building, regulations may insist upon the use of materials like brick or concrete that won’t readily catch alight if the battery enters thermal runaway. Capacity limits are also typical, as it’s undesirable to have an excessively large battery in a residential installation where it could one day become an unstoppable inferno in an inhabited area.
It might then seem, based on all the safety concerns around putting big batteries near inhabited structures, that a more remote installation would be best. However, standalone outdoor installations are often also subject to their own restrictions. For example, in Australia’s hot climate, outdoor installs must be protected to some degree from direct sunlight to avoid overheating issues that could lead to disaster. Garage or garage-adjacent installations generally require protection against potential vehicles impacts, too. For example, the NFPA 855 standard requires the use of hefty 4-inch bollards set 3-feet deep in concrete to protect against accidental vehicle impact in commercial installations, while noting that any risk of impact is unacceptable for residential garage installations.
These are just some of the hurdles you will have to clear if you wish to install a large storage battery in your home. There are so many others, from regulations around approved batteries and inverters, wiring rules, as well as the necessary signage to indicate to tradespeople and first responders that a large battery is connected to the home’s electrical supply. It can be a lot to take in, though for the average customer, it’s up to their home battery installer to ensure compliance in these regards. If you’re looking at such an installation, though, and you’re wondering why you can’t put your battery exactly where you like, just know that there are likely many good reasons behind it!
That Batterlution installation looks like shit.
With the (observed, measured) increasing instability of our local grid (brought on by increasing fraction of renewables, some say), I’m looking hard at emergency power solutions. All I need is enough power and energy to keep my freezer and gas furnace running, a few lights and other small loads: About 4 kWh/d, 2 kW max, and enough stored energy to carry through at least a 3-day outage, so 12 – 20 kWh.
I can’t make the numbers work for any kind of solar, and I like the trees that shade my house and anywhere else I might put them, so solar panels are entirely not in the equation.
Without a utility subsidy, grid-interactive battery storage doesn’t pay off, even with overnight 2.5 c/kWh prices and daytime $0.20/kWh.
Despite the decreasing cost of straight battery+inverter solutions, I can’t make those numbers work either. I keep coming back to a gasoline-powered generator and a couple of jerrycans of stored gasoline (rotated through the car biannually). I don’t like the idea of babysitting a generator and stored fuel, but that looks like the way it’s gotta be.
So, from the spreadsheets in front of this chair, it still looks like a fossil fuel generator still wins. Though even better would be a grid as reliable as it was a decade or two ago, where we went literally years without a power glitch.
Numbers don’t work here either from my view, nor with the co-workers whom I talk too for home installations.
We too (I work at a utility) see the ‘instability’ caused by solar and wind (bigger operations than home use). Probably time to start thinking about a home gas backup generator at some point, unless we get more nuclear/coal/gas plants out there. With AI/Bitcoin sucking up power, it exasperates the power problem…
I fly R/C with LiPo and even those small batteries are a fire worry. Having a wall mounted ‘big’ one … well, that sounds like a disaster in waiting. Hope one has good home insurance that covers….
Bottom line, it makes more sense to let the utility supply you/us the power and let them worry about the fires and such.
Don’t use LiPo for home battery storage when LFP are cheaper and far far more stable.
That has not worked so well for us folk in the Peoples Republic of Kalifornia. The utilities start almost as many major fires as lightning. The rates here are about the most expensive in the world, and continue to increase. Mostly because the utilities have been paying the big claims for burning down homes and killing their customers.
Take a look at https://diysolarforum.com/ and https://www.youtube.com/c/WillProwse/videos and make your own system. Batteries over the last 1-2 years have got shockingly cheap. https://batteryhookup.com/ is where I have got a lot from. Also use LiFePo4 (LFP), so much more safe than other Lion and longer lasting.
A “just in case” outage solution does not seem to work with batteries. They have limited lifespans. A 3 day outage, once every 10 years, probably better of going on a trip.
In many rural areas a 1-3 day outage is a several times a year occurrence. We have 3 large freezers and 3 refrigerators. We would lose thousands of dollars worth of food everytime the power was out if we were on the public wire and/or had no battery reserves.
LiPo are great for automotive applications where weight is a critical factor. For stationary backup power systems NiFe is a better option. Our family farm has a pelton wheel fed 20KWh bank that was installed in the 1950s by my great grandfather. My father reconditioned the cells in the late 90s. I will be reconditioning them again sometime in the coming 30s. They have a ~50 year service life, minimal maintenance requirements, and nearly no fire/explosion risk.
LiPo/LiFe are more readily available and cheaper initially, but they certainly arent the end all be all of power storage.
Nice when one can have hydropower on one’s property.
Just don’t live in any dustbowl areas.
Nickel Iron batteries have a very low charging efficiency. That probably doesn’t matter much if you have your own hydro generator, but it’s not great for solar power or charging from the grid.
I cant argue that theyre worthwhile for grid backup, I dont think much of anything is really unless youve got a huge difference in peak/offpeak rates.
I wouldnt say very low efficiency is fair.
NiFe gets 60-85% charge efficiency (we seem to be pretty much in the middle at ~75%) which may not seem great compared to LiPo’s 95-98% but when our stack was assembled (1956) the only real alternative available was Lead Acid which is about the same at 75% but a MUCH MUCH lower lifespan.
Our property is rated at 4.28 hours on solarmaps.
We would have to install 7-9.4kw worth of panels vs ~5.8kw if we were running lithium cells to match our hydro systems average daily power output.
Given Lithium chemistry batteries will need to be replaced 4-6 times in the 40-50 years NiFe batteries will last BETWEEN reconditionings. So if we were looking at solar the cost of extra panels makes waay more sense than lithium batteries do to me. YMMV
SpillsDirt, regarding the lifespan of lead-acid batteries, Trojan’s SPRE family of lead-acids are rated for 2400 cycles at 40% discharge. Even if I had to do that every night, that would still be nearly seven years. It may be a lot less than the lifespan of lithium batteries, but the per-kWH price is only a fraction as much, and the size and weight are not a problem like they are for a car where you have to carry them around.
My car can provide 80kWh at almost 2kW
Sure, that’s an option. I even used it during our last extended outage: Our car can make 55 kWh of electricity on a full tank of fuel, and its 120 V sine inverter can make 600W. I can (barely) run the furnace off it, but it won’t start my fridge or freezer and the alternator&battery won’t support a 2 kW inverter, hence the search for other solutions.
I’m pretty sure Bill has an EV with vehicle to load support. It’ll probably do 2kW at 240V. It’s a fairly major feature of an EV these days.
I know that and deliberately ignored it because, other than the fact that I can recharge my car with a jerry can without the grid present, what’s the functional difference? They both provide roughly the same amount of electrical energy from the on-board energy storage.
You need a larger alternator, maybe a second one.
Definitely a second battery.
The crazy stereo ‘community’ can help you.
If your car came as a cop car, that will simplify.
Those things are power pigs.
IIRC the largest GM non hybrid alternator is something like 200A.
Two of those should do.
Might bolt right in, but upgrade the power wires.
Propane and natural gas generators are also a thing. My friend recently had a house built that uses natural gas for the stoves and furnace with a sizable underground tank; he also installed a mounted generator that, on demand, runs off of that same reservoir.
Local storage for natural gas? How does that work? Refilled by a tanker, or from a high pressure gas main, or via a compressor? Also surprising to hear of an underground compressed gas tank.
But yes, a propane or dual-fuel generator is an option too, but they generally have a significant price premium and lower power output for a given size.
I asked that same question. He insisted it was “natural gas”. I just kind of shrugged on the point. It’s delivered by truck, either way. And the tank is composite, about 3/4 buried to ground level with a sod-matrix top, below the plane of the basement(on a slight slope).
I dunno about a composite(CF?) pressure vessel, but it apparently got the approval of the local code authorities. Maybe low-pressure? It is quite large, about 16×4 feet.
Your friend should purchase a long term contract for the natural gas because it’s going to skyrocket real soon now. The use has signed up to export more than 3 times its current export amount of LNG and with all the data centers being built with their own natural gas generators the price of natural gas is about to hit a mountain.
You can get LPG powered generators, and some of those are auto-starting too.
So, you’d only use the battery under grid outage conditions? I certainly agree with you about removing trees – I don’t like doing it either, is your place completely shaded, or just not getting full sun except for a few hours a day?
Even if solar panels aren’t getting more than 2-3 hours in the middle of the day (because of shading), that would be enough to keep the battery topped up and ready to go when the grid goes down.
But there’s few situations where solar PV + batteries can provide 100% under all circumstances. You can plan and build for a 3-day outage, then along comes a 4-day outage. And then you’re back to using the backup generator.
There was a cyclone here in 2011 where the power to the district was out for the best part of a week. I’m off-grid, all I had to do to maintain a normal life was keep the fuel up to the backup generator. Run it for a few hours to charge up the battery, re-fill it and repeat the next day. Meanwhile my on-grid neighbours had to throw out the contents of their fridges and freezers, and they couldn’t even flush their toilets – no power = no water pumps. So it comes down to how much you want to maintain those little comforts of modern living and what you are prepared to spend.
If you have gas (methane) why not convert the genny to run off it?
I would need to add a gas line to my christmas tree (the distribution stack of taps and valves) and run it outside to a fixed location for the generator. To do that legally requires permits and a licensed pipefitter, and would cost more than the generator itself. And it ties the generator to a fixed location.
But I suppose I could change the jets on my barbeque to burn natural gas, use quick-disconnect fittings to swap between the BBQ and jenny, and justify the piping that way…
Sweet, more regulations for me to ignore!
Have fun when your house burns down and maybe so do your neighbours because your tesla battery wall caught fire.
https://www.dailymail.co.uk/news/article-15105349/Tesla-Powerwall-2-recall-Australia.html
People forget the reason we have food regulations is because companies have put sawdust into milk to stop it from looking spoiled after it’s gone bad.
or you can use LFP batteries instead. I find it odd that so many regulations are just talking about “lithium” batteries and not talking about specific chemistry. Do we use and lump gasoline, diesel, alcohol, etc all in the same bucket?
There’s a good chance the utility companies are behind side regulations which cause home battery energy storage system prices to climb and climb.
You mean someone followed the regs and their house burned down?
This is interesting and helpful. We just got an system from Sunrun where the solar panels are feeding three powerwall batteries (I believe one main battery with two auxiliary storage units). Interesting because our local power company is pushing for more people to get off the grid with micro systems like ours, but we live in a region where wildfire is a very big risk and our home was threatened by wildfire back in 2004. So helpful because now I know if a fire ever makes it to my home, there will be no chance of salvage considering those three big batteries that are attached to the outside of my kitchen. This is a time to check my home insurance policy. Thanks for the heads up!
But also a little ironic- the same power company was found responsible for a recent devastating wildfire that took out an entire town on a nearby island. In response, they have started shutting power off to risky regions during certain weather conditions. This was a benefit Sunrun sold me on with their system- you’ll have power when they shut off the grid. Yeah if I’m not evacuated! And assuming that risk never comes into fruition of actual danger. Well life is a gamble I guess!
Tesla is starting to use LFP batteries in their powerwall units instead of LiOn. There’s a big difference in safety factor. Unfortunately the author of the article isn’t aware of this and lumps all Lithium based batteries together.
The chemistry is irrelevant to this article, which is about home battery regulations. These regulations do not tend to differentiate between different chemistries under the lithium umbrella.
Is LFP safer than other Li-Ion chemistries? Sure. Does it mean you can install them right by your bedroom window? No. They’re still flammable, even if to a lesser degree, and the regulations do not differentiate.
I’d like to see how the newer sodium-based batteries affect the economics of home solar. They’re supposedly 10x cheaper than lithium, and are nowhere near as dangerous from a fire perspective.
They have a lower power density than lithium, but that isn’t really a big consideration (vs, say, vehicle batteries).
This. I can’t understand why there isn’t a very low cost solution that happens to be much larger. I keep hoping that someone will come up with a system that uses old plastic 55 gallon drums.
I’m perfectly willing to dedicate a large portion of my back yard to that.
Shipping costs, probably.
Container size should be big enough.
Flooded lead-acid (FLA) used to be the low-cost + larger solution. But the price of those batteries is very sensitive to raw material costs, and now a set of FLA batteries – at least in Australia – is 2-3 times the cost of LiFePo, with less usable capacity!
Lithium has a massive head-start and volume behind it right now, but the others will come through eventually.
Battery tech today is where home computers were in the 80’s and 90’s – moving at pace along the price/performance curve.
“a huge step forward for renewable energy” I think you are over-egging the pudding, and you spelled “unreliable” wrong.
While regular Li+ and LiPo batteries are indeed hazardous, some “solar” battery makers are moving to more stable chemistries, like lithium iron phosphate.
A few thousand dollars? Last week I was quoted $20k for a solar installation without battery.
Quoted? Just buy them and put them up. Are you lazy?
Some jurisdictions do not allow self installation of solar.
Move or quit bitching.
a statement of fact isnt bitching. I dont even live in a state that prohibits self install. Im just aware that several states require them to be installed by licensed contractors.
We’re not supposed to even remove the trap from a drain without getting a permit. Does anyone pull a permit for that? Nope. We re-roofed 25 years ago, and the roofer didn’t pull the necessary permit. (I didn’t realize that until later.) No one has given us any trouble over it. I also installed a small solar back-up system about ten years ago, and again no one has given us any trouble over it. It has been wonderful to have, the times the electric company power went down.
Now you’re trolling. Stop it.
Many folks have found used 250W farm panels for $23USD to $40USD each. These used units may require replacing bypass diodes, and a careful check with a FLIR camera for shorted-cell defects (hot spot while loaded.) Need to buy 20% extra assuming some will be trash if you go that route.
People run low-voltage MPPT charged deep-cycle lead acid AGM packs on RV to direct power their 24vDC LED lighting, heat-pump, and laptop adapter. Only TVs and tools require AC inverters. Have a look around, and ignore the LLM AstroTurf ruminating about the inverter type panels no one buys for off-grid anyway since they fail open on pole-power loss. The LiFe power pack type are pretty good, but you will be swapping out the old battery every few years (depends if you deep-cycle them.)
As a side note, the rules for low-voltage panels on a detached A-frame are very different from roof top installations. Remember to take your peak power draw estimate, and multiply it by 5 for installed capacity.
Most home users will choose >10kW installations, and in Germany even apartment balcony units reduce energy costs by 30% on average (illegal in most of the US.)
Have a look around, and note the price ranges vary a lot. The Ham Radio community have many remote tower site projects posted to help. If you have the right location these do make sense. =)
73
Maybe mounted vertical.
https://youtu.be/I-Fz5T5c0OQ
Seems to be very country/region dependent, here in the UK 20k used to be a few panels slung on your roof, but my neighbours just paid under 10 for a ton of panels and a large battery system installed and prices are still dropping.
Then again the numbers for household electricity usage also seem to vary wildly – some places in the US are burning 5-10x what we do on average because they run AC hard all day & night.
It really seems like these batteries should be installed in, like, a brick shed detached from the home. Maybe built with a blow-off roof if that sort of thing would be useful. (As in, a roof that allows force or pressure or flame to vent in a safe direction rather than through the door or out an air vent onto the house etc.)
Biggest issue when a Lithium based battery is catching fire is not the fire itself, but the toxic smoke. Burning Li batteries produce huge amounts of toxic smoke within seconds when going into thermal runaway.
Never ever breath that smoke coming from a Li battery!
If a battery gets suspiciously hot, think about how to get (everyone) out. If it is starting sizzling or even starting to smoke, don’t try to extinguish anything. Just get yourself to safety. The smoke and the residue from a Li battery fire that is settling on surfaces will even quickly (days, maybe few weeks) even eat through paint coatings and zinq layers on steel.
Also never try to extinguish a Li battery fire. You simply can’t. There is no product available that really can extinguish burning Li cells. As long as there is combustible material inside, they will burn on and even supply themselves with oxygen from the inside.
Additionally don’t touch/clean any residue from thermal runaways of lithium battery fires bare hand (i.e. RC LiPos). There is – with other toxic stuff – hydrofluoric acid produced during thermal runaways. This stuff is very very nasty, can travel through your skin and can result in severe toxic effects on your body/organs hours after exposition.
Don’t want to scare anyone away from RC, mobile phone, power pack, …. batteries.
I also have some bigger RC LiPos at home (stored in a fire proof document safe/box) and also a solar system with LiFe solar batteries.
Just don’t act “heroic”/stupid and just get your family and others to safety and call the fire brigade. Nothing else you can do.
Water is an effective tool to fight a Lithium thermal runaway, but you needs lots of it.
It works to cool the reaction, not to exclude oxygen. You need a lot of it, and an effective drain route.
And this is how “professional” installers try to keep home solar / battery installations unsafe, by abusing the loophole that below 120 VDC installations in EU do not require permits:
https://i.sstatic.net/47Pc09Lj.png
If you have a house with an unused fireplace and chimney, it’s a great place for a battery installation.
In principle that would make sense (though I am skeptical that commercially available batteries would fit…), but if code requires them to be in garages or outdoors, not so good.
I have 24kWh of LFP outside, which can run my house on life support for a couple of days if there’s no sun, or indefinitely if the 10kW of PV on my roof is getting sun.
If only the big players wasn’t so greedy, batteries would not even be necessary.
My brother was selling energy all day to the grid, here in Brazil, while at work.
Once he got home, at night, the meter would spin to positive direction, but even so, it would never turn in to a debt to the grid, so theoretically he was still selling it in the month basis…
Well, now the same kind of regulators who are always worried about general safety are saying that my brother must pay some taxes as he is producing energy in his home… And he ended up paying the bills instead of zeroing it.
That’s so unfair, my brother simply installed a system of backup with stationary batteries and is now off grid.
What’s unfair about it?
Solar will drive the price of electricity 0-3pm to zero, everywhere with bright sun.
Nighttime, not so much.
Electric transmission is also not free.
Here in California, 20 years ago, a small power line to a new location in the woods was $10,000 per pole.
Surely twice that now, likely much more.
Your bother voted with his feet so to speak.
Which is fair, but also not free.
Im betting hes mistaken and its LPG.
Approximately 90.48 pounds of natural gas can be stored in a 16 foot long, 4 foot diameter tank at 3600 psi It is not feasible or economical to have 90 pounds of compressed natural gas (CNG) delivered for a typical residential application. A delivery of this size is extremely small for bulk transport.
A 16-foot long, 4-foot diameter tank is the equivalent to a 1000-gallon propane tank, can store approximately
3,360 to 3,600 pounds of LPG. A 1000-gallon propane tank, when full, can last between 6 months to over a year for a house, depending on usage, climate, home size, and appliance efficiency. This is a very common size for home delivery.
You slipped at least a decimal point on that tank capacity. Try again.
What kind of house burns 1000 gallons of propane in a 6 months or even a year? That’s 27 megawatt-hours!
My house is all gas: furnace, water heater, clothes dryer, kitchen stove and fireplace. It’s also 100 years old and not exactly the paragon of energy efficient insulation. Anything that needs heat here, it comes from gas. Last year I went through 1900 cubic meters = 19 megawatt-hours. Around the Great Lakes it’s not Alaska level cold here, but we still get real winters.
So where burns 1000 gallons in a year? A drafty farmhouse in North Dakota?
Feel free to correct my math.
V=π(4/2)²X16=201.06ft³
For compressed natural gas (CNG) at 3600 psi, a typical density value is approximately 0.45lb/ft³
201.06ft³ X 0.45lb/ft³ = 90,48 pounds of natural gas
https://www.pinnaclepropane.com/propane-tanks/find-the-right-propane-tank/1000-gallon
The amount of time a full 1000-Gallon propane tank lasts varies depending on usage:
6-12 months on average for households using multiple propane appliances.3-6 months in cold weather when homes rely on propane heating.
8-12 months in mild climates or when only using propane for specific appliances.
https://www.superiorpropane.com/about-superior-propane/blog/what-size-tank-do-i-really-need
A 1000-gallon propane tank provides space heating, cooking, hot water, pool heating, back up power and more for small businesses, commercial properties, or some large homes and can last up to 8 months or longer depending on applications and consumption patterns. This tank size is best suited for businesses that require a significant amount of propane for heating large spaces or operating numerous propane-powered appliances.
https://www.symankenergy.com/blog/how-long-will-my-propane-last/
You can pretty safely estimate that a 2,220 square foot house runs through about 700 to a little over 1,000 gallons of propane a year.
“For compressed natural gas (CNG) at 3600 psi, a typical density value is approximately 0.45lb/ft³”
Where did that come from? Density of natural gas at 3600 psi (24 MPa) is more like 13 lb/cu.ft (206 kg/m^3), 28 times the number you were given.
Your calculation also is for a flat-end tank. You’ll find it difficult to find a flat-ended tank to hold 3600 psi gas. Actually, you’ll find it difficult to find a tank of that size to hold 3600 psi, period. It would require 4 inch thick walls and would weigh in excess of 10 tons.
You are correct that I made a mistake on the density, I had 180-215 kg/m³ at 200-250 bar (around 2900-3625 psi) pulled up as a reference but neglected to plug it in correctly. ~2500# of CNG is more reasonable for delivery, HOWEVER, high-pressure CNG delivery is generally reserved for commercial or industrial customers. Its pretty rare to find a company that will service a residential customer.
The difference in volume between a pure cylinder and a normal tank isnt significant enough to be bothered with the maths to account for the rounded ends. You arguing that point is ridiculous.
A fairly modern home in Northern Wisconsin can easily go through well over 1000 gallons of propane per year.
Leaving aside the fact that Lead Acid is a lot safer, with minimal downsides of ventilation. The weight and size are usually not a big issue, and they are very recyclable, in fact they are the epitome of recycling gone properly.
Sizing it is another issue, need to make sure it isn’t drawn too low. So you need an accurate measurement of your solar production and longest draw off production.
Although a used Nissan Leaf pack is mighty tempting when the whole car is $2