5 ms·

I don't understand the discrepancy between EV kWh and house battery kWh. Some cars have > 100 kWh capacity. Why do I pay > 1000$ per kWh for a house battery? A

I don't understand the discrepancy between EV kWh and house battery kWh. Some cars have > 100 kWh capacity. Why do I pay > 1000$ per kWh for a house battery? At some point it is cheaper to just buy a car, even if you would never drive it. A Tesla Powerwall has 13 or so kWh? Why don't they use the car battery with nearly 10 times as much capacity? It is just unit prices that are far better for cars? Is the charge/discharge speed relevant? Is the technology different? Are the capacities for cars just fake? Preferably I would want 200kWh or more capacity for my home.

sgerenser 4y ago
House batteries are a much smaller market than batteries for EVs (at least right now). They also have other supporting components, safety features, etc. that add to the price. Since they’re normally installed as part of a solar install, they also usually qualify for a tax credit (between federal and state this can be over 50%) which further drives up the price because the vendor is able to capture a large chunk of the tax credit as profit.
- zihotki 4y ago
  Actually they require less safety features (they don't need to be crash-safe) and can use heavier batteries and components. Which should make them cheaper than EV's batteries in theory. But that market is in early stages with all associated downsides of early adoption, I agree with that.
  - boringg 4y ago
    There are other features for a home battery. There are shutoffs. Each job is a bit custom on the install + electrician work. Retail markup. You can use your car battery - though you will degrade that car battery much faster which is probably the battery you want to have better performance.
- AtlasBarfed 4y ago
  That's a failure of government with home solar. Home solar + storage adds community-level resiliency in disasters and will reduce the grid load needed for home EV charging and industrial level charging used by electric tractor trailers. It should be a major complimentary effort of governmental policy along with grid scale solar/wind, grid scale storage, and whatever load leveling we can effectively decarbonize. Good luck getting that through our deadlocked government. Especially since
discordance 4y ago
$300/kWh for home storage is readily available. E.g. https://signaturesolar.com/eg4-ll-lithium-battery-24v-200ah/ https://signaturesolar.com/eg4-ll-lithium-battery-24v-200ah/
- raxxorraxor 4y ago
  True, there are better prices by now. But 5kWh? I thought my smartphone would have that by now... Perhaps 200kWh is a bit exaggerated. And yes you also need a good quality inverter for your home that synchronizes with the net, but I actually don't believe this to be expensive high tech... Ideally I wouldn't want to put the energy I generate with solar, wind or differently back into the power net. In my country you basically give that away for free. There are reasons for that, but the most efficient way would be to use the energy yourself as much as possible. Sure, 5kWH is enough to soften peaks and there could already be huge benefit to this. But a bit more capacity would be really nice to really safe the energy of sunny days. Reminds me if disappointing USPs that let me play Tetris for an additional 7-8 minutes before I feel like civilization has broken down completely until power comes back.
  - vbezhenar 4y ago
    Phone battery is something like 4V. Watts depend on voltage. I guess home batteries use other voltage so their watt actually provides more electricity.
    - raxxorraxor 4y ago
      No, Watts should be independent of voltage, it is the product of voltage and ampere (don't know the exact English terms here). You perhaps mean ampere hours, I think that is often used for phones. But it is only ever meaningful if you have the respective fixed voltage and it often make sense for a batteries to quickly calculate how long they should last if you know how much ampere a device draws. It could also become a sensible metric if we always talk about 120V/240V for general household appliances of course.
      - 4y ago
deleted 4y ago
[deleted]
Schroedingersat 4y ago
Part of it is cars get a bunch of free tax money, but most of it is that cars were at the front of the queue and locked prices in ahead of time (before the self same orders pushed prices up) and they have actual pressure to compete. There are cheaper products, but reliability and trustworthyness is an issue. A good budget offering may decide to sell out their rep or start charging premium prices. Budget offerings are about $250/kWh right now, or there are some for about $350 with cold weather protection. In a few more years markets will mature a little and the price gap will be smaller.
- AtlasBarfed 4y ago
  They had better, with 230 wh/kg LFP and 150 wh/kg lithium-free sodium ion coming to mass production, and those chemistries are far safer than nickel/cobalt chemistries because they don't catch on fire, the "OEM" cost of a large battery pack will certainly drop under 100$/kWh, if it already hasn't. With sodium ion the cost should drop to 50$/kWh. I guess what might happen in a decade or so with EVs with "obsolete" batteries in the used market is that you just get a used EV and you have a powerwall and a secondary/tertiary city car.
  - Schroedingersat 4y ago
    What a wild and ironic twist if we actually get some increase in transit use because leaving the car at home pays for the ticket.
Isinlor 4y ago
Tesla is supply limited, so they can put prices high. That's probably about it.
sharemywin 4y ago
State level regulations around installation driving up prices?
- deleted 4y ago
  [deleted]
- danans 4y ago
  Nope, not that. See my sibling response above.
ajross 4y ago
House batteries are never purchased in isolation. They're what amounts to a luxury add-on to a much bigger solar system, so you'd expect to see a "markup". That may change with the recent rollback of net metering in CA, which is making a battery system a requirement to reach break even on cost.
- danans 4y ago
  > That may change with the recent rollback of net metering in CA, which is making a battery system a requirement to reach break even on cost. NEM3.0 doesn't make a battery a requirement to break even on costs, it just extends the payback time of solar without batteries by 3-5 years. It reduces the still absurdly long payback time of home battery storage somewhat, though. Only when you can sell power back to the grid with batteries at peak wholesale rates will batteries have anything like solar's payback time.
  - ajross 4y ago
    I've seen a lot of different numbers thrown around (and to be clear: I'm in Oregon and not part of the fight). Let it suffice that NEM3.0 makes the relative benefits of a battery for time shifting (and thus the costs of a solar system without a battery, as was typical for early installations) much, much higher.
    - danans 4y ago
      I guess it depends on the rate structure you have. Higher rate variance between off and on peak periods definitely helps with the economic case for batteries, since it offers an arbitrage opportunity. I haven't done the math yet to figure out how that variance relates to payback time for batteries, but would be a fun exercise.
AtlasBarfed 4y ago
Either Chinese companies are reaping huge profits on batteries, or the American companies that repackage them into their bespoke platforms (EGo batteries don't work with greenworks or ryobi AFAIK because they put different plastic shapes around the battery cells so you're locked into their ecosystem for example) are reaping the profits. Hopefully, 200-230 wh/kg LFP and 150 wh/kg sodium ion batteries should be a revelation in all use cases of batteries in the next year or so. Tesla gets to operate at the extremes of volume, so they get to demand the best prices I would imagine, but the markup still seems astronomical in other things (like tools, home powerwalls, etc). IMO there needs to be some governmental nudge. Battery prices (in theory) should be dropping in price such that many ICE-based tools will be fundamentally cheaper as batteries. An electric lawnmower shouldn't be more expensive than a very very dirty two stroke ICE lawnmower with the LFP/Sodium Ion that is coming to market. But a lot of electric tool makers are using the reduced sound and superior torque abilities of electric tools as a price premium product. Things like lawnmowers and leaf blowers and snow blowers being high performance electric tools is like a "starter EV" for millions of Americans: it teaches them about recharging batteries, how EVs are better than ICEs in many ways (quieter, better torque, less smelly, no gasoline to spoil over winter) and how to deal with the annoyances (recharging).
fsh 4y ago
The explanation is quite simple. Electricity from the grid is still very cheap. It therefore makes no economical sense to buy huge batteries for buffering your home solar panels. Since there is no demand, there are no products.
csours 4y ago
My guess is supply constraints. Tesla would rather sell cars than Powerwalls; other suppliers can't make a dent in the market because EVs are slurping up all the capacity at every level of the supply chain. This really is only a guess though.
danans 4y ago
As someone who recently self-installed home batteries (LiFePo), I learned quite a bit about what drives up prices. It's not regulation. If anything state incentives in California can drive down the prices (if you qualify for them), and federal incentives drop the price by 30%, thanks to the Inflation Reduction Act. In my experience, the big cost with home batteries are the same things that make artisinal custom designed and built homes expensive: the labor cost of the complex system design, installation and integration, and the premium charged because they are still marketed as a luxury product, not as a basic home appliance. Why the complexity? It should be easy to install batteries on a house, right? In reality, every house has an idiosyncratic set of challenges and decisions that need to be made when integrating battery storage: What loads do you want to back up, and for how long? Where will the backup sub-panel be installed, and how can the backup circuits be routed to it? Where is a safe location for the battery and the automatic transfer switch to be installed? They are all answerable, but there is no general solution and each one is on a case-by-case basis. And yes, this all does have to meet electrical codes (which exist for a reason), and needs sign-off by local building authorities, but they are not the main cost obstacle any more than they are for any major electrical upgrade to a house. Take away the "luxury premium" part, and this also explains why home rooftop solar will always be much more expensive on a per-watt basis than utility scale solar (and yes, utility scale solar doesn't include the cost of transmission, as with any grid scale generation source). Compare that to an EV, where thousands are assembled with predefined requirements, a known set of inputs, all in a purpose built environment (a factory). And even better, they come with a standard plug interface that we can use to send power back to the house or the grid! But hold on: if you want power when the grid goes down, you're going to need an islanding transfer switch and perhaps decide which loads to back up. I mean, do you really want to run your 40A jacuzzi heater or your 50A air conditioner off you car battery? In an ideal future, every house would be built with a standard connector (analogous to USB for phones or EV charger standards) that you could just plug a stationary storage system into. The houses would also be built to include an automatic transfer switch that islands the house during a power outage, and a smart load panel that dynamically decides what loads to back up based on battery capacity and user preferences. But right now, no such standards exist, and no house is built from the start that way, so everything is an expensive retrofit.
theshrike79 4y ago
Car manufacturers are buying every battery they can. If we reach a point where there is an actual secondary market for used EV batteries, the house battery market will start to boom. But 10+ year old batteries are still 85-90% healthy mostly, so it might take a while...

sgerenser 4y ago

House batteries are a much smaller market than batteries for EVs (at least right now). They also have other supporting components, safety features, etc. that add to the price. Since they’re normally installed as part of a solar install, they also usually qualify for a tax credit (between federal and state this can be over 50%) which further drives up the price because the vendor is able to capture a large chunk of the tax credit as profit.

zihotki 4y ago
Actually they require less safety features (they don't need to be crash-safe) and can use heavier batteries and components. Which should make them cheaper than EV's batteries in theory. But that market is in early stages with all associated downsides of early adoption, I agree with that.
- boringg 4y ago
  There are other features for a home battery. There are shutoffs. Each job is a bit custom on the install + electrician work. Retail markup. You can use your car battery - though you will degrade that car battery much faster which is probably the battery you want to have better performance.
AtlasBarfed 4y ago
That's a failure of government with home solar. Home solar + storage adds community-level resiliency in disasters and will reduce the grid load needed for home EV charging and industrial level charging used by electric tractor trailers. It should be a major complimentary effort of governmental policy along with grid scale solar/wind, grid scale storage, and whatever load leveling we can effectively decarbonize. Good luck getting that through our deadlocked government. Especially since

discordance 4y ago

$300/kWh for home storage is readily available. E.g. https://signaturesolar.com/eg4-ll-lithium-battery-24v-200ah/ https://signaturesolar.com/eg4-ll-lithium-battery-24v-200ah/

raxxorraxor 4y ago
True, there are better prices by now. But 5kWh? I thought my smartphone would have that by now... Perhaps 200kWh is a bit exaggerated. And yes you also need a good quality inverter for your home that synchronizes with the net, but I actually don't believe this to be expensive high tech... Ideally I wouldn't want to put the energy I generate with solar, wind or differently back into the power net. In my country you basically give that away for free. There are reasons for that, but the most efficient way would be to use the energy yourself as much as possible. Sure, 5kWH is enough to soften peaks and there could already be huge benefit to this. But a bit more capacity would be really nice to really safe the energy of sunny days. Reminds me if disappointing USPs that let me play Tetris for an additional 7-8 minutes before I feel like civilization has broken down completely until power comes back.
- vbezhenar 4y ago
  Phone battery is something like 4V. Watts depend on voltage. I guess home batteries use other voltage so their watt actually provides more electricity.
  - raxxorraxor 4y ago
    No, Watts should be independent of voltage, it is the product of voltage and ampere (don't know the exact English terms here). You perhaps mean ampere hours, I think that is often used for phones. But it is only ever meaningful if you have the respective fixed voltage and it often make sense for a batteries to quickly calculate how long they should last if you know how much ampere a device draws. It could also become a sensible metric if we always talk about 120V/240V for general household appliances of course.
    - 4y ago

deleted 4y ago

[deleted]

Schroedingersat 4y ago

Part of it is cars get a bunch of free tax money, but most of it is that cars were at the front of the queue and locked prices in ahead of time (before the self same orders pushed prices up) and they have actual pressure to compete. There are cheaper products, but reliability and trustworthyness is an issue. A good budget offering may decide to sell out their rep or start charging premium prices. Budget offerings are about $250/kWh right now, or there are some for about $350 with cold weather protection. In a few more years markets will mature a little and the price gap will be smaller.

AtlasBarfed 4y ago
They had better, with 230 wh/kg LFP and 150 wh/kg lithium-free sodium ion coming to mass production, and those chemistries are far safer than nickel/cobalt chemistries because they don't catch on fire, the "OEM" cost of a large battery pack will certainly drop under 100$/kWh, if it already hasn't. With sodium ion the cost should drop to 50$/kWh. I guess what might happen in a decade or so with EVs with "obsolete" batteries in the used market is that you just get a used EV and you have a powerwall and a secondary/tertiary city car.
- Schroedingersat 4y ago
  What a wild and ironic twist if we actually get some increase in transit use because leaving the car at home pays for the ticket.

Isinlor 4y ago

Tesla is supply limited, so they can put prices high. That's probably about it.

sharemywin 4y ago

State level regulations around installation driving up prices?

deleted 4y ago
[deleted]
danans 4y ago
Nope, not that. See my sibling response above.

ajross 4y ago

House batteries are never purchased in isolation. They're what amounts to a luxury add-on to a much bigger solar system, so you'd expect to see a "markup". That may change with the recent rollback of net metering in CA, which is making a battery system a requirement to reach break even on cost.

danans 4y ago
> That may change with the recent rollback of net metering in CA, which is making a battery system a requirement to reach break even on cost. NEM3.0 doesn't make a battery a requirement to break even on costs, it just extends the payback time of solar without batteries by 3-5 years. It reduces the still absurdly long payback time of home battery storage somewhat, though. Only when you can sell power back to the grid with batteries at peak wholesale rates will batteries have anything like solar's payback time.
- ajross 4y ago
  I've seen a lot of different numbers thrown around (and to be clear: I'm in Oregon and not part of the fight). Let it suffice that NEM3.0 makes the relative benefits of a battery for time shifting (and thus the costs of a solar system without a battery, as was typical for early installations) much, much higher.
  - danans 4y ago
    I guess it depends on the rate structure you have. Higher rate variance between off and on peak periods definitely helps with the economic case for batteries, since it offers an arbitrage opportunity. I haven't done the math yet to figure out how that variance relates to payback time for batteries, but would be a fun exercise.

AtlasBarfed 4y ago

Either Chinese companies are reaping huge profits on batteries, or the American companies that repackage them into their bespoke platforms (EGo batteries don't work with greenworks or ryobi AFAIK because they put different plastic shapes around the battery cells so you're locked into their ecosystem for example) are reaping the profits. Hopefully, 200-230 wh/kg LFP and 150 wh/kg sodium ion batteries should be a revelation in all use cases of batteries in the next year or so. Tesla gets to operate at the extremes of volume, so they get to demand the best prices I would imagine, but the markup still seems astronomical in other things (like tools, home powerwalls, etc). IMO there needs to be some governmental nudge. Battery prices (in theory) should be dropping in price such that many ICE-based tools will be fundamentally cheaper as batteries. An electric lawnmower shouldn't be more expensive than a very very dirty two stroke ICE lawnmower with the LFP/Sodium Ion that is coming to market. But a lot of electric tool makers are using the reduced sound and superior torque abilities of electric tools as a price premium product. Things like lawnmowers and leaf blowers and snow blowers being high performance electric tools is like a "starter EV" for millions of Americans: it teaches them about recharging batteries, how EVs are better than ICEs in many ways (quieter, better torque, less smelly, no gasoline to spoil over winter) and how to deal with the annoyances (recharging).

fsh 4y ago

The explanation is quite simple. Electricity from the grid is still very cheap. It therefore makes no economical sense to buy huge batteries for buffering your home solar panels. Since there is no demand, there are no products.

csours 4y ago

My guess is supply constraints. Tesla would rather sell cars than Powerwalls; other suppliers can't make a dent in the market because EVs are slurping up all the capacity at every level of the supply chain. This really is only a guess though.

danans 4y ago

As someone who recently self-installed home batteries (LiFePo), I learned quite a bit about what drives up prices. It's not regulation. If anything state incentives in California can drive down the prices (if you qualify for them), and federal incentives drop the price by 30%, thanks to the Inflation Reduction Act. In my experience, the big cost with home batteries are the same things that make artisinal custom designed and built homes expensive: the labor cost of the complex system design, installation and integration, and the premium charged because they are still marketed as a luxury product, not as a basic home appliance. Why the complexity? It should be easy to install batteries on a house, right? In reality, every house has an idiosyncratic set of challenges and decisions that need to be made when integrating battery storage: What loads do you want to back up, and for how long? Where will the backup sub-panel be installed, and how can the backup circuits be routed to it? Where is a safe location for the battery and the automatic transfer switch to be installed? They are all answerable, but there is no general solution and each one is on a case-by-case basis. And yes, this all does have to meet electrical codes (which exist for a reason), and needs sign-off by local building authorities, but they are not the main cost obstacle any more than they are for any major electrical upgrade to a house. Take away the "luxury premium" part, and this also explains why home rooftop solar will always be much more expensive on a per-watt basis than utility scale solar (and yes, utility scale solar doesn't include the cost of transmission, as with any grid scale generation source). Compare that to an EV, where thousands are assembled with predefined requirements, a known set of inputs, all in a purpose built environment (a factory). And even better, they come with a standard plug interface that we can use to send power back to the house or the grid! But hold on: if you want power when the grid goes down, you're going to need an islanding transfer switch and perhaps decide which loads to back up. I mean, do you really want to run your 40A jacuzzi heater or your 50A air conditioner off you car battery? In an ideal future, every house would be built with a standard connector (analogous to USB for phones or EV charger standards) that you could just plug a stationary storage system into. The houses would also be built to include an automatic transfer switch that islands the house during a power outage, and a smart load panel that dynamically decides what loads to back up based on battery capacity and user preferences. But right now, no such standards exist, and no house is built from the start that way, so everything is an expensive retrofit.

theshrike79 4y ago

Car manufacturers are buying every battery they can. If we reach a point where there is an actual secondary market for used EV batteries, the house battery market will start to boom. But 10+ year old batteries are still 85-90% healthy mostly, so it might take a while...