The thing is LFP or Sodium ion are both expected to have 5000+ useful cycles soon (or possibly even in production now). This means even if you use one full discharge overnight , this is like 15+ years of life of the battery, although I suspect calendar degradation will be much faster.
Higher the cycle life, lower the levelised cost of storage and this is what matters in my opinion. Best is to have some type of long term storage like a Diesel generator only for estimated 1-2 weeks of the year depending on location where it will be needed.
I feel V2G with 3 days backup and a house low power mode which can be utilised in emergencies might solve even this issue.
Oversizing solar to the extent possible for winter loads is also ideal because so far that does not seem to be the driving cost.
> Best is to have some type of long term storage like a Diesel generator
LNG or propane would be far superior fuel types for long term standby generators. Periodically exercising a machine that runs on CH4 results in very minimal buildup on internal components. Liquid fuels are much dirtier and can also go bad.
Diesel is used in situations where you can afford all of the crazy maintenance. It's worth the trade off if you can.
No, LFP is 8k-12k cycles, and sodium are expect to be 15k to perhaps 20k cycles. This is reflected in the manufacturer warranties, and many sources. Here's one:
that makes calendar aging the limiting factor even more. I feel that so many cycles can also aid in smoothing solar & wind (at turbine level) output and increase their utility.
I feel that long term energy storage will be split between thermal and non thermal in interesting ways and the market for them will open up after first level of daily disruption
20,000 daily cycles if 55 years. 10,000 daily cycles is 27 years. The expected usage case for these batteries is near daily usage.
I hadn't really thought about thermal tech in such extreme terms until your comment, but to me it appears to be the tape storage of our times. There will always be a fair amount of infrastructure hidden that almost nobody knows about, but it's going to be dwarfed in active usage by HDDs or SDDs.
The tech advantages really are that big for batters and other solid state energy tech over the moving parts thermal variety. Thermal tech hasn't had an upgrade like LTO-6 (or is it 7 now) and is pretty much at the end of its possible engineered capabilities, but batteries are just barely getting started on what they are capable of.
The article here concludes with one year long cycle, of the 1MW battery. There's some draw down even on the charge down, but a couple kWh against a 1MW pack is not super super notable. If it were cycle count alone degrading battery it'd still be an almost 5000 year battery (before becoming a 0.8MW battery).
As others are pointing out, we have stabilized chemistries even more, so 5k cycles is pretty low at this point.
Why go for a bigger battery when you can just put more panels on the roof to cover those winter days and waste the power the rest of the year?
I suspect the answer is somewhere in the middle - maybe two weeks of storage. Though of course prices change all the time so the correct action will change and you need to rerun the numbers as things degrade to decide your next action.
(Author here) My roof is full on both sides. There simply isn't any more room.
I do say:
> As solar panels increase in efficiency, it might be more sensible to replace the panels on my roof, or add some onto a shed.
Even in the darkest days of winter, they still generate something (unless they're physically covered in snow) - but they'd need to be 20x as efficient to power my typical winter usage.
In our part of the world, solar production during winter is incredibly low or 0 due to it being very cloudy, days being much shorter, sunlight angle on the panel very suboptimal. No amount of additional panels will get you through that streak.
It also depends somewhat on how much energy you use. I live in the Netherlands where everytime I bring it up, I'm told "that's just not possible, you will never make enough in winter", but these same people have no idea how much energy I use. On a bad day, I use maybe 10kWh and that's running the AC with the thermostat set to 19c overnight and a bit during the day at 22c. I don't have a giant fridge, I don't have any gaming PCs slurping 200W on standby, etc. My baseline usage is around 300-400W to run the old freezer that never turns off (70W), my network equipment, a fan in the garage to prevent moisture buildup, and some lights.
My 1.8kWh system at 20% output covers a great percentage of my baseline usage during the day! I'm probably going to add a small battery so I'm not penalized for sending energy back to the grid, but I'm not gonna need much until my kids get older and want new gadgets. The cool part about modern electronics is that we're generally getting more efficient too with newer tech. If I replace the old freezer, my baseline usage drops 20%+.
I don't disagree with your point that sometimes nature is simply just working too hard against your efforts, but I also wrote all this to say that some people need to really do the math and not rely on "common knowledge". Energy efficiency has come an extremely long way in the past decade and much of what was true when residential solar first started popping off is now outdated.
while that's true, getting close has major benefits. adding extra capacity for the winter also adds capacity for fall and spring. that production will reduce how many weeks the battery is needed for
Storing energy from the summer for the winter is a really inefficient way to do it. It's much better to massively over-provision the solar so you have enough energy - on average - for the winter. Then you only need a couple of week's worth of storage to account for extended cloudy periods.
Much cheaper, and you get a ton of extra free power in the summer. The only downside is a typical house roof doesn't have enough space. But a typical house doesn't have enough space for a 1 MWh battery either so...
I think this is something that may happen in the next decade.
The interesting impact will be on the grid itself. Why connect to the grid if you are self-sufficient?
Then the grid starts to degrade due to lack of maintenance, and the people that can't afford local storage become dependent essentially on a government maintained service.
Or should we be planning localized storage and grids at the same time, so we get the benefits of both scale and resiliency and redundancy.
People will be parking a mobile 100kWh battery at their house every night. We need integrated V2G and grid upgrades to make the most of this opportunity.
> Then the grid starts to degrade due to lack of maintenance, and the people that can't afford local storage become dependent essentially on a government maintained service.
Many services that we use in our daily lives are government maintained services, so electricity is no different than water, sewage, internet, roads, railroads, post, emergency services, public education, public health systems, trash and recycling services, parks and recreational spaces, disaster relief and response, and others.
We should absolutely ensure these services continue to be funded and maintained, because they're often not profitable to deliver. Especially to the sprawling population of the United States. That’s exactly why government support exists and should exist: to guarantee access to essential services that markets alone won’t reliably or equitably provide.
There's a certain type of person who fantasizes about being off-grid, but the few that actually live it know the hassle and generally want to get back on if feasible.
Battery costs might go down, but the space they take up on your property costs money as well, which only gets more expensive the more urban you are.
The island of Eigg has a micro-grid. Not individual houses, a micro-grid.
The UK is going to be a wind power island not a solar power island, and definitely not an individual solar power island.
I do not think this will happen. Getting most households to be self-sufficient is probably not as cost effective as centralized grid. One there's the economy of scale. Second, any peaks and troughs will generally be balanced out between households and the overall buffer (aka reserve) needed could be lower.
> Why connect to the grid if you are self-sufficient?
I think that starts to bleed into the "pre paid meter" vs contract argument.
but practically the difference between total self sufficiency and 90% is willingness to fork out cash.
I currently have a 13kwhr battery, which covers my domestic power needs for 75% of the year. (we'll start to draw on the grid in the next few weeks.) but in the dead of winter it'll only cover 20-50% of my daily need (excluding the car)
but for car power, thats a different beast. Even though I don't commute by car, with the charging at home, I now use around the same amount of power as the uk average house. (even with solar and storage. pre electic car era. )
If local storage becomes cheaper than the grid but some people can’t afford it (why, capital costs?) then the government would be better off addressing those capital costs directly.
However, you need to consider industrial and commercial use as well as domestic. Can you power a smelter using local solar?
I'm fully off grid today with no issues, even had power company remove power poles. I do heat with wood however. AC in the summer is no issue since that is when I get the most sun anyways.
This doom-loop is often repeated, but reality is far more complicated.
Very few people go fully off-grid, reality is people don't want that. Cost/benefit just isn't there unless you live off in the woods.
So instead, market structures react when penetration % becomes non-neglible. First you start seeing things like fixed-fees (minimum prices to maintain a grid connection, or "first x kWh are included"). And then you start seeing like what's in California with NEM3: the grid-export prices drop to "we don't want your excess solar" so people are incentivized to buy batteries. But because batteries make a system more complicated and expensive, people buy smaller systems overall.
So the "too much solar creates a disconnection spiral and the system falls apart" thing is a bit of fear-mongering. The system adapts, the changes in pricing create different cost/benefit ratios, and if nothing else, new AI datacenters will gobble up any power that doesn't need to flow to neighborhoods.
Something that isn't spoken about enough is that in developed Western countries, grids are actually significantly oversized due to reductions in electricity usage over time [1]. That link says 16% over, but the peak demand in the UK in 2024 was actually only 45MW [2], which I make more like a 30% reduction from the all-time peak.
Because of this, it feels like we should already have enough transmission capacity in a decent part of the network to cope with a re-organisation of where the sources and sinks are placed. Yes, we might need to do some work in the last mile, especially if V2G takes off, but things aren't nearly as bad as one might naively assume.
The trouble is the capacity is in the wrong place; the UK closed coal plants in (defunct) coalfields in the middle of the country, and built offshore wind farms which tend to be further north. There's plans for an offshore north-south connector to help with this.
Balcony solar is absolute awesome in germany. I get about 30% return on investment per year on my small solar panel. Hard not to do it. I have no idea why it is still a little niche
That's just low hanging fruit, the easiest and cheapest way to produce some solar power. But even if fully utilized, that is not going to come anywhere close to meeting most households' needs.
You forgot to mention anybody who has a yard that gets full sun can mount panels there as well. As far as fires you can say same thing about all the fires that currently occur because of propane, gas, and heating oil. Those have become some engrained in society for so long that you don't even think of that as a "fire hazard therefore you shouldn't even have it".
Solar and renewables alone don't make a grid. You would also need grid-scale batteries, and the cost is not the same.
The "improvements" in power transmission is about building more lines, these lines are not going to be significantly cheaper to maintain than previous generations, and if these investment/maintenance costs are shared among less, that means more expensive electricity. Currently, in my country, electricity transport and distribution are about one third of total cost.
You have to consider that electricity will be 3x over the next 50 years (for transportation and heating). So we are currently building out a lot of extra infrastructure.
Grid scale batteries will also primarily reduce cost by offering arbitration.
In case you didn't realize he is looking to store ALL of the summer generation into a battery and generate zero power in winter.. so rely entirely off of a battery during winter.. which is absolutely no feasible for a normal person and nobody would ever do.
I always thought about this myself in terms of personal sized long term, high density energy storage. Compressed hydrogen with a fuel cell is the obvious solution. Excess electric is used in a electrolysis cell and a matched compressor fills a bank of storage cylinders. More cylinders = more storage. Though likely very inefficient with a risk of fire or explosion.
Are there any other long term high density electric storage technologies that can fit in someones basement, garage, or even apartment closet?
> Compressed hydrogen with a fuel cell is the obvious solution.
To achieve volumetric energy density of hydrogen at room temperature that's on par with batteries (and that's charitably assuming you're using inefficient resistance heating with batteries) you need to store it at a pressure in the order of 100 bar.
You're better off with batteries realistically speaking.
Compressed hydrogen is no joke. It can escape most containers, actively degrades many grades of steel, has a very low ignition energy, and will explode over an enormous range of air/fuel ratios. Definitely not something to keep anywhere where you care about the roof :)
An odd thing about this article is that it ignores the deeper question: what balance of solar over-provisonioning + battery would most cost-effectively cover anticipated yearly needs?
I suspect that something like 3x'ing the solar (under 100k) would then let the author get away with much, much less battery, and result in a net cost savings.
Yeah seems like a relatively simple maths/econ problem to solve for, given some parameters like local solar power per m2 in the various seasons, electricity use in the various seasons and time of the day, and LCOE of solar and battery storage.
My guess is the differences in either choice aren't huge, as both solar and battery storage keeps getting cheaper.
Having an electric vehicle can really help, also. It basically soaks up excess solar power of an outsized installation during much of the year (making the payback time on the outsized installation very good), and can be charged away from the house during a few low-chance bad winter days when the outsized installation is enough to power the house but not the car. Electric cars are charged fully about 3 times per month on average in the US, so working around that with smart charging is not a complex challenge in the next decade.
Pretty quickly. There's also a point where it becomes a serious explosion risk too.
Every other fire you can stop if you're right there and you catch it. If a battery pack starts to go, you might have a few seconds before the local environment is incompatible with life.
The cars in people's garages are far bigger fire risks. For example it's not uncommon to have a 70kWh+ EV battery, and the chemistries used to get the extra energy density for cars are far more unstable.
LFP (rarely used for cars) is fairly stable. And sodium batteries are even more stable.
Not all battery technology is as volatile as Lithium-Ion or Lithium Polymer, LiFePO4 for example isn't subject to thermal runaway, nor are some of the Sodium-Ion batteries (although it's dependent on the exact chemistry being used).
Assuming heating oil is diesel, it's not very flammable and not a huge fire hazard. Soil pollution from leaks and spills seems like a bigger concern there. But I guess some people have large tanks of LPG which might be a bigger danger?
I'm sure it would be much more cost-effective to have community storage, rather than individual storage, and it would balance the load a lot if some users used more power during th day than at night.
Of course then you have the collective action problem, and convincing your neighbors that grid storage is actually a real thing that exists. And that grid storage is not of the wrong political partisanship. The box of what's considered "politically incorrect" is getting fairly large these days:
Snark aside, there are examples of community-scale energy infrastructure below grid-scale: see "district heating" and "co-gen plants". Sand battery people have been experimenting with neighborhood-scale infrastructure (though industrial heat uses is a better return on that tech right now)
EV battery capacity is expected to grow to 100kWh.
People will park them at home every night, and probably somewhere with a charging point during the day.
Smart house energy management should be able to pick up on that usage pattern and use the car battery for the house while making sure the car is kept ready for use.
In the same way that wifi/mobile/satellite comms can keep us "always connected", the changes in power generation and storage are going to keep us "fully charged".
In the UK you'd need a class D "loi-sonce" to be able to pull the shipping container sized battery trailer for that to work.
However, if you were wanting to use pure lead acid batteries for your house, because you'd be doing slow charge/discharge you'd probably be able to get away with just 1100 130ah lead acid car batteries.
I mean you'd be optimising for peak current, which isn't what you'd want. However it could be interesting to see what happens when you have ~500mega Amps at 48v. (24Mw would heat your radiators up pretty quick. )
for lithium, then you'd need 12-14 secondhand tesla/polstar batteries, which if they caught fire, might be a challenge to contain.
Did you take into account that lead acid batteries are recommended to only be discharged to 50% especially when used for solar ? If not thats now 2200 batteries and $200-$400K.
Not even close. A typical electric split will take 12a to maintain and that is just the heating/cooling system. Car batteries are meant for starts, not maintenance flow.
That is a trick question designed to make people argue and feel like there is some science or math to it. There is not. Nobody here can accurately predict weather far out enough to be a factor in this decision. The truth will vary by demand by family which may have variability throughout the year or decade. Another variable is the number of cloudy days which will vary as climate changes.
The answer is somewhere in the neighborhood of as much as one can safely store and afford accepting that batteries have a short life. Much like wells in cold climates the batteries should be in an underground insulated vault made from higher quality concrete as to keep fire hazards away from the home. That is also where whole-home generators and fuel belong, in their own vault so they can be easily maintained without having to rent an excavator to dig out the tank.
Even on cloudy days you can generate power. Unless it is very thick clouds I generate enough for my base loads even in complete overcast skies because I have an "excess" of PV panels.
The thing is LFP or Sodium ion are both expected to have 5000+ useful cycles soon (or possibly even in production now). This means even if you use one full discharge overnight , this is like 15+ years of life of the battery, although I suspect calendar degradation will be much faster.
Higher the cycle life, lower the levelised cost of storage and this is what matters in my opinion. Best is to have some type of long term storage like a Diesel generator only for estimated 1-2 weeks of the year depending on location where it will be needed.
I feel V2G with 3 days backup and a house low power mode which can be utilised in emergencies might solve even this issue.
Oversizing solar to the extent possible for winter loads is also ideal because so far that does not seem to be the driving cost.
> Best is to have some type of long term storage like a Diesel generator
LNG or propane would be far superior fuel types for long term standby generators. Periodically exercising a machine that runs on CH4 results in very minimal buildup on internal components. Liquid fuels are much dirtier and can also go bad.
Diesel is used in situations where you can afford all of the crazy maintenance. It's worth the trade off if you can.
No, LFP is 8k-12k cycles, and sodium are expect to be 15k to perhaps 20k cycles. This is reflected in the manufacturer warranties, and many sources. Here's one:
https://www.volts.wtf/p/whats-the-deal-with-sodium-ion-batte...
that makes calendar aging the limiting factor even more. I feel that so many cycles can also aid in smoothing solar & wind (at turbine level) output and increase their utility.
I feel that long term energy storage will be split between thermal and non thermal in interesting ways and the market for them will open up after first level of daily disruption
20,000 daily cycles if 55 years. 10,000 daily cycles is 27 years. The expected usage case for these batteries is near daily usage.
I hadn't really thought about thermal tech in such extreme terms until your comment, but to me it appears to be the tape storage of our times. There will always be a fair amount of infrastructure hidden that almost nobody knows about, but it's going to be dwarfed in active usage by HDDs or SDDs.
The tech advantages really are that big for batters and other solid state energy tech over the moving parts thermal variety. Thermal tech hasn't had an upgrade like LTO-6 (or is it 7 now) and is pretty much at the end of its possible engineered capabilities, but batteries are just barely getting started on what they are capable of.
The article here concludes with one year long cycle, of the 1MW battery. There's some draw down even on the charge down, but a couple kWh against a 1MW pack is not super super notable. If it were cycle count alone degrading battery it'd still be an almost 5000 year battery (before becoming a 0.8MW battery).
As others are pointing out, we have stabilized chemistries even more, so 5k cycles is pretty low at this point.
Why go for a bigger battery when you can just put more panels on the roof to cover those winter days and waste the power the rest of the year?
I suspect the answer is somewhere in the middle - maybe two weeks of storage. Though of course prices change all the time so the correct action will change and you need to rerun the numbers as things degrade to decide your next action.
(Author here) My roof is full on both sides. There simply isn't any more room.
I do say:
> As solar panels increase in efficiency, it might be more sensible to replace the panels on my roof, or add some onto a shed.
Even in the darkest days of winter, they still generate something (unless they're physically covered in snow) - but they'd need to be 20x as efficient to power my typical winter usage.
In our part of the world, solar production during winter is incredibly low or 0 due to it being very cloudy, days being much shorter, sunlight angle on the panel very suboptimal. No amount of additional panels will get you through that streak.
It also depends somewhat on how much energy you use. I live in the Netherlands where everytime I bring it up, I'm told "that's just not possible, you will never make enough in winter", but these same people have no idea how much energy I use. On a bad day, I use maybe 10kWh and that's running the AC with the thermostat set to 19c overnight and a bit during the day at 22c. I don't have a giant fridge, I don't have any gaming PCs slurping 200W on standby, etc. My baseline usage is around 300-400W to run the old freezer that never turns off (70W), my network equipment, a fan in the garage to prevent moisture buildup, and some lights.
My 1.8kWh system at 20% output covers a great percentage of my baseline usage during the day! I'm probably going to add a small battery so I'm not penalized for sending energy back to the grid, but I'm not gonna need much until my kids get older and want new gadgets. The cool part about modern electronics is that we're generally getting more efficient too with newer tech. If I replace the old freezer, my baseline usage drops 20%+.
I don't disagree with your point that sometimes nature is simply just working too hard against your efforts, but I also wrote all this to say that some people need to really do the math and not rely on "common knowledge". Energy efficiency has come an extremely long way in the past decade and much of what was true when residential solar first started popping off is now outdated.
I wouldn't say no amount. I think about 100kW of solar would still produce enough for the average house even in the depths of cloudy British winter.
Way too much to fit on a house though.
while that's true, getting close has major benefits. adding extra capacity for the winter also adds capacity for fall and spring. that production will reduce how many weeks the battery is needed for
Storing energy from the summer for the winter is a really inefficient way to do it. It's much better to massively over-provision the solar so you have enough energy - on average - for the winter. Then you only need a couple of week's worth of storage to account for extended cloudy periods.
Much cheaper, and you get a ton of extra free power in the summer. The only downside is a typical house roof doesn't have enough space. But a typical house doesn't have enough space for a 1 MWh battery either so...
I think this is something that may happen in the next decade.
The interesting impact will be on the grid itself. Why connect to the grid if you are self-sufficient?
Then the grid starts to degrade due to lack of maintenance, and the people that can't afford local storage become dependent essentially on a government maintained service.
Or should we be planning localized storage and grids at the same time, so we get the benefits of both scale and resiliency and redundancy.
People will be parking a mobile 100kWh battery at their house every night. We need integrated V2G and grid upgrades to make the most of this opportunity.
> Then the grid starts to degrade due to lack of maintenance, and the people that can't afford local storage become dependent essentially on a government maintained service.
Many services that we use in our daily lives are government maintained services, so electricity is no different than water, sewage, internet, roads, railroads, post, emergency services, public education, public health systems, trash and recycling services, parks and recreational spaces, disaster relief and response, and others.
We should absolutely ensure these services continue to be funded and maintained, because they're often not profitable to deliver. Especially to the sprawling population of the United States. That’s exactly why government support exists and should exist: to guarantee access to essential services that markets alone won’t reliably or equitably provide.
There's a certain type of person who fantasizes about being off-grid, but the few that actually live it know the hassle and generally want to get back on if feasible.
Battery costs might go down, but the space they take up on your property costs money as well, which only gets more expensive the more urban you are.
The island of Eigg has a micro-grid. Not individual houses, a micro-grid.
The UK is going to be a wind power island not a solar power island, and definitely not an individual solar power island.
I do not think this will happen. Getting most households to be self-sufficient is probably not as cost effective as centralized grid. One there's the economy of scale. Second, any peaks and troughs will generally be balanced out between households and the overall buffer (aka reserve) needed could be lower.
> Why connect to the grid if you are self-sufficient?
I think that starts to bleed into the "pre paid meter" vs contract argument.
but practically the difference between total self sufficiency and 90% is willingness to fork out cash.
I currently have a 13kwhr battery, which covers my domestic power needs for 75% of the year. (we'll start to draw on the grid in the next few weeks.) but in the dead of winter it'll only cover 20-50% of my daily need (excluding the car)
but for car power, thats a different beast. Even though I don't commute by car, with the charging at home, I now use around the same amount of power as the uk average house. (even with solar and storage. pre electic car era. )
If local storage becomes cheaper than the grid but some people can’t afford it (why, capital costs?) then the government would be better off addressing those capital costs directly.
However, you need to consider industrial and commercial use as well as domestic. Can you power a smelter using local solar?
Probably? https://reneweconomy.com.au/solar-battery-deal-for-giant-sme...
I'm fully off grid today with no issues, even had power company remove power poles. I do heat with wood however. AC in the summer is no issue since that is when I get the most sun anyways.
It's not the way that it was originally meant, but this is another interpretation of the phrase "energy too cheap to meter".
This doom-loop is often repeated, but reality is far more complicated.
Very few people go fully off-grid, reality is people don't want that. Cost/benefit just isn't there unless you live off in the woods.
So instead, market structures react when penetration % becomes non-neglible. First you start seeing things like fixed-fees (minimum prices to maintain a grid connection, or "first x kWh are included"). And then you start seeing like what's in California with NEM3: the grid-export prices drop to "we don't want your excess solar" so people are incentivized to buy batteries. But because batteries make a system more complicated and expensive, people buy smaller systems overall.
So the "too much solar creates a disconnection spiral and the system falls apart" thing is a bit of fear-mongering. The system adapts, the changes in pricing create different cost/benefit ratios, and if nothing else, new AI datacenters will gobble up any power that doesn't need to flow to neighborhoods.
Something that isn't spoken about enough is that in developed Western countries, grids are actually significantly oversized due to reductions in electricity usage over time [1]. That link says 16% over, but the peak demand in the UK in 2024 was actually only 45MW [2], which I make more like a 30% reduction from the all-time peak.
Because of this, it feels like we should already have enough transmission capacity in a decent part of the network to cope with a re-organisation of where the sources and sinks are placed. Yes, we might need to do some work in the last mile, especially if V2G takes off, but things aren't nearly as bad as one might naively assume.
[1] https://www.nationalgrid.com/stories/journey-to-net-zero-sto...
[2] https://www.neso.energy/news/britains-electricity-explained-...
The trouble is the capacity is in the wrong place; the UK closed coal plants in (defunct) coalfields in the middle of the country, and built offshore wind farms which tend to be further north. There's plans for an offshore north-south connector to help with this.
True, but don't forget you can put BESS on the sites of the old coal plants: https://www.bbc.co.uk/future/article/20240927-how-coal-fired...
Electricity needs are expected to rise significantly as we convert heating and transportation to electric.
A small addendum on the conclusions:
- every household, can do that, _if_ they have a roof. appartment buildings may not have enough roof for all the people in it.
- for those who can't access that, (that includes people, but also the industry, your mobile phone provider, etc.) prices will get worse.
- the fire brigade will love industrial-size battery fires in the neighbourhood.
Germans seem to be rather fond of balcony solar
https://en.wikipedia.org/wiki/Balcony_solar_power
Balcony solar is absolute awesome in germany. I get about 30% return on investment per year on my small solar panel. Hard not to do it. I have no idea why it is still a little niche
For some reason in the USA there is only a single state that has approved that (Utah).
It conflicts with some of the NEC (national electric code) requirements. That all needs to get sorted out.
The NEC is also in conflict with homeowners performing simple electrical work, such as replacing switches and outlets.
It is. But in this case the conflict is more fundamental - the NEC has no provision for a circuit that has multiple electrical supplies.
That's just low hanging fruit, the easiest and cheapest way to produce some solar power. But even if fully utilized, that is not going to come anywhere close to meeting most households' needs.
You forgot to mention anybody who has a yard that gets full sun can mount panels there as well. As far as fires you can say same thing about all the fires that currently occur because of propane, gas, and heating oil. Those have become some engrained in society for so long that you don't even think of that as a "fire hazard therefore you shouldn't even have it".
> You forgot to mention anybody who has a yard that gets full sun can mount panels there as well.
The overlap with people who have their own solar-compatible roof is probably large.
The fire thing is funny with cars. If an EV burns, it’s important news. An ICE car burning is unremarkable.
Solar and renewables in general are starting to reduce generation costs.
So once the improvements in power transmission are done prices should come down for everyone.
Solar and renewables alone don't make a grid. You would also need grid-scale batteries, and the cost is not the same.
The "improvements" in power transmission is about building more lines, these lines are not going to be significantly cheaper to maintain than previous generations, and if these investment/maintenance costs are shared among less, that means more expensive electricity. Currently, in my country, electricity transport and distribution are about one third of total cost.
You have to consider that electricity will be 3x over the next 50 years (for transportation and heating). So we are currently building out a lot of extra infrastructure.
Grid scale batteries will also primarily reduce cost by offering arbitration.
In case you didn't realize he is looking to store ALL of the summer generation into a battery and generate zero power in winter.. so rely entirely off of a battery during winter.. which is absolutely no feasible for a normal person and nobody would ever do.
I once did a related calculation on "How much of my garden do I need to dedicate to coppiced willow to heat my house for a week per year?"
I concluded that we're all going to need much bigger gardens.
Why worry about panels and batteries when you can have an Egg?
https://enron.com/pages/the-egg?srsltid=AfmBOoqW03cqyIhQ0OlG...
And the price of the egg?
The egg itself is extremely cheap. The only expensive part is the subscription to disable remote control rights from Enron's traders.
I always thought about this myself in terms of personal sized long term, high density energy storage. Compressed hydrogen with a fuel cell is the obvious solution. Excess electric is used in a electrolysis cell and a matched compressor fills a bank of storage cylinders. More cylinders = more storage. Though likely very inefficient with a risk of fire or explosion.
Are there any other long term high density electric storage technologies that can fit in someones basement, garage, or even apartment closet?
> Compressed hydrogen with a fuel cell is the obvious solution.
To achieve volumetric energy density of hydrogen at room temperature that's on par with batteries (and that's charitably assuming you're using inefficient resistance heating with batteries) you need to store it at a pressure in the order of 100 bar.
You're better off with batteries realistically speaking.
Compressed hydrogen is no joke. It can escape most containers, actively degrades many grades of steel, has a very low ignition energy, and will explode over an enormous range of air/fuel ratios. Definitely not something to keep anywhere where you care about the roof :)
The HTW Berlin has a autarchy calculator. Unfortunately only in German language: https://solar.htw-berlin.de/rechner/unabhaengigkeitsrechner/
They also test and publish yearly the latest battery combos.
Extremely underrated how important just a small battery is for autarchy, very useful site.
The calculator makes it very clear that adding more batteries becomes more and more inefficient.
Being 100% independent is just completely unnecessary.
An odd thing about this article is that it ignores the deeper question: what balance of solar over-provisonioning + battery would most cost-effectively cover anticipated yearly needs?
I suspect that something like 3x'ing the solar (under 100k) would then let the author get away with much, much less battery, and result in a net cost savings.
Yeah seems like a relatively simple maths/econ problem to solve for, given some parameters like local solar power per m2 in the various seasons, electricity use in the various seasons and time of the day, and LCOE of solar and battery storage.
My guess is the differences in either choice aren't huge, as both solar and battery storage keeps getting cheaper.
Having an electric vehicle can really help, also. It basically soaks up excess solar power of an outsized installation during much of the year (making the payback time on the outsized installation very good), and can be charged away from the house during a few low-chance bad winter days when the outsized installation is enough to power the house but not the car. Electric cars are charged fully about 3 times per month on average in the US, so working around that with smart charging is not a complex challenge in the next decade.
I think he can't imagine 3x'ing because he already has his house covered and only the shed roof remains empty.
But that is a super interesting question that immediately comes to mind.
I am pretty sceptical about batteries and see overbuilding renewables plus bitcoin mining to monetize excess as a more viable solution.
I'm considering buying enough batteries for my day usage, then recharging off the grid during off-peak hours. I can add solar later on.
At which point does this become a huge fire hazard?
A friend has his own battery setup in a shed. He has a ton of sand above it which would collapse in the event of a fire.
I have 1000 litres of heating oil in my back garden which is hardly unflamable. 10MWh of fuel.
Pretty quickly. There's also a point where it becomes a serious explosion risk too.
Every other fire you can stop if you're right there and you catch it. If a battery pack starts to go, you might have a few seconds before the local environment is incompatible with life.
The cars in people's garages are far bigger fire risks. For example it's not uncommon to have a 70kWh+ EV battery, and the chemistries used to get the extra energy density for cars are far more unstable.
LFP (rarely used for cars) is fairly stable. And sodium batteries are even more stable.
Nobody seems to think twice about storing gasoline, heating oil, diesel, and/or propane around their place.
None of those release hydrogen flouride when they burn (among other things).
Not all battery technology is as volatile as Lithium-Ion or Lithium Polymer, LiFePO4 for example isn't subject to thermal runaway, nor are some of the Sodium-Ion batteries (although it's dependent on the exact chemistry being used).
People are used to having 25MWh of heating oil tanks in rural locations, although those are supposed to be stored away from the house.
Assuming heating oil is diesel, it's not very flammable and not a huge fire hazard. Soil pollution from leaks and spills seems like a bigger concern there. But I guess some people have large tanks of LPG which might be a bigger danger?
LFP cells are used in these batteries, they are not the same chemistry as the li-po you find in smartphones.
Nobody would even blink if a rural home had a 500 gallon horizontal propane tank, and that represents 20x the energy content of a 1MWh battery pack.
It would make me nervous, although that's only due to my engineering background.
In any case, it all depends on what you want to stand next to. A large explosion, or a multi-day metal fire releasing clouds of hydrogen flouride.
I'm sure it would be much more cost-effective to have community storage, rather than individual storage, and it would balance the load a lot if some users used more power during th day than at night.
I think it's called a 'grid'.
Of course then you have the collective action problem, and convincing your neighbors that grid storage is actually a real thing that exists. And that grid storage is not of the wrong political partisanship. The box of what's considered "politically incorrect" is getting fairly large these days:
https://www.theguardian.com/environment/2025/sep/10/south-da...
Snark aside, there are examples of community-scale energy infrastructure below grid-scale: see "district heating" and "co-gen plants". Sand battery people have been experimenting with neighborhood-scale infrastructure (though industrial heat uses is a better return on that tech right now)
A car battery should be enough.
EV battery capacity is expected to grow to 100kWh.
People will park them at home every night, and probably somewhere with a charging point during the day.
Smart house energy management should be able to pick up on that usage pattern and use the car battery for the house while making sure the car is kept ready for use.
In the same way that wifi/mobile/satellite comms can keep us "always connected", the changes in power generation and storage are going to keep us "fully charged".
A house might use 20 to 30 kWh each day. Modern EVs have enough battery capacity to power some appliances for many days.
Vehicle-to-load ("V2L") is currently offered in vehicles made by Hyundai, Ford, GM, Volkswagen, Volvo, Mitsubishi and Nissan (the new LEAF).
Vehicle-to-grid (V2G) is more ambitious.
https://en.wikipedia.org/wiki/Vehicle-to-grid
The cost here is premature degradation of the battery due to additional charge/discharge cycles.
Not for the thought experiment of "I want my summer excess to power my winter usage" posed by the author.
In the UK you'd need a class D "loi-sonce" to be able to pull the shipping container sized battery trailer for that to work.
However, if you were wanting to use pure lead acid batteries for your house, because you'd be doing slow charge/discharge you'd probably be able to get away with just 1100 130ah lead acid car batteries.
I mean you'd be optimising for peak current, which isn't what you'd want. However it could be interesting to see what happens when you have ~500mega Amps at 48v. (24Mw would heat your radiators up pretty quick. )
for lithium, then you'd need 12-14 secondhand tesla/polstar batteries, which if they caught fire, might be a challenge to contain.
1100 car batteries might cost maybe $100-$200k and need replacing every 4 years.
Did you take into account that lead acid batteries are recommended to only be discharged to 50% especially when used for solar ? If not thats now 2200 batteries and $200-$400K.
I eyeballed the maths on that. 1100 * 12v*130ah should give you a .7mwh of leeway to not do "deep" discharge.
"loi-sonce", would be better "loi-sunse". That 'o' is very jarring.
I was going for beeeergminghum, but for cockney, the o is indeed jarring
Not even close. A typical electric split will take 12a to maintain and that is just the heating/cooling system. Car batteries are meant for starts, not maintenance flow.
You might want to factor latitude into your calculations.
https://www.recurrentauto.com/research/winter-ev-range-loss
That is a trick question designed to make people argue and feel like there is some science or math to it. There is not. Nobody here can accurately predict weather far out enough to be a factor in this decision. The truth will vary by demand by family which may have variability throughout the year or decade. Another variable is the number of cloudy days which will vary as climate changes.
The answer is somewhere in the neighborhood of as much as one can safely store and afford accepting that batteries have a short life. Much like wells in cold climates the batteries should be in an underground insulated vault made from higher quality concrete as to keep fire hazards away from the home. That is also where whole-home generators and fuel belong, in their own vault so they can be easily maintained without having to rent an excavator to dig out the tank.
Even on cloudy days you can generate power. Unless it is very thick clouds I generate enough for my base loads even in complete overcast skies because I have an "excess" of PV panels.
because I have an "excess" of PV panels.
Which aligns with as much as one can afford. If one calculated an exact amount they would not be able to get the results you are getting.