I have 1000 litres of heating oil in my back garden which is hardly unflamable. 10MWh of fuel.
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.
LFP (rarely used for cars) is fairly stable. And sodium batteries are even more stable.
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.
However, you need to consider industrial and commercial use as well as domestic. Can you power a smelter using local solar?
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. )
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.
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.
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.
I grew up in Australia used to a grid averaging perhaps an hour’s downtime in the typical year. But now I live in India, and not only is the power frequently off for hours at a time (it’s a rare week that lacks an hour of downtime, and five or ten hours isn’t uncommon), the quality of the power is also far lower, and it damages hardware. It’s normal for AC units to need mildly expensive component replacements every year or two due to electrical damage, even with the obligatory voltage regulator in place, whereas in Australia I think most people never need to professionally service their AC until it completely packs up after maybe 15 years. If you’re going to want a decent-sized inverter and batteries anyway to get reliable power, then so long as you can get enough solar panellage, getting those solar panels and more batteries and going off-grid becomes mighty attractive—I suspect a payoff period of under a decade, even with comparatively cheap grid power, partly on the strength of electronics living longer.
—⁂—
Somewhere along the way, it actually becomes mandatory to be connected to such services. In Australia I lived in a rural town of under 100 people, and I asked if I could disconnect from the town water supply, and was told no. So that was some sum of mandatory daily connection fee for something that I would have preferred to unsubscribe from. (Town water was only hooked up to some outdoor taps, and the toilet; the supply had only become treated/potable five years prior, so every house was still hooked up to their rainwater tanks. In fact, the guy I bought the place from said that twenty years earlier you didn’t use the town water on your garden because it would kill the plants.)
- 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.
So once the improvements in power transmission are done prices should come down for everyone.
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.
Grid scale batteries will also primarily reduce cost by offering arbitration.
A program like this shouldn't take more than a weekend to cover all the issues including a Hands-On lab. A second weekend could be added for ground mounted solar setups.
I'd be willing to pay a couple hundred bucks get such a ticket.
Any time you're exporting to the grid, you're losing out - the rates are never good. Check out the OP's graph. His setup is oversized by about 2x. He's exporting to the grid for most of the day, which is hardly useful, then pulling from the grid after 6pm - the worst of both worlds. Downsizing the solar setup 2x and investing that into batteries would be much better.
It's not a surprise that your bill is rising if people consume less during the day because they install balcony solar, but don't meaningfully change their peak consumption, and therefore, don't meaningfully reduce the grid investment required.
At least the blog's author has a battery setup which meaningfully moves their peak draw.
The overlap with people who have their own solar-compatible roof is probably large.
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.
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.
does it? Panels are not the most expensive part of the system any more. Overcapacity of panels isn't the bottleneck any more. Battery capacity or roof space might be instead.
I think it's called a 'grid'.
https://www.theguardian.com/environment/2025/sep/10/south-da...
It just makes much more sense to have a big battery where the local substation is, than for everyone to install megawatts of battery individually.
Are there any other long term high density electric storage technologies that can fit in someones basement, garage, or even apartment closet?
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.
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 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.
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.
FWIW, a MacBook Pro in active use uses like 45 watts max and an iPhone really like 2-7 depending on the use. I wouldn't worry too much about gadgets.
Way too much to fit on a house though.
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.
Our roof is an even East/West split. So one side powers our morning and the other side our afternoon.
We have east and south and our peak production is when the sun is at the south-east, in the middle of the two faces. The east face production drops off from there on out until it's a fraction of what the south face is generating.
Right now Denmark produces 1724 MW from solar panels even though it is an overcast and rainy day: https://energinet.dk/energisystemet-lige-nu/
Our current usage is relatively high: 5944 MW.
Remaining supply is: 3458 from windmills, 357 from fossils and 434 from import from other countries (mostly hydro/wind).
So if Denmark doubled the amount of windmills (it is a very windy country) and solar panels then Denmark would be able to run of windmills and solar panels even in the autumn.
2024:
May: 2494 kWh
Jun: 2323
Jul: 1915
Aug: 1634
Sep: 1008
Oct: 442
Nov: 185
Dec: 31
2025:
Jan: 43
Feb: 335
Mar: 980
Apr: 1510
My detached house has less space for solar panels than some smaller homes because all faces of the hip roof are triangular; lots of houses nearby that are semi's or terraced actually end up having more roof space because their roof faces are rectangular.
I managed to have 14x 465W panels total added on the east and south faces of my home, but the installer wanted an extra 40% of the total system price to add 5 more panels (and the 15th they couldn't fit on the south face, for 6 total on the west) because they'd have had to erect additional scaffolding and who knows what else. That was an absurd additional cost so we didn't do it, but that additional generation late into the afternoon would have been great for our peak usage at dinner time. My suspicion is they simply didn't want to do it, because the cost just doesn't add up.
On an overcast day at this time of year I can generate nearly enough to power the "baseline" of the house, but currently I receive 24p/kWh to sell the energy back, and I can charge the batteries at 15p/kWh over night, so I can break even if I can generate just enough to export to cover the night-time charge of the batteries.
I haven't had them long enough to run through winter yet so we'll have to wait and see, but based on the end of this summer, I could probably cover the winter usage with export payback through summer at the current tariff rates when we were generating about 100% more than we were using per day.
I suspect the introductory tariff is far more generous than I'll have access to in a year's time when it expires though.
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.
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.
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.
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.
https://www.volts.wtf/p/whats-the-deal-with-sodium-ion-batte...
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
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.
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.
Up until a year ago where I live, Chevron 94 Octane was ethanol free. I had issues with older carbureted engines after leaving gas in them for ~2 years. With E10 I wouldn't dare go that long as it can be so corrosive.
I'm going to have a hell of a time with LPG.
Diesel plus <any other kind of fuel> isn't available on cheap residential units I'm aware of, particularly as the ignition and fuel injection mechanisms are much more complex than a gasoline/propane mechanism.
Not without exception; there's some draw down after dinner even on the charge up sunny months. 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.
Unless you live in a location without much sunlight, it’s better to invest in a solar powered system with a transfer switch to go off grid.
If you size the system appropriately it can recharge the battery by day during an outage and now you can operate off-grid for a very long time.
Diesel generators come with maintenance overhead that adds up year over year. They also contribute nothing during normal times, as opposed to a solar install which can offset electricity costs or even earn money.
If you live somewhere dark this is less helpful, though.
Consumption also matters. Some people have eye-popping amounts of electricity consumption while other households get by with far less. The difference, including heating and cooling costs, is surprisingly large between the highest and lowest households.
A good diesel generator is going to need very little maintenance operating few hundred hours per year.
Why do people talk about engines like they are unreliable? They are modern marvels.
My Powerwall quietly sits there charged and waiting to be under load, and charges to full when storm mode is activated (or I activate it manually). It has a 10 year warranty, 15 years if part of a virtual power plant (which my storage participates in with the local utility). It requires no maintenance. I also received a 30% federal tax credit for the Powerwall, which the building will not receive for a generator.
TLDR Diesel generators where you might be without mains for a while and intend to replenish the fuel with deliveries during the outage, fossil gas for use cases where gas delivery pipelines are available (urban, suburban), propane for offgrid use cases (rural, cell towers, etc) where fuel longevity is a concern.
Generators need to be exercised and maintained. You are committing to fire that thing up for a few hours every month, just to make sure it's in running order when you need it (I used to work next to a hospital that fired them every week).
I had a 1990s car that started right up with 2015 fuel that sat in its tank for 9 months.
This can easily be automated, Generac will handle testing for residential generators.
Fuel is easy because we have an external tank with a visual gauge that you can read from several feet away. When they added DEF they neglected to add a DEF gauge that's as easy to read. Thank goodness they sell DEF at any old truck stop.
Do you really have a few hundred hours of power outage per year?
Around here, the power is so stable that we go multiple years without an outage that lasts longer than a few seconds.
If I installed a generator it wouldn’t a couple hundred hours per year. It wouldn’t run at all for years at a time unless I manually exercised it as yet another maintenance task for my already too long list of things to maintain.
You're sadly describing my situation. Dec sees 6 hours of light, less even, and while the sun does get above the horizon, it doesn't get over the top of the forest.
(The trees have no leaves, but there's still a lot of tree trunks between me and sun.)
Bah.
https://enron.com/pages/the-egg?srsltid=AfmBOoqW03cqyIhQ0OlG...
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-...
Your sources really only apply to Britain and other deïndustrialising countries. American and European energy demand is rising due to electrification and AI.
Yes.
I accept that AI is likely to take us in the wrong direction for a while. (I don't think it will actually be that long, once people realise that more training isn't getting more results.)
https://yle-fi.translate.goog/a/74-20138415?_x_tr_sl=auto&_x...
It was actually 1000 times that much.
They also test and publish yearly the latest battery combos.
Being 100% independent is just completely unnecessary.
I concluded that we're all going to need much bigger gardens.
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...
We don’t have a permanent stream, but we do have enough intermittent flow in the winter to keep a 55,000L tank full. So our install entailed building a huge tank, a filtration system for water ingress (as it’s also our potable water supply, and a firefighting reserve in summer), digging 400m of trench over nightmare terrain with 70m of vertical drop, crossing a road twice, burying 90mm HDPE water line, fibre and 4x25mm2 power (latter two not necessary for hydropower but useful to have, and if I’ve got a trench open I’m putting everything in it at once) - and then building a hydro shed, installing the turbine, connecting it to our grid via a grid tie inverter, configuring our grid to accept power from it, setting up automations to turn it off and on depending on power demand and the level in the tank, and of course all sorts of side quests to achieve the above.
It has been neither cheap (about €12,000) nor easy (perhaps six weeks of full days for me, if added up over the year it took), but it has given us enough extra power in the winter that the petrol generator is now under a pile of crap in the shed, getting dusty.
This seems like a $50000 bit of work. Will it ever pay off or was it more of a hobby project?
Reportedly, even the fairy stout wind turbines they use up there have short, brutal lives. I heard the story of a croo that had to lasso/tangle/jam the blades of theirs in a storm because it lost the ability to control its speed and the alternative was letting it overspeed and possibly tear itself apart. They aren't large in diameter, but at the speeds they turn even in normal conditions up there, catastrophic failure could be really bad.
It's uncommon for a reason. Wind generator capacity rises with the square of the rotor diameter. That means small-ish generators (let's say "small enough to be roof mountable without additional mechanical supports") are significantly below 1 kW of power. Seriously, the systems people by for their sailing yachts make around 50W from a nice breeze - enough for lights and to trickle charge the battery while docked, not nearly enough for a fridge.
Combine that with quite a number of moving parts, changing loads and exposure to weather, you get very short maintenance intervals and final lifetimes.
If you have any other option for power, its almost always economical to just use that.
It's so obviously better to reduce your need for heating and cooling than it is to increase your panel. battery, and HVAC size.
I've just setup electrical heating for my bedroom (HA PID sensor). Uses about 450KWh - $90 NZD worth of grid power per winter. Heat pump would take 20+ years to pay itself. Double glazing probably 30-40 years.
To make same amount of solar power per year I need a single $130 NZD panel.
2025 Code minimum is pretty decent if it's actually complied with, and 'net zero' middle ground with triple glazing is a worthwhile upgrade.
It's not adding to that cycle by reaching down into the depths of the earths crust to bring up carbon captured and sealed away for longer than human existence .. you know, that additional carbon that is referred to when increased carbon footprints are seriously talked about.
Particle emissions isn't what I responded to .. in terms of carbon and greenhouse gases what matters more is trees not being replaced.
In the course of, say, plantation growing timber for lumber generates sufficient burnable wood for landowners and a wider community - the final lumber trees are the ones that weren't weeded out earlier (and burnt) and have been routinely lopped of branches (more burnable wood) to minimize knots, etc.
Forrest management is a thing, timber for lumber, coppicing for regrowth, et al has been going on for several thousand years and has been part of traditional surface carbon cycle.
As has large scale grassland (and forest undercover) burning off for fire management.
If you're using daily, do you get... three? five years?
Looks like - https://cartroubleshooters.com/how-long-does-a-tesla-home-ba... - ten to fifteen years with a guarantee of 10 years at 70% from Tesla
Check for "Saltwaterbatteries", they are starting to reach consumer markets and literally cannot burn as the energy is stored as ... salt water.
The problem is if the promise from the name was true, they'd be everywhere - they're not, so invariably much like vanadiun-redox or iron-flow batteries it turns out all the other details make them more expensive and less performant.
Not necessarily. Lithium is still quite cheap, safety is not the number one demand - and it is mainly about optimizing production to achieve competive pricing.
So yes, mabye there are some blocking details I am not aware of, but otherwise I expect their time will come.
https://polarnightenergy.com/news/worlds-largest-sand-batter...
I have a 22*980Ah 3.2Vn LiFePo4 array, and it holds a theoretical 13kWh at the 60% "safe" cycling rate (not below ~20%, not above ~80%, 3.0V min to 3.4V max). Taking DC->AC conversion losses into account, that ends up around 11kWh of 230VAC, which is enough for a single "normal" 24h period without generation: that doesn't include hoovering, welding, or running the dehydrator or dehumidifier. The batteries alone were USD$3500; BMS, balancer, cabling, etc. hundreds more. If I take $4000 as the unit price, then 14 days worth of power for us would represent $56k into a depreciating investment. I don't think most people are going to go for that. $56k would pay a lot of electric bills.
I'm in Ireland, which is fairly temperate, and we heat with wood (including the hot water). If you heat with electricity and you want to float that load on battery through a dim February...brutal.
EDIT: holy shitballs, that's $141,189.74 if you buy it as Powerwalls from Tesla rather than parts from Alibaba.
And the price of LiFePo4 continues dropping, it is not a good deal if your cells are aboe $80 per kWh (which at 22kWh should be below $2000).
3.2v nominal per cell, 305Ah capacity: .976kWh per each. Call it .98. Not 980Ah, but 0.980 kWh.
.98 * 22 = 21.56kWh total pack cap.
*0.6 = 12.936 kWh available before conversion losses
We burn about 11kWh daily, so there's about a day in a full battery. Spring/mid summer worked well, but lately we aren't managing to store enough to get through the night, so I will probably add another 10 panels (5s2p) once I can find a grand I don't need.
And please take some proper rest, you protect the batteries using only 60% capacity, but allow your body go below 0%. I'm pretty sure thats out of spec.
In california, if you have AC and electric car that's 56 months.
The cost for AC dwarfs the cost to charge an EV.
It's been done with heat. Using cheap electricity in the summer to generate heat and store it in basalt. There's a small block of houses in The Netherlands that gets their heat that way: https://www.ecodorpboekel.nl/basaltaccu-is-opgebouwd-uit-duu...
There's more systems like this around the world, although they use different storage methods.
https://en.wikipedia.org/wiki/Seasonal_thermal_energy_storag...
My 5 kW solar array and 24 kWh battery is fine for my 1300 sq ft house, all summer long, even when it's cloudy, and it works great for clear winter days, but as you mentioned for extended days of bad weather, the battery runs empty. Fluffy white summer clouds aren't a problem, but thick winter rain clouds let in so littl light that the whole array can't even run a 200 W refrigerator, so a few days of rainy weather depletes the battery and I have to top it off with a generator.
Also, ironically now you have enough power to go fully off grid, it doesn't make any sense to do that because you can't sell your mountain of extra summer power!
[1]: https://www.photovoltaikforum.com/thread/226950-bericht-60kw...
Keep in mind that the UK is really far north, much farther north than most people expect, really, and the nights are really long in winter (there's up to 16 hours of night in London in December). And even your daylight hours aren't going to be sunny in average
So you'd have to over-provision a lot (like 10 or twenty times).
With 3 EV's in the house, and a 12.8kWp array, with a 10kWh battery, charging overnight in the winter on the cheap EV tariff (7p per kWh vs 27p per kWh) and exporting during the spring, summer and autumn at 15p per kWh I'm seeing an electricity bill of below 0.
Of course, with a shift in energy production to renewables, all of that maths may get upended, but for now, I'm going to break even far before my original estimates.
clearly, you're not in the US as renewables are considered the problem here and not part of the solution. i'm waiting for the administration to come out with clawback plans for all of the subsidies for home solar and even the EV subsidies. gotta pay for those tax cuts some how
Renewables pay for themselves and the lack of federal incentives no longer slows the rate they're being installed.
However, Trump has issued stop-work order on the only two projects, both multi-billion dollar, with issued permits. They are the ~800MW Empire Wind Project and the ~700MW Revolution Wind project:
https://www.utilitydive.com/news/trump-administration-offsho...
https://www.canarymedia.com/articles/offshore-wind/fishermen...
The Empire Wind project was allowed to continue after negotiation from NY's governor, but these sorts of mafia tactics will stop the development of new off shore wind projects. Multi-billion dollar projects getting shakedowns midway through is no way to run a country.
Perhaps even worse, it prevents the US form acquiring the construction skills to work on this on our own in the future. We are getting extremely far behind on a crucial technology for renewables at the population centers for northern latitudes.
nah, we'll just give out Halliburton style no bid contracts to companies owned by vice presidents. they've got plenty of practice pouring mediocre concrete pads underwater. at least when these let go, they won't spew oil
However, from how you describe it, you are getting lower costs than me! My electricity bill is lower than the standing charge, but this adds up to more than what you are paying. Train fares also seem to be costing me more, although I have done well out of compensation for late trains recently, so my trips to the south of England are averaging out at around £100 for the return journey.
I am beginning to question my life choices. Frugal was the wrong way to go. Why do I need this cardiovascular exertion when I could be getting around for less in a two-tonne EV?
I think I missed the boat. Getting a feed in tariff is far from given these days and the government grants for solar ended about a decade ago.
Also commute by train, and yeah, it's not cheap. My season ticket is £11k a year!
I think e-methanol synthesis is ~%50% efficient, so double the solar. Doesn't sound so bad.
Now if you could synthesize methane you could push it into the gas grid and run the meters backwards, thereby avoiding the need for storage... actually methane synthesis is even more efficient, >70%.
Edit: I again made the mistake to comment on a thread dealing with energy x politics. Sorry, I'll try not to do that again. I'm out. It's feral.
What voltage is UHVDC at those numbers? Who is supplying the equipment? Where are the demo installations? What's the cost?
Again, the goal is economic very long distance transfer of electric power. Not a Chinese university research project.
> "HVDC transmission has typically 30-50% less transmission loss than comparable alternating current overhead lines. (For comparison: given 2500 MW transmitted power on 800 km of overhead line, the loss with a conventional 400-kv AC line is 9.4%; with HVDC transmission at 500 kV, it is only 6%, and at 800 kV it is just 2.6%.)" [1]
There are quite a few of UHVDC lines in China, not much in the rest of the world. [0] I don't know what they cost, but maybe you can estimate it based on what they decided to invest over a 10y period.
[0] https://en.wikipedia.org/wiki/Ultra-high-voltage_electricity...
[1] https://web.archive.org/web/20180730045905/https://www.sieme...
As a first guess, one would think it makes more sense to eat 30% loss (so you need 1/0.7=143% installed capacity) than to need 200% capacity plus batteries since it's night about half the time on average. And afaik HVDC is more on the order of ~15% loss
The trick is the "HV" part. China is already running 1100kv on some of their HVDC lines. Transmission losses decrease with the square of voltage, so any increment from that point would be very substantial.
I didn't see any feral responses? Did you not like the ones that pointed out that losses over 800km are <3%, and so your assertion that Ohmic losses are the issue is essentially wrong?
That's just me being snarky, but we've been scaling towards this for decades, we just haven't fully gotten there. We can probably solve the technical problems, it seems the main issue to building a fully-connected worldwide power grid is that the cost of scaling that much isn't worth it (yet).
One of the problems with our reliance on oil is that so much comes from an unstable part of the world (although the oil itself contributes to the instability).
Cables under the ocean can be cut by anyone who can get to them with a submarine.
You would be look at cable literally going around the world - at least a good proportion of half way round to be useful. They will be vulnerable one way or another at some point.
Then there is reliability. There have been some fairly bad failures of national power grids. A failure in a global grid would be a lot worse.
which being very approximate is 15k gbp/year
The ROI of a large PV farm must be substantially better than a home scale install.
Should I interpret the 20-25% returns as being, your annual savings on the utility bill are 20-25% of the cost of your PV install?
Roughly speaking the electricity is about €0.06 with about €0.20 in taxes on top. So offsetting consumption nets me about €0.26 cents per kWh.
The installation of a 2800kWp system cost me about €2600 and generates between 2400-2750kWh annually, so about €650 euro. In a 10 year timespan that’s an IRR of 20%, creeping up to 25% for 20 years.
After the first year of having PV, I determined my own payoff time of about 5-7 years, so that was nice and self-justifying, and haven't dug deeper into details on that.
Did you DIY your install?
Plus, when people compare the cost of home solar vs utility solar, they often ignore all of the infrastructure (especially last mile infrastructure) that's needed to get the power from the utility scale solar farm to someone's house.
If you live somewhere with expensive electricity and decent sun (California, New Mexico, Arizona, Florida, the Carolinas, etc) it's usually worthwhile to put solar on your home. It's less effective than if someone competent were to spend the same money improving the grid, but in this day and age that's a lot to ask.
Batteries on the other hand feel like they take less space and thus could be colocated near consumption without having to be on consumer property. Warehouse size within the city. Transmission costs would be minimal.
Roofs have to handle several tons of wind pressure, snow, people walking on them and so on. They can handle solar panels no problem - which is why it's such a good idea to put solar panels on them.
If your roof can't hold up solar, it also can't hold up the people that need to work on it.
I can't put PV on my neighbours house, I have to buy land to put it on. My home still needs a grid connection so all that infrastructure still needs to exist. Except now it's even more complex.
PV and energy generation in general benefits massively from economies of scale. Home generation doesn't have that.
Even with a large house, homelab, and an EV, we barely pay for electricity over the year. Doesn't seem like a con to me.
We can still individually make better choices, and also eat our vegetables, etc, but in the aggregate public policy is more efficient to make the large scale changes we need
And perfect information. Too bad 0% of consumers have the expertise and time to fully audit the supply chain of every product/service even assuming they could get ahold of that information.
They don't force at gunpoint. They use cash and lies to convince. And the legal system to cow.
https://en.wikipedia.org/wiki/ExxonMobil_climate_change_deni...
https://en.wikipedia.org/wiki/Steven_Donziger
You aren't wrong that we should choose better. But what do you do when so much money and effort has been expended to ensure so many people don't know what better even is.
I have a grid detachable PV system with battery. It's been invaluable for grid blackouts in my area to have the capability even as I have paid (at least for the first couple years) a higher price per kwh for it. Over more years, it's really nice to have price insulation against utility price increase.
Actually, it's the other way around.
A rooftop solar doesn't require much: the land is already there (it's yours), there isn't any bullshit with permits, all you need is a ladder or a bucket truck, a few ultra cheap panels, an aluminum frame, an inverter and a few dozen feet worth of wiring.
A large scale solar farm however? The developer needs to find suitable land (challenging to do when competing against big ag), there's permit paperwork involved because solar farms ain't agriculture, they need to pay for a high voltage connection to the nearest substation, the huge ass panels need a really solid support construction that can withstand wind and weather and that needs a solid foundation as well, you need thousands of feet worth of wiring, complex and massive inverters, lightning arrestors, god knows what.
Oh and you get resilience against natural disasters for free on top of that. Some drunk driver plows into a power pole, some redneck shoots up some birds and kills the power line (yes, that happens so often that utilities release yearly reminders to please leave the birds alone), or a heavy storm / flood takes out entire substations for weeks, whatever - you throw the transfer switch, kill off all the non-essential consumers and can easily ride through a week worth of outage.
The answer is yes: it is a lot easier to make a PV farm than a home scale install!
Local solar requires far less grid, and expanding the grid is one of the greatest (political, not technical) challenges of this era in the US.
Unless you're accounting for the grid costs, the "cost" of utility vs. rooftop is not an apples-to-apples comparison.
As far as a "con" the only con is that the costs in the US for rooftop solar are multiples higher of other places, like Australia. That's the con. Australia also shows that rooftop solar is great for grid in general, greatly driving down costs.
Of course, rooftop solar is terrible for utilities, so you are going to encounter tons of astroturf denouncing it all over the web, and even face to face. Utilities are fundamentally threatened by consumres taking over more and more of their own electricity responsibility, especially as batteries get super cheap.
In many (most?) areas, wind picks up at night, wind can't really be "local", and demand is lower at night time so that's a great use for the grid.
Also, batteries are getting so cheap that people are putting multiple days' worth of storage on wheels, driving them around, and parking them at home during the evening peak and overnight.
When they are that cheap, adding 10-20 kWh of local storage is going to pay for itself in no time.
When my neighbor is overproducing solar during the day, that means that he's sending his power over to my house, which doesn't have solar. Which means that my neighborhood is pulling down less peak power. And the grid is sized for peak power, not for minimal power, so whenever that peak is lowered, it saves me money but costs the utility profits.
Because the utility gets to recoup a fixed profit rate off of any amount of grid they are allowed by the PUC to install, whether it was needed or not. My neighbor, with the solar, also pays lots of fees for the privilege of sending me power and requiring less grid.
This effect of shaving the peak is so extreme that solar causes the California duck curve. Though the storage that's been added in just the past two years has pretty much solved any problems needed for the evening ramp as the sun goes down, now.
It also seems likely that HVDC from sunnier areas like Spain or maybe even Morocco could be cheap enough. I'd recommend nuclear but EDF is having such great difficulty building it. HVDC and other exotic solutions like enhanced geothermal seem for more practical at the moment.
Perhaps local solar installations could be incentivized to include their own smaller scale storage...
It makes solar a very financially unattractive option unless there's storage attached to the system, and has drastically reduced the rate of residential solar deployment.
NEM3 was justified under the proposition that lower-income households were "funding" the higher income households to get solar. So as solar finally gets cheap enough for the lower income households, they changed the rules again so that only those rich enough to afford batteries and solar can save money.
NEM3 has a few nice things about it when looked at narrowly, but overall seems pretty disastrous for the state.
Residential solar installs are way down, that's correct, residential isn't the only venue for solar, and within residential storage capacity is skyrocketing and it's already having a measurable effect on the early evening peak. Lower peaks means less capacity needs to be built just to handle a few hours. This is good.
The unequivocally negative impact I don't have an answer for is the job losses for solar installers.
If that was the concern they literally did nothing to stop it. Instead of dealing with backfeeding from a distribution station, they went entirely the other direction.
Those grid costs, if they actually existed, were in isolated areas with high levels of solar, and NEM3 will continue deployments of solar in exactly those areas.
Solar is not "savings for some homeowners" it's literally keeping grid costs down for everyone, keeping our grid reliable on the hottest hardest to run days.
Don't underestimate the value of decentralization in some scenarios.
Once the panel arrives at your home it keeps making electricity for decades, without asking anyone's permission.
There are many benefits to letting homeowners do it. First of all you get a lot more solar deployed in much shorter time, because you mobilize hundreds of thousands of people to the effort immediately instead of having them wait for a solar plant. Homeowners pay for it, provide the area for it, hire and organize the workforce - small scale but "everywhere at once" so to speak.
The government/state/county doesn't need to wait for the land to be available, raise the money, build infrastructure to transfer electricity from a new large solar site to the consumers and so on. So for the "state" the ROI is better with home installs.
>responsibility for the climate crisis to consumers rather than industrial energy providers.
That's where the responsibility belongs through. Most of us drove fossil fuel cars for years, which is the largest single emission source. In democracies we could have voted for guys wanting gas to cost 50 bucks per gallon, or who would prohibit any more oil and gas to be traded. We didn't. We could have refused to travel for vacations, refused to buy goods shipped from overseas and so on - but we didn't. So this is on us.
Only kind of. The oil companies dusted off the old tobacco playbook. Democracies are unfortunately terribly vulnerable to well-funded liars.
A communal solar farm is not the same product as personal home solar anyway. When someone with surplus money decides to pay for their own solar it might be suboptimal ROI for them, but the rest of us get a little bit of solar benefits for 0 money.
And more importantly, solar starts replacing fossil fuels rightaway. No waiting for a communal, optimal ROI initiative to get started.
But of course, we should do those as well.
A home owner who puts PV on their home could instead have invested in a larger scale PV business and made more energy per dollar. By putting the panels on their home they have robbed us of electricity.
Most of the solar we have today exists because these "robbers" paid for it themselves, and got it done rightaway. We all benefit from it. Maybe you meant robber like Robin Hood? ;-)
Your idea seems to be that homeowners can somehow choose their ROI by adding solar to a central power plant instead of their homes.
But that's not the case, they can't do that. There's no checkbox that says "instead of having 20 solar panels on your roof we can add 25 to the central power plant" when you order solar for your home.
Utility solar and home solar is built from separate pools of money for different purposes, and I don't see how you can meaningfully compare ROI between them.
Edit: Also, money isn't the bottleneck so we're not missing out on anything. Every solar panel made is being mounted somewhere, there is no surplus being stored because we ran out of money.
One thing that could possibly work better IMO is something like a small local renewable fuel economy where excess power is used to produce hydrocarbon fuel by catalysis of electrolyzed hydrogen with carbon sources, and individuals can purchase this fuel to recover the energy, or possibly the power plant could use it during solar lows.
The advantage of this type of system is that it’s not really capacity limited, as long as you have enough fuel storage, which is simple to build more of.
of course, you could just use alcohols distilled from fermented plants instead, but that’s not as sexy.
Or, alternatively, 1 liter of petrol has enough energy to lift a 3 tonne cement block 1 kilometer upwards.
Over the past decade there's been several startups trying to do gravitmetric non-hydro grid storage, and even with favorable conditions (e.g. a large free train track on the side of a mountain) they can't get the economics to work. Plus, that tech is never getting cheaper, like batteries are every day.
Even better - both. Increase the independence and redundancy in several steps, making the grid more reliable and less prone to failure from single events.
>It’s simply not realistic to think every private dwelling can or should have this kind of capability,
Why not? You can get 10 kwh of storage for the price of a phone and laptop. Any EV has more battery than what's needed to power a home for days, some of them already have the capability to do so when combined with the right charging station.
Of course not everyone will have it, but surely battery storage could become as common as air conditioning or central heating even at current prices.
I started that way before going fully off-grid to avoid subsidising the fossil fuel industry here. Plus ~70% of my bill was fixed charges, and they wouldnt pay for excess solar generation above what I used.
I think this sort of mega home battery bomb could be avoided through legislation by offering free grid connections. So I 'pay-in' 10kWh today, and maybe my account is credited with '5kWh' for later use. I'm sure we would see a much bigger uptake of home solar with such a scheme.
So instead of 1:1 credits, the power company buys it from you at what they would pay their producers (read, several times less than what they charge you).
It's a fucking scam.
My power company limits the size of panels and time limits net metering (they don't even do it anymore for new solar installs). So you can either not do solar or go completely 100% off grid with only one step.
It's a fucking scam. The engineer justified it to us when he was signing off on our solar install as "well when we do 1:1 credits c that's like you stealing from your neighbors. They don't want to pay your the full retail cost. They want to pay you what we pay the power producers."
When I asked if that meant my neighbors would have the ability to pay less, he just sort of looked flatly at me.
An absolute scam.
Edit;
Sorry, I forgot to add;
1. They also won't allow battery storage while connected to the grid. If they wanted to buy surplus but allowed my to store my own production, I would be fine with it.
2. They also net bill daily. So while I may produce extra within the billing cycle, they zero out excess production daily.
1. They also won't allow battery storage while connected to the grid. If they wanted to buy surplus but allowed my to store my own production, I would be fine with it.
2. They also net bill daily. So while I may produce extra within the billing cycle, they zero out excess production daily.
So it is plenty reasonable that you wouldn't get 1:1, especially if the grid is already able to satisfy all demand during peak sunlight by using just base load + solar. Some power companies turn it into a scam anyway and set grossly disadvantaged prices for consumers, but just because it's not 1:1 doesn't mean that it is a scam.
But talking about the cost of transmission sure does highlight issues with this billing model. Because if it's going to the neighbor there's negligible transmission. The engineer's argument was very stupid.
A) add solar panels covering 1/3rd of the terrace
B) use it for all non-floor-space electricity (lifts, common areas, pumps, parking lots)
C) Give the rest for deductions as part of NEM.
Once we move in, I'm interested to see the tariff for the export and how much it will save us.
The alternative (the current model where I live) is to have the government be responsible for grid stability, in which they will add taxes and fixed grid connection fees to pay for that service. Crediting overproduction won't make the costs lower for the government, so any such credits will just be a form of subsidy.
A couple buffer batteries in each home should eventually help even out pricing with everyone trying to sell during peak demand times. But yeah, grid stability might be a fun challenge.
Early subsidy plans were short sighted and came from politicians, not grid operators, and gave homeowners a massively inflated sense of the usefulness of the meager kWh they produce. Power is cheap, infrastructure is not. It's far better deal for the commons if you use all the kWh you produce (via storage) and pay what it costs to deliver a grid connection when you fall short.
There are several things you might want to consider:
- wind, there are smallish turbines that you can put on your roof that generate a few kwh. Also when the sun doesn't shine. Extended periods without any wind at all are rare. 2-3 weeks would be a lot. That probably drops the amount of battery you actually need quite a lot.
- Second hand EVs are relatively cheap and come with some affordable batteries that are probably larger and cheaper per kwh than most commercial domestic storage solutions. Not for everyone but if you can wire things together, that might not be a bad option. Especially if you can get ,a good deal on some well used EV with a half decent battery. Relatively low loads might increase the life that battery has if you just use the car for storage.
- You don't have to generate the power next to the battery. Some cars can provide power to your house; when your house battery runs out, you can just use public chargers and drive back and forth to top up your house batteries. A bit of a chore but probably better than investing in batteries you don't need most of the year. Not a bad option if you live off grid. Batteries on wheels in general are a thing. Electrical semi trucks come with > 500-600kwh typically. That's a lot of power that you can move between your home and your charger. Container sized batteries are a thing. If you want to, you can get about 3-4mwh on your property. It's not going to be cheap. But it's doable. The point here is not that you can have a huge amount but that you could stretch a modest amount quite far by simply driving to and from the charger. Of course if you have a grid connection, using that is more convenient and cheaper.
- The capacity factor of your batteries is going to be a function of how often you cycle them. If you rarely cycle them fully, they are going to be relatively expensive. So, while hoarding batteries might make you feel nice and comfortable, it's not a great economical choice to make until batteries become a lot cheaper.
- The money you save on not paying for grid power needs to be balanced with the cost of a battery and how long it will last you (10-20 years?). If your monthly bill is 100, you might spend 1200$ per year and 12000$ for 10 years. So, that's your budget for a huge battery. If you factor in that it will have a low capacity factor, it might last quite long. Twenty or even more years. I have a lithium ion battery screwdriver that's nearly 20 years old; still fine. Because I rarely use it. So your budget could be 20-30K$ Adjust as needed based on grid prices and usage.
- As others mention, generators are relatively cheap and they do work if you can stand the noise and exhaust fumes. Not clean. But relatively cheap.
It's a valid thought experiment to repeat until the cost adds up. Your opportunity cost while you don't invest in this stuff is basically what you will continue to spend on the grid. Which is probably not horrible for most people. Until those cost curves cross, you are better off waiting. Or compromising and buying a battery that won't solve the whole problem but is cheap enough that it will earn itself back in a reasonable time.
It's trade off between need and cost. If you absolutely need to be off grid, it's doable if you have the space and resources. But it's not going to be cheap. Until then, some hybrid solution is probably more optimal.
Huh? A single Tesla Powerwall 3 stores just about the same 13.5 kWh the author describes as being the battery size they need [1]. And they are by far not the only ones offering ready-to-install battery packs.
Fully electric vehicles with vehicle-to-grid wallboxes enable even larger systems.
The price of batteries has declined by 97% in the last three decades: https://ourworldindata.org/battery-price-decline
But also, the expensive thing about batteries is typically the amount of power they can produce. The post used lithium ion batteries as a reference point, and those typically have a power rating between 1 and 4 hours - meaning they can fully discharge an entire summer's worth of stored energy in 4 hours... which is probably not something you need to pay for.
If you want a ton of really cheap long term energy storage, you'd look into a technology more like hydrogen fuel cells. The raw power (for standard home, 10 kW is plenty overkill) is going to be more expensive than lithium, but for storage you just need a bunch of hydrogen stored somewhere safe (probably buried underground in your yard). That's much, much cheaper than lithium ion batteries on a per kWh basis, especially if you are scaling up into the MWh territory.
And, the other big cost saving solution is to just add more panels. It means you'll be overproducing in the summer and you'll have to curtail, but some curtailment in the summer is a lot cheaper than finding a way to ferry all of that energy into the winter. Then you have extra panels in the winter and you don't need as much storage to be fully self sufficient.
Methane when burned releases the CO2 back into the atmosphere, but if you're mining the CO2 from the atmosphere to begin with it pretty close to carbon neutral fuel.
https://news.osu.edu/turning-carbon-emissions-into-methane-f...
I know the tech is not quite there yet, but it’s getting closer every year.
When your fuel cell can be stationary and heavy and large, you can hit efficiencies above 50% without cogeneration and above 80% with cogeneration.
Oh thank god our atmosphere has no oxygen in it!!
Also Hindenberg.
Model 3 or Y with 70-80KWH capacity battery ~~ $40-50,000
Powerwall price: ~$15,000 for 13.5 kwh storage.
You're paying around double for a fancy case and the UI.
After modeling scenarios based on historical usage PER HOUR, I was able to show that if we had enough solar generation during peak late afternoon hours, we would be able to ‘survive the night’ on batteries until morning solar generation resumed. This means my 14kw solar panels coupled with 3 batteries gets me completely off grid for 9 months out of the year. That’s not bad considering I get 7ft of snow during winter months and I am surrounded by very tall trees.
Optimize on hourly generation not daily, most solar companies use DAILY numbers without a clue on hourly usage. I currently get 0.08$ for every 1$ in electric production, so there is very little benefit in producing electricity when you don’t use it. Optimize your system based on your usage not on DAILY production. If electric companies would give me credit of say 0.90$ per 1$ then the equation changes, but electric companies would rather benefit from your overproduction, be careful as these systems are not cheap!
https://www.suncalc.org works great for shade calculations, I was surprised when I checked tree shadows for different times a year.
However, due to the fact that PG&E keeps shifting our peak hours, we actually get more credit for producing in the afternoon, so when we expand our house, I'm planning on having all the panels (as much as possible) on the west-facing roof.
Also, we plan to install air conditioning at that time, so it will be helpful to be able to handle that peak demand.
It depends what you are optimising for. East/west makes a lot of sense to optimise for morning and evening sun. Especially as during the middle of the day electricity prices usually drop due to excess solar.
And usually the efficiency is much worse than 98%.
Oh, and also batteries such as the tesla power wall can only be charged and discharged about 1000 times before they have lost a lot of capacity. So generating when you use also makes your batteries last much longer. You could think of this as a cost of battery depreciation per kWh stored.
Also, there's a lot of factors that go into play. For example, this assumes the batteries are fully charged and discharged. If you do something smarter like going down to 40% and up to 80% then they end up being able to do a lot more cycles. In fact, battery age starts mattering more than the cycles.
But besides that, LFP batteries are currently being used in home battery storage (including powerwalls) because it's cheaper and it has 5000->10,000 cycles before dropping to 70% capacity.
Generally, though, I'd agree that having more generation throughout the day is better than having perfectly optimized generation.
Here it is more than 3x, so if I can charge a battery and run off of that for those 3 hours, I am saving money.
And it's not that I can lose money, a charge in the battery doesn't become stale.
Except in my case it is! I wanna do most of my charge at noon when I'll have far more than I can export. Export first, then charge!
Powerwall's cycle life is much better than 1000. The Powerwall warranty guarantees 70% capacity after 10 years of daily cycles (i.e. 3650 cycles). This means they expect the capacity to be substantially above 70%.
We posted an analysis of Powerwall capacity retention: https://www.netzero.energy/content/2025-02/powerwall-analysi...
... to have pulled some corporate restructure which leaves a bankrupt legal entity responsible for the warranty claims before they start costing any real money.
Trouble is you don't really know how much excess power you've got until you crank up battery charge current.
I think it depends on how you've configured it. My never charges the battery up from solar. I think it estimates how much power you'll need based on the configuration and charges accordingly. I've noticed on hot summer days mine will charge a bit in the morning then stop, then in the afternoon when the AC kicks on and off it will charge between AC cycles.
So, instead of living in a desertifying moonscape with jacked-up insurance costs, we bailed for around the 100th meridian west where there aren't forest fires or earthquakes. And no hurricanes or floods either. The most concerning things are hail and wind which can be more-or-less mitigated and/or insured for, while tornado risk here is on the order of 0.0001%/structure/year.
Plus modeling goes only so far when your behaviors change. I found it's incredibly hard to model this when there's so many variables.
Also 12 degrees south would put a mountain partially in view of the panels, and mountains don’t provide much light here. (I don’t mean the mountains would block the sun, just a band of otherwise visible sky)
When we do have high intensity light, the late afternoon is when we want it, and also when the sun is most off to one side of the sky.
My advice: over panel as much as you can. We can fully charge our batteries while running the farm and 6houses in three hours of full sunlight, so we still get plenty on overcast days, and even on the few darkest days we make about 70%. We have to supplement the solar about 60 days a year total, burning a total of 300 gallons of fuel over the year for a small farm and 6 houses.
The batteries shipped to your home inclusive of all taxes and fees, UL listed, are only $5,400 today from a variety of reputable suppliers.
This is obviously different than urban london but I wanted to point out just how economical this is for huge swaths of the country and how absolutely absurd some of the pricing I see on things like tesla powerwall are.
Note: There are a lot of components to an installed battery system that effect pricing such as racking, wires, busbars, breakers, etc, etc. I am referring only to the enclosed battery units with BMS.
https://www.expertpower.us/products/10800w-50kwh?_pos=2&_sid...
That's 50KWH of battery, plus the 10.8KW of solar, inverters, etc., all for $17K. That system is microgrid (not grid following) capable; so, you can run it during a blackout. The switchover is pretty good, too, so you don't need a second backup system.
Example kit:
https://signaturesolar.com/complete-off-grid-solar-kit-eg4-6...
Add in a 15 kWh module and it's roughly the same price with better customer service, reliability, less parts, etc.
However, I would just get an EG 18k PV, 45 kWh of EG5 batteries and 11.4 kW of solar panels from signature solar and that would cost you $18.5k
No inspector will sign off on a non-listed piece of electrical equipment, especially for a homeowner.
I repeat, do not connect electrical equipment to your home’s electrical distribution network unless it is tested by one of the labs listed in the link below, especially if it is hardwired.
[0] https://www.osha.gov/nationally-recognized-testing-laborator...
https://www.apexiummall.com/index.php?route=product/product&...
https://yixiangpower.com/products/yixiang-vertical-15kw-diy-...
Both would cost roughly $4800~$5500 for that total size.
If you want good customer service, dependable, UL listed, and correctly priced, then this is the king: https://signaturesolar.com/eg4-wallmount-indoor-battery-48v-...
UL listed ~45 kWh will cost you $10k, not $5.4k.
Shade and clouds of any kind, even very minor, have a HUGE effect on the production of a solar array.
I don't know how far south you are, but 15-20° of latitude has a significant impact on the effectiveness of solar, especially during winter.
Are you sure you're in the UK?
Even when it gets very hot in the day(100+), the nights almost always drop down to 63 or less. Meaning if you have a well sealed house you can suck up cold air during the night and ride it out in the day and have very low cooling costs. Coupled with low humidity from an arid environment means you can also let the house get hotter before it feels like it is time to turn on the AC.
My panels are ground mounted and pointed in the ideal direction. I think this contributes to their efficiency because the ground helps cool them during the hottest periods but it is a tricky thing to nail down. On a previous home I had roof mounted panels and they seemed to perform much worse, difficult to identify the exact reason though.
What about installation? DIY?
I think the main consideration for any outbuilding would be whether it was water-tight, had some level of climate control, and was secure against theft.
This would remain relative to climate and security needs though as you're pointing out.
But, as I say in the post, this is a bit of fun looking at extremes.
This is ridiculous. It's like asking how much propane do I need to store in summer to go the whole winter? You would need a tank so big it could fill up propane tankers. Thus why we get regular deliveries of propane throughout the year on an as-needed basis... and why you should only have enough battery to store the peak energy use for a couple days at most. If you have an extended period of no sun, first you reduce your energy use, and then you top up with a generator. This is far cheaper and more flexible than having a gigantic battery array for an edge case.
22kWh in battery (self-contained units, BMS, heating element, etc) costs <$4400 in the US, shipped from China, for a reputable (but not pricey-brand) battery provider. More than enough to power most homes (in Northeast US, cold winters without much sun) for a couple days. Add in everything else you need (wiring, solar panels, power inverter(s), MPPT(s), generator, etc) and you get to $6.5k-$9k
Batteries are similar to solar panels in this regard. With solar, the first couple of kilowatt-peak delivers the biggest savings. With batteries, it's the same with the first couple of kWh of storage capacity.
In my case, it's configured to track the readings of my digital electricity meter. The battery charges itself when my solar panels produce excess power and discharges when it detects grid consumption. Throughout the day, it buffers the intermittent solar power, and during the evening, night, and early morning hours, it keeps my grid power consumption close to zero.
One thing that I never see mentioned is how to support on-demand instant hot water heaters.
The 6.5 gal/min heater (what it takes to fill a tub) that I'm installing uses 100A at 220v when operating!
I haven't found any battery system that can support that.
Do "totally off-grid houses" all use a typical electric storage tank hot water heater? For my solo occupation, that's a lot of hot water storage over times when almost none is being used.
I do have a smaller water heater under the kitchen sink, so that the giant one doesn't have to run for that usage.
How do off-grid homes deal with the high instantaneous current consumption of on-demand water heaters?
Heating slow(er) and storing is going to be easier than suddenly ramping up for a shower.
Seems like we'll get to a point where adding extra panels "makes economic sense" long before this kind of storage makes sense.
Mexico City, Santa Fe, places like this are great for your proposed setup. Wherever you likely live, probably not.
The problem is economics with for-profit generation, not storage cost: If the cost of generation from PV was equitable, you would "store" your volts in the supply chain and withdraw from the bank over winter. Then the storage (at loss to transport) would be in Dams and other long duration spaces.
The problem is that wH-for-wH doesn't take into account distribution costs, which is most of the residential cost of electricity, and that a wH at noon in July doesn't cost the same to generate as a wH at 2am in February.
For most jurisdictions you can look up the large industrial rates to find the wholesale energy rates. Residential solar is worth about half of that 'reliable' electricity rate.
They even power homes 100% offline, including homes impacted by natural disasters in LA.
If you seek home backup, generally you don't want to pay to run your home at full load during an outage. Surely in an outage you won't charge your car, or run your over or dryer, or your air conditioner on full etc. Consider how much power you need when conserving, unless you are expecting an apocalypse style outage. Get enough battery for that.
It behooves you to ensure that winter solar power exceeds your usage before even to consider buying any batteries.
780kWh/month for 2,000sq 1970 Texas natural-gas ranch-sytle home in December. I would need 1400kWh just to be able to start charging batteries (which includes 780 daytime usage) so that all-night-long nighttime usage are still battery-available/supplied.
It gets worse during A/C usage months.
Battery-store power for residential are at best transient and temporary.
Public ones explode often.
I learned all this with homemade battery pack and windmill-powered generation in 1973. Solar cells were pricy then, 10 of those large-stamp-sized solar panel were $166 (in 1973 dollars) and still could not keep one red jumbo LED lit all night long.
When your PV panels are producing excess power during the day, spin up a GPU and rent it out through a cloud provider. Spend the money on the power your home consumes at night.
thelastgallon•4mo ago
joemazerino•4mo ago
Jeremy1026•4mo ago
KaiserPro•4mo ago
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.
giveita•4mo ago
bot403•4mo ago
KaiserPro•4mo ago
mnw21cam•4mo ago
LiFePO3 batteries don't take as much wear from cycling, so they usually wear out from time elapsed instead of over-use. It's economically sensible to cycle LiFePO3 batteries as frequently as possible to get as much "benefit" out of the investment. They're great for time-shifting energy production by charging them at a cheap time of day and discharging them when you need the energy at an expensive time of day.
Ylpertnodi•4mo ago
KaiserPro•4mo ago
rswail•4mo ago
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".
nxm•4mo ago
heresie-dabord•4mo ago
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