My biggest problem with batteries for grid outages is that the only outages I am actually concerned with would drain them to zero before the outage is resolved. For short term, smaller/portable batteries are fantastic at bridging a few hours. Plug the wifi & fridge in and you can sometimes go for 2-3 days.
I am not aware of any economically feasible way to run my 5+ ton HVAC system full-time on batteries after a hurricane just reset all the infrastructure, and you do need to run it full time because of the insane humidity and latent heat that follows a tropical system. Doing the math, I'd need something approaching 800kWh of storage to ride through this kind of event (7+ days). This is approaching half a million dollars in batteries. I can install an extremely nice 1800 RPM generator for ~15% of this cost, which would also include a year's worth of propane buried on the property.
I think a simple generator on an ATS remains undefeated from an engineering perspective. If you have an air cooled unit, the maintenance is not much more complicated than with a lawnmower. You just have one extra spark plug to deal with, and sometimes the oil pressure sensor needs replacing. I can get my stubborn Honda generator to start with all kinds of weird tricks. If my Ecoflow battery starts to act weird, I have very little recourse by comparison.
Batteries alone are not suitable for long duration outages, but solar+batteries, designed correctly, can not only supply enough power during long outages, it can get you to be off-grid entirely in the first place at a dramatically more cost effective number than your $500k quoted - perhaps 1/5 or less for a system suitable for your needs of 115kWh per day. So while the system might be more expensive than a generator alone, it can still beat on value because it provides power all year round.
You also do an unfair comparison here - you are OK with portable batteries providing only fridge & WiFi for a couple hours, but expect whole-hole batteries to last a week. Many people use whole-home batteries to bridge typical outages that last <24 hours, and do so without ever having to notice any change of use of their home - powering their full heating/cooling etc.
Batteries and generators are also not mutually exclusive. You can install a solar+battery system because it makes economic sense and pays for itself while providing zero-downtime backup for most outages, while also backing that up with a generator for longer term edge case outages eg long extended outages during the winter or where there is an unusually long “solar drought” - it really depends on how much resilience you are designing for.
It's nice to do this for more than just the direct economic costs. The generator doesn't have to run 24/7 since the batteries absorb the excess power produced by the generator. This means less fuel wasted as well as less noise produced. I used to have two small generators that I could run (and team, if needed) but adding a battery component meant being able to sleep at night without a combustion engine burning fuel all night long.
Yup, even better if you power a battery charger with the generator, but let loads be handled by the battery+inverter. You don’t need to provision the generator for peak loads (which can be quite high), or even worry about high harmonic distortion from a cheap generator screwing with your electronics. It basically turns your system into a fully ‘online’ UPS.
Also, really handy for diesels which will ‘wet stack’ if you only run them for short periods.
Provision a generator size which you expect to run say 6-10 hours at a time (at say 70-80% rated load) to fully charge your batteries, and a battery bank sized for 3-4 days of load.
Keeps your total gen hours much lower, much more efficient fuel wise (you can set the ideal load using your charger, and it will keep it that way regardless of increasing/decreasing loads), doesn’t require as big a generator if you have things like AC compressors, heat pumps, etc. with high start loads, and gives you a lot of redundancy and flexibility.
Best of all worlds. Especially if you have natural gas, or get a tri-fuel and keep propane handy.
I’ve been looking into a smaller scale option to run limited items medium term on part time hours…
Best option so far involves a mix of batteries that are charged from the mains when available and topped up from a mix of solar and a LPG/multi-fuel generator.
But unless you want to go very large on the solar and generator size it’s unlikely to cover everything full time.
Assuming you have enough solar, how about running your 5+ ton HVAC system only when there is enough production? And properly insulating your home, of course, using it as a thermal battery of sorts.
If there is a grid outage, surely one can shift consumption to solar production hours while using the battery for the always-on systems (fridge, lights, some computing...).
Yes this is what I do with power outage with solar and battery and 5 to, I have to modify my behavior and conserve, increase ac some from day 73 to 77, shower during the day when there is excess power etc.
If there are clouds lowering solar output the ac isnt running as much either or at night.
If I wanted to run as though the grid was up would probably need double the size solar and battery.
Yeah it's hard for batteries alone to compete with generators, unless we put a lot of weight on things like noise, or are just focused on small loads like fridges.
I think the more interesting comparison is generators vs solar, though it depends on the local weather etc.
Oil generators have an “artificially” low price because there’s a lot of demand for oil for other things. If the other sources of demand go away, the price may become unfavorable even if gas generators make a lot more sense from a redundancy perspective.
Recovered biodiesel (fryer oil) is always gonna be a thing to some degree. Either chemical synthesis or just plain devoting some agricultural output in the future doesn't sound completely insane.
>I think a simple generator on an ATS remains undefeated from an engineering perspective.
Let me just inject a bit of nuance here to avoid what I think is an unintentional sleight if hand...
For the small sliver of the population that lives under threat of a large area week long blackout in a hot humid climate, I think a simple generator on an ATS remains undefeated from an engineering perspective.
For the vast majority of the population, it's incredibly rare to lose power for that long, and need AC 24/7 afterwards. It basically only happens in the gulf.
In the spirit of nuance, the vast majority of the population of Florida is at risk. Something like 10% of the US population in total could be impacted directly. You don't actually have to live on the coast to get rocked by a hurricane. Ike took out power for millions in Ohio.
Correct, but you don't need 24/7 AC in ohio during hurricane season. Your reference storm was in September, when Ohio basically needs no heat or AC at all. The nuance is the extreme emergency energy demands (mandatory constant AC) are pretty rare.
These replies and the down votes are just reinforcing why I made my comment. People are unable to grasp nuance, apparently even when it is spelled out.
> For the small sliver of the population that lives under threat of a large area week long blackout [...]
I've lost power for weeks from snow, wind, storms, and ice, living in the central midwest and mid south. We lose power almost every time it rains in the spring and summer for many hours.
How about reducing energy use? In general, but then especially after a grid-destroying event that keeps you offline for a week? You surely don't need to have everything HVAC running on full blast in the whole house during that time. And your laundry and next oven long cook can probably also wait until the grid power is back.
If you then add some solar into the mix, it doesn't sound as dramatic anymore.
There is something in between flashlights and a grid scale battery that van power your full electric home.
I just have a plugin battery that I can run the lights, fridges, phone chargers off of for 24 hrs. That is good enough for me, and I think most people. Anything shorter, and it's not necessary to run the rest, much longer, there also isn't because apparently shit hit the fan and we're not necessarily assuming the power comes back on in the next weeks or ever.
I have 18kw of solar and 30kwh of batteries with a 5ton ac it will run it will run indefinitely assuming the sun comes out, if it doesn’t I have a chargeverter that can keep the batteries charged off my RV’s diesel generator or gas portable.
My solar system generates excess power daily and has zero maintenance, the generators are pure money sinks for backup power and require regular maintenance.
Options are nice.
Also heat pump water heater and dryer help reduce load along with efficient variable speed hvac and good insulation.
Fuel is a problem during a storm too and a buried large propane tank is a good way to go but very expensive on top of installation.
An electric car with bi directional charging would add to flexibility either charging from home system or being able to go find power and bring it home.
Ideally I would like a gasoline hybrid with power out like a F150 power boost and a fully electric with large battery and V2L any Tesla would do now as they all have 2400w out I believe Cybertruck can do more. My chargeverter can take 120v or 240v
I just run 120v extension cords from my EV during power outages (it has 2 15A capable outlets). I added a manual transfer switch to my furnace so it can be plugged into an extension cord, and I can power my furnace, blower, refrigerator and freezer, wifi and internet for a couple of days.
I really wanted to set up an automatic transfer switch for the whole house from my car in v2h mode, but I found it impossible to spend any amount of money and be confident that the system would actually work with my current EV (the wallbox quasar _sounds_ promising but I couldn't find any reports that it actually _works_)
A fundamental problem here is that V2H during an outage requires a disconnection device (in the NEC this is a “microgrid interconnect device”), and the manufacturers of such things have made no effort whatsoever to standardize the control protocol. This means that you cannot build an islanded-V2H-ready house and just plug in a car. So the whole concept is kind of dead in the water.
At least Tesla is vertically integrated enough to pull it off within their own product portfolio, but this has approximately no value if you want to use a non-Tesla car.
It’s unfortunate and inconvenient. However A transfer switch requires <3 minutes to engage. If a car was able to supply 30-50 amp via compatible plug it would work reasonably well even absent unified v2h standard.
Most recent teslas support 20amp at 120v output via official $100 cable adapter. Some other cars support about 20amps too, eg RivianR2. While it falls short of desirable amperage the car manufactures can bridge the gap if they wanted to. Even now I can run the bare minimum of workloads - a full size fridge, a small AC or Microwave, LED lights, and phone chargers.
You can't do just V2H, but Enphase and others have moved to simpler meter collars and grid disconnect for exactly this reason.
The main question for this thread remains who the Enphase / ISO standards friendly OEMs will be. With Tesla saying they'll allow it now, maybe others will get onboard, but the risk is that they wall themselves off.
This entire area is a mess, I spent a year or so trying to get bidirectional charging set up at home in the UK. I even went to several of the vendors mentioned in that post and said "I've got basically a blank cheque and permission to do whatever you want however you want, even use it all as a case study to make this work" and nowhere could/would do it.
The most frustrating thing is it looks like V2G is easier and more accessible than V2H[1]: it's easier to give control of your battery to your energy provider and bypass your house to help the energy companies than it is just to power your own home with your own car battery.
Technically, this is ridiculous. You don't bypass your house when you do V2G.
My tinfoil hat is clearly making me too cynical when I say this, but I think it's this way because of the relationship between energy providers and law makers. These are the same energy providers that use "changes in wholesale pricing" to justify increasing how much they sell me electricity for, whilst reducing the amount they pay me for the solar electricity I sell them.
You can do it with an F150 lightning if you have the 10kW inverter. Rather than use the charge port and the official charger, you use the 30A 240V plug in the bed to power your panel. You can charge the truck while using this too.
I can go most of a week on the Lightning's battery, and it will shut down the 240V 30A outlet well before leaving me stranded. Thankfully the longest outage we've had in my lifetime (and I'm not a young man) is 3 days, for an extremely rare severe ice storm.
One of the problems with companies like GM is that they still see this as a premium feature and require their hardware (not just a charger). Tesla requires not only their chargers but also their inverters and cars.
What is missing is a spec that inverters and cars and chargers can all follow, then we will see mass adoption.
CHAdeMO had that spec, but of course is obsoleted now.
If I understand things correctly tho many of the V2L solutions just work with pretty much any car that does CCS, regardless of whether the manufacturer officially supports this or not. My Polestar2 for example doesn't official have any kind of V2H/V2L option but I've heard of many success stories.
Tesla just brought this functionality to new Model 3 and Model Y cars as of Oct 1. It requires at least one Powerwall 3 to enable bidirectional V2H - what they call Powershare. But those cars can now power the home and charge from solar while the grid is offline.
I really wonder if part of the reason this isn’t more widespread is that utilities with variable rate electricity pricing would get burnt on it. Imagine charging during cheap time then dumping 5-20kWh back onto the grid during expensive time. You could have a positive ROI on a vehicle you regularly drive (timing permitting)
No, the main barrier is concern over warranties for the vehicles.
In California, the law requires that vehicles still hold up to 70% of their original charge after 8 years and 75% in the future [1]:
> and d., to deteriorate to less than 70% for a warranty period of eight years or 100,000 miles, whichever first occurs, for 2026 through 2030 model years, and 75% for a warranty period of eight years or 100,000 miles, whichever first occurs, for 2031 and subsequent model years.
The law is unclear on bidirectional charging and whether this would give manufacturers an out. So they're cautious.
Why? That's the entire point of moving towards dynamic tariffs. In the systems I'm familiar with the utility company makes money through a fee charged on top of the market purchase/sale price, much like an investment broker.
Maybe. I did the math and in our area a Powerwall would roughly pay for itself over the speced lifespan of the device, IIRC that was just the cost of the device not the cost of installation. I did that calculation ~4 years ago, so maybe it has changed, but definitely do the math, I was surprised.
Why shouldn't utilities pay for this? You're provide grid load balancing. Theoretically their pricing should be considering this? It's not actually free to you since charging and discharging your battery costs money.
But naturally the situation is they want to be the ones paid the big bucks for such services.
> The only way I can see to do this today is with Tesla Powershare + Cybertruck, which says "If the system includes a UL 1741-listed solar system
Since this was posted Tesla rolled out PowerShare to recent ModelY and some other cars. Not sure about solar recharge though. Where I live storms come in winter and I have natgas so most of the power will go to fridges and electronics, which will hopefully last long enough.
Wouldn't the charge / discharge cycles reduce the life of the car battery? I presume the same is true of in-home batteries, but although an in-home battery is an extra capital expense, I imagine the replacement cost of in-home batteries is quite a bit lower, isn't it? Would be interested to know more about the medium-to-long term economics of this.
> Wouldn't the charge / discharge cycles reduce the life of the car battery?
While I'd presume the answer here is "yes", I'd also presume we're talking like a fraction of the vehicle's lifetime charge cycles. Like, (generously/conservatively) 20 to 40 cycles total over the life of the vehicle, no? How often would you estimate your power going out?
The point wouldn't be just for backup during outages. It would be growing your kWh of storage and doing daily TOU optimization. That increases the charge / discharge profile by a lot.
Though for an 80 kWh or larger battery, you're only likely to store up and discharge 10-ish per day maybe this way? (Assuming you have actual dedicated BESS, and this is supplementing that). Still that's ~30 cycles per year, which is nothing in the grand scheme of a vehicle battery.
I don't think that wear would be worse than driving around. Unless you go out, recharge, and come back, by definition you only have a single charge single cycle to give.
My thinking is that driving has a typical burn rate (eg 1 kWh/mile or whatever), so the battery will be designed around this load pattern. Using it as a battery backup may be pulling a lot faster than optimal and cause additional wear.
It is probably only a minor impact, but I could believe it is outside the design constraints.
For something you (hopefully) don't have to do that often, it seems negligible. But if you're charging and discharging the car daily to do arbitrage you might eventually notice the degradation
I live rural and I'm hoping the next decade will bring a wave of cheaper safer sodium ion battery options. Something I'd feel a lot more comfortable with putting in or around my home since they don't have thermal runaway issues, their materials are theoretically cheaper, and they can withstand colder temperatures.
While I'd like to use my EV as backup, the cost and integration issues right now are just not sensible. The utilities and manufacturers have made it too cost prohibitive.
LiFePO4 are much more robust against thermal runaway, omit a lot of the expensive materials that are in typical Li-NMC batteries, and have a better cycle life. They still can't be charged below 0°C, they have worse specific energy, and they generally can't handle the same peak power output, but they're a better choice for fixed storage applications IMO.
GP is referring to sodium ion batteries. They’re even cheaper materials wise (no lithium) and have even more favorable outcomes for freezing conditions.
Worse energy density and similar or potentially worse number of cycles, but that’s being worked on.
But an important difference is that LFP is available today. Expecting a dramatic shift to sodium ion anytime soon is wishful thinking. Battery tech evolves steadily but slowly.
CATL is already producing sodium ion at competitive prices. Expect 5-10 years to end up with a flood of stationary battery products based on them, at prices less than LFP.
I'm not sure what the laws are like in the USA I assume they are similar to elsewhere.
However I think there are two problems here that have to be solved:
1) you need to island your house, that is, physically disconnect your house from the grid
2) once you have disconnected the grid, you then need to provide some sort of pilot sine wave to allow the plug to function.
I have an islanding system for my (house) battery and solar, so in theory, I could have a bidirectional charger whilst being off grid. However both my car and charger don't support that (my charger is also deeply shit, and has no local API access.)
The bigger problem, which is tangentially touched on, is that vanishingly few chargers can actually support islanding. It makes the installation harder, and drives up the compliance and installation cost[1]. this means that you are taping together two disparate systems together (or going all in on enphase, which also has a limited local API)
There isn't a spec for a household systems to talk together to do energy management. currently I use homeassistant to monitor the variable electricity prices, car plug status and how happy the fucking powerwall is, so that I can make sure the car charges from solar, without draining the house battery to 0, or only charge at night when the price us uber cheap (and also not drain the house battery).
The amount of sysadminig to make that work reliably means that no normal person is able to achieve it. The problem for consumers is that there isn't any motivation for manufactures to work together on this. because they want to vertically integrate.
[1] The installation cost for what is effectively a very thin software wrapper around a local contactor is egregious.
> I have an islanding system for my (house) battery and solar, so in theory, I could have a bidirectional charger whilst being off grid. However both my car and charger don't support that (my charger is also deeply shit, and has no local API access
...
> The amount of sysadminig to make that work reliably means that no normal person is able to achieve it. The problem for consumers is that there isn't any motivation for manufactures to work together on this. because they want to vertically integrate.
We are in a very similar position. The issue is every company in this area is like you say: deeply shit with limited local API access. Setting up bidirectional charging in the UK is technically, really not that hard, especially with islanding handled at the household level.
Good luck trying to get someone willing to put their career and certifications on the line to actually do it though.
Part of the challenge is finding an electrician willing to work like a sysadmin and do things because they know how they work, rather than only doing things they've explicitly been taught as in line with (dated) regulations.
My biggest problem with batteries for grid outages is that the only outages I am actually concerned with would drain them to zero before the outage is resolved. For short term, smaller/portable batteries are fantastic at bridging a few hours. Plug the wifi & fridge in and you can sometimes go for 2-3 days.
I am not aware of any economically feasible way to run my 5+ ton HVAC system full-time on batteries after a hurricane just reset all the infrastructure, and you do need to run it full time because of the insane humidity and latent heat that follows a tropical system. Doing the math, I'd need something approaching 800kWh of storage to ride through this kind of event (7+ days). This is approaching half a million dollars in batteries. I can install an extremely nice 1800 RPM generator for ~15% of this cost, which would also include a year's worth of propane buried on the property.
I think a simple generator on an ATS remains undefeated from an engineering perspective. If you have an air cooled unit, the maintenance is not much more complicated than with a lawnmower. You just have one extra spark plug to deal with, and sometimes the oil pressure sensor needs replacing. I can get my stubborn Honda generator to start with all kinds of weird tricks. If my Ecoflow battery starts to act weird, I have very little recourse by comparison.
Batteries alone are not suitable for long duration outages, but solar+batteries, designed correctly, can not only supply enough power during long outages, it can get you to be off-grid entirely in the first place at a dramatically more cost effective number than your $500k quoted - perhaps 1/5 or less for a system suitable for your needs of 115kWh per day. So while the system might be more expensive than a generator alone, it can still beat on value because it provides power all year round.
You also do an unfair comparison here - you are OK with portable batteries providing only fridge & WiFi for a couple hours, but expect whole-hole batteries to last a week. Many people use whole-home batteries to bridge typical outages that last <24 hours, and do so without ever having to notice any change of use of their home - powering their full heating/cooling etc.
Batteries and generators are also not mutually exclusive. You can install a solar+battery system because it makes economic sense and pays for itself while providing zero-downtime backup for most outages, while also backing that up with a generator for longer term edge case outages eg long extended outages during the winter or where there is an unusually long “solar drought” - it really depends on how much resilience you are designing for.
> You can install a solar+battery system because it makes economic sense and pays for itself
Would take longer than 20yr at current power rates in many US locales.
It's nice to do this for more than just the direct economic costs. The generator doesn't have to run 24/7 since the batteries absorb the excess power produced by the generator. This means less fuel wasted as well as less noise produced. I used to have two small generators that I could run (and team, if needed) but adding a battery component meant being able to sleep at night without a combustion engine burning fuel all night long.
Yup, even better if you power a battery charger with the generator, but let loads be handled by the battery+inverter. You don’t need to provision the generator for peak loads (which can be quite high), or even worry about high harmonic distortion from a cheap generator screwing with your electronics. It basically turns your system into a fully ‘online’ UPS.
Also, really handy for diesels which will ‘wet stack’ if you only run them for short periods.
Provision a generator size which you expect to run say 6-10 hours at a time (at say 70-80% rated load) to fully charge your batteries, and a battery bank sized for 3-4 days of load.
Keeps your total gen hours much lower, much more efficient fuel wise (you can set the ideal load using your charger, and it will keep it that way regardless of increasing/decreasing loads), doesn’t require as big a generator if you have things like AC compressors, heat pumps, etc. with high start loads, and gives you a lot of redundancy and flexibility.
Best of all worlds. Especially if you have natural gas, or get a tri-fuel and keep propane handy.
You can run your hvac fan and an oversized dehumidifier for a while off batteries. You don't need the whole hvac system.
I’ve been looking into a smaller scale option to run limited items medium term on part time hours…
Best option so far involves a mix of batteries that are charged from the mains when available and topped up from a mix of solar and a LPG/multi-fuel generator.
But unless you want to go very large on the solar and generator size it’s unlikely to cover everything full time.
Assuming you have enough solar, how about running your 5+ ton HVAC system only when there is enough production? And properly insulating your home, of course, using it as a thermal battery of sorts.
If there is a grid outage, surely one can shift consumption to solar production hours while using the battery for the always-on systems (fridge, lights, some computing...).
Yes this is what I do with power outage with solar and battery and 5 to, I have to modify my behavior and conserve, increase ac some from day 73 to 77, shower during the day when there is excess power etc.
If there are clouds lowering solar output the ac isnt running as much either or at night.
If I wanted to run as though the grid was up would probably need double the size solar and battery.
Yeah it's hard for batteries alone to compete with generators, unless we put a lot of weight on things like noise, or are just focused on small loads like fridges.
I think the more interesting comparison is generators vs solar, though it depends on the local weather etc.
Oil generators have an “artificially” low price because there’s a lot of demand for oil for other things. If the other sources of demand go away, the price may become unfavorable even if gas generators make a lot more sense from a redundancy perspective.
The future cost would likely be based on chemical synthesis.
Recovered biodiesel (fryer oil) is always gonna be a thing to some degree. Either chemical synthesis or just plain devoting some agricultural output in the future doesn't sound completely insane.
Power density of dino juice is virtually undefeated
>I think a simple generator on an ATS remains undefeated from an engineering perspective.
Let me just inject a bit of nuance here to avoid what I think is an unintentional sleight if hand...
For the small sliver of the population that lives under threat of a large area week long blackout in a hot humid climate, I think a simple generator on an ATS remains undefeated from an engineering perspective.
For the vast majority of the population, it's incredibly rare to lose power for that long, and need AC 24/7 afterwards. It basically only happens in the gulf.
> For the vast majority of the population
In the spirit of nuance, the vast majority of the population of Florida is at risk. Something like 10% of the US population in total could be impacted directly. You don't actually have to live on the coast to get rocked by a hurricane. Ike took out power for millions in Ohio.
https://www.facebook.com/100044470387919/posts/ohio-remember...
Correct, but you don't need 24/7 AC in ohio during hurricane season. Your reference storm was in September, when Ohio basically needs no heat or AC at all. The nuance is the extreme emergency energy demands (mandatory constant AC) are pretty rare.
These replies and the down votes are just reinforcing why I made my comment. People are unable to grasp nuance, apparently even when it is spelled out.
> For the small sliver of the population that lives under threat of a large area week long blackout [...]
I've lost power for weeks from snow, wind, storms, and ice, living in the central midwest and mid south. We lose power almost every time it rains in the spring and summer for many hours.
>in a hot humid climate
It seems you cut off part of the quote. I know it can get hot in the midwest, but places like Florida are borderline "humans shouldn't live here" hot.
How about reducing energy use? In general, but then especially after a grid-destroying event that keeps you offline for a week? You surely don't need to have everything HVAC running on full blast in the whole house during that time. And your laundry and next oven long cook can probably also wait until the grid power is back.
If you then add some solar into the mix, it doesn't sound as dramatic anymore.
There is something in between flashlights and a grid scale battery that van power your full electric home.
I just have a plugin battery that I can run the lights, fridges, phone chargers off of for 24 hrs. That is good enough for me, and I think most people. Anything shorter, and it's not necessary to run the rest, much longer, there also isn't because apparently shit hit the fan and we're not necessarily assuming the power comes back on in the next weeks or ever.
I have 18kw of solar and 30kwh of batteries with a 5ton ac it will run it will run indefinitely assuming the sun comes out, if it doesn’t I have a chargeverter that can keep the batteries charged off my RV’s diesel generator or gas portable.
My solar system generates excess power daily and has zero maintenance, the generators are pure money sinks for backup power and require regular maintenance.
Options are nice.
Also heat pump water heater and dryer help reduce load along with efficient variable speed hvac and good insulation.
Fuel is a problem during a storm too and a buried large propane tank is a good way to go but very expensive on top of installation.
An electric car with bi directional charging would add to flexibility either charging from home system or being able to go find power and bring it home.
Ideally I would like a gasoline hybrid with power out like a F150 power boost and a fully electric with large battery and V2L any Tesla would do now as they all have 2400w out I believe Cybertruck can do more. My chargeverter can take 120v or 240v
I just run 120v extension cords from my EV during power outages (it has 2 15A capable outlets). I added a manual transfer switch to my furnace so it can be plugged into an extension cord, and I can power my furnace, blower, refrigerator and freezer, wifi and internet for a couple of days.
I really wanted to set up an automatic transfer switch for the whole house from my car in v2h mode, but I found it impossible to spend any amount of money and be confident that the system would actually work with my current EV (the wallbox quasar _sounds_ promising but I couldn't find any reports that it actually _works_)
A fundamental problem here is that V2H during an outage requires a disconnection device (in the NEC this is a “microgrid interconnect device”), and the manufacturers of such things have made no effort whatsoever to standardize the control protocol. This means that you cannot build an islanded-V2H-ready house and just plug in a car. So the whole concept is kind of dead in the water.
At least Tesla is vertically integrated enough to pull it off within their own product portfolio, but this has approximately no value if you want to use a non-Tesla car.
It’s unfortunate and inconvenient. However A transfer switch requires <3 minutes to engage. If a car was able to supply 30-50 amp via compatible plug it would work reasonably well even absent unified v2h standard.
Most recent teslas support 20amp at 120v output via official $100 cable adapter. Some other cars support about 20amps too, eg RivianR2. While it falls short of desirable amperage the car manufactures can bridge the gap if they wanted to. Even now I can run the bare minimum of workloads - a full size fridge, a small AC or Microwave, LED lights, and phone chargers.
A manual switch doesn’t solve the problem: there still needs to be a way to inform the inverter that the switch is open.
You can't do just V2H, but Enphase and others have moved to simpler meter collars and grid disconnect for exactly this reason.
The main question for this thread remains who the Enphase / ISO standards friendly OEMs will be. With Tesla saying they'll allow it now, maybe others will get onboard, but the risk is that they wall themselves off.
This entire area is a mess, I spent a year or so trying to get bidirectional charging set up at home in the UK. I even went to several of the vendors mentioned in that post and said "I've got basically a blank cheque and permission to do whatever you want however you want, even use it all as a case study to make this work" and nowhere could/would do it.
The most frustrating thing is it looks like V2G is easier and more accessible than V2H[1]: it's easier to give control of your battery to your energy provider and bypass your house to help the energy companies than it is just to power your own home with your own car battery.
Technically, this is ridiculous. You don't bypass your house when you do V2G.
My tinfoil hat is clearly making me too cynical when I say this, but I think it's this way because of the relationship between energy providers and law makers. These are the same energy providers that use "changes in wholesale pricing" to justify increasing how much they sell me electricity for, whilst reducing the amount they pay me for the solar electricity I sell them.
[1] https://octopus.energy/power-pack/
You can do it with an F150 lightning if you have the 10kW inverter. Rather than use the charge port and the official charger, you use the 30A 240V plug in the bed to power your panel. You can charge the truck while using this too.
And then after a little while you can be without power AND stranded!
I can go most of a week on the Lightning's battery, and it will shut down the 240V 30A outlet well before leaving me stranded. Thankfully the longest outage we've had in my lifetime (and I'm not a young man) is 3 days, for an extremely rare severe ice storm.
One of the problems with companies like GM is that they still see this as a premium feature and require their hardware (not just a charger). Tesla requires not only their chargers but also their inverters and cars.
What is missing is a spec that inverters and cars and chargers can all follow, then we will see mass adoption.
CHAdeMO had that spec, but of course is obsoleted now.
If I understand things correctly tho many of the V2L solutions just work with pretty much any car that does CCS, regardless of whether the manufacturer officially supports this or not. My Polestar2 for example doesn't official have any kind of V2H/V2L option but I've heard of many success stories.
One of the biggest misses in NACS (J3400) is bi-directional power in the spec. SAE J3400/2 will fix it.
Tesla just brought this functionality to new Model 3 and Model Y cars as of Oct 1. It requires at least one Powerwall 3 to enable bidirectional V2H - what they call Powershare. But those cars can now power the home and charge from solar while the grid is offline.
I really wonder if part of the reason this isn’t more widespread is that utilities with variable rate electricity pricing would get burnt on it. Imagine charging during cheap time then dumping 5-20kWh back onto the grid during expensive time. You could have a positive ROI on a vehicle you regularly drive (timing permitting)
No, the main barrier is concern over warranties for the vehicles.
In California, the law requires that vehicles still hold up to 70% of their original charge after 8 years and 75% in the future [1]:
> and d., to deteriorate to less than 70% for a warranty period of eight years or 100,000 miles, whichever first occurs, for 2026 through 2030 model years, and 75% for a warranty period of eight years or 100,000 miles, whichever first occurs, for 2031 and subsequent model years.
The law is unclear on bidirectional charging and whether this would give manufacturers an out. So they're cautious.
[1] https://www.law.cornell.edu/regulations/california/13-CCR-19...
Why? That's the entire point of moving towards dynamic tariffs. In the systems I'm familiar with the utility company makes money through a fee charged on top of the market purchase/sale price, much like an investment broker.
Maybe. I did the math and in our area a Powerwall would roughly pay for itself over the speced lifespan of the device, IIRC that was just the cost of the device not the cost of installation. I did that calculation ~4 years ago, so maybe it has changed, but definitely do the math, I was surprised.
Why shouldn't utilities pay for this? You're provide grid load balancing. Theoretically their pricing should be considering this? It's not actually free to you since charging and discharging your battery costs money.
But naturally the situation is they want to be the ones paid the big bucks for such services.
> The only way I can see to do this today is with Tesla Powershare + Cybertruck, which says "If the system includes a UL 1741-listed solar system
Since this was posted Tesla rolled out PowerShare to recent ModelY and some other cars. Not sure about solar recharge though. Where I live storms come in winter and I have natgas so most of the power will go to fridges and electronics, which will hopefully last long enough.
Wouldn't the charge / discharge cycles reduce the life of the car battery? I presume the same is true of in-home batteries, but although an in-home battery is an extra capital expense, I imagine the replacement cost of in-home batteries is quite a bit lower, isn't it? Would be interested to know more about the medium-to-long term economics of this.
> Wouldn't the charge / discharge cycles reduce the life of the car battery?
While I'd presume the answer here is "yes", I'd also presume we're talking like a fraction of the vehicle's lifetime charge cycles. Like, (generously/conservatively) 20 to 40 cycles total over the life of the vehicle, no? How often would you estimate your power going out?
The point wouldn't be just for backup during outages. It would be growing your kWh of storage and doing daily TOU optimization. That increases the charge / discharge profile by a lot.
Though for an 80 kWh or larger battery, you're only likely to store up and discharge 10-ish per day maybe this way? (Assuming you have actual dedicated BESS, and this is supplementing that). Still that's ~30 cycles per year, which is nothing in the grand scheme of a vehicle battery.
Duh, yes, slow brain day.
I don't think that wear would be worse than driving around. Unless you go out, recharge, and come back, by definition you only have a single charge single cycle to give.
My thinking is that driving has a typical burn rate (eg 1 kWh/mile or whatever), so the battery will be designed around this load pattern. Using it as a battery backup may be pulling a lot faster than optimal and cause additional wear.
It is probably only a minor impact, but I could believe it is outside the design constraints.
For something you (hopefully) don't have to do that often, it seems negligible. But if you're charging and discharging the car daily to do arbitrage you might eventually notice the degradation
I live rural and I'm hoping the next decade will bring a wave of cheaper safer sodium ion battery options. Something I'd feel a lot more comfortable with putting in or around my home since they don't have thermal runaway issues, their materials are theoretically cheaper, and they can withstand colder temperatures.
While I'd like to use my EV as backup, the cost and integration issues right now are just not sensible. The utilities and manufacturers have made it too cost prohibitive.
LiFePO4 are much more robust against thermal runaway, omit a lot of the expensive materials that are in typical Li-NMC batteries, and have a better cycle life. They still can't be charged below 0°C, they have worse specific energy, and they generally can't handle the same peak power output, but they're a better choice for fixed storage applications IMO.
GP is referring to sodium ion batteries. They’re even cheaper materials wise (no lithium) and have even more favorable outcomes for freezing conditions.
Worse energy density and similar or potentially worse number of cycles, but that’s being worked on.
But an important difference is that LFP is available today. Expecting a dramatic shift to sodium ion anytime soon is wishful thinking. Battery tech evolves steadily but slowly.
CATL is already producing sodium ion at competitive prices. Expect 5-10 years to end up with a flood of stationary battery products based on them, at prices less than LFP.
I'm not sure what the laws are like in the USA I assume they are similar to elsewhere.
However I think there are two problems here that have to be solved:
1) you need to island your house, that is, physically disconnect your house from the grid
2) once you have disconnected the grid, you then need to provide some sort of pilot sine wave to allow the plug to function.
I have an islanding system for my (house) battery and solar, so in theory, I could have a bidirectional charger whilst being off grid. However both my car and charger don't support that (my charger is also deeply shit, and has no local API access.)
The bigger problem, which is tangentially touched on, is that vanishingly few chargers can actually support islanding. It makes the installation harder, and drives up the compliance and installation cost[1]. this means that you are taping together two disparate systems together (or going all in on enphase, which also has a limited local API)
There isn't a spec for a household systems to talk together to do energy management. currently I use homeassistant to monitor the variable electricity prices, car plug status and how happy the fucking powerwall is, so that I can make sure the car charges from solar, without draining the house battery to 0, or only charge at night when the price us uber cheap (and also not drain the house battery).
The amount of sysadminig to make that work reliably means that no normal person is able to achieve it. The problem for consumers is that there isn't any motivation for manufactures to work together on this. because they want to vertically integrate.
[1] The installation cost for what is effectively a very thin software wrapper around a local contactor is egregious.
> I have an islanding system for my (house) battery and solar, so in theory, I could have a bidirectional charger whilst being off grid. However both my car and charger don't support that (my charger is also deeply shit, and has no local API access
...
> The amount of sysadminig to make that work reliably means that no normal person is able to achieve it. The problem for consumers is that there isn't any motivation for manufactures to work together on this. because they want to vertically integrate.
We are in a very similar position. The issue is every company in this area is like you say: deeply shit with limited local API access. Setting up bidirectional charging in the UK is technically, really not that hard, especially with islanding handled at the household level.
Good luck trying to get someone willing to put their career and certifications on the line to actually do it though.
Part of the challenge is finding an electrician willing to work like a sysadmin and do things because they know how they work, rather than only doing things they've explicitly been taught as in line with (dated) regulations.