What EV can power your home?
Discussion
As we're all (nearly) wincing at the pump and at energy bills these days, I've looked more and more at PV panels at home, and EVs. There is a lot of debate that solar power doesn't make much financial sense in the UK, unless you got an amazing Feed In Tariff in the past, or have some method of storing excess energy to plug gaps at night/in winter. However, batteries are £thousands to store a couple of GBP worth of electricity.
This leads me to look at used EVs, and wonder if they are a 'cheap' way of buying energy storage. They have a dual use, in that they're your car, but can also store energy. They spend the majority of their life sat outside your house, which is ideal for this scenario, and if you're driving it it is less likely that you'll be using much energy at home. Depending on the car, most people probably don't use more than a small amount of the battery's capacity in daily use, so you're likely to have excess to use for home needs.
Is the tech there yet to be able to do this? I've seen it mentioned for some cars, but not in any detail. Most of the search results are a copy and paste on different websites of a promotion for a US EV pickup. Is it something that could be retrofitted to any EV, or does it depend on lots of variables that I don't yet appreciate?
This leads me to look at used EVs, and wonder if they are a 'cheap' way of buying energy storage. They have a dual use, in that they're your car, but can also store energy. They spend the majority of their life sat outside your house, which is ideal for this scenario, and if you're driving it it is less likely that you'll be using much energy at home. Depending on the car, most people probably don't use more than a small amount of the battery's capacity in daily use, so you're likely to have excess to use for home needs.
Is the tech there yet to be able to do this? I've seen it mentioned for some cars, but not in any detail. Most of the search results are a copy and paste on different websites of a promotion for a US EV pickup. Is it something that could be retrofitted to any EV, or does it depend on lots of variables that I don't yet appreciate?
Google V2G - lots of trials/test etc.
I think the number of vehicles is quite limited - Nissan Leaf being one.
It is in theory a good plan - you can utilise 50-100kWh of storage which would otherwise just be sitting there idle.
It depends on your usage pattern of the EV of course. If you are expecting to collect solar energy, then the vehicle needs to be at home in the day time.
It also gives the EV batteries a fair number of extra charge/discharge cycles - which might actually improve their life rather than shorten it.
It needs a proper charger/inverter (as opposed to an EVSE) for connection.
I think the number of vehicles is quite limited - Nissan Leaf being one.
It is in theory a good plan - you can utilise 50-100kWh of storage which would otherwise just be sitting there idle.
It depends on your usage pattern of the EV of course. If you are expecting to collect solar energy, then the vehicle needs to be at home in the day time.
It also gives the EV batteries a fair number of extra charge/discharge cycles - which might actually improve their life rather than shorten it.
It needs a proper charger/inverter (as opposed to an EVSE) for connection.
A car is an expensive asset to try using to save a few quid on your home electricity bill.
Unless you can prove it's not diminishing the life of the battery whatsoever, then it doesn't make sense.
Except maybe for a major power cut like a 'named storm'.
Or maybe a leased car, where you have no interest in the long term battery health?
Unless you can prove it's not diminishing the life of the battery whatsoever, then it doesn't make sense.
Except maybe for a major power cut like a 'named storm'.
Or maybe a leased car, where you have no interest in the long term battery health?
Pulling a few hundred or even a few thousand watts from a battery designed to put out hundreds of thousands of watts really isn't going to wear out the battery that much, and as mentioned, when properly managed it can extend the batteries life.
Better option imo is to use a second life battery as your home battery, because when "too worn" for our car, something like 80% of the origninal capacity is still available...
Better option imo is to use a second life battery as your home battery, because when "too worn" for our car, something like 80% of the origninal capacity is still available...
You can only currently buy Chademo V2G chargers in the UK, so a Leaf is your best bet. Most of them are supplied as part of trials, but they do come up for sale now and again second hand (they’re expensive!)
CCS bidirectional charging is coming - Wallbox are launching a unit that’s capable - but I don’t know if there are any compatible cars yet!
CCS bidirectional charging is coming - Wallbox are launching a unit that’s capable - but I don’t know if there are any compatible cars yet!
Max_Torque said:
Pulling a few hundred or even a few thousand watts from a battery designed to put out hundreds of thousands of watts really isn't going to wear out the battery that much, and as mentioned, when properly managed it can extend the batteries life.
Better option imo is to use a second life battery as your home battery, because when "too worn" for our car, something like 80% of the origninal capacity is still available...
There's a certain amount of vague arm waving about how batteries age through cycling and how some magic optimal cycling 'might' improve their life.Better option imo is to use a second life battery as your home battery, because when "too worn" for our car, something like 80% of the origninal capacity is still available...
Some people (more politicians than engineers?) are very keen to sell people the concept of using cars for grid storage.
The idea that knackered EV batteries will still have 80% of their capacity probably doesn't apply any more.
Modern Battery Management Systems will actively switch cells in and out to get the best out of an aged battery, once the BMS can't get a useful range out of it, it's probably not much use for anything else.
The problem is a lack of data, because current battery (and EV) technology hasn't been around long enough to tell us what ageing will really look like.
Max_Torque said:
Pulling a few hundred or even a few thousand watts from a battery designed to put out hundreds of thousands of watts really isn't going to wear out the battery that much, and as mentioned, when properly managed it can extend the batteries life.
Better option imo is to use a second life battery as your home battery, because when "too worn" for our car, something like 80% of the origninal capacity is still available...
Thats my vague plan when my current car has run its courseBetter option imo is to use a second life battery as your home battery, because when "too worn" for our car, something like 80% of the origninal capacity is still available...
NugentS said:
Max_Torque said:
Pulling a few hundred or even a few thousand watts from a battery designed to put out hundreds of thousands of watts really isn't going to wear out the battery that much, and as mentioned, when properly managed it can extend the batteries life.
Better option imo is to use a second life battery as your home battery, because when "too worn" for our car, something like 80% of the origninal capacity is still available...
Thats my vague plan when my current car has run its courseBetter option imo is to use a second life battery as your home battery, because when "too worn" for our car, something like 80% of the origninal capacity is still available...
An 80% useable i3 120ah battery is still going to offer 100+ miles of range even in winter?
SWoll said:
Why would an 80% useable battery be too worn out? And assuming that happens outside of the manufacturers warranty as is likely are you really going to pay out to replace it at that point?
An 80% useable i3 120ah battery is still going to offer 100+ miles of range even in winter?
It's like dead power tools, you have a group of cells in series to get a useful voltage, one of that group dies, the others can't work.An 80% useable i3 120ah battery is still going to offer 100+ miles of range even in winter?
As battery management improves, groups are switched around and all the cells wear out more equally, so when it's dead, it's more like 80% dead than 20% dead. It's more complex than that obviously, but today's cars should be better at getting life from batteries than the 10 year old cars wearing out now.
It's tougher in Hybrids, where a small battery pack can see a lot of cycles in a week.
Toaster Pilot said:
You can only currently buy Chademo V2G chargers in the UK, so a Leaf is your best bet. Most of them are supplied as part of trials, but they do come up for sale now and again second hand (they’re expensive!)
CCS bidirectional charging is coming - Wallbox are launching a unit that’s capable - but I don’t know if there are any compatible cars yet!
I've got a v2g charger as part of a trial. It's usefulness is limited though because I can't get a smart meter...CCS bidirectional charging is coming - Wallbox are launching a unit that’s capable - but I don’t know if there are any compatible cars yet!
The trial ends soon and I will have the option of keeping the charger for a fee.
OutInTheShed said:
Modern Battery Management Systems will actively switch cells in and out
No they don't. (not for passcar anyway)(I design BMS systems for a living btw)
You can't just switch out a cell for the following reasons
1) The cost of the bypass: The cell bypass would have to carry the full pack current. To provide a full current bypass for every cell in the battery would be incredibly expensive
2) The Pack voltage needs to be kept as high as possible, otherwise the load must pull more current (P = V x I) which would then wear out the pack even faster
Most OE automotive batteries consider an 80% SoH to be the EOL / Warranty threshold, although obviously the vehicle will still drive and operate as normal. In reality, once below this point then the run-away effects of cell ageing quick in quickly in high power batteries (like those in a BEV pass car) and the ballancing system will struggle to keep up, meaning a real world range reduction below 80% will occur. (The battery is only as good as it's worst cell for most series arranged architectures)
SWoll said:
Why would an 80% useable battery be too worn out? And assuming that happens outside of the manufacturers warranty as is likely are you really going to pay out to replace it at that point?
An 80% useable i3 120ah battery is still going to offer 100+ miles of range even in winter?
Cos stuff like voltage sag at low state of charge can result in the bus voltage being too low for the power electronics, either simply a derate or things like DCDC converters start shutting down. An 80% useable i3 120ah battery is still going to offer 100+ miles of range even in winter?
You can’t think of battery’s like a bath of water
JonnyVTEC said:
SWoll said:
Why would an 80% useable battery be too worn out? And assuming that happens outside of the manufacturers warranty as is likely are you really going to pay out to replace it at that point?
An 80% useable i3 120ah battery is still going to offer 100+ miles of range even in winter?
Cos stuff like voltage sag at low state of charge can result in the bus voltage being too low for the power electronics, either simply a derate or things like DCDC converters start shutting down. An 80% useable i3 120ah battery is still going to offer 100+ miles of range even in winter?
You can’t think of battery’s like a bath of water
Max_Torque said:
Most OE automotive batteries consider an 80% SoH to be the EOL / Warranty threshold
Warranty threshold perhaps (although many are 70%) but EOL? Perhaps if they are looking to sell you a new and very expensive battery, but in reality?Edited by SWoll on Wednesday 27th April 08:05
Agree with OP's initial comments. At current prices, payback on PV is c.9 years, so I looked into home batteries as a way of buying cheap off-peak electricity to utilise during peak hours. Tesla's Powerwall is over £12k (fitted, including the gateway) and has a lead time in excess of 12 mths. It can store a max of 13.5kw so should be good enough for most of our daily peak consumption but the payback is again around 9 years (assuming 8ppkw offpeak, 35ppkw peak).
Understand the ID Buzz is designed with V2G capability. No doubt some modification of home electrics will be required but should be significantly cheaper than acquiring an entire battery from Tesla et al. I'm expecting other manufacturers to follow this trend over the course of next few years to a point where it's common technology. Obviously there will be winners and losers from this, those without off-street parking for example won't benefit initially, but if it can reduce peak grid demand then it should in theory help keep peak prices lower in the longer term.
Understand the ID Buzz is designed with V2G capability. No doubt some modification of home electrics will be required but should be significantly cheaper than acquiring an entire battery from Tesla et al. I'm expecting other manufacturers to follow this trend over the course of next few years to a point where it's common technology. Obviously there will be winners and losers from this, those without off-street parking for example won't benefit initially, but if it can reduce peak grid demand then it should in theory help keep peak prices lower in the longer term.
Edited by Inky81 on Wednesday 27th April 10:53
Any Chademo car after 2013 can do it. LEAF, NV200, Outlander, probably that Lexus too...
CCS cars cannot. The standard to allow it is years late and behind schedule. There is no hardware available (though some companies are advertising vapourware) for public ownership. And you couldn't legally install one at this time anyway (similarly the Chademo trial chargers are limited once the trial finishes).
I look forward to the CCS cars and chargers being available. Why buy batteries when you have 50-100kWh sat on the drive during day (WfH).
The only time the car will be your only supply and physically isolated from the grid is when the system detects a power cut, and then your car can be used for emergency power within the limits of power export it has.
CCS cars cannot. The standard to allow it is years late and behind schedule. There is no hardware available (though some companies are advertising vapourware) for public ownership. And you couldn't legally install one at this time anyway (similarly the Chademo trial chargers are limited once the trial finishes).
I look forward to the CCS cars and chargers being available. Why buy batteries when you have 50-100kWh sat on the drive during day (WfH).
ashenfie said:
My worry that with this approach is, if you turn use the electric shower in the morning 7.5kwh -10.5kwh thats going to be bad for the car, unless the power switches back to grid under high demand
It uses both. Just like if you have solar panels.The only time the car will be your only supply and physically isolated from the grid is when the system detects a power cut, and then your car can be used for emergency power within the limits of power export it has.
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