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If all car manufacturers can offer bi-directional charging as default, without an increase in vehicle price, the potential offered by vehicle-to-grid charging i

If all car manufacturers can offer bi-directional charging as default, without an increase in vehicle price, the potential offered by vehicle-to-grid charging is massive. The grid can be more easily balanced and consumers will have the potential to generate revenue from the EVs. A UK trial involving 330 Nissan Leafs (https://www.ofgem.gov.uk/publications/case-study-uk-electric-vehicle-grid-v2g-charging https://www.ofgem.gov.uk/publications/case-study-uk-electric...) saw some participants earn up to £750/year, with grid savings potentially being £3.5 billion. The downside of the trial was the need for a dedicated, expensive bi-directional charger, highlighting the need for the functionality to be integrated into the car.

ajuc 5y ago
There's an opportunity for a company that signs contracts with EV owners to use their car batteries when they are parked for distributed grid balancing and in exchange they replace these batteries after they drop to let's say 80% capacity. That company can then recycle the used batteries or use them in stationary battery banks for a few more years before recycling them. I wonder how it pans out financially, but it seems it could work.
- skinkestek 5y ago
  This actually sounds like a brilliant idea. A shame everyone is busy.
- sandermvanvliet 5y ago
  This is what we're doing with Jedlix (I'm the Technical Director there). Currently we're doing grid balancing and load optimizations so you as EV driver make money while you charge (!) and at the same time you help to keep the electricity grid stable. Of course that works well with times that there is over capacity on the grid and there is a lot of flexibility in the car (time plugged in vs charge demand). When there is a lot of production (lots of solar for example) and not a lot of demand (during the daytime) that energy can go nowhere. At night there is usually a lot of demand but less renewable power production (it's dark after all). This is one of the areas where we will leverage vehicle-to-grid to power homes using renewable energy and also allows to more efficiently use the solar power you yourself produce (if you have a PV set up). Have a look at https://jedlix.com https://jedlix.com if you have an EV.
  - ajuc 5y ago
    Nice, but AFAIU you only shift the charging time, you don't discharge car batteries to balance the grid, right? That's still great, but it won't let us use solar power at night.
    - sandermvanvliet 5y ago
      Currently we shift only indeed on the public part of the platform. Discharging is in development with our partners (EV manufacturers)
IanCal 5y ago
The size of batteries in cars is huge too. I was looking at a home battery, and the tesla powerwall is one of the better ones for a relatively high power output (assuming you can get one somewhere). That's around £10k+ for 13.5kWh, while a volkswagen ID3 has a 58kWh battery and costs £33k. That's less per kWh, and it's also a brand new car. It'd power my entire house for days, and is capable of charging drastically faster (so my home power supply would easily be the limiting factor) and I assume capable of discharging faster too (?).
marvin 5y ago
I read somewhere that the inverters in most newly-produced Teslas are capable of doing this already, from a hardware perspective. Might have been one of Munroe’s teardowns. No official word on why it isn’t supported yet.
- dfox 5y ago
  It is my understanding that for "sane" charger topologies (ie. without tricks that share power components between charger and drivetrain) of the power level required for EV charger the SMPS comes out capable of bidirectional operation somewhat by default because active rectifier and inverter is (topology-wise) the same thing (and the symmetry is quite obvious in typical implementation).
goodcanadian 5y ago
The downside of the trial was the need for a dedicated, expensive bi-directional charger, highlighting the need for the functionality to be integrated into the car. I have been heavily involved in that project (writing firmware for the charger). I also have one on the side of my house connected to my car. I don't personally see any particular need for it to be integrated into the car. The main issue is cost, but that cost doesn't go away if it is in the car instead of on the wall. Either way, the hardware is there and the house wiring will have to support it. It is also important to keep in mind that the charger is essentially a prototype. The main cost is the bidirectional power module. Future versions will likely be considerably cheaper as manufacturing matures and economies of scale kick in. EDIT: From a regulatory point of view, it is probably easier to have the technology in the charger as the grid operators (Distribution Network Operator - DNO) do not like having unknown generators being connected to their grid. You have to notify the DNO (and in some circumstances, get advanced permission) when you install solar or indeed, a V2G.
- jacquesm 5y ago
  And if it's on the wall it will not be automatically scrapped when the car is scrapped as well as allowing you to easily switch vehicles and maintain that functionality.
- kieranmaine 5y ago
  That's interesting about the DNO. When notifying the DNO about the V2G installations does the property then become a generator? Re. economies of scale I'd argue that an auto OEM can achieve better economies than a charger manufacturer
  - goodcanadian 5y ago
    Well, the V2G is considered to be like a generator. You are generally allowed to install one device of up to 3.68kW on a install and notify basis. This is the same rules that would apply for a solar installation or whatever. If you want more than one device or you want to exceed 3.68kW, you will need permission. There are a whole series of increasingly complex rules after that.
londons_explore 5y ago
> a dedicated, expensive bi-directional charger The electronics to do this typically cost no more than a regular charger. In fact, with a firmware upgrade, many cars and chargers could do bidirectionality already. The main cost so far is that few car manufacturers are prepared to enable bidirectional functionality unless they get a substantial cut of the profits of doing so. It's a business decision not to enable it.
- goodcanadian 5y ago
  You appear to be talking about alternating current bidirectional charging. There is no standard for that (and none in development that I am aware of). Also, I am not aware of any vehicle that has the onboard inverter that would be necessary (except possibly, the F150). Existing bidirectional chargers are direct current chargers. Basically, they connect directly to the car's battery and communicate with the car's battery management system. This is the same way that rapid chargers work. The main cost is the bi-directional inverter/rectifier, but that cost will come down.
  - londons_explore 5y ago
    Correct - there is no standard for AC bidirectional charging. But someone could write one, and lots of existing cars could support it with a firmware update. Cars onboard chargers tend to use synchronous rectification[1], which means the power can flow the other way if software wants it to. Most DC rapid chargers could likewise support it, although again it would require new firmware to be written for the car (to not abort when it sees current flowing outwards), and new firmware for the charger. If you disassemble a car or charger, the thickest traces are the power path. If there are no diodes in the power path, then its likely the charger uses synchronous rectification and could support vehicle to grid with just firmware changes. [1]: https://en.wikipedia.org/wiki/Active_rectification https://en.wikipedia.org/wiki/Active_rectification

ajuc 5y ago

There's an opportunity for a company that signs contracts with EV owners to use their car batteries when they are parked for distributed grid balancing and in exchange they replace these batteries after they drop to let's say 80% capacity. That company can then recycle the used batteries or use them in stationary battery banks for a few more years before recycling them. I wonder how it pans out financially, but it seems it could work.

skinkestek 5y ago
This actually sounds like a brilliant idea. A shame everyone is busy.
sandermvanvliet 5y ago
This is what we're doing with Jedlix (I'm the Technical Director there). Currently we're doing grid balancing and load optimizations so you as EV driver make money while you charge (!) and at the same time you help to keep the electricity grid stable. Of course that works well with times that there is over capacity on the grid and there is a lot of flexibility in the car (time plugged in vs charge demand). When there is a lot of production (lots of solar for example) and not a lot of demand (during the daytime) that energy can go nowhere. At night there is usually a lot of demand but less renewable power production (it's dark after all). This is one of the areas where we will leverage vehicle-to-grid to power homes using renewable energy and also allows to more efficiently use the solar power you yourself produce (if you have a PV set up). Have a look at https://jedlix.com https://jedlix.com if you have an EV.
- ajuc 5y ago
  Nice, but AFAIU you only shift the charging time, you don't discharge car batteries to balance the grid, right? That's still great, but it won't let us use solar power at night.
  - sandermvanvliet 5y ago
    Currently we shift only indeed on the public part of the platform. Discharging is in development with our partners (EV manufacturers)

IanCal 5y ago

The size of batteries in cars is huge too. I was looking at a home battery, and the tesla powerwall is one of the better ones for a relatively high power output (assuming you can get one somewhere). That's around £10k+ for 13.5kWh, while a volkswagen ID3 has a 58kWh battery and costs £33k. That's less per kWh, and it's also a brand new car. It'd power my entire house for days, and is capable of charging drastically faster (so my home power supply would easily be the limiting factor) and I assume capable of discharging faster too (?).

marvin 5y ago

I read somewhere that the inverters in most newly-produced Teslas are capable of doing this already, from a hardware perspective. Might have been one of Munroe’s teardowns. No official word on why it isn’t supported yet.

dfox 5y ago
It is my understanding that for "sane" charger topologies (ie. without tricks that share power components between charger and drivetrain) of the power level required for EV charger the SMPS comes out capable of bidirectional operation somewhat by default because active rectifier and inverter is (topology-wise) the same thing (and the symmetry is quite obvious in typical implementation).

goodcanadian 5y ago

The downside of the trial was the need for a dedicated, expensive bi-directional charger, highlighting the need for the functionality to be integrated into the car. I have been heavily involved in that project (writing firmware for the charger). I also have one on the side of my house connected to my car. I don't personally see any particular need for it to be integrated into the car. The main issue is cost, but that cost doesn't go away if it is in the car instead of on the wall. Either way, the hardware is there and the house wiring will have to support it. It is also important to keep in mind that the charger is essentially a prototype. The main cost is the bidirectional power module. Future versions will likely be considerably cheaper as manufacturing matures and economies of scale kick in. EDIT: From a regulatory point of view, it is probably easier to have the technology in the charger as the grid operators (Distribution Network Operator - DNO) do not like having unknown generators being connected to their grid. You have to notify the DNO (and in some circumstances, get advanced permission) when you install solar or indeed, a V2G.

jacquesm 5y ago
And if it's on the wall it will not be automatically scrapped when the car is scrapped as well as allowing you to easily switch vehicles and maintain that functionality.
kieranmaine 5y ago
That's interesting about the DNO. When notifying the DNO about the V2G installations does the property then become a generator? Re. economies of scale I'd argue that an auto OEM can achieve better economies than a charger manufacturer
- goodcanadian 5y ago
  Well, the V2G is considered to be like a generator. You are generally allowed to install one device of up to 3.68kW on a install and notify basis. This is the same rules that would apply for a solar installation or whatever. If you want more than one device or you want to exceed 3.68kW, you will need permission. There are a whole series of increasingly complex rules after that.

londons_explore 5y ago

> a dedicated, expensive bi-directional charger The electronics to do this typically cost no more than a regular charger. In fact, with a firmware upgrade, many cars and chargers could do bidirectionality already. The main cost so far is that few car manufacturers are prepared to enable bidirectional functionality unless they get a substantial cut of the profits of doing so. It's a business decision not to enable it.

goodcanadian 5y ago
You appear to be talking about alternating current bidirectional charging. There is no standard for that (and none in development that I am aware of). Also, I am not aware of any vehicle that has the onboard inverter that would be necessary (except possibly, the F150). Existing bidirectional chargers are direct current chargers. Basically, they connect directly to the car's battery and communicate with the car's battery management system. This is the same way that rapid chargers work. The main cost is the bi-directional inverter/rectifier, but that cost will come down.
- londons_explore 5y ago
  Correct - there is no standard for AC bidirectional charging. But someone could write one, and lots of existing cars could support it with a firmware update. Cars onboard chargers tend to use synchronous rectification[1], which means the power can flow the other way if software wants it to. Most DC rapid chargers could likewise support it, although again it would require new firmware to be written for the car (to not abort when it sees current flowing outwards), and new firmware for the charger. If you disassemble a car or charger, the thickest traces are the power path. If there are no diodes in the power path, then its likely the charger uses synchronous rectification and could support vehicle to grid with just firmware changes. [1]: https://en.wikipedia.org/wiki/Active_rectification https://en.wikipedia.org/wiki/Active_rectification