4 ms·

Vehicle to grid is only 80% efficient and prematurely wears the battery. Given that utility scale solar is much cheaper than residential solar, I wouldn’t be s

Vehicle to grid is only 80% efficient and prematurely wears the battery. Given that utility scale solar is much cheaper than residential solar, I wouldn’t be surprised if utility scale energy storage is also cheaper than vehicle storage. Lithium ion is optimized to be light, which is not an requirement for grid storage, which could make use of molten salt, pumped hydro, compressed air, or hydrogen electrolysis.

slashdotdash 6y ago
Vehicle to grid may actually improve battery health and keep them healthier for longer. > “This new research into the potentials of V2G shows that it could actually improve vehicle battery life by around ten percent over a year.” This requires intelligent usage where the battery state of charge is kept within a limited window, not fully charged or drained. [1] https://warwick.ac.uk/newsandevents/pressreleases/clean_energy_stored/ https://warwick.ac.uk/newsandevents/pressreleases/clean_ener... [2] https://www.sciencedirect.com/science/article/pii/S0360544217306825 https://www.sciencedirect.com/science/article/pii/S036054421...
- new_realist 6y ago
  I don’t think reducing the effective range of your car to preserve battery life will be very popular; people want the freedom to drive as far as they can, because it’s hard to predict when they will need that capability, and charging is very slow. If someone does have a very predictable routine they can just not overcharge their car in the first place and save the discharge wear.
  - magicalhippo 6y ago
    > people want the freedom to drive as far as they can, because it’s hard to predict when they will need that capability, and charging is very slow For most people, if they really need to drive hundreds of miles unexpectedly, I doubt spending 15 minutes at a high-speed charger to top up the batteries will be an issue.
    - new_realist 6y ago
      As someone who drives an EV, I can tell you that it’s not the long distance trips, it’s having an unexpectedly busy day of errands in cold weather that gets you—realizing that you’re starting out at only 50% charge, which means you can’t make that last trip into the suburbs at the end of the day. There are very few fast chargers in densely populated areas and they’re often malfunctioning, or have queues. They also hurt your battery, so not to be used on a regular basis.
      - speedgoose 6y ago
        In Norway where chargers are a lot more common, it's not an issue. Of course if I want to charge at 4pm at a popular place it may be a queue but most of the times many chargers are available and functional.
      - magicalhippo 6y ago
        > There are very few fast chargers in densely populated areas I live in Norway so not a huge issue, and I expect it to get better. Circle K for example is pushing hard to build high-speed chargers at their stations.
  - Cthulhu_ 6y ago
    That's one use case of car driving, yes, but most people have a fixed daily / weekly routine. Plus it could be a setting, where people can tell the car to top it up overnight instead of optimize for battery life.
- taneq 6y ago
  As I read this, it's basically saying that a battery used for V2G power would spent more time at a lower state of charge which doesn't degrade the battery as fast, to such a degree that this factor outweighs the extra cycles on the pack? Seems like an extraordinary claim - I'd want to see it demonstrated experimentally and not just assumed based on a model (no matter how many times they say the model is 'verified').
  - hwillis 6y ago
    They did run an experiment on actual batteries. It's still only one kind of cell, but they have actual experimental evidence: https://ars.els-cdn.com/content/image/1-s2.0-S0360544217306825-egi10HBXMVPXKW_lrg.jpg https://ars.els-cdn.com/content/image/1-s2.0-S03605442173068...
goodcanadian 6y ago
We're involved in the first large scale V2G trial in the UK.[1] Our round trip efficiency is about 90%, which is better than pumped hydro which serves the same purpose.[2] Part of the point of the trial is to see what the impact is on the battery, but as a sibling comment mentions, there is evidence that it is actually better for the battery than just letting it sit. [1] https://www.indra.co.uk/v2g https://www.indra.co.uk/v2g, https://www.ovoenergy.com/electric-cars/vehicle-to-grid-charger https://www.ovoenergy.com/electric-cars/vehicle-to-grid-char... [2] https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...
- new_realist 6y ago
  How can round trip efficiency be 90%, when the one-way 240V charging losses to my Tesla alone are greater than that (at 83.61%)? Is it lack of three phase power in the US that is killing me?
  - orwin 6y ago
    You can't ask for three phase power in the US? Surely it have to be there but restricted to business, no? I remember seeing laundries and restaurant in small towns
    - selectodude 6y ago
      Large factories can get 480V 3 phase power in the US, but even laundries and restaurants get 240V “split phase” which is technically still single phase, just two power lines that would normally be going to two houses instead going to the same place. We have a very wonky power grid here due to how early on it was built. The rest of the world had the ability to see our mistakes and fix them after WW2.
      - rsynnott 6y ago
        I'm not sure if it's age so much as bad (in the long run) choices at the time. European power grids have been around for a while (and some have their own oddities; the historical use of ring circuits in UK and Ireland domestic installations produced lasting weirdness, for instance).
taneq 6y ago
It's the battery wear that I'd be mainly worried about. I'd much rather be burning cycle life on a Powerwall than on a $100k car.
- brianwawok 6y ago
  Model3 is more like a 40k car, and you can replace the battery in 10 years for a lot less than 40k I suspect
  - taneq 6y ago
    In my part of the world even an SR+ is $81k drive-away price. An LR with no other options is over $100k.
    - natch 6y ago
      I suspect you’re counting VAT as part of the price, which makes the claim inaccurate. It’s a $40k car with a TCO equivalent to a $26k car, which in your part of the world has taxes and fees that bring your out of pocket cost up. That doesn’t make it a $100k car. It makes it a $40k car that has heavy tariffs where you are.
Glench 6y ago
> given that utility-scale solar is so much cheaper than residential storage... That likely isn’t given! I haven’t looked into it thoroughly but apparently most of the cost of utility solar is transmission and billing. Australian residential solar is really booming right now because it’s 6-7 cents / kwh. See Saul Griffith of Otherlab’s article: https://medium.com/otherlab-news/green-new-deal-how-much-does-fixing-climate-change-cost-the-us-d542bb9e67c8 https://medium.com/otherlab-news/green-new-deal-how-much-doe...
pmorici 6y ago
The probable reason that Tesla has put this in but hasn't enabled it yet is that they are on the verge of announcing new battery technology their so called "million mile battery" that is rumored to not have the issues of current technology with respect to limited charging cycles.
jessriedel 6y ago
What this article needs is someone numerate who can at least do an order-of-magnitude estimate of the costs and benefits. When operating at scale, what will the marginal cost in terms of battery wear-and-tear be for storing 1 kWh and returning it to the grid? And how much will that storage be worth in terms of the difference between daily high and daily low electricity prices? Very frustrating that a putatively semi-technical publication like Electra doesn't even attempt this, or ask their interviewees estimates.
loceng 6y ago
https://news.ycombinator.com/item?id=23249269 https://news.ycombinator.com/item?id=23249269

slashdotdash 6y ago

Vehicle to grid may actually improve battery health and keep them healthier for longer. > “This new research into the potentials of V2G shows that it could actually improve vehicle battery life by around ten percent over a year.” This requires intelligent usage where the battery state of charge is kept within a limited window, not fully charged or drained. [1] https://warwick.ac.uk/newsandevents/pressreleases/clean_energy_stored/ https://warwick.ac.uk/newsandevents/pressreleases/clean_ener... [2] https://www.sciencedirect.com/science/article/pii/S0360544217306825 https://www.sciencedirect.com/science/article/pii/S036054421...

new_realist 6y ago
I don’t think reducing the effective range of your car to preserve battery life will be very popular; people want the freedom to drive as far as they can, because it’s hard to predict when they will need that capability, and charging is very slow. If someone does have a very predictable routine they can just not overcharge their car in the first place and save the discharge wear.
- magicalhippo 6y ago
  > people want the freedom to drive as far as they can, because it’s hard to predict when they will need that capability, and charging is very slow For most people, if they really need to drive hundreds of miles unexpectedly, I doubt spending 15 minutes at a high-speed charger to top up the batteries will be an issue.
  - new_realist 6y ago
    As someone who drives an EV, I can tell you that it’s not the long distance trips, it’s having an unexpectedly busy day of errands in cold weather that gets you—realizing that you’re starting out at only 50% charge, which means you can’t make that last trip into the suburbs at the end of the day. There are very few fast chargers in densely populated areas and they’re often malfunctioning, or have queues. They also hurt your battery, so not to be used on a regular basis.
    - speedgoose 6y ago
      In Norway where chargers are a lot more common, it's not an issue. Of course if I want to charge at 4pm at a popular place it may be a queue but most of the times many chargers are available and functional.
    - magicalhippo 6y ago
      > There are very few fast chargers in densely populated areas I live in Norway so not a huge issue, and I expect it to get better. Circle K for example is pushing hard to build high-speed chargers at their stations.
- Cthulhu_ 6y ago
  That's one use case of car driving, yes, but most people have a fixed daily / weekly routine. Plus it could be a setting, where people can tell the car to top it up overnight instead of optimize for battery life.
taneq 6y ago
As I read this, it's basically saying that a battery used for V2G power would spent more time at a lower state of charge which doesn't degrade the battery as fast, to such a degree that this factor outweighs the extra cycles on the pack? Seems like an extraordinary claim - I'd want to see it demonstrated experimentally and not just assumed based on a model (no matter how many times they say the model is 'verified').
- hwillis 6y ago
  They did run an experiment on actual batteries. It's still only one kind of cell, but they have actual experimental evidence: https://ars.els-cdn.com/content/image/1-s2.0-S0360544217306825-egi10HBXMVPXKW_lrg.jpg https://ars.els-cdn.com/content/image/1-s2.0-S03605442173068...

goodcanadian 6y ago

We're involved in the first large scale V2G trial in the UK.[1] Our round trip efficiency is about 90%, which is better than pumped hydro which serves the same purpose.[2] Part of the point of the trial is to see what the impact is on the battery, but as a sibling comment mentions, there is evidence that it is actually better for the battery than just letting it sit. [1] https://www.indra.co.uk/v2g https://www.indra.co.uk/v2g, https://www.ovoenergy.com/electric-cars/vehicle-to-grid-charger https://www.ovoenergy.com/electric-cars/vehicle-to-grid-char... [2] https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...

new_realist 6y ago
How can round trip efficiency be 90%, when the one-way 240V charging losses to my Tesla alone are greater than that (at 83.61%)? Is it lack of three phase power in the US that is killing me?
- orwin 6y ago
  You can't ask for three phase power in the US? Surely it have to be there but restricted to business, no? I remember seeing laundries and restaurant in small towns
  - selectodude 6y ago
    Large factories can get 480V 3 phase power in the US, but even laundries and restaurants get 240V “split phase” which is technically still single phase, just two power lines that would normally be going to two houses instead going to the same place. We have a very wonky power grid here due to how early on it was built. The rest of the world had the ability to see our mistakes and fix them after WW2.
    - rsynnott 6y ago
      I'm not sure if it's age so much as bad (in the long run) choices at the time. European power grids have been around for a while (and some have their own oddities; the historical use of ring circuits in UK and Ireland domestic installations produced lasting weirdness, for instance).

taneq 6y ago

It's the battery wear that I'd be mainly worried about. I'd much rather be burning cycle life on a Powerwall than on a $100k car.

brianwawok 6y ago
Model3 is more like a 40k car, and you can replace the battery in 10 years for a lot less than 40k I suspect
- taneq 6y ago
  In my part of the world even an SR+ is $81k drive-away price. An LR with no other options is over $100k.
  - natch 6y ago
    I suspect you’re counting VAT as part of the price, which makes the claim inaccurate. It’s a $40k car with a TCO equivalent to a $26k car, which in your part of the world has taxes and fees that bring your out of pocket cost up. That doesn’t make it a $100k car. It makes it a $40k car that has heavy tariffs where you are.

Glench 6y ago

> given that utility-scale solar is so much cheaper than residential storage... That likely isn’t given! I haven’t looked into it thoroughly but apparently most of the cost of utility solar is transmission and billing. Australian residential solar is really booming right now because it’s 6-7 cents / kwh. See Saul Griffith of Otherlab’s article: https://medium.com/otherlab-news/green-new-deal-how-much-does-fixing-climate-change-cost-the-us-d542bb9e67c8 https://medium.com/otherlab-news/green-new-deal-how-much-doe...

pmorici 6y ago

The probable reason that Tesla has put this in but hasn't enabled it yet is that they are on the verge of announcing new battery technology their so called "million mile battery" that is rumored to not have the issues of current technology with respect to limited charging cycles.

jessriedel 6y ago

What this article needs is someone numerate who can at least do an order-of-magnitude estimate of the costs and benefits. When operating at scale, what will the marginal cost in terms of battery wear-and-tear be for storing 1 kWh and returning it to the grid? And how much will that storage be worth in terms of the difference between daily high and daily low electricity prices? Very frustrating that a putatively semi-technical publication like Electra doesn't even attempt this, or ask their interviewees estimates.

loceng 6y ago

https://news.ycombinator.com/item?id=23249269 https://news.ycombinator.com/item?id=23249269