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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthorJamster
    • CommentTimeFeb 7th 2024
     
    Hi all,

    Am thinking about battery storage options to partner with our existing PV & ASHP but am also looking at electric car options in the medium term. However, my elderly car is on its last legs potentially so I am wondering if its the right time to combine the two.

    From what I understand, a bi-directional charger and a car with V2H (vehicle to home) 'technology' should be able to function in the same way as a more conventional home battery setup and I could use the EV as my home battery essentially and still leaving enough charge for the shorter trips that are the majority of my usage?

    From reading around though, bi-directional chargers are perhaps not quite 'there yet' and V2H enabled cars are limited too. I've not found anything conclusive online yet, in particular around the V2H functionality. Has anyone gone down this route yet - my thinking is a 2nd hand EV is going to be a better price per kW than any domestic battery?
    • CommentAuthorphiledge
    • CommentTimeFeb 8th 2024
     
    AFAIK bi directional chargers have been developed but were only available for a number of trials that have been going on over the last few years. I believe that outside of the trials, which have now ended, you can't at the moment legitimately connect one of these chargers to the grid. I think there's ways of hacking round the lack of chargers but not likely to be legitimate for on grid use.

    I think that right now the results of the trials are being digested to come up with a UK spec. With an increasing number of new cars supporting bidirectional charging I hope the spec and chargers aren't too far away.

    If you're wanting to use a secondhand EV you're very limited in choice as I think there's only the Nissan Leaf and maybe a mitsubishi that support it. Bear in mind that the Leaf uses a CHADEMO spec connection which isn't very popular so getting a CHADEMO V2x charger might be a problem.

    No idea why we're so far behind withV2x as it seemed to be readily available in Asia over a decade ago!
    • CommentAuthorJamster
    • CommentTimeFeb 8th 2024
     
    Thanks Phil - that's really useful.
    • CommentAuthortony
    • CommentTimeFeb 8th 2024
     
    My friend Anthony was involved with V2g trials and did a PhD on it ten years ago.

    I don’t see it as that sensible as it stresses the vehicle battery, ther is also the problem of increasing electricity use overall as the batteries are not 100% efficient
    • CommentAuthorphiledge
    • CommentTimeFeb 8th 2024
     
    There's no doubt that inversion and charging inefficiencies will always result in some loss but that is only really a concern if you are charging at peak times. If charging off your own PV or off peak when there's surplus electricity then the concern over losses is somewhat/wholly offset by reducing your grid demand at peak times, assuming that's most people's goal

    AFAIK large grid scale battery banks are being installed in quite significant volumes so its fair to assume that battery losses are considered acceptable/worthwhile for the benefits they offer??
  1.  
    After several years of nearly being available, V2G is now nearly available on the VW range.

    In that they can now discharge at 10kW DC, but you have to find an approved chargepoint with a G99 inverter in it - none available yet.

    https://electrek.co/2023/12/07/details-emerge-volkswagen-id-4s-big-10kw-v2g-capability/

    (10kW is 13 horsepower, which is a small fraction of the power that it discharges when the car is driving, so shouldn't be much stress on the battery).
    • CommentAuthorphiledge
    • CommentTimeFeb 9th 2024
     
    I believe that the chargers have been developed as they were used in the trials.

    What I understand the hold up to be is the lack of agreed specification/approvals from the Gov/ENA/DNOs.
  2.  
    Yes, there is nothing approved that I could find yet.

    RobL wrote about the 4kW chademo chargepoint for the Ovo trial which sounded a bit "still under development"

    http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17889&Focus=302597#Comment_302597

    Afaict there is no 10kW bi-di DC chargepoint with G99 approval yet, to utilise the VW capabilities. They did their trials in Germany with a Hager DC chargepoint which is approved over there

    https://hagergroup.com/de/medien-und-publikationen/nachrichten/e3dc-bidirektionales-laden

    (In German - use google translate)
  3.  
    "The E3/DC brand products rely entirely on low-loss direct current technology: With EDISON V2H, the vehicle is flexibly charged with solar power via the CCS plug and, if necessary, returns the energy to the E3/DC home power plant without conversion. Its integrated inverter uses the vehicle battery as a second DC power source in addition to the PV system. "
    • CommentAuthorcjard
    • CommentTimeFeb 9th 2024
     
    I work for a charge point operator who is actively engaged in several ongoing V2X (not just home; we're looking at eg charging broken down ambulances off off kind passing Teslas etc) projects - the advice here is right; it's not there yet - some of that is lack of support in protocols, charge points and surrounding software to control it all, some of that is manufacturer resistance too and the big unknown of how on the hook they'll be for the effects of V2X on the battery.
    One project involves bidirectional wireless charging and they're plain up ripping the charge controller out of the vehicle and replacing it. Other projects are in earlier stages with manufacturers that are looking to enable V2X as a USP and building it into vehicles that are still on the prototyping bench.
    For the projects we've completed and concepts proven we've used vehicles that will do it (Leafs) - one of the main aims thus far having been to shift supply from "when it's generating renewably" (the day time) to "when it's needed for 10 million kids to watch YouTube" (the night time) and perform grid balancing/energy market smoothing :) but the whole lot is a mess at the moment and every charge point maker who has enabled anything like it does it in a different way so there isn't a lot of traction. At some point it will make its way into an adopted spec and the landscape will become more clear, but even then I'm not holding my breath, having seen the considerable variations in implementations of the widest adopted charge point control protocol, OCPP1.6 (which has no dedicated V2X provisions)
    • CommentAuthorowlman
    • CommentTimeFeb 9th 2024
     
    <blockquote><cite>Posted By: cjard</cite>...........At some point it will make its way into an adopted spec and the landscape will become more clear, but even then I'm not holding my breath,</blockquote>



    Let's hope they make a better fist of it than the gang that finalised the, "not so Smart meters" did; I'm guessing they won't, too many conflicting interests at play.
    • CommentAuthorJamster
    • CommentTimeFeb 12th 2024
     
    Thank you everyone - so the take home at the moment is that there's nothing really established in the marketplace yet, and the first things that arrive might not last the distance so think about the car and charger as a coupled purchase rather than a one off.
    • CommentAuthorRobL
    • CommentTimeFeb 12th 2024
     
    I think that's a fair summary.
    We used to have V2G, then V2H. It worked well during Covid, as the car was at home most of the time. Not so great afterwards, as it isn't there, and we plan on changing car! The software was clunky, and the charger pretty much only compatible with the Leaf. We have a home battery now, it's a lot better tbh. Nb: the home batt+inverter was cheaper than the alleged cost of the V2H unit(we were on a free trial) - the high "price" was because it was so low volume. I gave it away in the end, as it could only be used by a handful of approved people due to software lock-in.

    Perhaps one day the charger built into every car will be bidirectional, I could see that working - quite a few Tesla's have that already I think - it's just not enabled yet! It's not difficult engineering, nor would it add a lot of cost - it needs standards setup etc - but had better get a crack on as fixed installation batts are getting cheaper and cheaper, so the incentive is reducing.
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 12th 2024
     
    Posted By: RobLfixed installation batts are getting cheaper and cheaper
    Really? Why so - say more?
    • CommentAuthorRobL
    • CommentTimeFeb 12th 2024
     
    We got our home batt from fogstar (uk) as a kit, £2500 for 15.5kWh. I hear of people getting that size for quite a bit less, if direct from China. Those Eve280 type batteries are around $100 per kWh from china, here’s a nice graph linked, down and to the right!

    https://farsuperov.life/product_details/33366193.html

    Rumour has it that sodium ion batts will be around one day, and there’s no shortage of raw materials for them, they can keep getting cheaper for a while. Not so good for cars though, as lower energy density, so heavier:

    https://energypost.eu/sodium-ion-batteries-ready-for-commercialisation-for-grids-homes-even-compact-evs/#:~:text=The%20cost%20of%20a%20Na,making%20them%20bulkier%20and%20heavier.
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 12th 2024
     
    Posted By: fostertom
    Posted By: RobLfixed installation batts are getting cheaper and cheaper
    Really? Why so - say more?
    Ahhhh - 'installation' not insulation Batts then (as the 'no energy needed' alternative to greening your energy?).
  4.  
    An interesting article about sodium batteries and the proposal that they would be suitable for lower range urban cars. (Due to higher weight / kWh)

    The article points out that the average daily journey in Europe ranges from 19 km to 5 km / day but this hides the problem - which is the occasional long journey.

    My experience of 1 year with an EV shows that longer journeys definitely need 'malice aforethought' e.g. my son lives a 200km round trip so to avoid the need to top up on route (a time consuming pita) planning is needed and as a result of a night time hospital requirement early on in the year I now don't let the range go below 150 km. For me a 250 km range car (proposed by the article) would not be acceptable.

    I won't be considering V2G or any V2# any time soon.
    • CommentAuthorrevor
    • CommentTimeFeb 13th 2024
     
    <blockquote><cite>Posted By: RobL</cite>We got our home batt from fogstar (uk) as a kit, £2500 for 15.5kWh.</blockquote>

    That is a good price. I paid 5K in 2021 for 10kw but was German made with Korean cells and built like a tank in a thick iron casing. There are a few organisations around that do battery packs made from recycled EV's. A friend bought a 20 Kw one from a BMW for about £2K complete with BMS and is working well. Personally I would not consider one.
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