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Integrating future V2H EV charger into soon to be installed residential solar system

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  • Integrating future V2H EV charger into soon to be installed residential solar system

    Greetings everyone, my first post in this great forum I am trying to get more educated on bi-directional EV charging/V2H instead of buying an expensive/sizable external battery.

    Last week I signed my contract to install solar panels in our house (SE Texas area). Now I have an opportunity to do the install in a way to 'future proof' it for V2H set up as in about a year I would like to get an EV for city driving (second vehicle). My affordability factor will most likely sway me towards a used EV, and since I want V2H it will have to be a Nissan Leaf (no other option I could find in the used EV market so far).

    To my research here are some options for bi-directional charging now or in the near future:

    1) Hoping Solaredge latest HD Wave inverter/hub will support bi-directional charging with a firmware update in the near future. This is not for sure but something to find out more about through my solar panel installer. Cost: $2K to $3K range
    2) dcbel r16 solar inverted/bi-directional charger combo. This would be my ideal choice but not available in my area yet and no timeline to my knowledge. Cost: $5K
    3) Wallbox Quasar bidirectional home DC charger. Available now but the priciest of all so far at $4K just for the charger!
    4) Nuvve upcoming residential bi-directional EV charger. Cost: ?. I have sent them an email to find out more.
    5) Fermata Energy’s V2X systems. Cost: ?. I have sent them an email to find out more.

    Any other thoughts on this? Until I get a detailed engineering analysis from my installer I will not know about the recommendation to go micro-inverters vs central inverter but I would like to leave my options open for bi-directional charging to have an EV car battery for emergency purposes only.

    Thanks in advance!

  • #2
    Could be wrong, but I don't know of any EVs that support vehicle-to-home charging. Possibly the upcoming Ford F150 will. As a result, no solar equipment and no vehicle chargers support V2H at this time. Rather than spend a bunch of money now trying to hit a moving target, I would just wait till this comes to fruition a lot farther.

    Actually, I do know of a V2H setup - mine. I converted my CAT electric forklift to 48Vdc and charge it from a NOS Sunny Island that can keep my house and my solar alive when the shtf. Good luck to the rest of you when that happens....
    Now I just need to get some Li-ion batts into the forklift.... Anyone know how to convert a salvage Tesla battery pack to 48V?
    Last edited by solarix; 09-20-2021, 09:39 PM.
    BSEE, R11, NABCEP, Chevy BoltEV, >3000kW installed

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    • #3
      The OP is correct that the Nissan Leaf supports V2H but it is through Chademo and the V2H Chademo device is either still vaporware or unobtanium.

      It is an interesting concept but early estimates are that it will be expensive because the interface has to be direct to the high voltage traction battery. So far not many EVs have said they will support it.
      I cobbled something that might be considered V2H for less than $200. I used it once to keep a refrigerator cool and some power tools charged during a power outage. It consists of a 1000 Watt 12 volt pure Sine Wave inverter that I connected to the 12 volt battery of one of my Teslas. Since both my Teslas charge the 12 volt battery from the traction battery at up to 50 Amps, I had plenty of capacity for that task. I should mention that my refrig was a modern one with a variable speed compressor that had no surge so a 1000 Watt inverter worked fine.
      My long term plan is to install an Outback Skybox with some LFP batteries for up to 5kW of capacity to power essential loads. I have the Skybox and the batteries from a home that I sold so it is just a matter of reconfiguring them. That investment was less than $10,000 and will allow me to use a recently installed GT solar system during power outages. I need to use my cars during power outages to check on other family members so V2H is impractical for me.
      9 kW solar. Driving EVs since 2012

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      • #4
        Thank you for the responses solarix and Ampster. From my research the use of the Nissan Leaf for VH2 purposes has been going on for several years in Japan so here in the USA we are just catching up with the proven technology.

        The dcbel r16 system it seems the more V2H to residential PV integrated one but it will take a while to arrive in my area (being sold/distributed in California now and then New York). I would presume the Wallbox Quasar would work but I am not sure how it would integrate with an existing residential PV system. I need to find out more. I presume the 30% taxt credit would also apply to the Wallbox Quasar.

        To me if one has a used Nissan Leaf (30 to 40 kW battery) as a secondary car then V2H becomes more of a win-win situation for emergency power out situations vs a separate residential backup battery that cost $$$. Since the car battery would only be used for emergency situation battery degradation would be kept at a minimum. I am not interested in selling back battery power to the grid (V2G).

        Any body else with feedback, please post.

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        • #5
          DC based V2H is certainly here with Nissan Leaf. However, keep in mind that Nissan is phasing out CHADEMO for CCS so CHADEMO based V2H is a deadend.

          In any case, none of the products including Nissan Leaf and the bidirectional chargers have any direct integration support for solar except for dcbel which is not available to you. So, you can make your solar system ready for V2H by installing a transfer switch and use line side tap for your solar system to prevent potentially damaging interaction between V2H and solar. This is same as the common generator/solar setup.

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          • #6
            Originally posted by solardreamer View Post
            ..........
            In any case, none of the products including Nissan Leaf and the bidirectional chargers have any direct integration support for solar except for dcbel which is not available to you. So, you can make your solar system ready for V2H by installing a transfer switch and use line side tap for your solar system to prevent potentially damaging interaction between V2H and solar. This is same as the common generator/solar setup.
            Does that mean that V2H, as it exists now, would not be able to AC couple with a grid tied solar inverter when the grid is down? If so the GT inverter would be useless when the grid is down just like it is useless with a generator when the grid is down.
            9 kW solar. Driving EVs since 2012

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            • #7
              Originally posted by Ampster View Post

              Does that mean that V2H, as it exists now, would not be able to AC couple with a grid tied solar inverter when the grid is down? If so the GT inverter would be useless when the grid is down just like it is useless with a generator when the grid is down.
              Yep, it's not surprising given that the bidirectional EV chargers are all first generation with very few customers at this point. Also, most EV owners much less the general population don't have home solar systems. So, I doubt V2H will come standard with AC coupling and island grid management anytime soon. Perhaps as an add-on option at some point.

              In general, I doubt most EV owners (including me) would be willing to pay thousands$ for the bidirectional chargers for DC based V2H as more and more EV's (e.g. F150 Lightning,ioniq 5) come out with AC based V2H option for much less.



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              • #8
                A friend of mine already has solar on his roof but was looking to add a battery. I talked him out of it since there are no incentives and it would cost way too much. He plans to buy an EV with the hope that V2H will eventually be a thing. An EV battery is way bigger than current house batteries such as my LG Chem RESU10H.

                With that said, there's a lot that goes into a robust V2H system:

                1) Car with V2H capability - I know the Leaf has the capability and the IONIQ 5 does with an adapter for 120V 15A. This is a decent start but not quite what you would need to backup a house. My assumption is that a V2H car would need to be capable of Level 2 charging in reverse so 240V 40A = 9.6kW. This would be more than enough to power 95% of homes during an outage.

                2) EV Charger with V2H capability - Such an EV charger would have to be hardwired (plug in chargers would be dangerous in reverse). This charger would be capable of taking the DC charge back from the car and converting to 240V AC. I'm not an electrical engineer but having a device that can work bi-directionally doesn't sound as simple or cheap as a normal EV charger.

                3) Automatic Transfer Switch - Something has to be able to isolate your house from the grid to prevent backfeeding.

                4) Communication - This is by far the most important. All of the items above have to communicate. When the transfer switch detects grid power loss, it has to communicate that to the EV charger and EV. The EV has to allow the EV Charger to draw power immediately to keep the EV Chargers electronics powered up. Then the EV has to meet whatever demand the EV Charger sees similar to a generator.

                In a way, V2H would be like a Tesla PowerWall 2 with a separable battery that you can drive. The Powerwall 2 as a standalone device is essentially like the EV + Bi-directional EV Charger. That also requires the automatic transfer switch to isolate the house from the grid during an outage. A PowerWall 2 doesn't require solar to work and neither would a V2H system.

                If there was one company that makes this capability mainstream, I'd bet my money on Tesla. Since they manufacture the solar, inverter, transfer switch, EV charger and EV, they would be best positioned to get all of those working together via software to make it work reliably and safely.

                But I wouldn't hold my breath...

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                • #9
                  Tesla has the least incentive to do anything V2H compared to other EV manufacturers as they don't want to hurt their home battery business.


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                  • #10
                    Thanks all for the replies and reasoning this being a more complex set up. Ok, complex now but it looks like dcbel r16 is trying to figure out and make it all integrated.

                    soby you make very good detailed points about V2H. I also agree with solardreamer that Tesla might have the capability but not the will to set up a well integrated V2H PV residential system. In this regard I wonder how a Wallbox Quasar would integrate into a PV system with either a Solaredge inverter or a PV system base on micro-inverters. They state here that it supports also V2H:

                    “Wallbox Quasar was engineered to transform electric vehicles into powerful energy sources. The bidirectional charging technology lets you charge and discharge your EV, allowing you to power your home or the grid with your car battery. With Quasar, your EV battery is not just for driving, it also gives you extra energy to power your life.”

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                    • #11
                      dcbel's solar integration appears to be only for on-grid operation so solar won't work during grid outages.

                      In general, bidirectional chargers will only work in charge or discharge mode at any one time with non-trivial direction switching time partially due to CHADEMO/CCS bidirectional charging protocols. So, unlike traditional AC coupled hybrid inverter systems (e.g. Magnasine) which have separate charger/charge controller and discharger/inverter that run simultaneously, a bidirectional charger by itself is won't likely be able to manage the transient conditions in an island grid with grid-tied solar.

                      Frankly, the V2H/solar integration issue is conceptually the same as the generator/solar integration issue/wish that many home solar owners have raised for years now. Solar vendors don't seem interested in offering a solution as they just want to push dedicated home battery systems.

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                      • #12
                        Originally posted by solardreamer View Post
                        Tesla has the least incentive to do anything V2H compared to other EV manufacturers as they don't want to hurt their home battery business.

                        It would provide a viable alternative solution for homeowners that already own solar panels and a Tesla EV. Tesla can't meet the demand for PowerWalls so they are only bundling them with solar. For people that already have solar, Tesla can give them a killer home backup solution by supplying:

                        1) Transfer Switch - Backup Gateway 2
                        2) V2H EV Charger - Repackage the electronics from a PowerWall 2 (minus the battery) as an EV charger.

                        The R&D to make #2 above happen is minimal and those two items shouldn't cost more than $5,000. Add another $1,000 for installation and you'd have a 50-100kWh battery ready to provide backup power to your home whenever it's plugged in in your garage. That would be way WAY cheaper than a dedicated PowerWall solution with that capacity. I'd be all over that and it would make a Tesla EV that much more valuable.

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                        • #13
                          By the way I was checking online the price of a new Nissan Leaf battery (30 or 40 kW I am not sure): somewhere in the range of 6 to 7 grands. Not bad for that size. I wonder if it can be hooked up to a Solaredge system or similar. The problem would be the size. We put both our cars in the garage right now and the space is very limited with everything else (four bikes, shelves, etc.).

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                          • #14
                            Originally posted by soby View Post

                            It would provide a viable alternative solution for homeowners that already own solar panels and a Tesla EV. Tesla can't meet the demand for PowerWalls so they are only bundling them with solar. For people that already have solar, Tesla can give them a killer home backup solution by supplying:

                            1) Transfer Switch - Backup Gateway 2
                            2) V2H EV Charger - Repackage the electronics from a PowerWall 2 (minus the battery) as an EV charger.

                            The R&D to make #2 above happen is minimal and those two items shouldn't cost more than $5,000. Add another $1,000 for installation and you'd have a 50-100kWh battery ready to provide backup power to your home whenever it's plugged in in your garage. That would be way WAY cheaper than a dedicated PowerWall solution with that capacity. I'd be all over that and it would make a Tesla EV that much more valuable.

                            Sure, Ford has already done it. Tesla would rather build out more gigafactories to selll PW's than V2H. They want to build a virtual power plant business around all the PW's they sell which wouldn't work with just V2H. Perhaps more competition will change their thinking but I don't anytime soon.

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                            • #15
                              Originally posted by solardreamer View Post


                              Sure, Ford has already done it. Tesla would rather build out more gigafactories to selll PW's than V2H. They want to build a virtual power plant business around all the PW's they sell which wouldn't work with just V2H. Perhaps more competition will change their thinking but I don't anytime soon.
                              I didn't realize Ford built the F-150 Lightning with this in mind. I'm really impressed: https://www.youtube.com/watch?v=Zxe352yOYyk

                              Now I want to know more about the home integration to make the V2H backup power a reality.

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