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DIY Supersmart EVSE with SE electric meter?t

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  • DIY Supersmart EVSE with SE electric meter?t

    I have 62 330w panels & 10 kW & 7.6 SE inverters that give me max 17.6 kWac production. I have full electric 4 BR home in hot climate with AC, two 80 gal HPHW tanks, pool pump & HPHW pool heater. I have 2 EVs with 40 amp/ 9.6 kW & 32 amp/ 7.6 kW on board chargers, respectively. Depending on how much AC I use & miles I drive, my production could almost approximate my consumption. I want to maximize self consumption & minimize grid export $0.10/kWh & import $0.30/kWh. With multiple big loads it is difficult to coordinate.

    The Zappi is a supersmart evse marketed in UK that can limit ev charging to surplus solar energy. Theoretically, I would need 2 Zappis. Is there any supersmart evse in US that can limit ev charging to surplus solar?

    If not, I could install a zwave 40 amp switch on each of the evse that could be programmed to query my inverter thru its API and only turn on an evse if my surplus solar exceeded a certain threshold such as 5 kW for small evse & 7 kW for larger evse. (Yes, I have an electric meter installed with my inverter.) Has anyone tried that?

    (I know that I may also need more solar.)

  • #2
    Sorry, I just realized that I previously discussed some of this here.
    My SE 7.6kW inverter has a built in ev charger but the attached screen shots indicated to me that I wasn't just using surplus solar as intended. The red on the consumption graph is importation, which I want to avoid.
    After reading more about SE ev charging, I may have figured out my problem. SE suggests using a charging schedule of 10p-8a. That is the cheapest time to charge in some areas but not HI. In HI TOU, the OFF PEAK rate time is 9a-5p, which also is when I may have excess solar. So I created a charging schedule of 9a-5p and chose the option of using surplus solar on the SE app. Because I chose to charge from 9a-5p, I would have used "surplus solar" whether I chose that option or not. However a charging schefule of 9a-5p will import any energy needed to complete the charge, which is not desired. If I added a charging schedule of 10p-9a and plugged my car in at 6p, it would charge me completely from the grid and not use any surplus solar, which is also not desired. Maybe I should not enter any charging schedule then hopefully charge only with surplus solar then manually top off after sunset if needed. Anyone know if that would work?
    Attached Files

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    • #3
      Charge from 10A - 2pm. That's generally the strongest sun hours, and if you have surplus, that's where it would be.

      Adjust for local conditions - cloudy afternoons 1-5pm or whatever.

      Or look as your last year averages of selling to PoCo, and set those hours as your charge hours. But without communications from your solar inverter (which sees production and loads) how is the car going to know when you are selling or consuming.
      Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
      || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

      solar: http://tinyurl.com/LMR-Solar
      gen: http://tinyurl.com/LMR-Lister

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      • #4
        Originally posted by Steeler.Fan View Post
        I have 62 330w panels & 10 kW & 7.6 SE inverters that give me max 17.6 kWac production. I have full electric 4 BR home in hot climate with AC, two 80 gal HPHW tanks, pool pump & HPHW pool heater. I have 2 EVs with 40 amp/ 9.6 kW & 32 amp/ 7.6 kW on board chargers, respectively. Depending on how much AC I use & miles I drive, my production could almost approximate my consumption. I want to maximize self consumption & minimize grid export $0.10/kWh & import $0.30/kWh. With multiple big loads it is difficult to coordinate.

        The Zappi is a supersmart evse marketed in UK that can limit ev charging to surplus solar energy. Theoretically, I would need 2 Zappis. Is there any supersmart evse in US that can limit ev charging to surplus solar?

        If not, I could install a zwave 40 amp switch on each of the evse that could be programmed to query my inverter thru its API and only turn on an evse if my surplus solar exceeded a certain threshold such as 5 kW for small evse & 7 kW for larger evse. (Yes, I have an electric meter installed with my inverter.) Has anyone tried that?

        (I know that I may also need more solar.)

        Yes, OpenEVSE has function to divert surplus solar production to EV charging to avoid backfeeding grid. However, it's only has 1A (~240W at 240VAC) EV charging control granularity at this point which is not as granular as the Zappi which has ~50W control granularity.
        Last edited by solardreamer; 10-13-2020, 01:49 PM.

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