Home charging - solar diversion

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Chuq
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Home charging - solar diversion

Post by Chuq » Sun, 18 Mar 2018, 16:04

(This is one of a number of topics related to home charging. Since the questions are separate, I'll post each in a separate thread! Other threads - Simple type 2 outlet for home charging, Load sharing)

My last home charging post is a relatively simple one - because I have a video to explain it :)

Has anyone seen a charger like this available in Australia - which takes excess solar and puts in a car before sending it to the grid?

The even trickier variation is - does such a system exist that integrates with the "load sharing" system as mentioned in my other thread? (Linked above)


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Re: Home charging - solar diversion

Post by jonescg » Sun, 18 Mar 2018, 19:09

I have built a load-shifting battery. It charges off the mains power via a timer so it only comes on during sunlight hours. Then when I get home at night I can plug in to the inverter, delivering up to 7 kWh to the vehicle (usually 3 or less though - it's only a scooter). It's perfect for people who only drive a Leaf or iMiEV 40 km a day but aren't getting paid to export power to the grid. I should do a build thread...
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Re: Home charging - solar diversion

Post by coulomb » Sun, 18 Mar 2018, 20:13

Chuq wrote:
Sun, 18 Mar 2018, 16:04
Has anyone seen a charger like this available in Australia - which takes excess solar and puts in a car before sending it to the grid?
Interesting. They talk as if the power is continuously variable, but I suspect that there are actually only 3 practical power levels when charging something like a Leaf:
  • 6 A @ 240 V ~= 1.4 kW
  • 9.6 A @ 240 V ~= 2.3 kW (not seen on the video)
  • 15 A @ 240 V ~= 3.6 kW (up to 3.8 kW depending on the mains voltage)
  • If the vehicle has a higher power charger (6.6 kW is optional on some Leaf models), you could use higher J1772 current levels: 18/24/30 A for 4.3/5.8/7.2 kW.
Maybe these are the only power levels you can use, so the "balancing act" might be off up to a kilowatt or so some of the time. Presumably they arrange things so that in "eco plus" mode, that kilowatt will just get exported rather than telling the charger it can go to the next higher current level, which requires importing some grid power. So you won't quite get perfect use of all your spare renewable energy (solar or wind), because of the J1772 fixed current levels. Maybe one day they'll come out with a different specification that allows for continuously variable current levels.

[ Edit: power level -> current level ]
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Re: Home charging - solar diversion

Post by dgh853 » Mon, 19 Mar 2018, 11:03

I have one of the Zappi's at my home in Sydney. Works well as an EVSE however the firmware doesn't support three phase yet so I'm not able to use it in the Eco+ (solar only mode) effectively as it doesn't read the solar export/usage across all three phases ( I have a three phase solar inverter).

It's quite configurable with respect to charging limits - 16A or 32A maximum, timers etc and I have mine linked to my meter box wirelessly via the Harvi and three CT clamps.

Relatively low cost and a good EVSE. Once I get the firmware upgraded I can report back on its effectiveness on three phase.

In terms of variability it changes in 1A increments from 6A up to 32A in the solar EVSE setting. I have only seen it climb to 10A in this mode because that's the max I could export through one phase which was all it was reading with the current single phase firmware. The Eco mode runs at 6A and the Boost mode runs up to 32A if your car/charger can handle it.

The solar EVSE Eco+ mode does work correctly on that single phase arrangement - turning on when there is more than 6A (~1400W) excess solar available and increasing to ~10A - my max solar through one phase) and when the solar export reduces below 6A then it goes into a configurable countdown period (currently 60 seconds for me). If the export goes above 6A again then it will restart charging, if it stays below 6A then the charger goes into standby waiting for more spare solar capacity to become available. In that case it waits 60 seconds of 6A spare solar before truning back on. That setting I guess is there to prevent the EVSE turning on and off too frequently for the vehicle to handle due to clouds/house loads.

In terms of load sharing it is possible to put a limit in the Zappi so that no more than a certain current is drawn through the phase/s (or individual circuit I suppose) that the Zappi is measuring. Let's say you have a 32A circuit with other things running. You could place the CT clamp on that circuit and it will limit the charge rate available from the Zappi based on the spare capacity on that circuit ie. it would take into account other devices on the same measured circuit. If 20a was already running then it would set the EVSE to 12A (assuming user specified 32A in the Zappi configuration). in that sense it can be used to prevent overloading of a circuit by the EVSE switching on or ramping up while other devices are in use.

Bottom line - it does what it says on the tin - just not for three phases homes yet.
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Re: Home charging - solar diversion

Post by coulomb » Mon, 19 Mar 2018, 17:07

dgh853 wrote:
Mon, 19 Mar 2018, 11:03
In terms of variability it changes in 1A increments from 6A up to 32A in the solar EVSE setting.
I'm glad to be found wrong in this case.

In terms of load sharing it is possible to put a limit in the Zappi so that no more than a certain current is drawn through the phase/s (or individual circuit I suppose) that the Zappi is measuring.
Wow, neat. I suppose it's much the same behaviour, just limiting the current through the measured circuit to a value other than zero. Good on them for implementing that. Quite a crowd sourcing success, by the sound of it, 3 phase excepted for now.

Thanks for your experience report.
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Re: Home charging - solar diversion

Post by reecho » Mon, 19 Mar 2018, 17:46

Also the OpenEVSE can do this but it requires a little tinkering... Not a polished retail product like the Zappi..

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Re: Home charging - solar diversion

Post by reecho » Mon, 19 Mar 2018, 17:47

coulomb wrote:
Sun, 18 Mar 2018, 20:13
Chuq wrote:
Sun, 18 Mar 2018, 16:04
Has anyone seen a charger like this available in Australia - which takes excess solar and puts in a car before sending it to the grid?
Interesting. They talk as if the power is continuously variable, but I suspect that there are actually only 3 practical power levels when charging something like a Leaf:
  • 6 A @ 240 V ~= 1.4 kW
  • 9.6 A @ 240 V ~= 2.3 kW (not seen on the video)
  • 15 A @ 240 V ~= 3.6 kW (up to 3.8 kW depending on the mains voltage)
  • If the vehicle has a higher power charger (6.6 kW is optional on some Leaf models), you could use higher J1772 current levels: 18/24/30 A for 4.3/5.8/7.2 kW.
Maybe these are the only power levels you can use, so the "balancing act" might be off up to a kilowatt or so some of the time. Presumably they arrange things so that in "eco plus" mode, that kilowatt will just get exported rather than telling the charger it can go to the next higher current level, which requires importing some grid power. So you won't quite get perfect use of all your spare renewable energy (solar or wind), because of the J1772 fixed current levels. Maybe one day they'll come out with a different specification that allows for continuously variable current levels.

[ Edit: power level -> current level ]
The J1772 specification for level 2 can be from 6A to 80A in 1A increments....

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Re: Home charging - solar diversion

Post by HuffnPuff » Tue, 20 Mar 2018, 05:43

Sounds like something I'd be interested in. Is there anything that would use excess solar for charging, then also use the vehicle battery to power the home and recharge off peak? ie if the car is in the garage during peak usage hours in the evening then it could power the house and recharge off peak to enable driving during the day.

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Re: Home charging - solar diversion

Post by Rusdy » Tue, 20 Mar 2018, 13:58

dgh853 wrote:
Mon, 19 Mar 2018, 11:03
I have one of the Zappi's at my home in Sydney...
How much it cost you?

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Re: Home charging - solar diversion

Post by Chuq » Tue, 20 Mar 2018, 19:37

Thats for the info everyone!

@jonescg The charging a battery looks interesting... if I went that route I would get a proper home battery system and just charge that during the day, then discharge to the car battery at night.. not very efficient though and increases cycles on the home battery unit.

Also you might be blessed with unlimited sunshine over there in WA but here in Tassie you can't exactly predict the sunny hours with a timer. :D It could look like a nice day at 8:30 then at 10:00 it's pouring rain!

@HuffnPuff I haven't considered V2G at the moment, certainly an option though. I do think that grid services will be available via other means, such as controlled load EV chargers, which (when there are enough EVs in service and plugged in simultaneously) will be just as beneficial and better for battery health.

I guess in the future we'll have something like an energy router for our home. Think of a box with lots of connections:
- Grid
- Solar
- Home battery
- Residential load
- EV (x2)

And it routes between them all based on certain conditions. The Powerwall app (and now doubt other battery providers) has this feature right now - for the first four items of the list above. Only very basic conditions (e.g. prefer the battery over the grid) although it's just software....

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Re: Home charging - solar diversion

Post by jonescg » Tue, 20 Mar 2018, 19:42

Haha, that's effectively what this system does, however you're right, a hybrid inverter would manage the PV input as well. I measured the VA leaving the storage battery and the VA entering the scooter and it was about 75% efficient :D

Ah well, when the energy is free...
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Re: Home charging - solar diversion

Post by dgh853 » Wed, 21 Mar 2018, 19:47

Rusdy wrote:
Tue, 20 Mar 2018, 13:58
dgh853 wrote:
Mon, 19 Mar 2018, 11:03
I have one of the Zappi's at my home in Sydney...
How much it cost you?
My Zappi was just under AUD1000 including delivery
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Re: Home charging - solar diversion

Post by Rusdy » Thu, 22 Mar 2018, 10:10

dgh853 wrote:
Wed, 21 Mar 2018, 19:47
My Zappi was just under AUD1000 including delivery
Wow, at that price, which includes the charger, definitely compete with basic EV charger! Way worth it. Unless, some people (like myself) love batteries too much and collect more debt by getting PW2. :lol:

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