Solar power - EV - home battery?

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Talkiet

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#296165 26-May-2022 11:28

Is anyone aware of a solution, available IN NEW ZEALAND, able to be installed legally where a solar system can charge your EV and the EV battery can function as a battery for the house overnight?

I am aware that limited EVs current support this bidirectional flow, but with the cost of fuel seemingly ratcheting only upwards, and power prices doing the same - this seems like a really obvious synergy. I have spoken to a couple of solar installers and while they both say it's coming, I get the feeling that they are speaking about the ecosystems they are aligned with and I wonder if anyone in NZ is currently offering this.

Cheers -N

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Chippo

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#2918816 26-May-2022 11:44

You're a few years early.

It's hard enough convincing the EV Manufacturers to sell into NZ - The VW ID series is being entirely ignored by VW NZ, with the ID.5 pretty much the only RHD car announced to officially support bi-directional charging so far.

Until the cars themselves support this - we're not likely to see too much innovation on the house side. The Leaf is a perfect example of this, with it being technically possible but because it needs to use the DC side, the equipment is just horrifically expensive.

A side-note, I was really excited by the potential savings of charging my car with solar. 3 Years in to that now, I've saved about $75 - and yet to pay off the Hub required to connect the EVSE to WiFi, let alone the investment in time. The 10c delta between Export and Off-Peak Tarrifs just cancel out the savings. That makes future technology useful for Backup Power and little else.

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richms

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#2918888 26-May-2022 12:22

I would be concerned about the needless cycling of the car battery doing this. Overnight would be a significant discharge on the car, and then whatever is needed to drive around the next day would probably end up with it being a full cycle daily almost.

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davidcole

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#2918890 26-May-2022 12:31

richms:

I would be concerned about the needless cycling of the car battery doing this. Overnight would be a significant discharge on the car, and then whatever is needed to drive around the next day would probably end up with it being a full cycle daily almost.

Wouldn't a house use a lot less that the drain while driving?

I dont have any products to mention, but it was a thought that when I finally pulled trigger on an EV I did want one with bi-directional and to use the car as a battery for load balancing and if there are power outages.

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richms

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#2918898 26-May-2022 12:39

davidcole:

Wouldn't a house use a lot less that the drain while driving?

I dont have any products to mention, but it was a thought that when I finally pulled trigger on an EV I did want one with bi-directional and to use the car as a battery for load balancing and if there are power outages.

50kWh battery in a car for example. Maybe 1/2 the usage on average being done when there was no solar production at all would mean that it would be about 1/3rd the battery capacity used assuming my usage is spread over the whole day, but its not because I am not home most days so more of it will be in the evening/night than the day time so I would expect that to power the house overnight from the time I get home to plug the car in, till I leave in the morning would take about 30kWh out of the car. Then its not home during the day to charge off the solar because I have it out with me.

If I had multiple cars and could alternate them between one at home charging during the day and driving the other one then it might work, but at that point a home battery would probably cost less and be less hassle.

The outage side of things I can see value in, but with what the gear and integrated wiring needs to split out loads and stuff, that also can be applied to a home battery installation which again is going to be more use than a car that is often not there so no UPS protection when I am out.

Its like all the use cases for the bidirectional wireless charging that some phones have. It sounds great but is essentially useless in almost all daily situations.

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Talkiet

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#2918918 26-May-2022 13:29

richms:

Its like all the use cases for the bidirectional wireless charging that some phones have. It sounds great but is essentially useless in almost all daily situations.

Unless you work from home and can't use all the power your solar cells make during the day. Current solar batteries start at around 4.5khw with a current Tesla Powerwall being around 13.5.... 4.5 is near useless and 13.5 would not even get me through the night if it was fully charged (but would do most of it)...

Even the smallest car battery is going to be 3-4 times as large as the current Powerwall... For someone that works from home, the system I describe would mean essentially no draw from the grid during summer.

(No, I am not interested in an offgrid solution)

But yes, it seems like this isn't available in NZ at this stage - Seems like the Wallbox Quasar bidirectional charger is, or will start to be, deployed in Australia soon - although it's not cheap.

Cheers - N

Please note all comments are from my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.

Dingbatt

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#2918931 26-May-2022 13:51

I guess the ultimate in this situation (V2H) is if you live near one of the free DC public chargers (from the likes of Vector), you whip down, fill your car up and then use it to run your house for the night!

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richms

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#2918941 26-May-2022 14:05

Dingbatt:

I guess the ultimate in this situation (V2H) is if you live near one of the free DC public chargers (from the likes of Vector), you whip down, fill your car up and then use it to run your house for the night!

For what a charge of a car is worth and the time taken to do it, I don't think it would be worth it.

But parking up and mining bitcoin in your car might be worth it?

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SomeoneSomewhere

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#2919879 28-May-2022 22:46

Talkiet:

richms:

Its like all the use cases for the bidirectional wireless charging that some phones have. It sounds great but is essentially useless in almost all daily situations.

Unless you work from home and can't use all the power your solar cells make during the day. Current solar batteries start at around 4.5khw with a current Tesla Powerwall being around 13.5.... 4.5 is near useless and 13.5 would not even get me through the night if it was fully charged (but would do most of it)...

Even the smallest car battery is going to be 3-4 times as large as the current Powerwall... For someone that works from home, the system I describe would mean essentially no draw from the grid during summer.

(No, I am not interested in an offgrid solution)

But yes, it seems like this isn't available in NZ at this stage - Seems like the Wallbox Quasar bidirectional charger is, or will start to be, deployed in Australia soon - although it's not cheap.

Cheers - N

Smallest car battery sizes are in the 15kWh range I believe (though newer and higher-end cars are much larger), and powerwalls and their competitors are generally gangable. If you want more capacity, install more of them. It's likely to be much cheaper to buy batteries standalone than with a car wrapped around them.

Nighttime power in NZ is generally cheap. The savings come from offsetting the 5-9PM peak load period. Between 11PM and 7AM, use the grid.

As noted, you probably don't want to run the car down to empty in case you want to drive it somewhere first thing in the morning, so realistically you would want 20kWh perhaps for the night load, 20kWh for driving around, and another 10kWh to avoid needing to fully cycle the battery.