Say hello to our new vehicle-to-grid (V2G) charger!

I am a believer in renewable electricity combined with battery storage to make our country energy independent. I can afford to be an early adopter and so have a 4kW solar system that helps to power our house and immersion water heater. We do not need gas water heating from mid-late April to mid-late October depending on the sunshine we get.

I am augmenting this with a Tesla Powerwall 2 battery that will mean I should be able to extend to time my home is electricity self-sufficient. I have now heard that Ovo is going to offer a vehicle to grid charging/reclamation scheme. My 40kWh batteried Nissan Leaf will be able to soak up solar or Economy 7 electricity and discharge to the grid at peak times to earn me a bit of cash, AND, level out demand on the grid meaning that we will not need extra generating capacity to charge my car.

Think about that a moment. A miilion electric cars charging on home grown solar or Economy 7 cheap electricity will mean that we could do away with coal, gas and nuclear generation. That is, if we increase our solar and wind generation enough to be stored in our batteries.

This is indeed an intriguing announcement today. I've been trying to assess how it is able to provide the V2G functionality, and I've noted two things thus far:You're far more clued up than I am.

I ordered the Powerwall 7 months ago so there was no hint of V2G coming this soon then. It looks as though the switching & software for disconnecting from the grid will not be available from Tesla until much later this year (KoffKoff).

I read somewhere that the older Nissan Leafs can be connected up for V2G and are doing so in Japan.

I told Ovo that I don't really want a smart meter until they roll out SMETS2.

I think there is a difference between V2G and a static battery like the Powerwall. Don't forget, the Leaf can be charged from Economy 7 as well as my solar or daytime rate electricity.

I can charge the Powerwall using solar or Economy 7 and could flog it to Ovo when they need it at breakfast and tea time. If they had the facility to take it.

The Powerwall is costing me £5,000 plus VAT & fitting. Vat for the battery is 20% but if I have a solar installation too it drops to 5%. Obviously, I am having another couple of 300W panels, inverter etc as well as the battery for the same cost as just having the battery.

I am wondering how "smart" the V2G system is? Will have the same solar facility as the myergi Zappi I've got fitted. At present, the solar is powering this computer, a washing machine as well as pushing a few electrons into the car.

Hi,
I am in the process of building our own house and I am trying to make it generate enough to be self sufficient and power our Leaf and Env200. We have installed 3 phase power and I am planning on 12kw of PV.
I was planning on installing 2 Tesla Powerwalls but the cost is about the same as the value of our current 30kw Leaf. I would like to get a new Leaf when they introduce a 60kw version, we find the range of the 30kw is occasionally a headache.
It seems logical to keep the old Leaf for my children if I can combine it with V2G.
Although having 3 EVs in the house seems crazy, it does mean that there would nearly always be one around to leave plugged into the V2G.

I am not really worried about battery degradation of the cars, I assume the same battery pack technology is used for storage as for cars ?

Hi,
Yes we are building in the Cotswolds, have you started work yet ?
I have waited a while for Nissan to actually progress their home storage system, Tesla seems the only option actually available, but I will happily wait a bit longer for details of the OVO, but using what I have instead of buying home storage seems worth finding out about.

Hi, I'm new to the forum and follow the subject of sustainable energy with interest.. I am an electrician and use an eNV200 to get around which I love and works really well for me. I've had it nearly 2 years now, it's the 24kWh battery so limited range but is fine for me, around 60 safe miles in the summer.
I'm in the process of having a Powerwall eco 3 home battery installation as part of a trial called Pete. Only 3.5 units of capacity but then my solar is only 2.9kWp.

Transparent, I wd just like to comment on one of your previous posts concerning the maximum household current draw.. its not quite as simple as adding up all the maximum circuit design amps.. it's a lot less than that due to something called Diversity eg a cooker is assumed to draw 30% of its design current, a ring circuit less than that probably. Electric showers and fast chargers, yes they will draw close to what they rated at. Also a 100A fuse won't blow at 100 amps! Sounds strange but it will be more than that and possibly only after several minutes of over current, depending upon how much..

Good morning @Mikgle... another member from sunny Devon :)

That's sounds a very interesting set-up you have at home. Perhaps you could post more on the Forum area for Home Storage about your reasons for wanting to trial the Powervault and how you are integrating it with your PV array.

I don't want to comment more here because others won't find in within a V2G thread.

Thanks for bringing up the matter of diversity.

I have reached a set of agreements with the Forum Moderators, part of which involves me curbing my enthusiasm for posting stuff that's too deeply technical. As I'd like to expand on the subject of diversity, can I just shout out to @Darran_OVO, that I didn't start this - it's @Mikgle who raised it!

(I try to stick to my arrangements with Darran - especially as I'm currently running in credit to the tune of two pints of real ale!) :P

I'm assuming you've noticed what I wrote about the total household load threatening the 100A Main Fuse on 20apr18 on this thread about the OVO Home Storage unit, because it wasn't here on this page. (I'm adding the link so that others can follow what we're discussing).

Yes I'm au fait with the concept of diversity. Non-sparkys can get a glimpse of this principle by adding up all the values of the fuses/trips in your consumer unit, and noticing that this exceeds 100A... but yet the Main Fuse doesn't blow of course!

I was trying to raise this topic using a "fair comparison" by referring mainly to those electrical devices which provide a long-term constant loading of the circuit. Thus I specifically included an EV fast-charger and electric shower by name, yet only generically mentioned the 30A power ring and the electric cooker circuit.

I probably should've mentioned storage radiators too.

As you're a sparky, I think others would value you mentioning more about what to take note of before considering adding an EV Boost Charger to their home consumer unit.

You are quite right to raise the issue of the time taken for a fuse to blow... which reduces depending on the amount of over-current it is handling.

I have power-monitors on a couple of my devices here which I now know take a lot of power on first being switched on. At the smaller end of the market, I've just built a solid-state PC that runs off 10-30vDC (variable). The internal DC-DC converters take a massive current of more than 10-times the normal running-amps, which surprised me.

At the larger end of the scale I have a 240v AC well-pump, which will reliably blow a 7A fuse at least once a week, and yet is rated 1kW. On further investigation, the switch-on surge is closer to 30A !

It's now on its own 32A rccd :)

Assessing diversity is more than a finger in the air guess isn't it?!

Hey @Brucey85

Our OVO Engineers are currently using the Nissan ENV200 with the 24kwh battery. This is 100% electric, not a plug-in hybrid.

The exciting news is our fleet is already around 12% full EV at the moment, but we are eagerly awaiting order dates for the same vehicle but with a 40kwh battery which will extend the range of the vehicle by about 50-60 miles and increase the % of fleet vehicles that are full EV to 40% by the end of the year!

Hope that helps!

Darran

@Absolute Zero

Yes as I mentioned above we are waiting for order dates so we can place an order for the new 40kwh ENV200s!!

Interesting info re the Leaf, wasn't aware of that. Be good to know if anyone else is aware of it and how they are managing it?

That's interesting feedback @Absolute Zero.

There must be some failsafe "temperature management" in the 40kWh Leaf to impose the charge limitation at 39degC. But I'll agree it sounds crude.

If it's in the main vehicle's software, then I'd expect Nissan to issue an upgrade of the firmware through main dealers. But if it's embedded in the controllers sat on each of the 48-stacks which make up the Leaf's floor-pan assembly, then they may not have an upgrade route.

This is an important issue for OVO to consider with the new V2G charger.
Perhaps it needs to detect the model of the Leaf and limit discharge to 20% capacity when feeding the Grid, for example.

@Darran_OVO, I assume the R&D Team are reading this Thread, aren't they?

Thanks for clarifications @Absolute Zero,

If temperature is such a problem, perhaps we should have our car batteries charged whilst at Absolute Zero :P

Yes, I understand the basic principles of battery chemistry and why there have to be compensations made for rises in temperature. My own house has devices running from a (lead-acid based) off-grid system for which I've had to calculate how to handle the charge/discharge regimes. What I've learned over the years applies to what we're discussing here.

My batteries can only take so much charge-per-minute. This differs according to their state-of-charge and temperature.

My main way to limit this uses a (bought-in) switching regulator. If my electricity sources (PV panel and wind-turbine) are feeding in too much juice, the regulator slowly increases the amount that it siphons off into a dump-load. This pulse-width modulation is fine for most occasions.

If Nissan used the same approach with the 40kWh Leaf, then their charge-regulator would slowly restrict the current-flow whilst monitoring that the cell-temperature doesn't rise above 39degC.

However, my in-house off-grid battery array sometimes also has to cope with sudden overloads, such as a very strong gust hitting the wind-turbine when the batteries are pretty well fully-charged already. The main dump-load system simply isn't enough.

At those times a further regulator is switched in, offering an additional dump-load to absorb the energy and protect my £1000 battery-array. It's coarse, but effective.

Now if that's what's happening to the Leaf, then I think the design needs re-tuning. I expect there's a temperature sensor embedded into each of the 48 cell-packs. They need this in any case to measure the rate of charge (delta-temp/delta-time if you understand the technique).

If those temperature sensors see a rise above 39degC as requiring emergency action, they may well send a "cut current" notification to the main car's computer, which then drops out of rapid-charge mode.

So instead of the charging regime slowly decreasing the current to keep the batteries below temperature, you get a sudden switch to a standard-rate charge... which is not what you want!

Now there's a lot of conjecture in what I've just described. But it all depends on where in the Leaf the charge-limiting is being done - the main computer, or the embedded units monitoring each cell-stack. If it's the former, then surely a software upgrade could be done.

I wonder how they're intending to change things in the 60kWh variant?
Forced air-cooling to match the rise i temperature perhaps.

Can you just confirm that the V2G as well as providing power to the grid can also be used to power my home from my Nissan Leaf?

Secondly does this V2G also act like the Zappi where by it takes power from my solar panels when there is excess power available?

Thanks Jeremy

Can you just confirm that the V2G as well as providing power to the grid can also be used to power my home from my Nissan Leaf?

Secondly does this V2G also act like the Zappi where by it takes power from my solar panels when there is excess power available?The idea of V2G is that the electricity can go both ways. From grid to EV or house and from EV to house and grid. If I get to be part of the trial, I intend to store solar in the car and Tesla Powerwall 2 and allow the EV to be used by the grid at peak periods.

As to a Zappi-alike, I don't think so, yet? I suspect it will be dumb as far as allocating solar goes and your solar will power your house and EV when there's enough.

Now I've confused myself....