Tesla Powerwall thoughts


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I'm thinking of installing a Tesla Powerwall and would be interested in your thoughts. We are thinking of connecting it to solar panels to be installed on the flat roof of our 1930s semi giving us free electricity in the summer months. The installer has also suggested connecting the Powerwall to an electricity tariff that offers cheap units between 11pm and 6am so that during the winter months the battery charges up with cheap electricity overnight and then you run your appliances off the battery during the day. The idea is to go off grid as much as possible.

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Gibbsy wrote:

I'm thinking of installing a Tesla Powerwall and would be interested in your thoughts. We are thinking of connecting it to solar panels to be installed on the flat roof of our 1930s semi giving us free electricity in the summer months. The installer has also suggested connecting the Powerwall to an electricity tariff that offers cheap units between 11pm and 6am so that during the winter months the battery charges up with cheap electricity overnight and then you run your appliances off the battery during the day. The idea is to go off grid as much as possible.



Thanks for your post, Gibbsy.

A few people at our office will actually soon be trialling in home batteries like the Powerwall and Nissan xStorage, so it'll be interesting to find out what their experience is - I'll keep you posted if I hear anything.

I think you'd definitely need an economy 7 meter to see the full benefit of the battery. An economy 7 meter clocks day and night-time usage separately, so you can be charged a cheaper rate for your usage at night.

If you have a smart meter, it can be changed to economy 7 remotely. Otherwise, we can install an economy 7 meter for you.

Let me know if you decide to go ahead with the Powerwall.

Max
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Hi,
I have a smart electricity meter on the Greener Energy Plan 100% renewable electricity until 10Aug17. (Renewal date soon!)
I am waiting for a Tesla Powerwall2 to be installed in the next few months in my London flat.
We have no solar or wind generators but hope to exploit the 7 hour low cost electricity at night to charge the battery. We will then use battery power during the high cost 17 hour period.

I would like to go on Dual Tariff Economy 7 using 100% renewable electricity from 10Aug17

Does OVO Energy offer this as an option? If so what is it called and how do I apply for it?
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NickinHP wrote:

Hi,
I have a smart electricity meter on the Greener Energy Plan 100% renewable electricity until 10Aug17. (Renewal date soon!)
I am waiting for a Tesla Powerwall2 to be installed in the next few months in my London flat.
We have no solar or wind generators but hope to exploit the 7 hour low cost electricity at night to charge the battery. We will then use battery power during the high cost 17 hour period.

I would like to go on Dual Tariff Economy 7 using 100% renewable electricity from 10Aug17

Does OVO Energy offer this as an option? If so what is it called and how do I apply for it?



Wise move, @NickinHP

We can offer you the Economy 7 (eco 7) version of the Greener Energy plan. We could make the change now, offering you the eco 7 tariff rates that were available when you fixed, until your contract expiry. As you specified the 10th August renewal date as being your preferred date, let's leave things as they are for now.

As your smart meter is set up as a single rate meter (not eco 7), your renewal options (visible via My OVO now as it's within 7 weeks of your renewal date: http://ovoener.gy/myovo), will only show this single rate Greener Energy tariff. We'll need to make the change to your smart meter at our end, after we've checked that you're happy with the eco 7 prices. For me to check these prices with you, I'll need your details via a PM. I'll send this now.

Tim
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Tim...what is a PM???????
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NickinHP wrote:

Tim...what is a PM???????



Good question - PM stands for Private Message. You should have received an inbox notification from @Tim_OVO but if you haven't, let us know.

Lucy
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Hi, I read somewhere that if I have PV connected with a battery (like Tesla PW) I cannot use the grid to recharge the battery during off-peak tariffs when sun is not enough.
Is that right? It looks very strange to me.
Thanks
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Dont think that is true. The whole odea of off peak tarif is to encourage electricity use during the night when it is more readily available from whatever source.
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Would be good to have a definitive answer to the question: Can a Powerwall be charged from both the grid and PV panels PV in the day and Grid at night.. I asked a TESLA salesman....hmmmm
feel a little more product knowledge is needed!
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Thete are some very good utube videos by Fully Charged which cover all aspects of green energy, Tesla power walls etc. You will find your answer I am sure. They have powerwall installed and running with solar and grid connected
Powerwall cannot be charged by the grid, or from eco 7 at night.

Have been told that eco 7 charging will be carried out with the Installation‎ of firmware in the new year but no date given.
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Charging from the grid using economy 7 may be an interesting future proposition, but I would only commit after a spreadsheet session had convinced me there was financial benefit!
I would also suggest a quick viewing of fullycharged on youtube. I'm really keen on a PV/powerwall solution that will charge my Leaf up overnight. On fullycharged, the setup has enough capacity to charge the powerwall during the day and also heat the hot water cistern, reducing the gas bill. As far as I remember you can also have economy 7 feed in when required (if not, it is an intended tesla firmware upgrade) - although the best way to use the powerwall is to completely discharge it overnight (i.e. charging your car) so that it can be filled up from the solar during the day. This doesn't seem to fit with economy 7 topup - except I guess in winter when the solar PV is too low to fill the battery. I know you have to match the pv to the battery as leaving it discharged for long periods over winter is not good for it. I'm just now getting quotes for pv/powerwall and it is quite expensive (hoping for £10k-£12k) and the payback is probably over 15 years depending on usage. I'm also hoping to upgrade my Leaf to the 2018 model and investigate V2G
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I too am investigating V2G, with the possibility of buying a Leaf.

As I understand it, there are two distinct factors to consider:

1. The physical connection to/fro the Leaf. Nissan offer their own range of 3 types of charge-station for home connection. Actually the fastest one can be ignored unless you happen to have 3-phase available!

The main constraint is that domestic properties are supplied through a 100A fuse, owned by the DNO. Since the Leaf cannot detect how many other power-hungry devices are active, its current-draw needs to be constrained. Your DNO would be miffed if they were forever being called to customer premises to change the fuse because someone turned on an electric shower whilst the car was charging!

Of course, this constraint is alleviated if the property already has charge stored in a home-battery such as the Tesla Power-wall or OVO's XStorage. But these have a much smaller capacity than the new 30kW Leaf.

Moreover if the Leaf is to be fast-charged from another battery then it should be possible to do so using its DC-charging capability rather than wasting energy by converting to 240v AC and back again.


2. The viability of V2G relies on you being able to optimise the times when you sell your stored charge back to the Grid.

OVO are in a position to handle this on behalf of their customers because they have some magic software to handle massed arrays of battery-storage sites. I don't know how it works, but I do appreciate that this is the key to supplying the Grid very fast when demand suddenly peaks.

Moreover, the forthcoming trials of OpenLV technology will allow monitoring of demand at individual sub-stations (typically
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Bah... OVO's software is truncating my posts this morning..... Dunno why. Perhaps it's a hint to favour brevity!

As I was saying:

.... demand at individual sub-stations (typically less than 200 homes). Access to this data will allow micro-management of power-balancing across the Grid. I'm hopeful that National Grid will be prepared to pay top-price for energy that can be made available so quickly.

All this will require customers to have SMETS2 meters and a new App which will permit the user to preset how much of their stored charge may be resold back to the Grid and during what time-frames of the day.

In turn this will require a new Tariff based on the industry-standard HH (Half-Hour) period rather than the current coarse system of a standard rate set for the year and a reduction for the Economy-7 option.

There is much to be considered.
So, my conclusion is that, although I would love to do all this V2G, home storage stuff now, we are probably at least a year away from it being all singing all dancing. Unless of course you can get onto one of the recently announced trials
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... which is what I am suggesting, @johnbleaf !

I don't know where you live, but if OVO want to progress with both Home-Battery Trials and V2G, then they'll need test sites. Why not put your name forward?
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Also interested in home battery storage and V2G. Have registered :)

https://www.ovoenergy.com/electric-cars/v2g
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We've currently got 4kWp of panels on the roof and are looking to increase our self-consumption (we export about 80% of what we generate at the moment).

We can't stretch to a Powerwall but our installer has been fitting a number of the Sofar ME3000SP systems (coupled with PylonTech batteries in multiples of 2.4kW). Like the Powerwall, these batteries sit on the AC side of the inverter, so can be charged from the mains if/when the sun doesn't appear.

Some installer web sites are claiming that the Sofar system can do its charging from Economy7, which is encouraging, although I'd like to see an actual example installation (previous tech support from Sofar reps hasn't been accurate).

We'll probably hold off deciding until April 2019. At that point the Feed-In Tariff is due to expire for new entrants, and installers might be offering sweeter battery deals as their panel installation work slows down further.

Do let us know how you get on if you decide on the Powerwall.

Regards,
Pete
FYI, the Powerwall 2 final testing with the new firmware that allows economy 7 charging when needed is almost ready for rollout.
I've had a Powerwall 2 working for just over a week. The initial objective is to better match the fluctuating supply from a nominal 4kW solar array with the fluctuating household demand. The battery has achieved that objective although, to date, the array output hasn't yet been enough to get the battery anywhere near fully charged. I'm therefore looking forward to the firmware update so that I can switch to economy 7 for partial top-up with off-peak mains power. How much to top up before 7am will depend on my forecast of the array output for the day.

Anyone interested can study my performance data at https://pvoutput.org/intraday.jsp?id=64956&sid=57751. The graph for 19th March shows that at about 22:20 the battery automatically did a partial top-up from the mains because the charge level had dropped to about 3%. That's the charge level directly reported by the battery. It stops providing power at 5% which shows on the Tesla app as 0%. The electronics for keeping the battery on standby use some power - perhaps a bit more than 1%/day.
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Battery storage is a great idea if you have solar PV or are having it installed.

I always recommend that a monitoring system to verify actual export of energy is installed, this way you can get a properly sized battery matching both your demand and maximising the energy store to discharge ratio.

The requirement for charging from economy 7/10 tariffs or indeed from the grid at anytime is what is called Time Of Use (TOU). TOU is not yet a clearly defined standard and will be available soon and regulated correctly. This is important to those on existing PV system contracts. You do NOT want to mess with your Feed In Tariff, especially if its an original tariff on the super high rate. This is more of an issue for installing DC coupled storage so a Powerwall 2 will be fine but always check first.

Make sure your installer is completing the G100 application, this can be fast tracked for approved equipment, most kit is approved and if it isn't, then I would definitely recommend not having it fitted.

V2G is a way off yet. This is being tested by Nissan at present and it will be based on this testing that the regulations and working method is likely to be based. It will happen for sure, so there is nothing wrong with being prepared.

So yes, get a battery but only once you know your true export. If an installer is pushing without knowing this for sure, then they should be treated with caution.

Cheers

Simon
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We have an EV and hopefully soon a 2 car EV family. I do not have solar but with 2 EV's it might make sense and reduce the payback period from the current 15-20 years. A battery makes lots of sense-however the cost of a decent size storage battery such as the Tesla powerwall extends the payback a lot more. It makes so much sense to use the storage available in 2 EV's that lets face it sit idle for 80% of the time.

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