edf battery offer

michaels wrote: »

Thanks again for more info.

If you put the battery and PV onto the same invertor then how does that work with your fit and generation meter. Does this meter do net metering?

In this scenario, you have to make sure you have a 2 way generation meter - some are, some aren't. The meter goes up when you use the solar power rather than when you generate it - i.e power you generate goes into the battery unmetered, but is metered on the way out. Because you can charge the battery from the grid (which is what I do using off peak electricity), other things being equal the generation meter would then measure this and you're FIT payments would be higher than they should. So what happens is that as the grid power flows into the battery, the generation meter goes down and everything works out OK.


Because of this, this configuration potentially involves the cost of having a new generation meter installed, and whether this is needed or not you still have to tell whoever makes your FIT payment.


A further consideration involves efficiency. Because you lose a bit of energy when you charge the battery, store it and take it out again, connecting the panels to the PowerVault directly reduces your FIT payments slightly. Efficiency losses mean that when you charge from the grid the meter goes down more when you put the grid power into the battery than it goes back up when you take it out.



Set against this, connecting the panels directly to the PowerVault has other efficiency advantages because it removes solar DC - grid AC - battery DC conversion, you just have solar DC - battery DC charging which is more efficient. So worth knowing about but not a huge issue.

Reed_Richards wrote: »

I looked at the EDF offer but I could not see if was open to people who already have a battery but might want to use the PowerVault as a second battery. Presumably EDF don't let you fully charge the PowerVault so they can charge it a bit more as necessary.

On the first point, I see no reason from an EDF contract perspective why you couldn't use this as a second battery, but from a technical point of view I suspect having two different battery systems would be challenging as you may find that one battery tends to discharge into the other - a bit like the issue of using a battery alongside an iBoost.

On the second point, no, EDF don't stop you either fully charging or discharging the battery, you are free to use this as you please, with the proviso that they can charge and discharge the battery whenever they want as long as it is in a state that allows them to do so. Your battery is managed as part of a pool of batteries so they rely on the fact that at least some of the batteries will be usable for them at any given time.

My understanding is that putting charge into the battery is rare and the more common scenario is that they are discharging the battery to cope with demand surges (or supply failures).

This might sound like a bad thing, but keep in mind that without the battery you would be exporting the energy anyway, so in one sense it isn't costing you anything when they take energy out, merely effecting the timing of the export. The "cost" to you is that if they do take some power you may not have time to put it back before you need it, so in effect you are losing a little bit of battery capacity. How much remains to be seen as this contract is too new for there to be any data, but my expectation is that the loss of capacity is likely to be small. Battery storage is very quick to respond at EDF's command if needed, so it is in their interests to save this as a last line of defense as needed and my expectation is that they are likely only to discharge the battery for a few minutes here and there through the day.

Note that if you are on metered exports, you will get paid your export rate for anything they take out. Conversely, on the (probably rare) occasion they charge your battery, that will go through your normal supply meter and you will be charged for this - i.e. it isn't free electrcity. Having said that, the energy is then in your battery for you to use when you want, so (other than any efficiency losses) in one way it hasn't cost you anything. Like before, though, this is eating into your battery capacity so you can't put free solar energy into the space occupied by the paid for grid energy.

These export and supply payments just go through your normal FIT payments and electricity bills, they're completely independent of the EDF contract.

As you can see this gets confusing quite quickly, but having looked into it in some detail and based on my (limited) experience to date I'm personally convinced this is a good deal and the £1500 up front for the 4kWh system will more than compensate you for the occasionally slight loss of battery capacity.

One upside not to be overlooked is that because EDF/PowerVault have paid you up front it is in their interests to ensure that your battery system continues to perform as best it can for as long as possible. So this isn't a "take the money and run" scheme for them, they have a powerful, vested interest in providing after sales service that is second to none. If your battery isn't working well for you, it isn't working well for them either. In practical terms, even though the battery was working well from my perspective, EDF/PowerVault have already done a couple of upgrades (at no cost to me) to squeeze a little bit more capacity from the batteries.

michaels wrote: »

Thanks again.

Power vault seem to offer a scheme where instead of an upfront discount you get £20pm. Isn't that a better deal?

You're welcome. You will have gathered from my posts that I'm a PowerVault fan I'm starting to wonder if I'm being a bit too enthusiastic and not presenting a balanced view.

I know they had an offering like this at some point in the past, but is that still current? If so, can you post a link?

pile-o-stone wrote: »

I like the new design of the powervault, much better than the previous washing machine style.

Hi

Agreed, but this does give me a slight concern because it has the look of something you could install in your hallway and I think some of the marketing photography is a bit misleading in this respect. The noise of the fans would stop me doing this (and I suspect most people) and also with one thing and another there are a fair few cables running to it, not really clear on the photos. In the general scale of things not a huge issue but worth considering.

On the subject of the grid services contract, this article is well worth reading to provide some insight:

https://www.theguardian.com/business/2019/aug/12/three-blackout-near-misses-in-three-months-says-national-grid?CMP=Share_iOSApp_Other

As mentioned before, the PowerVault is one of the few battery systems that has the hardware built in to respond to frequency dips, which is how EDF know to switch it on to discharge and support the national grid when it struggles, and why EDF have partnered with PowerVault. There are settings in the PowerVault that EDF/PowerVault set remotely to tell the battery system to start discharging when the frequency drops to a certain level.

You could read the Guardian article in a couple of ways.

On the one hand, if, as the article highlights, the grid frequency often drops then the battery will discharge often (albeit for short periods) which means that EDF will get more out of the deal than you will. So is the grid services a good deal?

On the other hand, you could take the article as a sign of just how important frequency response is and take the view that having a battery system with frequency response built in as a good way of future-proofing your investment. You can always opt-out of the EDF contract at a later stage if something else better comes along, and it's also hardly in EDF's long term interest to set the frequency threshold to take advantage of their early customers.

I take the second of these views, but there are no guarantees here and anyone going for this needs to make their own decision on this. This is a new market and there is little data and a lot of judgement and trust involved. I'm not wanting to be negative, and would still be happy to recommend the deal to anyone, but just want to balance my views a bit with some of the risks.

Related to this whole frequency response thing is that for it to work, you need to let EDF/PowerVault tune and manage the battery system for you. Some will see this as a good thing anyway (on the "life's too short to fiddle with battery settings" argument) but others (including many of the tech enthusiasts on this forum) would probably be frustrated/disappointed about lack of visibility of the myriad of settings that EDF/PowerVault tinker with and the lack of ability to change those settings themselves.

I have just received this offer from EDF too.
Is the inverter included in the box pictured? My system is 8 years old now and I was told when it was installed that the inverter would last about 10 years so I'm thinking it may well be worth it for me to get the powervault as I could switch to its inverter if the old one goes wrong. I have a total generation meter so am assuming the FIT would be calculated from the meter on the powervault.
It strikes me that EDF would be dumping electricity in summer on days like today when its sunny and drawing in the winter evenings. However I have an eco 50:50 tariff so could charge it overnight or weekends in the winter I suppose.
I think I'm going to have to read the Ts and Cs carefully and have a think about this one!
We were lucky to just get our system put in before the FIT was reduced and are very happy with it. It has paid for itself by now so in some ways I am reluctant to change a system unless it offers a real advantage.