On-grid domestic battery storage

JKenH

orrery wrote: »

We're all in it for the toys, so just get on and buy it.

Well said, far too much sensible advice on here.:)

Coastalwatch

Either this has been posted before or Mart must be taking a day off. Anyway an interesting move by EDF although not yet incentivised enough for me to take the plunge!

EDF Energy is to target the UK’s solar households with a discounted offer of battery units from Powervault in exchange for them signing up to a ten year contract allowing the supplier to use the storage capacity in the energy services market.

On the plus side you don't actually have to sign up to your energy with EDF in order to purchase.

The new partnership is offering existing solar PV owners as much as £2,000 off the cost of a home battery system if they sign up to EDF Energy grid services. If taken up, this will allow the energy stored in a Powervault 3 battery to form part of an aggregated network that can be used to help balance the grid.

Applying the figures of our usage to my simple spreadsheet the 4.1kWh unit would take 16.4 yrs to achieve a ROI. Of course it may be far less for others. Oh, the ROI of the 8.2 kWh unit, perhaps more useful to us is 18.2 yrs! Maybe I'll take a second look to see if payback could arrive a little sooner!

https://www.solarpowerportal.co.uk/news/edf_energy_targets_solar_homes_with_discounted_battery_offer

Zarch

Coastalwatch wrote: »

Either this has been posted before or Mart must be taking a day off. Anyway an interesting move by EDF although not yet incentivised enough for me to take the plunge!
On the plus side you don't actually have to sign up to your energy with EDF in order to purchase.
Applying the figures of our usage to my simple spreadsheet the 4.1kWh unit would take 16.4 yrs to achieve a ROI. Of course it may be far less for others. Oh, the ROI of the 8.2 kWh unit, perhaps more useful to us is 18.2 yrs! Maybe I'll take a second look to see if payback could arrive a little sooner!

https://www.solarpowerportal.co.uk/news/edf_energy_targets_solar_homes_with_discounted_battery_offer

Its positive that these things are happening.... but even with the discount these batteries seem twice as expensive as they should?

The price is even more galling when you consider they will be scraping off some of it for themselves at certain times so already benefiting from the install?

Zarch

An interesting comment from the EDF Site about them putting energy into your battery overnight if there is excess generation (assuming for free?). This would certainly skew any ROI calculations.

Obviously the million dollar question, how often would this happen?

https://www.edfenergy.com/for-home/battery-storage-technical-spec

The domestic scale batteries will all operate as a group, not individually, so an individual battery will not be responding to peaks and troughs of the grid by itself. As an example, in 24 hour period, the householder may see additional charge being fed to the battery during the night if there was excess wind energy available on the grid, but there is not enough demand on the network to make use of it.

Alternatively, during the peak demand hours of early evening the battery would be used to power the house completely. Effectively, it’d remove the household’s consumption from the grid, thereby reducing demand. At all times the health of the battery is monitored and shown in the Powervault portal, where the amount of charging up, discharging and energy savings can also be seen.

orrery

Zarch wrote: »

An interesting comment from the EDF Site about them putting energy into your battery overnight if there is excess generation (assuming for free?)....

I'd doubt that - I'd assume that the installation would be entirely house side of the meter. You pay E7 rates to charge it up and use the power (@ zero additional cost) at peak times.


This would imply that they're not planning to export your power, just effectively take your house off the grid at peaks.

Zarch

As an example, in 24 hour period, the householder may see additional charge being fed to the battery during the night if there was excess wind energy available on the grid, but there is not enough demand on the network to make use of it.

If that is the case, I don't understand what they mean by this?

JKenH

Lots of small print with the EDF battery. There is none of that malarkey with the Moixa offering and Moixa offer a lifetime warranty on the battery if you sign up to Gridshare with them. (It is replaced if it falls below 70%). They don’t discount their battery upfront but make a fixed payment annually which can be exchanged for a share of the profits when Gridshare is up and running.

Zarch

Had Moxia in-touch today.

We have just released a 4.8 kWh battery for £3950.00 inc Vat & Installation, it comes with a 10 year standard warranty, but this is extended to a lifetime warranty with our GridShare platform , where we pay you £50 per year tax free.

Exiled_Tyke

Zarch wrote: »

Had Moxia in-touch today.

Well with a few assumptions:

1. store and use say 4kWh a day (so just over 80% discharge)
2. can achieve this for a generous 200 days of the year.
3. 10 year life
4 Electricity at 15pp Kwh.

Then after 10 years the system has paid back a staggering £1,200 so a wonderful investment. I don't understand the other option but I can't see making up the necessary difference. And of course extending further into the future really eats into any meaningful NPV calculation.

JKenH

Exiled_Tyke wrote: »

Well with a few assumptions:

1. store and use say 4kWh a day (so just over 80% discharge)
2. can achieve this for a generous 200 days of the year.
3. 10 year life
4 Electricity at 15pp Kwh.

Then after 10 years the system has paid back a staggering £1,200 so a wonderful investment. I don't understand the other option but I can't see making up the necessary difference. And of course extending further into the future really eats into any meaningful NPV calculation.

I think the Moixa offering may work for some people but not everyone. (It doesn’t for me as I shall explain.)

First and foremost it depends on the size of your system - that will determine how many days you can generate 4kwh that is available to go into the battery. So you need a decent size system. There will be days, particularly at this time of year when you can’t fill the battery. I have an east/west roof which performs particularly badly through late autumn and winter. Ideally you need a south facing roof to get the maximum number of days charging.

Secondly you need to consider your daylight consumption. If you are out all day then there will be more days when you have 4kwh available. In the summer and for much of spring and autumn you should be ok as you only need to generate about 6kwh to fill the battery and cover your base load. However if you are out all day can you consume 4kwh from the battery in the evening/overnight?

Ifyou have an EV or an immersion heater and an IBoost type device then that will compete with the battery for your spare consumption and significantly reduce the number of days you can fill the battery. Look at other ways of using your spare PV first such as ASHPs. (I am at home all day, have an IBoost and am looking at getting an ASHP so you will see I am not an ideal candidate for a battery)

Moixa offer a lifetime warranty so I am not sure that the calculation should be restricted to 10 years. How long you intend staying in your house would be a more appropriate basis for calculating the lifetime ROI.

Electricity costs may go up but best to ignore savings from this. (You can offset any future savings here against the loss of interest on your investment - thanks Mart for that idea).

No one quite knows how Gridshare will work out as it is not yet up and running. Currently you get £50pa but the original idea was to share profits from selling back to the grid at peak times. I am led to believe that peak rates can be as high as 60p/kwh but others on the forum will have far more knowledge of this. Maybe try and firm this up with Moixa.

The new Moixa battery is quite different to the old one in terms of charge and discharge rates and much more useful. You may find that the battery will partially cycle several times a day when your load exceeds available PV even during daylight hours. Even the old one did this but its functionality was compromised by low charge and discharge rates. I wouldn’t bank on a lot here but it might be worth another 1 kwh per day.

You may also be able to charge the battery from E7 if you have that available which might be a benefit in spring, autumn and winter.I think Moixa are introducing new AI to facilitate this. As TOU tariffs become more widespread the opportunity to charge at low cost and avoid peak rates could potentially save £0.8/1 per day even on rainy days in winter.

If you have more than a 4kwp array, it faces south, don’t intend to move, are out all day, have an E7 or TOU tariff and don’t have any other device to divert PV it could well work for you. Even if you are missing one of those qualifications it might still work.

Run the sums again using the assumptions which apply to you and the figures (for the lucky few) might look a lot better.