Green Building Forum - Contemplating some storage for my grid-tied PV

Contemplating some storage for my grid-tied PV

DamonHD — Sun, 30 Sep 2018 20:42:49 +0100

Contemplating some storage for my grid-tied PV

djh — Sun, 30 Sep 2018 21:04:16 +0100

At 1.6 kWh/d savings it'll still take a long while to pay for itself though, won't it?

FWIW, my daily daytime consumption in August was 3.0 kWh and nighttime (E7 definition) was 1.2 kWh.

Contemplating some storage for my grid-tied PV

DamonHD — Sun, 30 Sep 2018 21:27:03 +0100

There is no expectation of financial payback for this project.

Rgds

Damon

PS. Yes, I'd like to get our consumption down a bit again.

Contemplating some storage for my grid-tied PV

djh — Sat, 05 Jan 2019 15:14:07 +0000

FWIW, I just got an email from EDF offering subsidised batteries: https://www.edfenergy.com/for-home/battery-storage

No connection or recommendation etc. Just FYI

Contemplating some storage for my grid-tied PV

DamonHD — Sat, 05 Jan 2019 17:41:31 +0000

Yes, I know Powervault reasonably well, and it was a candidate for my system.

Also, we are working with EDF and you can now buy our Radbot (smart rad valves) via them:

https://trv.edfenergy.com/product/radbot-edfe/

Radbot is based on the OpenTRV open source work.

Rgds

Damon

Contemplating some storage for my grid-tied PV

owlman — Sat, 05 Jan 2019 19:01:40 +0000

I know you don't expect a financial payback Damon, others however may do, and I came across this rough comparison, I can't vouch for the accuracy, also I have no connection to the company.

https://blog.spiritenergy.co.uk/homeowner/powervault-3-vs-powerwall-2-chemistry-0

Contemplating some storage for my grid-tied PV

bxman — Sat, 05 Jan 2019 20:38:50 +0000

I may have missed it but I could not see any provision for recieving payment for energy sent back to the grid in support of EDF balancing the grid.
Energy that came either from your PV panels or from the grid presumably through your smart meter for which you would I assume be charged .

it appears that EDF have the benifit of this feature with no cap on the percentage of discharge at any one time and apparently no contribution for the cell life that will be depleated by this action .

looks like win win for EDF.
Maybe I am just a cynic or simply failed to find answers in the published T&C

Contemplating some storage for my grid-tied PV

dickster — Mon, 07 Jan 2019 11:05:18 +0000

We've just had a 2.3kW Sunpower x21 pv array with Solar Edge inverter and Tesla Powerwall 2 installed, cost 11.5K and moved over to Ecotricity.

Should generate around 1,800 kWh per year, around what we use a year. Plan to use E7 to charge in dull weather, perhaps balancing the grid a tiny bit.

Totally ridiculous on the financial front, will take maybe 40+ years to pay off, (dead by then), nevertheless I can now tick that semi-green box and get on with sorting out my sheds, (anyone like to help?!!).

Contemplating some storage for my grid-tied PV

philedge — Mon, 07 Jan 2019 19:16:43 +0000

Posted By: bxmanI may have missed it but I could not see any provision for recieving payment for energy sent back to the grid in support of EDF balancing the grid.
Energy that came either from your PV panels or from the grid presumably through your smart meter for which you would I assume be charged .

it appears that EDF have the benifit of this feature with no cap on the percentage of discharge at any one time and apparently no contribution for the cell life that will be depleated by this action .

looks like win win for EDF.
Maybe I am just a cynic or simply failed to find answers in the published T&C

I may have mis read it but I dont think they use your battery to feed the grid. I read it that they will charge your battery when theres surplus generation, but when theres a peak in demand you have to use only the battery and cant draw off the grid.

Contemplating some storage for my grid-tied PV

Pile-o-Stone — Mon, 07 Jan 2019 20:50:52 +0000

I also received the offer from EDF. I was also wondering about how they would take power out to feed the grid, especially as I would want to charge the battery not just with Solar, but also E7. It'd be annoying to be paying to charge up the battery on E7 at night for EDF to then use that energy for free!

Contemplating some storage for my grid-tied PV

bxman — Wed, 09 Jan 2019 22:42:10 +0000

EDF have kindly provided me with some more information ..
namely

"The Powervault 3 system is designed to charge from your solar system during the day, before discharging to meet the loads in your home during the evening. It is also designed to charge from low-cost, off-peak electricity during the night (e.g. Economy 7) so you can use that cheap electricity when you wake up the following day. EDF Energy, as part of the "grid services" offer, will occasionally want to adjust the charge and discharge rates of your Powervault 3 system to respond to sub-second changes in grid frequency (which are caused by spikes in demand or supply of electricity nationally). This means your Powervault 3 system may suddenly increase or decrease its charge or discharge rate to help smooth out the spikes. In practice, these sub-second adjustments are minute and so you will be hard-pushed to see any significant change to the normal charge and discharge cycle of the Powervault 3 described above. The 'grid service' control is designed to maximise benefit to the grid and minimise cost to the customer. For example, if, in the height of Summer, the grid has too much electricity on the network, the control will ensure that your Powervault 3 system is charging from solar at its maximum rate to minimise the amount being exported to the grid. Conversely, in Winter, if there is a peak in demand, the control might increase the Powervault 3's inverter output to meet more loads in the home (which effectively means you reduce your demand from the grid).

. By taking up EDF Energy's 'grid services' offer, you are benefiting from a large, up-front discount (> Â£1,500 - Â£2,000, depending on the battery capacity chosen) on the cost of a new Powervault 3 home battery system. This discount is designed to more than cover the cost of any electricity used to support the grid that you could otherwise have used in your home (for the lifetime of the contract). "

I believe there are some schemes where you do get remunerated at a premium rate for the energy you supply at these times of peek demand .

Contemplating some storage for my grid-tied PV

WillInAberdeen — Wed, 09 Jan 2019 22:46:57 +0000

What are your obligations if you sell the house, or decide to replace/remove the battery, or switch to another supplier?

Contemplating some storage for my grid-tied PV

bxman — Thu, 10 Jan 2019 18:34:12 +0000

@WillinAberdeen
if you remove or terminate you have to re-inburse the discount on a monthly pro-rata basis .

I imagine if the new owner was willing to continue the arrangement all would be fine
I do not know but I suspect it is like the feed-in arrangement and that it is not linked to the supply of electricity to the property .

Further clarification from EDF

In summer will charging only be done at it's maximum rate only when there is a surfeit on the grid; so on other occasions some of the domestic PV surplus will feed back to the grid .even though the battery has capacity to accept charge .?

Sorry, I may have used a bad example here. The Powervault 3 is designed to minimise your export of solar to the grid so, if your panels are generating at peak capacity, the Powervault 3 will be charging at its highest rate in order to capture all of it. However, occasionally the Powervault 3 may be charging at a lower rate than it could be, in which case the grid balancing control will override the system and accelerate the charging rate. A better example would have been charging during Economy 7 times; if the grid had too much supply on the system and its frequency was peaking, the grid balancing control would override the Powervault 3's Economy 7 charging regime and increase its charge rate. I hope this makes better sense.

Will the individual battery be manged so as to reduce the customers import to the minimum possible based on the established household history Or follow a standard procedure for all participants of the scheme ?

Powervault 3 is designed to minimise customers' import from the grid and maximise consumption of on-site solar generation; this is it's modus operandi. However, by opting into EDF Energy's "grid services" offer, the system will occasionally by called upon to respond to peaks in either demand or supply of electricity, which will override the standard, default operation of the Powervault 3 system.

And in winter the system will charge from E7 and reduce domestic demand from the grid giving priority to this reduction at times of peek national demand or to minimise the customers import of full priced power?

The answer to this is the same as above - just for Economy 7 charging rather than solar.

Are there battery voltage triggers that will determine when charging and discharging periods occur ?

The minimum loads and/or generation required to discharge or charge the Powervault 3 are ~200W - 250W.

It does look as though it is initially being manged by a Manger who is on the ball.

Honest answers by return what a pleasent surprise . Thank you Charlie