On-grid domestic battery storage

mmmmikey

So I think it would be fair to say there's limited enthusiasm for the PowerVault / EDF Grid Services contract option then! Someone will be telling me my thinking is stark raving bonkers next - but surely no-one would say something like that on this forum Welcome back, joefizz, I see you've added travel to exotic foreign locations (Liverpool) to your list of eco-crimes



I don't disagree with any of the points made, but I'm not seing anything I haven't considered and factored into my thinking. My post wasn't intended to make the case for this, it was really just to explain how I understand that the grid services contract works, to answer questions and inform the discussion.



The reaction to the leap of faith it involves provoked exactly to reaction I expected, and very clearly it's not going to appeal to most here.



I've just agreed an installation date for next week so I'm definitely going for PowerVault / EDF. Why?


1. At £3,299, assuming no or little impact of the grid services contract on the return, with a following wind it just about works for me for seeing my money back in it's lifetime (but probably not it's warranty period). (Let's not go round the loop of where these figures come from again, but suffice to say they include assumptions about off-peak tarriffs, much of the charging done with off-peak electricity, my personal tax position, etc.)



2. At £4,859 (which is the effective worst case cost for the grid services contract eroding the payback), I'd almost certainly be down but it wouldn't bankrupt me - I'd just have to buy a cheaper car when it comes up for replacement. I can live with any hit because of the fun-factor.



3. I'm expecting the grid services contract to have limited impact in my particular case (I can post more on this if anyone's interested) so expect the cost to be nearer £3,299.


4. This is still a big premium over the Pylontech / Sofar option. But (a) everything that PowerVault is doing commercially resonates with me and I'd like to see a British tech company succeed (b) their technical support is easily accessible and excellent (c) the solution feels future proof - hardware support for frequncy response, APIs for control of smart appliances, remote management upgrades via the web etc. (d) the price includes the installation and a full manufacturer backed warranty.


As far as grid services contracts are concerned, I'm absolutely convinced that these are the way of the future and quite happy to put my money where my mouth is. There's no data to support this but neither will there be unless someone starts using them. Whether the EDF contract stacks up is a complete unknown but the risk is manageable and I'm happy to take it. For me this is an interesting and engaging project in retirement and worth it for that alone.



I will post data as and when I have it - presented to prove I was right, of course



Thanks Mike

Solarchaser

zeupater wrote: »

Hi

Don't seem to remember Zarch making too many posts over the last few days & there aren't too many that have mentioned ~1000kWh/year, but to avoid any foot of the alphabetic table confusion, <cough>, until the battery solutions hit somewhere near the £150/kWh raised earlier, I'll be sticking with my current set-up, as should anyone with a near-typical usage pattern & around/under UK average electricity consumption and expecting a solution to show any form of saving over importing from the grid ...

This Z's still quite content to hold onto a 'first thoughts' solution ...

HTH
Z

It was Mmmmikey I was replying to

joefizz

zeupater wrote: »

Did you not consider the option of running two immersions from one controller with priority on the upper one & relying on thermal stratification to allow a single cylinder to effectively have two storage volumes for varying solar generation conditions?

I looked at a range of options...
First one I looked at was the iboost type thing, back when it was export estimated rather than metered. I knew that that particular days were numbered so for my usage the over the counter iboost and alternatives werent going to be financially worthwhile. I also preferred the multiple output options rather than single feed.
Which led me on to looking down the self build route. You know my background by now so then went down looking at the arduino route. I bought the kit and even wrote some of the software to have a 4 output solar diversion system.
The arduino is something I'll go back to because I can measure output and cut it to certain things when I start importing, wait for the battery to charge up now and so on.

With that I then looked at replacing the 3kw immersion with a 1kw one which was the cheapest option of the lot (about 20 quid I think) but again I currently have a variable immersion timer and 15 mins was enough to stratify enough water to have a shower so didnt think extending that etc.
I looked at replacing the cylinder (which is about 40 years old) with various options, the two smaller coil method you mention or indeed just a smaller tank completely or indeed additional small separate header tank.
This could all be controlled by the arduino, or just a logic board with switch bank in the hot press, or just a series of buttons until I could be bothered building the rest ;-)
Id almost convinced myself on a new tank and was already allocating the old copper one to a new garden project. I might have to replace the tank though at some point so can revisit that then.



The smaller header tank then brought me on to pumped solar water collector (diy of course ;-)) as I use similar on the camper in summer rather than the gas boiler... ..that might be an option to install if the tank is replaced and use solar collector to raise the temp of shower only water and use a small immersion to boost, but then that leads on to if I get used to it do I fit an oil coil for winter...

anyway I digress...
I was fairly moving towards the battery system anyway so added the ability to just push the timer button on the immersion to the list in the plus column for the battery, having been used for years to doing just this with the oil boiler in summer for on demand water heating.


From talking to installers the main selling point (and why it was at the price point its at for fairly rudimentary electronics) was all tied up with the estimated export returns so people could make out like bandits with free hot water and get paid for export they werent making. If I hadnt got the battery Id wait for that to roll out to the rest of the uk and pick one up cheap off ebay and fit a timer to it to do all of the above. I went through a couple of weeks bidding 30 quid for used older ones off ebay for a while and gave up.



In the end with the battery at 4.8kw and if clouds went over the sun during the 15 min push button process the battery would top out and Id draw import. Its why my bill for the third quarter last year was 8 quid, I hadnt noticed this a lot of time. Still cheaper than using oil just to heat hot water due to different way the water is heated by the immersed oil coil. The 9.6kw battery will supply all the immersion on top of other load.


I am definitely going to go back to revisit the arduino stuff because I now can get sensors to monitor the battery feed as well as the mains input/output so might do some interesting stuff with that but I really need a summer and winter data with the new battery and not ballsing about with the solar array again, just to give me some base data to work off.


For those interested in the arduino, there are (or were) places online in the uk that will do 'kits' but I dont think the guy is electrical qualified so caveat emptor and you might need to plug a few wires in or buy a soldering iron to get round that (no CE mark or certification etc). A lot of the bog standard software is out there gratis as well. Overall I think the cost of that is in a similar ballpark to the iboost and all that so not much of a saving unless you consider the tinkering and flexibility in it and of course no warranties and not plug and play.


Im eventually looking at making this all self intelligent control, when I redid the house I did RJ45 cable to every room so might as well make some use out of it (side note, moving away from wifi eventually back to hard lines). Not quite faraday cage or tinfoil hat although I used to go to a pub near one of the sites I worked in England and its selling point was that its upstairs lounge had been turned into a faraday cage so none of our pagers or mobiles would work whilst in there...

1961Nick

mmmmikey wrote: »

So I think it would be fair to say there's limited enthusiasm for the PowerVault / EDF Grid Services contract option then! Someone will be telling me my thinking is stark raving bonkers next - but surely no-one would say something like that on this forum Welcome back, joefizz, I see you've added travel to exotic foreign locations (Liverpool) to your list of eco-crimes



I don't disagree with any of the points made, but I'm not seing anything I haven't considered and factored into my thinking. My post wasn't intended to make the case for this, it was really just to explain how I understand that the grid services contract works, to answer questions and inform the discussion.



The reaction to the leap of faith it involves provoked exactly to reaction I expected, and very clearly it's not going to appeal to most here.

You get full marks from me for trying something as cutting edge as this.

Even if it doesn't work out, you can still pay the £1500 & 'reclaim' the battery for your sole use.

Do you know what monitoring you will get with the package? It would be a deal breaker for me if I couldn't see what 'service' the grid was getting from my battery.

"Personal tax position"....hmmm, I wonder if we've done something similar?;)

mmmmikey

1961Nick wrote: »

Do you know what monitoring you will get with the package? It would be a deal breaker for me if I couldn't see what 'service' the grid was getting from my battery.

"Personal tax position"....hmmm, I wonder if we've done something similar?;)

Hi


When I looked at the monitoring previously it was very primitive and targeted at non-techie consumers. Not much more than what's gone in, what's come out and current charge level, and not very granular. It may have improved - the underlying data is there and displayed on a web portal, it's just a question of what they choose to display and whether it's available in raw form even if not displayed. I'll get a better idea next week after it's been installed. It's actually not too much of an issue for me because my existing usage pattern is so predictable I'll be able to reasonably accurately deduce the impact of the bits of the grid services contract that matter to me.



As far as tax is concerned, nothing dodgy, just retired early unexpectedly with money in the wrong places so tax efficient to spend now to save in the future because of timing of various allowances.

joefizz

mmmmikey wrote: »

So I think it would be fair to say there's limited enthusiasm for the PowerVault / EDF Grid Services contract option then! Someone will be telling me my thinking is stark raving bonkers next - but surely no-one would say something like that on this forum Welcome back, joefizz, I see you've added travel to exotic foreign locations (Liverpool) to your list of eco-crimes

Cheers! Not many people consider their overall eco impact, in fact very few people even think about their daily use as a paid employee of a company adding to the effect, nor indeed any regular commute.
I give my vegan planet saving nephew some grief when he wears jeans as they probably used more water in their manufacture than I will drink in my entire life... anyway, we won ;-)...



Unsurprisingly I applaud your decision to go ahead for very simple reasons. Ive heard people talking about this and trialing it out to help future safeguard the network and make it more resilient.
Its people like me who minimised their domestic use who have caused a lot of the problems with solar installations and wind adding to them.

The networks were designed to have stonking great power stations at the end of the line with flows mainly just going one way.
Right now the load balancing is a big issue as the last thing you want is for one of your nuclear power stations to suddenly decide to shut down. They take a while to restart, could be days, weeks or even millenia...
It should work out for you as at some point if its adopted it will be easy to transfer between contracts. Right now if you have a field and buy a load of 1MW diesel generators, you too are in the STOR business, just happy that someone is considering something other than diesel.

They are called STOR sites because with diesel poisoning kids in cities and killing baby polar bears nobody wants to know theres 20 of the big things in that weird looking site at the bottom of the street.
Well that and not attracting attention to the big shiny portable things and the big tanks of diesel fuel beside them...



My plan has always been that this is a process, not a series of discrete purchases, at some point things will break, be upgraded, replaced, added to and your purchase whilst in monetary terms may not work right here right now, may do a couple of years in the future with energy prices being a big driver of that, or indeed they might pay more for your STOR so you can buy yourself out of the edf contract and sign a different one with someone else. Then again edf or whoever might want to buy your contract out and... well its all imponderable but if you arent in you cant win.


Good luck with it and Id certainly be interested in any reports as Ive been approached for a similar trial myself but had already bought the kit (I will give them access to my data though).

Martyn1981

Zarch wrote: »

How low does it need to go for people to start getting tempted?

Just thinking out loud, are there days where you could possibly get more than 4kw out of it each day? Ie you use it through the night, fill it in the morning via solar, midday clouds, dip into battery with washing on etc, sun comes out again, battery fills back up..... then its full again for evening use?

For me, I'd like to see a 10yr payback, but battery size and cost, will depend on how things change going forward, so hard to pin those two factors down at the moment. Perhaps a bit under £2k for 5kWh usable, or around £3.5k for 13.5kWh useable (Tesla PWII).

I'd have thought there is a lot of opportunity to get more than 4kWh out of a 4kWh unit in a day - Probably around this time of year, plenty of day long generation, but varying up and down, rain showers etc etc, so the batt would make lots of micro-cycles helping to balance white goods, kettle, ASHP etc, but still having a full charge for the evening. Just to be clear, I'm thinking gen bouncing between 500W and 2kW or even 3kW, and more kWh than needed, but not necessarily enough generation at any given time.

1961Nick

Martyn1981 wrote: »

I'd have thought there is a lot of opportunity to get more than 4kWh out of a 4kWh unit in a day - Probably around this time of year, plenty of day long generation, but varying up and down, rain showers etc etc, so the batt would make lots of micro-cycles helping to balance white goods, kettle, ASHP etc, but still having a full charge for the evening. Just to be clear, I'm thinking gen bouncing between 500W and 2kW or even 3kW, and more kWh than needed, but not necessarily enough generation at any given time.

That's exactly the usage pattern I see happening on a Saturday when I'm at work & the Kilowatt Queen is at home alone. She doesn't do sequencing of white goods so batteries + pv provides somewhere between 3 kWh & 6.6 kWh & generally prevent import from happening. It's not perfect because there's a time lag flipping between charge & discharge - usually less than 0.5 kWh import & export over the day.

Exiled_Tyke

"How low does it need to go for people to start getting tempted? "

I'm guessing I'm coming up with the same answer as Mart. I'm looking for 10p per kWh. When you divide total cost by the total number of units of leccy which can be stored (or more precisely, recovered from storage) over the useful (warranted) life of the battery.

Whilst we are no where near this yet. My criterion is still loose as it doesn't take into account the time value of money (discounting) and I don't think it's right to assume and electricity is gong to go up in price massively.

No one seems to mentioned the VAT situation when adding batteries with a PV system. Is this still an issue? I was toying with getting a couple of extra panels with a microinveter which would cost about the same as the VAT saving.

joefizz

Exiled_Tyke wrote: »

No one seems to mentioned the VAT situation when adding batteries with a PV system. Is this still an issue? I was toying with getting a couple of extra panels with a microinveter which would cost about the same as the VAT saving.

I got full VAT when installing as it wasnt part of the initial install. I also got stung heavily for shipping to NI - quite literally shipping as initially the pallet was taken off the lorry and off the ferry and left in the port for 2 days because there was a mistake in the paperwork and didnt state it was lithium batteries - special handling precautions. Knew better for the upgrade batteries and cheaper but if Id ordered all at once then Id have made reasonable savings. Whats costs me 10k so far will probably cost the next person a bit more than 8k if all done at once.



On the subject of extra panels and microinverters, full VAT on those as well so thats why I went through my original install supplier. They get a bulk discount so that offset a lot of the VAT costs and allowed them a little profit. They also delivered them to my door at no extra cost, just waited until they were doing a job near me. So overall was cheaper than me buying in person and getting them shipped to the house.
Got the extra cable and connectors online and used aluminium angle to create the mountings rather than go for the specific standard solar rails and mountings.