On-grid domestic battery storage

EVandPV

Our 2 Pylontechs (4.8kwh) with Lux ac controller should payback in around 7-8 years, maybe quicker if leccy prices rise.
This is including savings made from grid charging overnight in the winter on the Octopus Go tariff.
We only had ours installed a few weeks ago but like Nick, that's assuming savings of around £300-£350 a year.

mmmmikey

I'm reckoning on payback in about 12 years.

In my view, the crucial thing here is what effect changing tarriff structures have on pricing. If you look back to the begining of this thread you'll see that much of the discussion is based on electricity costs staying much the same in real terms (i.e. allowing for inflation) over the life of the batteries and a fixed tariff os the order of 12p/kWh.

But that is looking like an increasingly questionable assumption as the availability of TOU tarriffs grows. If you're on a tarriff such as Octopus Agile you could be saving 20p/kWh + if you manage your consumption to use any battery power at the optimal time.


Also, worth factoring in the ability to cycle the batteries more than once per day which is soemthing that doesn't factor into the posts from a couple of years ago much.


I suspect all our crystal balls are predicting something different re: tarriffs making your question difficult to answer, but my best attempt would be to say that battery storage is now at the stage where you have a reasonable chance of breaking even during it's life and if you are able to manage consumption carefully and choose your tariff wisely there's a good chance of turning a profit.


My own philosophy was to see the investment in batteries as a more or less free way of significantly reducing my carbon emissions with a chance of saving money too, confident in the knowledge that if they lose anything it will be such a small amount spread over a long period that I won't notice it. Being a savings-rich and income-poor recent retiree, there are also other advanatges to me in respect of "paying for my electricity up-front"

rugbyleaguesmate

Thank you for your responses, all sensible and reasoned arguments. I've had my solar PV 3 years and produce about 7 Mwh per year in the typical bell curve. 3 months ago I got my first electric car with home charge, A Bmw I3s with home charger. I love the car and almost all my charging is done at home.

I have Octopus Agile as a tariff, and get paid FIT. I'm employed, but lucky for me I just do 3 12hr days a week. There are 3 of us in my family and there is only 1 day a week when at least one person isn't in.

Its early days but I was thinking about how I can cover consumption when Agile goes expensive between (4pm and 7pm).

Then I think that electricity for me is really quite cheap so have I got all the savings I need out of it now and perhaps I need to just learn to move my consumption away from the busy periods??

joefizz

Hi Folks,
Been away for a while and hope you all had a good Christmas and New Year.
Did my stats today and had said to a few folk Id post them via PM but seeing as Ive seen this post, heres my data.
Now. First of all, treat all this with a large dose of salt and ask any questions on the data and I'll explain, dont make assumptions or whatever as there are a lot of variables in there - such as oil consumption looks the same but I only bought 2019s lot 2 weeks ago and going on it took me 15 months to use that I may not have to buy any in 2020 which will skew the figures.
Just did the meter reading for the latest bill and in the last 10 years prices have gone from sub 14p a kwh to almost 20p kwh with the latest bill.
The usage figures are all taken from bills/readings, the prices have been rounded up/down and there are a lot of seasonal variations including bad winters/ long trips away both in either summer or winter (most of winter 2010 was in south america hence the drop in usage.


What is interesting is that I read a report over the holidays about people with solar panels using more electricity than they did previously so looked at my own data. I halved my usage from 2009 to 2015 and then doubled it again last year with migration of a lot of things back to electricity.
So whilst the figures have increased Ive not bought petrol for lawnmowers, strimmmers, hedge cutters, etc and stopped using the gas bbq in summers (cook in oven then transfer to charcoal bbq for finishing off now) since solar installation.
Figures for the last few years are skewed because of price rises in september, (cant be bothered posting monthly figures - tldr and all that) installation of batteries at different times and ashp in april.
This is now the first full year of everything in the system working together and I see there is scope for converting the gas bbq to electric.


With my last years usage I am borderline E7 but it wouldnt save me any money really with the standing charge, below battery threshold daytime use (weve mentioned it on here) but might allow heating other than oil in the wee small hours but again would increase boiler service charge and if I do lower the oil usage below 600l a year then Im either going to have to get smaller loads or use additives (although Ive used 5 year old heating oil 50/50 with new ok in the past).
For me, its probably now reached the point of diminishing returns.


I'll repeat my pinch of salt points above and why I have mentioned in the past not wanting to measure ROI effectively. I can make up any old crap like if I used the same electric as now at todays prices then ROI would be x years as opposed to 12 or so (from the figures - again not using the increase in costs in the future). So take the prices bit with a pinch of salt.
Many things can change, oil can go down then up, ROCs could be withdrawn (seen a proposition paper on this after the election - UBI could mean that gets taken away completely - but I digress).
As Ive mentioned before I planned to FIRE at 50 (which I did last month) so it was a case of minimising outgoings where possible so Im about the stage of not paying for energy at all, which is where I want to be really - or thereabouts.
E7 or TOU is in the future for me but that will depend on how mild winters are and if I can use the ASHP (and or get another one) etc etc etc DYOR etc.


Anyway the data... .. I dont think there are any typos in it ;-)

2009
Oil - 1000 litres - £362
Electricity - 4200 units - £590

2010
Oil - 1600 litres - £703
Electricity - 3990 units - £580

2011
Oil - 1000 - £586
Electricity - 3820 units - £600

2012
Oil - 1032 - £548
Electricity - 3670 units - £580

2013
Oil - 1022 - £601
Electricity - 3170 units - £497

2014
Oil - 1000 - 504.53
Electricity - 1990 units - £337

2015
Oil - 1000 - £363
Electricity - 2200 units - £350

2016 - solar installed september
Oil - 2000 - 597.18
Electricity - 1830 units - £258 - self use units 680 - export units 108 - rocs + export - £52
Electricity costs (£206)

2017
Oil - 1100 - £421
Electricity - 1479 units - £194 - self use units 2334 - export units 2264 - rocs + export - £441
Electricity costs (-£247)

2018 - 4.8kwh battery installed July
Oil - 1100 - £571
Electricity - 1137 units - £177 - self use units 2735 - export units 1963 - rocs + export - £515
Electricity costs (-£338)

2019 - battery upgraded to 9.6kwh January
Oil - 1000 - 428.55
Electricity - 811 units - £120 - self use units 2808 - export units 1814 - rocs + export - £537
Electricity costs (-£417)

Solarchaser

Theres 2 things to say about batteries I think.
1. The costs seem to have stagnated somewhat.

I bought my 7.2kwh of batteries 14 months ago, as I really wanted to take the plunge.
I always have wanted much more storage, but the indications were the battery prices were tumbling, and I have to say, in the 18 months I've been watching, especially pylontech batteries, they have pretty much been exactly the same, or risen slightly, so I'd hoped they would have fallen by now and I could pick up more batteries for less money, but that's not the case.

2. There is an awful lot of pleasure to be gained by seeing your battery percentage increase, knowing it's not going to the grid, and then later seeing it decrease as you power your own home.

I put in the batteries 14 months ago, but also added more solar just under a year ago, so I'll be posting my findings at the start of February when I have clear data.

At the moment I'd say the combination of extra solar (no fit) and batteries will have an roi of 10 years.

1961Nick

mmmmikey wrote: »

Being a savings-rich and income-poor recent retiree, there are also other advanatges to me in respect of "paying for my electricity up-front"

You could also take the view that the return on a battery investment is currently a lot better than buying an annuity.

Zarch

Nice update from PowerWall about their Agile API integration:

"Working closely with @beisgovuk & @octopus_energy, we have now created an API to automatically track #AgileOctopus pricing signals

All units with Agile optimization are now successfully following our new optimised SmartSchedule, taking the work off your hands"

https://twitter.com/power_vault/status/1217788891027124224

I'm wondering if it also does scheduled discharges when Agile Outgoing prices are high (4pm to 7pm), around 12p per unit.

Kernel_Sanders

1961Nick wrote: »

You could also take the view that the return on a battery investment is currently a lot better than buying an annuity.

Not if it conks out before you do....

Martyn1981

Kernel_Sanders wrote: »

Not if it conks out before you do....

Try to be more positive, you might die much earlier than expected.

joefizz

Martyn1981 wrote: »

Try to be more positive, you might die much earlier than expected.

My 25 year old microwave is about to give up the ghost.
I wont be spending the money on replacing the brand because I wont need another 25 year old microwave.
3 year warranty might be enough ;-)

Wonder when it will get to the stage I dont even worry about best before dates ;-)