edf battery offer

scouselegends

Hi, I’m giving the 8kw powervault offer some serious thought. I have an ASHP and use circa 8000kwh a year as such. I have a 4kw pv system, and would likely look to couple with Octopus Go tariff. But the main reason to do this is to reduce my electric spend currently around £90pcm. Does anyone have similar usage etc, have you seen bills reduce significantly? Cheers

mmmmikey

scouselegends wrote: »

Hi, I’m giving the 8kw powervault offer some serious thought. I have an ASHP and use circa 8000kwh a year as such. I have a 4kw pv system, and would likely look to couple with Octopus Go tariff. But the main reason to do this is to reduce my electric spend currently around £90pcm. Does anyone have similar usage etc, have you seen bills reduce significantly? Cheers

I have a 4kWh PowerVault and I'm on an E7 tarrif with annual usage of 6000kWh and based on (limited!!!!) experience so far reckon I'm going to save about £15 to £20 per month, but this is still an estimate because I haven't run it through the winter months yet. I'm still refining my estimates as the weather and my heating pattern changes.

Lots of ifs and buts and variables, but based on this you might expect to save something like £30 to £40 per month at most on Octopus Go. My wording here is intentionally vague as usage patterns vary quite a lot and have a big bearing on payback.

Solarchaser

Is the 8k after solar or before?
I had around 7.5k usage before solar, which then cut it back to around 5.5k 4 years ago.

With a 6kw system for the last 10 months (not powervault) it looks like I'm down to around 4k kw usage.

However I have added an ev which has increased usage by around 1200kw, and then also added 6.6kw of solar.... so my figures are definitely skewed by the extra solar.

So I'd imagine my usage is nearer to 9k, but with solar and batteries I think I'll be at about 4k kw for the year

scouselegends

Thanks. My 8k useage is after/with solar. As I say I’m struggling to justify the spend in many ways at the min. Although I really like the idea and concept of it all. The battery will cost circa £5k, if I base on current savings of maybe £40pm I’d just about break even over 10years... although clearly I’d expect energy prices to increase in that time. So it’s only here if really see a saving ! #dilemma

Solarchaser

If you instead of going powervault, went with sofar me3000sp and 4 pylontech batteries you would be at around £3800 according to Ebay, so I'd imagine somewhere like think renewables would be cheaper still.

Not 100% like for like, but a decent comparison.

Alot depends on how much solar you use, of what you generate.

You are a very high electric user.
If you imagine for arguments sake you were to buy 10kwh useable of pylontech and an me3000sp for around £4500 from ebay and were able to cycle it with solar only 180 times a year. (I've just checked my 10 month old system and I'm at 168 cycles, so 180 cycles seems about right)
Assuming you are on a 14p/kwh tariff, and ignoring the micro cycling you save £250/ year.
In reality I'd wager it would be at least £300 with micro cycling, but it's hard to pin down.

Now if we then looked at switching to a time of use tariff like octopus go, which is 5p/kwh for several hours overnight, and say from october to February you filled and drained the batteries on the overnight tariff, ignoring for a moment the conversion losses to and from batteries, and ignoring the solar you would get during these months, let's say 150 days, so 150 cycles at 5p instead of 14p saves you an additional £135.
So around £430/year ish and with multiple caveats.

You are still looking at a 10 year payback, but its clearer to see that it would be an easy 10 years.

For the powervault 8kwh system, it would be around £345/ year saving

1961Nick

Solarchaser wrote: »

For the powervault 8kwh system, it would be around £345/ year saving

I'll be charging my Pylontech batteries (10.2kWh useable) on the Octopus Go 5p tariff over the winter months. That plus solar charge should equate to a saving of just under £345/pa.

(The 'Go' 5p units will cost about 5.8p after factoring in round trip losses.)

Solarchaser

How long have you had your 10kwh pylon Nick?
And if your sofar is newer than mine, are you able to see how many kwh you have had discharge through the batts?

I've an older sofar which doesnt talk fully to solarman

Reed_Richards

scouselegends wrote: »

Thanks. My 8k useage is after/with solar. As I say I’m struggling to justify the spend in many ways at the min. Although I really like the idea and concept of it all. The battery will cost circa £5k, if I base on current savings of maybe £40pm I’d just about break even over 10years... although clearly I’d expect energy prices to increase in that time. So it’s only here if really see a saving ! #dilemma

Do you know how much energy you export to the grid? I don't mean the deemed export based on generation but the real figure. If you are on the FIT scheme and your export is deemed, not measured, then it doesn't matter how much electricity you really use.

So if you have an 8 kWh battery and it has a minimum state of charge of say 20% then you can potentially save around 6.4 kWh per day assuming you export more than this now. There will be some murky days when you don't fully charge your battery and some sunny days when you charge your battery, use some charge then recharge it. I would guess, and it's just a guess, that these might even out.

Now Solarchaser writes about a much smaller number of cycles than there are calendar days. I don't understand this; I have had a battery since March and there have been only a few days since then when I haven't been able to fully charge it during the day. If Solarchaser is right then either I'm missing the point somewhere or winter will be terrible. Or perhaps I just have more headroom than he/she does, I generate about twice as much as I use.

Solarchaser

In mid summer I could start a day with 30% battery. So not a full cycle.
Similarly in the murkier days, if the battery only gets to 80% or in theory. 99%, then it's not a full cycle.

That's why I was asking Nick for his data as I believe he has the same system as me, but a newer version where he is able to see the cumulative discharge against cycle numbers.

1961Nick

Solarchaser wrote: »

How long have you had your 10kwh pylon Nick?
And if your sofar is newer than mine, are you able to see how many kwh you have had discharge through the batts?

I've an older sofar which doesnt talk fully to solarman

Mine was installed at the beginning of February. The Solarman app gives me both the charge & discharge, although I did add an import/export meter to the ac cable to check the accuracy - pretty accurate on the discharge reading, but 4% under reading on the charge. I should be able to get better data now that the inverter is idle for longer periods. We’ve had such a good summer that the only time I would have been able to regularly catch it idle was in the early hours of the morning.