The £5k price you have seen is I believe a replacement price. i.e. You give them your old battery pack and they give you a new one to replace it. The article I found was dated 2014 so I don't know what the current price is. And the price may or may not be subsidised of course, since it's only for captive customers who own a Leaf.

The batteries in a Powerwall AFAIK are those very same post-vehicle batteries getting a second life in the kinder regime of a domestic installation.

Posted By: jamesingramfor ref approx £5k ex will get you 3.5kW- 17.6kWh HV system, at trade

“HV”?

HV = High voltage , PV (DC-DC) direct to battery (100-400v)
rather than LV (48v) DC-AC-DC double inversion more common with retro fit battery systems

thats for a SolaX triple power
LGchem HV are more expensive
Pylontech LV a bit cheaper.
not sure what mark ups other people are charging ,
theyre pretty expensive already. I work on the standard builders 15%ish for most stuff , but it all a bit variable, (quick nose around and its probably 20-25%)
since the internet was invented the list and discount pricing seems very dated. I still find it funny the old school builder merchants think theyre doing you a favor giving you 60% discount whilst still charging twice what anyone can get things delivered to their door next day for 10am for

For many reasons collected over many years I do not want my money to go to China.It is very difficult to find other sources but they are around. I am able to source a German designed and assembled battery made from cells manufactured in Korea. It is actually quite difficult to find out where battery components come from. In enquiring from one EV manufacturer where the batteries were made, as I was considering one of their models they would not divulge where the cells came from but would state where they were assembled.

You ask the manufacturer. Some will tell you others won't. Asked recently a British manufacturer who gave me quite a bit of technical info but did not reply when I asked where the cells came from. The British distributor of the German battery told me it was all made in Germany but when I asked the actual manufacturer where the cells came from they told me. I do not believe one is told deliberate untruths it is more in the realms that they think they know but don't know that really, they don't know. I wanted non Chinese solar panels asked UK sales office which models came from Korea was told ordered they came made in China. Took a while to get them exchanged but they came good in the end. Often you have to be like a dog with a bone keep checking and cross checking until it all adds up. Been caught out too often. Needed solar cable checked spec on sellers website was suspicious checked the manufactures website it was different. Emailed them was told no one in UK sourced cable from them. Back to UK seller they checked up on their supplier of the cable, they had switched source and not told the seller. So spec on website was wrong. It is a minefield all down to lack of attention to detail just like the rest of the building industry.

Are there any plug-an-play systems that also providing islanding in the event of a power cut? i.e. act as a UPS? We've had 3 brief power cuts in the past month and lots since we moved in. Given that we have a new underground connection, I find that somewhat annoying and would like to fix the problem.

Posted By: djhAre there any plug-an-play systems that also providing islanding in the event of a power cut? i.e. act as a UPS? We've had 3 brief power cuts in the past month and lots since we moved in.

Your issue will be that the power in the house should disconnect from the supply when there is a power cut so when they come to fix it, the line is not live (from your end). A UPS just supplies onward power i.e. everything goes through the UPS. Whatever you had would need to be on the supply side of your consumer unit.

This was one of the issues when there was the large power outage a while back. The strike on the sub station caused the disconnection of something like half a MW of embedded generation.

Posted By: revorI too have outages sometimes just a couple of seconds so there is no advantage having UPS in this situation

That's exactly the situation I want to protect against. And that's what UPS do protect against, among other things.

I suspect most of the failures we get are switching transients where the DNO automatically reroutes around some crappy piece of their overhead wire somewhere. But that's enough to reboot my PC, wipe the clocks on all the kitchen devices so they need to be reset, stop the PVR in the middle of recording and sometimes take down some of my pi and make them fail to reboot. So any interruption at all is very annoying.

from what I can tell you want to get a hybrid inverter, it handles grid disconnections (as far as I am aware but I haven't completely confirmed this yet, you may need an additional piece of equipment) and can supply power immediately when the grid goes down

Something like this - https://www.victronenergy.com/inverters-chargers/multiplus-12v-24v-48v-800va-3kva

From what I can make out there are very few hybrid inverters that handles auto grid disconnects. The Tessla system as mentioned has the box called gateway that handles the switch over this is covered in one of the fully charged you tube videos. But this takes a few seconds despite its expense. I think if it was immediate they would have done it. The difference between a UPS and a battery I guess is that an UPS e.g.that powers the computer the UPS does not feed into the grid at 230 volts it powers the equipment it is protecting.

https://www.youtube.com/watch?v=gP51JjnWvLo&list=PLzD0K2OhbVfEaxtwOfUmiDE17pf__Ialo&index=7&t=80s

One of the popular hybrid inverters Solax and its accompanying battery does not switch over automatically it can be configured so that you have a manual switch which disconnects you from the grid and over to the battery. It seems the hybrid systems are geared up to help you manage usage and store your excess solar production and store cheap night energy but needs a feed from the grid. The Delios is the only one I have found so far that will switch over automatically but that is not to say there are others. I have the same issue as DJH get a power dip have to go round resetting clocks very frustrating on ovens that have cost £1000 which are in themselves programmable. It might be worth exploring the Powervault3 as in their brochure they use the term UPS. Available next January. The only way, certainly currently to avoid dips and disruption to supply, is go off grid.

Somewhat tempted by the Powervaul home batteries so I thought I'd ask for the wisdom of the crowd. Price list in Revor's link above. Looks like one version recycles car batteries. I wonder if there is any chance of them paying back in the lifetime. Any thoughts?

Posted By: revoran auto changeover to battery in event of grid power cut after 30 seconds

I'm not sure I understand that. You mean the power has to go down for thirty seconds and then the battery brings it back? I'm not sure I see the point of that since everything will still reboot then surely? What happens when the mains comes back?

Think the delay is something to do with forcing all the loads to shutdown and motors to run down to a stop, so that when the inverter starts in off-grid mode, it doesn't have to synchronise. If there was an interruption of mains supply, and then the inverter quickly started up but was not synchronised with the spinning loads or potentially any other inverters in the house, then could be damaging/dangerous. Would imagine it does the same when reconnecting to the grid, there's some stuff in G83 about it.

The grid usually comes back on within a few seconds, so no point switching to off-grid mode until you are sure that the grid is going to be down for a while.

Shhh, not a sparky....

Robin, I suspect the answer to your question is 'no'... The peak price period on a smart meter tariff is now only a few hours eg 4-7pm. Mornings and early afternoons are off-peak. Unless for some reason you must use a vast amount of power between 4-7pm, won't be worth buying a battery to store up power for that short period.

You can effectively 'store' off-peak power for free, by shifting your usage to when power is cheap, eg EV charging or immersion heaters etc.