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Powervault Lauches Energy Storage - Lithium-Ion And Lead Acid And Old Nissan Batteries


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#1 readiescards

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Posted 29 April 2016 - 06:26 AM

http://www.powervault.co.uk/

"Powervault’s latest systems are available from 2kWh to 6kWh, with lead acid or lithium ion batteries, at a typical installed price of £2499-4999 (inc VAT)."

Tech spec:
http://www.powervault.co.uk/wp-content/uploads/2016/04/Powervault_Technical-Specification_April-2016.pdf

#2 cjard

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Posted 29 April 2016 - 06:38 AM

I wonder if these things are vat reclaimable.. One of the conditions for an item to be reclaimed is "normally installed in that type of house" which can't yet be true.. In fact, I'm not even sure when it would become true

#3 SteamyTea

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Posted 29 April 2016 - 07:18 AM

*
POPULAR

A quick look at the spec and it has a constant load of 800VA (about 800W) and a peak of 1.6 kW for 1 second).

I am not sure how useful that is, would run lighting and most of my fan heater.
A lot of it will depend on how the diversion management works.
It is easy to see how you can have it charge during the day, then discharge when it is dark, but how about when you have partial loads switching during the day when it is also meant to be charging.

Then, if you look at the expected life of the batteries 17-20 years for the lithium, 5-7 for the leads, you can only get about half the capacity out of them on average if you want to maximize their life, so about 1 to 3 kWh/day. That works out at about 22p/day saved at 15p/kWh or about £80/year.

If you think that spending around £3750 to save £80/year (break even is after 47 years), then they are a, and I hate this term, game changer.
Home storage, unless you are off grid or want a hobby, is just not worth it when it is more then grid supplied. Better off finding ways to save £80 quids worth of juice a year.

Edited by SteamyTea, 29 April 2016 - 07:20 AM.


#4 readiescards

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Posted 29 April 2016 - 07:23 AM

Thanks @steamtea - more useful!

#5 SteamyTea

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Posted 29 April 2016 - 07:32 AM

Whenever I go and look at people that live off grid, the battery bank is the size of two large sofas, so about half the size of my kitchen.
From that they run a laptop (they all have laptops) and a couple off small lightbulbs.
I really want small, affordable storage, trouble is the physics is against it.
I follow stories about breakthroughs in batteries, and once you have cut though the hype, a break though seems to be a 1 or 2% improvement.
To put that into perspective, you will get better performance by taking out 1 in 10 LED downlighters, or only half filling your car with fuel.

Edited by SteamyTea, 29 April 2016 - 07:33 AM.


#6 DamonHD

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Posted 29 April 2016 - 07:51 AM

Heat storage is coming along at a clip now compared to electricity:

* 60kWh in 1t (~2m^3) of PCMs (eg Sunamp Stack): a real product

* Nominal 500kWh/m^3 storage in (de)hydrated silicates (so all of my seasonal heat storage in about 3m^3): still in the lab but plenty of papers published

So I could get all my daily and seasonal heat energy (diverted from PV) in the corner of my kitchen where the gas combi is now, kinda sorta.

Seasonal battery storage with actual real shipping products would still require me to dig a basement and spend more than my house rebuild costs to save ~£250/y going off grid, so maybe a millennium payback crudely, though there are many variants now such as Zcell. I do have ~2kWh of usable battery storage (4kWh of gel lead-acid) off-grid to keep my tiny RPi going overnight and over-winter.

I know the Powervault people somewhat and I'm pleased to see how far the project has come.

However I would specifically want to be able to prevent imports from the demand spikes from kitchen wet goods heating water (dishwasher, washing machine) that I cannot otherwise control the timing of very precisely, which would require ~2kW peak output power injection for ~10 minutes a few times per day, so the Powervault would not cover my main target, and as an alternative I could just (say) run my lighting loads from my existing off-grid store instead, eg with an automatic changeover switch. That would take a bunch of night imports away and have much lower than 800W peak demand, and costs might be down in the £2k range all in.

If you want to build yourself something that has a similar effect to Powervault and don't mind ~50% round-trip losses with lead-acid, go wild here:

http://www.bimblesol...elf-consumption

Rgds

Damon

Edited by DamonHD, 29 April 2016 - 07:54 AM.


#7 SteamyTea

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Posted 29 April 2016 - 07:57 AM

I still think that thermal storage is the best bet, as long as it is well insulated.

Damon,
Have you thought of selling up and building your own place?

#8 jsharris

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Posted 29 April 2016 - 08:00 AM

I was looking at this yesterday evening and pondering about it. For our house it would remove our base load completely, and leave us with just the grid for peak loads when the PV wasn't generating. I need to do the detailed calculations but it looks as if the cheaper lead acid system "might" be worth it, as it seems that the same boxes of electronics can be transferred over to a lithium pack when the time comes for replacement, assuming that the price drops as anticipated.

We're an odd case though, with a higher than average base load (mainly because of the MVHR, the sewage treatment plant and the water UV disinfection unit) and so we automatically save around 1.2 kWh just from having the base load powered by PV each night. That gives an an annual saving of about 438 kWh minimum, in reality it'd probably be closer to 600 kWh by the time I properly factor in all the base loads. That's a saving of around £85 a year, so nowhere near enough to warrant buying their cheapest unit.

There would undoubtedly be a few small peak load night time savings too (our heating system on full blast (for us) uses around 800W or so for maybe an hour in very cold weather) but I very much doubt if we could ever save more that £100 a year from any system like this.

At those sort of payback times it becomes an investment for reasons other than saving money, and leaving inside environmental reasons the biggest of those for us would be the 800W power cut power capability. The question is, do I want to pay this much of a premium just to get a power cut free home?

#9 DamonHD

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Posted 29 April 2016 - 08:06 AM

The Powervault design will only act as an (800W) UPS for the socket on the unit; it doesn't stand between your house and the grid.

The self-consumption designs can, in some variants, island your system if the grid goes down, giving you the option to keep more stuff up and running.

For me the goal would be to reduce the losses (~5%--10%) in exporting/reimporting energy to/from the distribution network, which implies round-trip efficiencies (battery and inverter/charger) of the order of 95--90%, which none of them are that I can see, yet. (The good Li batteries are about at that level by themselves, but the inverter/charger is not energetically free.)

Rgds

Damon

#10 DamonHD

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Posted 29 April 2016 - 08:09 AM

View PostSteamyTea, on 29 April 2016 - 07:57 AM, said:

I still think that thermal storage is the best bet, as long as it is well insulated.

Damon,
Have you thought of selling up and building your own place?

One day. That's what my other half tells me I should do. And indeed would like to do.

But I can't see it happening soon, unless maybe I manage to sell my shares in my last start-up and the new one takes off!

Rgds

Damon

PS. Note that the nice thing about the seasonal heat store with hydration is that it's not actually stored hot so far as I can tell, so no insulation needed. It *would* need to be hermetically sealed though!

#11 ProDave

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Posted 29 April 2016 - 08:10 AM

The way I am looking at it, is I will almost certainly be going DIY not MCS and FIT. So the saving on the MCS premium will pay for this sort of battery storage system.

So overall cost about the same, but a more useful installation, with more flexibility to please yourself.

But as always, it's not the initial cost that bothers me, it's replacing the batteries in 10 years time, and again and again..... That's why I am a lot more keen on a NiFe system. I keep hoping that those will start getting made in bulk again and a battery storage system using them marketed on the long battery life as it's unique selling point, and that could bring the prices down.

#12 DamonHD

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Posted 29 April 2016 - 08:18 AM

Note that in that Bimble selection there are NiFe cell options, so you can do it right now with approved equipment. Pricey compared to say lead-acid. TCO, I don't know.

I remain unconvinced by NiFe, but decent Li chemistry cells should get you 10 or more years of calendar life and/or daily cycling now, and the power electronics may be obsolete or at least tired by then.

Rgds

Damon

#13 SteamyTea

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Posted 29 April 2016 - 08:41 AM

Does anyone know how the power delivery system works on these systems. Is it a basic 'I got charge, there is a load, I am off' system or can it be set to dedicated loads, either my power i.e. anything that is drawing over 5A or individual appliances i.e washing machine, kettle, hair dryer.

Also, and I could look this up but hope someone already knows, is the charging/discharging of battery (take your pick of chemistry) degradation an accumulative thing.
So 100 1% charge/discharge cycles is the same as 1 100% discharge. Or more realistically does 5 10% discharges/recharges do the same damage as 1 50% discharge/recharge?

#14 DamonHD

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Posted 29 April 2016 - 08:51 AM

There's a huge variety of configurations possible in terms of autoswitching loads from mains or injecting power to neutralise imports and islanding or not.

(For me, because grid-tieing any more PV, even that little that I'd have room for, would be a paperwork nightmare in terms of G59 and the fact that I have metered exports, I'd probably extend things electrically by dynamiclally switching more loads/circuits from grid as I already do in a small way, and/or self-consume more of what I already generate a la Sunamp and kin, rather than injecting more power into the grid.)

Also the cycling and calendar life thing is entirely dependent on chemistry and construction. And lead-acid really doesn't enjoy being held below 50% full, whereas others don't care, or at least not as much or not that that threshold.

Rgds

Damon

Edited by DamonHD, 29 April 2016 - 08:55 AM.


#15 DavidWright

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Posted 29 April 2016 - 08:57 AM

View PostSteamyTea, on 29 April 2016 - 07:18 AM, said:

A quick look at the spec and it has a constant load of 800VA (about 800W) and a peak of 1.6 kW for 1 second).

I am not sure how useful that is, would run lighting and most of my fan heater.
But that's only relevant if you are trying to run the lighting and fan heater during a powercut. At any other time the grid is there to balance things out.
The Powervault works along side the grid (just as a GTI does). It's not an off grid solution. The 800W that are available during a powercut are supplied from a special socket on the unit (that needs to be turned on specifically).

View PostSteamyTea, on 29 April 2016 - 07:18 AM, said:

Then, if you look at the expected life of the batteries 17-20 years for the lithium, 5-7 for the leads, you can only get about half the capacity out of them on average if you want to maximize their life, so about 1 to 3 kWh/day.
The quoted capacities already take DoD into accounts, i.e. the nominal full size battery capacity of the 4kWh system is 8.8kWh.

I'm not saying this is a good economic solution here and now, but I think you may wish to re-read the technical specs. before applying the maths?

#16 SteamyTea

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Posted 29 April 2016 - 09:01 AM

Yes I know it runs in parallel to the grid, just as a PV system does. Why I asked about the demand side management as many homes could end up with flat batteries at about 7PM just as the PV is generating less.

Only the lead acids have a voltage quotes and that implies 30% DoD.
Anyone know what LiFePO they are using?

Edited by SteamyTea, 29 April 2016 - 09:05 AM.


#17 DavidWright

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Posted 29 April 2016 - 09:06 AM

View PostSteamyTea, on 29 April 2016 - 08:41 AM, said:

Does anyone know how the power delivery system works on these systems. Is it a basic 'I got charge, there is a load, I am off' system or can it be set to dedicated loads, either my power i.e. anything that is drawing over 5A or individual appliances i.e washing machine, kettle, hair dryer.
So far as I can see it sits in the house hold system in just the same way that a GTI does, and monitors the (traditionally) incoming mains using a CT. Based on what it sees at the CT and its state of charge it can either draw off some (at up to 800W) of the energy (if you would have been exporting and it would like some charge), or feed in (at up to 800W) energy (if you would have been importing and it has charge to offer).

The unit itself hasn't got a clue what appliances you are running.

In the event of a powercut, the device seems to have the same anti-islanding arrangements as a GTI, i,e. is will not supply power to the house wiring (& thus grid). There is however have a socket on the unit itself that can provide up to 800W during a powercut (battery state permitting).

This is just a guess, but I imagine there is probably some sort of battery management (i,e, maintenance) system in addition to the scenario I've pictured above?

#18 DavidWright

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Posted 29 April 2016 - 09:12 AM

View PostSteamyTea, on 29 April 2016 - 09:01 AM, said:

Yes I know it runs in parallel to the grid, just as a PV system does. Why I asked about the demand side management as many homes could end up with flat batteries at about 7PM just as the PV is generating less.
Where "flat" means ~50%DoD, and depending of the PV available during the day and the household load during the day.

What's the issue? If the Powervault reaches its lower limit you are back to using mains. Without a powervault you'd have been using the mains earlier. Some people will find that attractive (even though it's not economic). Everyone needs a hobby... ;)

If you want to run completely off battery then most households will need a far bigger battery and more PV than most on-grid systems have, however it that's the aim then you want a full properly designed off-grid system , not a Powervault.

Edit: typo

Edited by DavidWright, 29 April 2016 - 09:13 AM.


#19 SteamyTea

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Posted 29 April 2016 - 09:30 AM

Yes, my issue is with how long the batteries really last, hence my other questions about the load management.

I am not totally dismissing them, apart from on price, just want to know what could realistically be delivered.

Edited by SteamyTea, 29 April 2016 - 09:31 AM.


#20 DavidWright

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Posted 29 April 2016 - 09:46 AM

View PostSteamyTea, on 29 April 2016 - 09:30 AM, said:

Yes, my issue is with how long the batteries really last, hence my other questions about the load management.
Since they offer "60 month warranty: parts & batteries" it seems likely that they have systems that are designed to look after the batteries?