xStorage - Opinions

Casati

This might be better in the Construction forum but I'd like to get folks opinion on this use of old Nissan Leaf power packs - x Storage Home

Basically these 'second life' Leaf power packs are used in a residential environment - either to be charged up on night rate or via Solar P.V. for use during the peak periods. They are 4.2kw and they have a 10 year life.

http://electricalsector.eaton.com/energystorage_Nissan_xstoragehome

Any idea on how a second life Leaf battery would last another 10 years? Also as this is only 4.2kw and based on the size of the unit I guess its only part of the battery pack? Does this seem like it might be worth €4000?

cros13

Casati wrote: »

Any idea on how a second life Leaf battery would last another 10 years?

They provide a capacity life of 10 years. i.e. the nameplate capacity for that period. They won't magically stop working at the 10 year mark but they will steadily lose the majority of their capacity by the 20 year mark (20 years into it's 2nd life as storage).

Casati wrote: »

Also as this is only 4.2kw and based on the size of the unit I guess its only part of the battery pack?

Yes, as I understand it the 4.2kWh xstorage is composed of 12 Leaf modules (4 cells per module, 12 modules would have a nameplate capacity of 6kWh at manufacture so Nissan are saying at 10 years they expect 70% of capacity to be retained). There are 48 modules in a Leaf's pack. This is a module:

Casati wrote: »

Does this seem like it might be worth €4000?

Absolutely not. Tesla are selling the 13.5kWh Powerwall 2s for €6300. And they'll give you a 20 year capacity warranty for an extra 10% fee.

Casati

Thanks - I guess next question would folks think the Powerwall is worth the cost? Makes me think that these units will guarantee very good scrappage values on 10 year old Leafs

Any idea if either of these powerpacks can be used along with a P.V. panel to improve the BER rating - I'll post this with the construction experts if nobody knows the answer here.

cros13

The powerwall can be worth the cost in Ireland in some situations, particularly if you have a reasonable amount (3 - 4kW+) of solar PV installed (because you'll get nothing for exported power here)

unkel

cros13 wrote: »

The powerwall can be worth the cost in Ireland in some situations, particularly if you have a reasonable amount (3 - 4kW+) of solar PV installed (because you'll get nothing for exported power here)

Break even point calculation?

cros13

unkel wrote: »

Break even point calculation?

Depends on the how much you do yourself or with standard tradesmen vs the "specialist" installers.

There's about €200-300 additional unavoidable expense on top of the powerwall for the meter and cabling.
So. €6500.

3kW of good quality REC panels is about €2000 inc VAT.
3kW Bosch inverter is €500 inc VAT.
Roof mounting kit + cabling + switchgear + sparks and roofer. €1-1.5k

So ~€10k all in. That's assuming you do cable runs and other easy stuff yourself and leave final connection to the electrician and the roof mounts to the roofer.

If you're a medium to heavy electricity user you'd have payback in well under 10 years. Under 5 years if they bring in a decent feed in tariff over 10c/kWh.

unkel

Assuming I do no work myself. €10.5k in your list + another €1k = €11.5k total outlay?

My roof is 100% south facing in south Co. Dublin. How many kWh per year per kW panel did you use in your calculations?

What if I don't want storage. Any way of sending electricity from panels to EV battery storage? If so, outlay?

I'd be reluctant to spend serious money while we're all waiting till the government p1sses and gets off the pot about any feed in tariff. But it does no harm to have some ideas of what is possible and how much they cost (and payback)

The cost of electricity in Ireland is far too cheap to even contemplate buying storage batteries, Solar PV etc.

Mot people would make more savings on buying an EV compared to petrol or diesel.

I did mention this before but when using Solar PV, you'll struggle to fill a battery in Winter and you'll have far too much in the long Summer daylight hours.

The best way to do this is to export to grid, then the grid becomes your unlimited ultra cheap storage battery and best yet, it's scalable to your needs........ Buy the power back when you need it.

cros13

unkel wrote: »

Assuming I do no work myself. €10.5k in your list + another €1k = €11.5k total outlay?

At the moment the cowboys that pass for installers in Ireland would charge you almost €10k for the 3kW of solar without the storage.
There is no way of using them and getting a reasonable payback term.
The DIY equivalent is circa €3k, using better quality panels and a better inverter.

Most of the solar installers won't touch a storage system as technically everything needs to be certified against the Irish Addendums to the european standards... which no manufacturer is bothering to do with their current products. Same applies to the Bosch inverter, the only approved products of theirs are several generations old.

unkel wrote: »

My roof is 100% south facing in south Co. Dublin. How many kWh per year per kW panel did you use in your calculations?

I did a rough estimate based on my previous calculations (using Helioscope PV design tool) for larger ground mount arrays with zero shading at a similar latitude to Dublin (sites along the M7). I pro-rated the production based on the size of the array (2760kWh) and halved the consumption (to 5000kWh) to better reflect a typical home. I assumed all production was either stored (without accounting for the ~10% loss) or used.

unkel wrote: »

What if I don't want storage. Any way of sending electricity from panels to EV battery storage? If so, outlay?)

Yes you could do a kind of smart charging setup. DIY.. the RS485 on the Tesla Wall Connector plus a raspberry pi. Pre-made - BMW's Wallbox Pro.

Deleted User wrote: »

The best way to do this is to export to grid, then the grid becomes your unlimited ultra cheap storage battery and best yet, it's scalable to your needs........ Buy the power back when you need it.

Yes, but at the moment nobody is offering you that option.

unkel

cros13 wrote: »

I did a rough estimate based on my previous calculations (using Helioscope PV design tool) for larger ground mount arrays with zero shading at a similar latitude to Dublin (sites along the M7). I pro-rated the production based on the size of the array (2760kWh) and halved the consumption (to 5000kWh) to better reflect a typical home. I assumed all production was either stored (without accounting for the ~10% loss) or used.

So what's the total annual production in kWh per kW of PV panel?

cros13 wrote: »

Yes you could do a kind of smart charging setup. DIY.. the RS485 on the Tesla Wall Connector plus a raspberry pi. Pre-made - BMW's Wallbox Pro.

And what about my question that I want to charge the EV battery, but do not want storage (Tesla Wall)

cros13

cros13 wrote: »

Yes, but at the moment nobody is offering you that option.

No, at the moment there is no FIT offered in Ireland.

My point still stands, what do you do with the excess in energy in Summer when your battery is full ? and in Winter you can't get much energy.

So non of this is really feasible yet until battery costs come down a lot more or there is a FIT offered.

The Government could offer a Grant for Solar PV installation which could create a lot of jobs but knowing Ireland , installers would find a way to make an excessive profit .

Casati

its good to see the batteries used after they aren't suitable for car use but Im surprised they are as expensive when you think about the fairly limited capacity - I'll do more maths on that as I'll likely be investing in p.v. panels this year.

Probably the next generation of these will be the norm in new houses in 5 years

cros13

I agree entirely, if there was a feed-in tariff there would very little opportunity to make the maths work on storage.

On the other hand if you want to do solar anyway or you are able to time self-consumption combined with storage and nightsaver you can make it work.

My goal for my new home is to potentially go off-grid or maintain only a 2kVA unmetered link to the grid. For my parents place it was to offset daytime consumption and store enough to cover evenings until the night saver kicked in. Which I was able to come up with a plan to do 9 out of 12 months of the year.

cros13

unkel wrote: »

So what's the total annual production in kWh per kW of PV panel?

2760/3 = 920 kWh/kWp

unkel wrote: »

And what about my question that I want to charge the EV battery, but do not want storage (Tesla Wall)

Yes... that was what I answered. The BMW Wallbox Pro has two inputs, one for grid connection and one for local microgeneration. It can prioritize use of your PV production over grid power when it's available:



You can DIY a similar setup using a power meter and popping the Tesla Wall Connector into slave mode, telling it what power to draw based on your PV production over RS-485.

The point I'm trying to make is that the excess is far to excessive in the longer daylight hours to make self consumption practical and then to get a battery ? sure you can get a small one but chances are it won't be nearly enough.

My partners parents in Germany can generate around 70 Kwh from a 14 Kw/p array on a good Sunny Summer day. They sell it to the grid and buy it back for the storage heaters in the cooler months.

They might use 4-7 Kwh per day, that's a big ass battery , 70 Kwh per day , sometimes 40,50,60 etc etc.

You can scale it down obviously but the same principle applies.

cros13

Deleted User wrote: »

My partners parents in Germany can generate around 70 Kwh from a 14 Kw/p array on a good Sunny Summer day. They sell it to the grid and buy it back for the storage heaters in the cooler months.

They might use 4-7 Kwh per day, that's a big ass battery , 70 Kwh per day , sometimes 40,50,60 etc etc.

The battery I was quoting a price for holds 13.2kWh (the DC version is 13.5kWh) and includes a built-in two-way inverter for €6,200. Scaling your example PV array from 14kWp to 3kWp reduces the 70kWh example yield to 15kWh. Things are changing quick.

70 Kwh per day for instance, not every day but lets say for arguments sake, that's 490 Kwh per week, using at best 8Kwh per day = 434 Kwh to store......... That's a big ass expensive battery. I don't know how much they need for the storage heaters but the Germans would rather sit with blankets around them before they'd turn the heat on........

In winter , can't remember what they generate to be honest but it's a hell of a lot less per day obviously, on a sunny winters day they can still generate a fair bit but I don't have exact figures.

A small battery to tie you over for the peak hours is absolutely fine but still uneconomical really at this time so in reality Grid storage is the only thing that makes sense and let Eirgrid and the ESB worry about storage, this is where electric cars can have a huge impact.

It's a shame we have no 3 phase supply to homes here and that we're limited to about 5.5 KW to the grid. The potential is huge for Solar PV in Ireland.

bipedalhumanoid

Casati wrote: »

Any idea on how a second life Leaf battery would last another 10 years? Also as this is only 4.2kw and based on the size of the unit I guess its only part of the battery pack? Does this seem like it might be worth €4000?

My jaw hit the ground when I saw that. You can buy a complete brand new 24Kwh Leaf battery for $6500 in the US or £4920 in the UK. Why on earth would anyone pay €4k for one module of a second hand battery?

Or take a trip to the states, where you can buy a second hand 2012/13 Nissan Leaf for $6500. Take the battery out, send it home and sell the car for scrap. You get a whole battery with 40k miles on it.

Actually forget all of that. If people are paying €4k for battery modules, I'm going the states and I'll sell you a module for €2k and still make a tidy profit.

I think for 5,500 Euro's you can have a brand new (current Gen) Leaf battery in Ireland once capacity has reduced to 75%.

By the time most people that own a updated Gen Leaf (132+ reg) need a new battery the cost could be half that or less.

bipedalhumanoid

Deleted User wrote: »

I think for 5,500 Euro's you can have a brand new (current Gen) Leaf battery in Ireland once capacity has reduced to 75%.

By the time most people that own a updated Gen Leaf (132+ reg) need a new battery the cost could be half that or less.

I don't really understand this comment. We're not talking about replacing existing car batteries here. We're talking about buying car batteries to use in the house.

Second hand leaf battery modules are being sold for €4000 for 4KWh worth of modules, for use in the house. By comparison you can buy an entire brand new 24KWh battery for $6500. That's not the replacement cost of a battery, it's the full cost if you're not trading in a battery.

cros13

Well in fairness it's not just the modules you're paying for... It's also the custom power electronics and fancy wall mount packaging.

DragonEV

cros13 wrote: »

You can DIY a similar setup using a power meter and popping the Tesla Wall Connector into slave mode, telling it what power to draw based on your PV production over RS-485.

I know Maxem has hardware to control a TWC this way, but do you know any open source project or documentation of the rs485 protocol that can tell a TWC what power level to supply a car with?

cros13

DragonEV wrote: »

I know Maxem has hardware to control a TWC this way, but do you know any open source project or documentation of the rs485 protocol that can tell a TWC what power level to supply a car with?

Reverse engineering the protocol is one of the things on my long list of projects I haven't got around to yet.

I had assumed that I could just effectively do a replay attack with the messages on rs485 to get the slave TWC to pull the right current.

I did a quick dump using one of the serial protocol analysers from work and it looks like it's a bit more complex with a handshake occurring on startup (though it doesn't look like there's any anti-replay on the actual messages passed).
I haven't got back to looking at it since.

DragonEV

cros13;105183338

Reverse engineering the protocol is one of the things on my long list of projects I haven't got around to yet.

Darn, I keep hoping someone's already documented it.  We're talking about the protocol over here: teslamotorsclub dot com/tmc/threads/new-wall-connector-load-sharing-protocol.72830


MITE46 has apparently gotten some successful control of HPWCs (aka TWCs) installed at a Cal-tech research project and he says the protocol is easy to figure out once you get past that initial handshake signal.  I plan to start experiments tomorrow, assuming the rain stops.
It would also be helpful if you posted the dumps you took along with a brief explanation of what they represent.  I've been studying two logs others have posted and they seem rather different in message length which makes me think maybe someone was missing data or something.  Having a third example might clear that up.

cros13

DragonEV wrote: »

It would also be helpful if you posted the dumps you took along with a brief explanation of what they represent.

I'm afraid I have the wall connectors in my weekend place, I won't be down there again for another week or two.

I'll have a quick look on my NAS to see if I kept the terminal logs from the last round of tests.