Tesla Powerwall - is this the answer we have been waiting for?

murphaph

murphaph wrote: »

They are modular. 2.5kWh modules. If they price them like the Teslas they'll sell in Germany due to the shocking price of electricity here. FIT exists here but self consumption is preferred financially for anyone installing nowadays. I guess the viability off such products will always come down to local market forces.

So how do you store all the Summer Kwh ? My Partners parents have 14 KwP on their roof in Baden Wurttemberg which can generate over 70 Kwh on a good sunny day in Summer and a lot less in Winter. That's a big battery needed, but not only that, if they generate 70 Kwh daily and use maybe 10 then they've got a lot of wasted energy with no where to go without grid storage.

They have 14 Kwp to run the storage heaters in winter, so all that excess in Summer is bought back in winter.

I just don't think battery storage is a viable option for our climates, perhaps in locations where there is usually pretty much the same amount of direct sunlight Winter and Summer then you can easily size your storage to match your consumption.

murphaph

Deleted User wrote: »

So how do you store all the Summer Kwh ? My Partners parents have 14 KwP on their roof in Baden Wurttemberg which can generate over 70 Kwh on a good sunny day in Summer and a lot less in Winter. That's a big battery needed, but not only that, if they generate 70 Kwh daily and use maybe 10 then they've got a lot of wasted energy with no where to go without grid storage.

They have 14 Kwp to run the storage heaters in winter, so all that excess in Summer is bought back in winter.

I just don't think battery storage is a viable option for our climates, perhaps in locations where there is usually pretty much the same amount of direct sunlight Winter and Summer then you can easily size your storage to match your consumption.

It will obviously be viable at a certain price point. For an extreme example, imagine the batteries were free. Instead of selling all your excess home made energy for 9c to the grid in high summer, you can save enough in your free battery to get you through the night and sell the rest-during summer you don't buy any energy from the grid. You obviously gain from this arrangement. The rest you continue to sell for 9c.

Now say the battery costs €100...probably still makes sense to buy one, right? I mean, you'll get that back in a few weeks tops. At some price point it does not make financial sense, but these batteries are getting cheaper, more compact and require less maintenance. They are certainly on my radar now, but I will be running numbers before purchasing (and after my PV system without battery is up and running) to see exactly how such a battery can fit in to our system.

We'll run our heat pump from the PV. This can also run in reverse in summer to provide cooling, so our PV array is already more viable before batteries. Storage heaters obviously can't provide any cooling benefits in summer.

I see the batteries as an add on that can increase my rate of self produced energy consumption, that's all. If they are priced right, they are viable. If not, then they aren't. It's all about the price. These things cost 10k a few years ago, and took up much more space. Now they're a third the price and the size of a rucksack. things are going the same way the panels themselves went...towards a commodity product.

murphaph

There's also solarwatt, which is closely tied to BMW through a chief shareholder and BMW board member.

They reckon that their unit can function effectively for at least 15 years (they say it's been conservatively calculated at that).

Interesting times ahead now with Tesla, Daimler and BMW (indirectly) all vying for market share in this sector. I think we can reasonably expect prices to fall further.

murphaph

murphaph wrote: »

It will obviously be viable at a certain price point. For an extreme example, imagine the batteries were free. Instead of selling all your excess home made energy for 9c to the grid in high summer, you can save enough in your free battery to get you through the night and sell the rest-during summer you don't buy any energy from the grid. You obviously gain from this arrangement. The rest you continue to sell for 9c.

Now say the battery costs €100...probably still makes sense to buy one, right? I mean, you'll get that back in a few weeks tops. At some price point it does not make financial sense, but these batteries are getting cheaper, more compact and require less maintenance. They are certainly on my radar now, but I will be running numbers before purchasing (and after my PV system without battery is up and running) to see exactly how such a battery can fit in to our system.

We'll run our heat pump from the PV. This can also run in reverse in summer to provide cooling, so our PV array is already more viable before batteries. Storage heaters obviously can't provide any cooling benefits in summer.

I see the batteries as an add on that can increase my rate of self produced energy consumption, that's all. If they are priced right, they are viable. If not, then they aren't. It's all about the price. These things cost 10k a few years ago, and took up much more space. Now they're a third the price and the size of a rucksack. things are going the same way the panels themselves went...towards a commodity product.

No you are still missing the point, if from a 14 Kwp Solar array you generate 70 Kwh daily over 7 days on a bright Summer day and use 10 Kwh daily then you need to store 420 Kwh for just a week so you can see how impractical battery storage is ?

Now if you need 6,000 Kwh on top of your winter production, how do you store this ?

I am sorry but grid storage is the only sensible approach here.

If you live in sunny southern climate and know you will on average get 8 hours of direct sunlight a day you can down size your array because you don't have to store all the Summer generation for winter because in winter you generate roughly the same amount of Kwh so you more easily use size a battery to your needs which don't change much winter or Summer and your amount of daylight hours doesn't change much.

murphaph

Deleted User wrote: »

No you are still missing the point, if from a 14 Kwp Solar array you generate 70 Kwh daily over 7 days on a bright Summer day and use 10 Kwh daily then you need to store 420 Kwh for just a week so you can see how impractical battery storage is ?

Now if you need 6,000 Kwh on top of your winter production, how do you store this ?

I am sorry but grid storage is the only sensible approach here.

If you live in sunny southern climate and know you will on average get 8 hours of direct sunlight a day you can down size your array because you don't have to store all the Summer generation for winter because in winter you generate roughly the same amount of Kwh so you more easily use size a battery to your needs which don't change much winter or Summer and your amount of daylight hours doesn't change much.

I'm not missing any point. You are suggesting you need to store all the energy you produce on a long hot summer's day in a battery. I never suggested that at all. I suggest you store, just enough energy to get you through the night and sell the rest to the grid. I'm not talking about storing energy for more than a few hours, just time shifting its use a bit. Same in winter, though this will be less successful obviously and you'll be buying more energy from the grid during winter for sure.

It's not a magic bullet, but at the right price it is a game changer. You can dramatically increase the % of self produced energy you use by time shifting with a 10kWh battery. You still run your heavy loads on a timer at midday if possible (eg washing machine, heat pump) and then run your lighting, TV, computers etc. off the battery as far into the evening as you can before reverting to mains (if you have to).

You seem to be suggesting storing energy from summer to use in winter or something, is that right?

murphaph

murphaph wrote: »

I'm not missing any point. You are suggesting you need to store all the energy you produce on a long hot summer's day in a battery. I never suggested that at all. I suggest you store, just enough energy to get you through the night and sell the rest to the grid. I'm not talking about storing energy for more than a few hours, just time shifting its use a bit. Same in winter, though this will be less successful obviously and you'll be buying more energy from the grid during winter for sure.

It's not a magic bullet, but at the right price it is a game changer. You can dramatically increase the % of self produced energy you use by time shifting with a 10kWh battery. You still run your heavy loads on a timer at midday if possible (eg washing machine, heat pump) and then run your lighting, TV, computers etc. off the battery as far into the evening as you can before reverting to mains (if you have to).

You seem to be suggesting storing energy from summer to use in winter or something, is that right?

Yes that was what I was suggesting because there is no feed in tariff in Ireland at this time so sending so much excess power to the grid would be insane.

If you have a feed in tariff why would you want a batter if you get paid for generation ? you just buy back the excess you sent when you were not using it.

I work shifts so have to charge at peak rate during the day when I work nights so I could charge the battery at night and use the energy to charge the car during the day, however this would be madness because the price difference is 8 cent , 8 cent night and 16 cent day. So the pay back on a battery would make it uneconomical for this.

murphaph

Deleted User wrote: »

Yes that was what I was suggesting because there is no feed in tariff in Ireland at this time so sending so much excess power to the grid would be insane.

If you have a feed in tariff why would you want a batter if you get paid for generation ? you just buy back the excess you sent when you were not using it.

I work shifts so have to charge at peak rate during the day when I work nights so I could charge the battery at night and use the energy to charge the car during the day, however this would be madness because the price difference is 8 cent , 8 cent night and 16 cent day. So the pay back on a battery would make it uneconomical for this.

So for some people in some markets these batteries make sense, as I said above. In the RoI there's no FIT for new installations right now, that surely changes the sums completely to the north or to here in Germany.

We have FIT here, but it only pays 9c. We pay 31c now for energy during the day. Just using these figures, a PV system with no battery will amortise in about 8 years. After that, it's free energy from the PV array until something breaks. You want the battery because you pay more than 3 times more for bought electricity than what you get for exporting it. It hasn't made financial sense to export to the grid (assuming you can find a sensible use for the energy) here in Germany since 2011. Self consumption of home produced energy is the name of the game here. The FIT is your "fall back".

Up until now the batteries (ones you'd reasonably be likely to install within the fabric of an airtight house) were north of 10k and my sums said they were not ever likely to pay for themselves as they would go life expired before they did. At 3.5k however the sums look different and when Tesla's Gigafactory opens and the new Accumotive plant in Kamenz, Saxony opens, there will be far more manufacturing capacity and Tesla at least says Gigafactory is the first of many. We are looking at significant price drops in Li-ion units over the next 5 years, probably much sooner. Nobody expected a 10kWh unit to be available for 3.5k before 2020. We're 5 years "ahead of schedule" if you will.

I can see these units costing a grand in about 3 years. Then it's a total no brainer as electricity will be 35c here by then (when I came here in 2008 it was 20c!!). now it likely makes sense for people like us with typical 9-5 workdays.

murphaph

murphaph wrote: »

So for some people in some markets these batteries make sense, as I said above. In the RoI there's no FIT for new installations right now, that surely changes the sums completely to the north or to here in Germany.

We have FIT here, but it only pays 9c. We pay 31c now for energy during the day. Just using these figures, a PV system with no battery will amortise in about 8 years. After that, it's free energy from the PV array until something breaks. You want the battery because you pay more than 3 times more for bought electricity than what you get for exporting it. It hasn't made financial sense to export to the grid (assuming you can find a sensible use for the energy) here in Germany since 2011. Self consumption of home produced energy is the name of the game here. The FIT is your "fall back".

Up until now the batteries (ones you'd reasonably be likely to install within the fabric of an airtight house) were north of 10k and my sums said they were not ever likely to pay for themselves as they would go life expired before they did. At 3.5k however the sums look different and when Tesla's Gigafactory opens and the new Accumotive plant in Kamenz, Saxony opens, there will be far more manufacturing capacity and Tesla at least says Gigafactory is the first of many. We are looking at significant price drops in Li-ion units over the next 5 years, probably much sooner. Nobody expected a 10kWh unit to be available for 3.5k before 2020. We're 5 years "ahead of schedule" if you will.

I can see these units costing a grand in about 3 years. Then it's a total no brainer as electricity will be 35c here by then (when I came here in 2008 it was 20c!!). now it likely makes sense for people like us with typical 9-5 workdays.

I think my Partner's parents get something like 32 C/Kwh FIT. I must check.

@31 C/Kwh it might make sense, is it 3.5K for 10 Kwh Powerwall ?

How do you connect it to the mains without reaching the grid ?

My daily average consumption since I got the Leaf is 15.2 kwh daily, that's a lot of storage, I'd need 20 Kwh battery.

According to the online calculators I need about 8 Kwp to meed my yearly needs. The excess being bought back in winter. If only we had that FIT.

Before I got the Leaf the house consumption was about 6.6 Kwh average daily so I could use a 10 Kw battery for storage.

murphaph

Deleted User wrote: »

I think my Partner's parents get something like 32 C/Kwh FIT. I must check.

Old rules. The FIT is on a sliding scale here. It drops every month to account for the falling prices in the PV equipment. They would be in the position where a battery would make no financial sense at present as they pay essentially the same for energy as they export it for, possibly less if they have night rates where they are.

Deleted User wrote: »

@31 C/Kwh it might make sense, is it 3.5K for 10 Kwh Powerwall ?

The 10KWh one is 3.5k$, the 7kWh one is 3k$. The 7kWh one is actually optimised for daily cycling. The 10kWh one is more intended as a battery back up during a power cut.

Deleted User wrote: »

How do you connect it to the mains without reaching the grid ?

It connects through your inverter. It's a DC:DC device. With the Powerwall (and the Accumotive etc.) you need a compatible inverter, so the price of that has to be factored in for anyone who currently has an incompatible one. For people (like me) planning a brand new system from scratch, this cost is irrelevant as you'd need to buy some inverter anyway.

Deleted User wrote: »

My daily average consumption since I got the Leaf is 15.2 kwh daily, that's a lot of storage, I'd need 20 Kwh battery.

I don't get you. Your car has the battery already and you charge it during the day, right? You'd need no bigger a Powerwall (etc.) as anyone else as far as I can see.

murphaph

murphaph wrote: »

The 10KWh one is 3.5k$, the 7kWh one is 3k$. The 7kWh one is actually optimised for daily cycling. The 10kWh one is more intended as a battery back up during a power cut.

What's the Euro prices ? Installation is likely to be expensive also.

murphaph wrote: »

I don't get you. Your car has the battery already and you charge it during the day, right? You'd need no bigger a Powerwall (etc.) as anyone else as far as I can see.

Well, I would charge it during the day when I come off nights, but wouldn't get much charge in winter mostly.

If I lived somewhere with a decent bit of space I would have a hybrid system of wind and Solar PV. But wind turbine installation costs are extortionately high.

murphaph

I don't believe wind is financially viable at all for most domestic settings tbh. You need "clear air" for them to work anyway properly. You really need a good high tower/mast to get it up into the clean air. Attaching those small ones to your roof seems like a gimmick to me. The wind is really "dirty" so close to structures, unpredictable and gusty.

I do not know the Euro price of the Tesla. The SolarWatt (4.4kWh base model) is currectly 5.5k. No prices available yet for the Accumotive product (though Daimler are on record as saying they would be competitive on price with Tesla). To be quite honest, I think the prices are going to fall off a cliff in the near future as manufacturing capacity is greatly expanded. I will probably keep my powder dry on the battery for now and install the system with the battery in mind, but hold off a year or so to see where prices are. These products aren't really available yet anyway, only to pre-order (except the SolarWatt myReserve)

murphaph

quentingargan wrote: »

It is 6kw on single phase and 11kw on three phase. 25A and 16A respectively. On three phase you can go above 11kw, but you need to pay €700 for a desktop survey to see if the local grid can use your power, and about the same again for a Mainspro relay.

Why you would do that when you don't get paid for the exports is, of course, a mute question. :rolleyes:

Just for comparison I took a look at our connection here on the outskirts of Berlin. We have the smallest connection type available ~100A 3 Phase. They allow us to feed in up to 30kW as standard. They actually draw your attention to this figure in the letter that comes out with the connection confirmation.

AFAIK the Irish grid is well built and robust. I wonder is there a genuine technical reason why the max allowed power is so low compared to here on a like for like connection? Is there some fear of grid instability on the ESB's part I wonder?

murphaph

murphaph wrote: »

Just for comparison I took a look at our connection here on the outskirts of Berlin. We have the smallest connection type available ~100A 3 Phase. They allow us to feed in up to 30kW as standard. They actually draw your attention to this figure in the letter that comes out with the connection confirmation.

AFAIK the Irish grid is well built and robust. I wonder is there a genuine technical reason why the max allowed power is so low compared to here on a like for like connection? Is there some fear of grid instability on the ESB's part I wonder?

30 KW ? That's nuts !

The grid here afaik isn't capable and the max I think is 11 Kw on 3 phase to the grid. Or should I say "was".

5 Kw on single phase.

Will be decades before our Grid reaches German standards.

Single phase to homes will show how bad it really is in the years to come as more people buy EV and want to charge at 30 amps.

If you imagine a single housing estate with cars 200 cars charging at 6.6 kw, that's an extra 1.3 Mw , there's no way our current system could handle that , transformers would be blown all over the place. So I think the grid needs massive over hall. Estates already have 3 phase but homes do not and it is expensive in Ireland as usual.

murphaph

I've spent a little time comparing the Tesla and the Mercedes batteries. They are fundamentally different-Tesla is like a 350Vdc battery, Mercedes is the "traditional" 48Vdc.

According to the Mercedes data sheet, the only listed compatible charge inverters are Sunny Island units. Looking at these online it seems the architecture means to charge a battery from PV you first have to invert it to AC through the PV inverter and then rectify to DC through the Sunny Island and then to finally use the stored energy you invert again through the Sunny Island.

According to the info I have found from SolarEdge (currently only SolarEdge and Fronius seem to support the Tesla), the SolarEdge way of doing things is to take the high voltage DC off the PV array and connect it through their StorEdge interface to the battery. When you use the stored energy in your AC network it is inverted once through the SolarEdge inverter.

I would like to know more about how the other inverter manufacturers are going to integrate the Tesla into their eco-systems.

SolarEdge has release notes on how to prepare a system for the Tesla in furture.

quentingargan

Victron is another company making a lot of battery storage systems, with some better functionality than the Sunny Island.

AC-Coupling where you use a standard grid-tied inverter and use a Victron inverter-charger to convert that to DC and back again isn't as daft as it seems. The AC inverter is a standard component at very competitive prices, and any power used at 230V AC at time of production doesn't go near the battery or get converted at all. The inverter/charger seamlessly switches from inverting to charging.

I'd prefer to stick to proprietary products and the standard 48V. I have yet to be convinced that any lithium ion battery is cost effective when cycling costs are taken into account

murphaph

Any thoughts on Solarbatterie?

quentingargan

quentingargan wrote: »

I have yet to be convinced that any lithium ion battery is cost effective when cycling costs are taken into account

+1
Proprietary servicing and support gear I imagine will be expensive and they just don't have the same potential for homebrew power contrivances.
10kWh is a small battery, that's only 6kWh usable for li-ion or 5kWh lead acid

Better off with a set of submarine/forklift/stationary telecomms/static inverter batteries imho. Guess they're not as fashionable.

The ideal battery setup would divert AC generators to AC loads and charge batteries/diversion control when there's no demand. While DC controllers are the work horse battery chargers and run any DC loads/diversion only being inverted when the AC coupled generators need support. Minimal losses.
I rather keep it simple and DC couple/invert.
AC coupling comes into it's own when your generators are hundreds of metres away from your charger/load the combined cost of a GTI and smaller cable can make a practical solution where ELV DC generators are just impractical.
It's often the case off gridders adopt ex Grid Tied turbines for battery systems that were decommissioned due to complaining neighbours/poor siting. These can sell quite cheap as they're not eligible for FITs on the used market.


From what I hear the newer sunny islands don't play nice with other manufacturers DC coupled equipment in the same system and autoset the frequency to 60hz if it can't rule the roost. :mad:

Studer Xtender can AC couple too.

There's also naughty ways of doing it with inverters that have a genset support feature.

Sir Liamalot

Sir Liamalot wrote: »

+1

Better off with a set of submarine/forklift/stationary telecomms/static inverter batteries imho. Guess they're not as fashionable.

The life of li is a lot more than for lead acid, forklift, telco etc. + you have much more usable kWh.

10% more usable power to Li-ion but no peukert exponent so if you discharged a lead acid at C50 you'd get 20% extra capacity so 10% more than li-ion.
The cycle life of li-ion is about half LA, there's a plethora of EVs running on Panasonic laptop/drill cells.

murphaph

Can't you much more deeply discharge a li ion than lead acid without adversely affecting its lifetime? I think Tesla's warranty is 10 years too, right?

My understanding was that you need to buy a good deal more lead acid because you should only discharge them to 50% or so...am I wrong on that score?

murphaph

murphaph wrote: »

Can't you much more deeply discharge a li ion than lead acid without adversely affecting its lifetime? I think Tesla's warranty is 10 years too, right?

My understanding was that you need to buy a good deal more lead acid because you should only discharge them to 50% or so...am I wrong on that score?

Yes you're quiet right, and Lithium Ion can give you much more capacity at higher C rates for far longer than Lead Acid. And Lithium depending on chemistry has between 1000 100% cycles to about 5000 at 70% charge discharge V 100-300 for Lead acid at full cycles. And maybe 500 at 50% DOD.

Lead acid might be cheaper but long term value of Lithium is much better.

You can discharge Li-ion 60% between 20% to 80% charge for best long term use.
Lead acid 50%. 100% to 50%.

Warranties don't mean a whole lot. You can charge extra for a substandard product and gamble that your % warranty claims are offset by the extra price margin not to mention that the market price of a warranty return in 6 years will be substantially less than current value due to economy of scale and clever marketing.

10 years isn't a measure of energy.

Mad Lad I see those cycle count claims all the time but have you ever seen it published by an independent laboratory? Link please?

Sir Liamalot

Sir Liamalot wrote: »

You can discharge Li-ion 60% between 20% to 80% charge for best long term use.
Lead acid 50%. 100% to 50%.

Warranties don't mean a whole lot. You can charge extra for a substandard product and gamble that your % warranty claims are offset by the extra price margin not to mention that the market price of a warranty return in 6 years will be substantially less than current value due to economy of scale and clever marketing.

10 years isn't a measure of energy.

Mad Lad I see those cycle count claims all the time but have you ever seen it published by an independent laboratory? Link please?

This is just one I have the time to search for at this time, from A123 Systems, it's a LiFeP04 cell, doesn't have the energy density of the Tesla cells but got longer life and they can't go on fire. I'm not sure how safe Tesla's newer cells are but I'm sure the Specifications are provided by Panasonic somewhere, maybe on the Tesla forums.

I have not got independent tests but these cells are good and well respected. Even Chinese built LifeP04 batteries these days are excellent , depending on the source.

http://www.a123systems.com/Collateral/Documents/English-US/A123%20Systems%20ANR26650%20Data%20Sheet.pdf

I would only use Lead acid if I got them at a really cracking deal but they're only suitable for cranking engines these days because they can still pull several hundred amps for a short amount of time, this is really all they're good at but modern lithium is vastly superior, Where Lead Acid currently has the advantage is in extremely cold climates where lithium batteries would have to be heated.

You don't need Lead acid to crank engines these days , the only reason they're used is because they're cheap.

You can buy a portable battery booster these days not much larger than a large box of matches capable of cranking 3.0L engines but you wouldn't want to keep these in the house !

The Tesla power wall would be vastly superior, but you got to compare it to the cost of Lead acid, if 10 Kwh of lead acid works out 50% cheaper then it's still not necessarily cheaper because you only really get 5 Kwh of lead acid and 50% of the cycle life at best.

I don't know of the 10 Kwh or whatever size powerwall is that the actual "usable" capacity or not ?

murphaph

My gut feeling is that LA makes sense if you can freecycle them or get used cells at a very good price. I do not believe that they are preferential to Li-ion where you have to buy both new.

The warranty does mean a lot. You can compare the price as it is to other products and make your decision based on that price. It is irrelevant to you how much of that price is the manufacturer's insurance against warranty claims. The same happens with cars and basically anything with a warranty, but it's still important to have with a large capital item.

You're right that 10 years isn't a measure of energy but Mercedes at least state that their batteries will have greater than 80% of their initial usable capacity after 10 years. They also state that their 5kWh unit (so 2 2.5kWh modules) will have a usable capacity of 4,6kWh. Their 7.5kWh unit will have 6,9kWh and their 10kWh will have 9,2kWh. These appear to be much higher than the 60% figure mentioned above? They guarantee 4000 full cycles.

https://schlauerspeichern.de/Batteriespeicher_Datenblatt_Home_DE_EN.pdf

Sonnenbatterie have recently doubled their cycles to 10,000 from 5,000 previously. I'm not sure what changed to allow this huge jump tbh. They also quote "usable capacity" on all their batteries, so I think they factor in the max discharge before damage. They also warranty the battery for 10 years but state it has a design life of 20. Nobody can say for sure if that's realistic I suppose.

http://www.sonnenbattery.com/en/sonnenbatterie/technical-information/

I'm keeping my powder dry on storage just for the moment. Have a meeting with an installer about our planned system tomorrow. We'll initially lay it out so it can be interfaced to a Li-ion based solution later, when they get even cheaper. My personal preference right now is towards SolarEdge and panel level optimisation. There have been reports that the rules may well change here and it will be required of PV owners to retrofit bypass relays or similar to ensure in the event of fire, that the fire brigade can safely douse the PV array and enter the building. The SolarEdge has such safety built in to the system (AC pulled from inverter causes each module to drop to 1Vdc, so max 40Vdc or so coming down into inverter-no danger to fire fighters spraying water about the place. The fire brigade here will pull the main fuses in the mini-pillar outside your house before fighting the fire).

My point on warranty is that it's not an assurance of quality.
If these batteries based on 18650 cells are the same as laptop batteries why then do laptop batteries not last 10 years?

Sir Liamalot

Sir Liamalot wrote: »

My point on warranty is that it's not an assurance of quality.
If these batteries based on 18650 cells are the same as laptop batteries why then do laptop batteries not last 10 years?

These days there are many types of 18650 , I'm not sure how many laptops have lithium Cobalt which is the most dangerous of all but offer the highest energy density and probably the lowest discharge rates.. There are far different than the NCA cells tesla use made by panasonic.

Laptop batteries have very basic protection in the sense that they won't over charge or discharge but they usually allow for maximum charge and discharge cycles for maximum run time like your mobile. This has obvious effects on life.

Most laptops batteries sit at 100% charge for days on end while plugged into the mains which is incredibly bad for longevity and capacity will drop pretty quickly. This is for Lithium Cobalt, the most common and not only that but then full charge/ discharge cycles reduce capacity even faster and if they get very warm in the laptop this is another way to shorten life.

My old 8 year old dell laptop battery still has 70% capacity probably helped by the option to set the laptop not to charge the battery past any % which obviously helped. I wasn't particularly kind to it either.

Regarding the Mercedes Batteries they could be lithium Titanate, these are becoming popular for grid storage and have up to 10,000 cycles.

murphaph

The Merc batteries only have 4000 cycles. It's the Sonnenbatterie one that quotes 10k cycles, 10 year warranty and "expected lifetime" (whatever that means) of 20 years.

I expect the price point of these will be forced down by Tesla & Co. and if I had a choice right now of taking any of the "big Li-ion" batteries for free, it would be Sonnenbatterie, but I think a Powerwall in 12 to 18 months and then another one in 8 years is a better option for a paying customer, but each to their own.

The comparison to consumer electronics batteries is sort of moot. They don't need to even think about optimising battery lifetime in a laptop or phone. The last thing Dell, Lenovo etc. want is for your battery to last forever....it's a surefire way to get you to consider that new laptop if the battery begins to lose capacity. The products powered by these small Li-ion batteries are not intended to be used for a decade-quite the opposite from the point of view of the manufacturers. You obviously will use your house in a decade so the specs for a house battery are going to be totally different.

In the same vein I suppose not all LA batteries are created equal. I hear the likes of car batteries are a terrible choice for solar storage, for example.

4000 cycles is a lot of cycles , especially as with EV batteries they won't usually see full cycles daily and they will already have some headroom top and bottom.

Used EV batteries will eventually be used for storage, nothing wrong with EV batteries as long as the protection electronics are still functioning.

murphaph

Deleted User wrote: »

Used EV batteries will eventually be used for storage, nothing wrong with EV batteries as long as the protection electronics are still functioning.

I'd say this will be a massive market in a few years tbh. It's a perfect synergy-used EV Li-ion cells still have more than enough useful life to function as stationary storage in a house for another few years. It's like using old forklift batteries today, but there will be a much larger supply of EV batteries than forklift batteries. Probably something Tesla themselves would be in to.

Well I've got a my ~12kWh used AGMs I expect to be commissioning sometime next year on a cumulative bi-directional energy meter.
Would any lithium fanciers like a challenge?
First one to 80% capacity loses.

murphaph

murphaph wrote: »

I'd say this will be a massive market in a few years tbh. It's a perfect synergy-used EV Li-ion cells still have more than enough useful life to function as stationary storage in a house for another few years. It's like using old forklift batteries today, but there will be a much larger supply of EV batteries than forklift batteries. Probably something Tesla themselves would be in to.

Yeah I'm sure Nissan and Tesla will reuse EV batteries or break packs up and sell individual cells to another company who will test them and match them to other batteries with very close specs and maybe reassemble the cells into much lower voltage for home storage.

The Tesla battery is so big it should be usable after 15 years , reduced range of course but still usable.

Sir Liamalot

Sir Liamalot wrote: »

Well I've got a my ~12kWh used AGMs I expect to be commissioning sometime next year on a cumulative bi-directional energy meter.
Would any lithium fanciers like a challenge?
First one to 80% capacity losses.

Would be no competition, once the lithium is protected with good electronics it should last many years.

But AGM was a good choice, they offer better cycle life and can cycle them to 80% capacity compared to 50% for normal Lead acid.

They do however need AGM specific chargers or charge controllers and will die early if used with normal lead acid charging equipment. Not 100% sure about this but AGM required less voltage than regular lead acid.

AGM are more tolerant to cold than Lithium.

A July 2013 built U.K Leaf Taxi has lost just 10% capacity or a little less after 165,000 Kms and 1,700 fast charges and over 5,000 Normal charges. Amazing for a battery that's cycled so much ! No AGM could ever get close to this !

After nearly 10 months My leaf and nearly 24,000 Kms has lost no capacity.

Deleted User

Deleted User wrote: »

Would be no competition

My thoughts exactly. I think it'd be a good idea start a thread and compare the two systems.

Deleted User wrote: »

But AGM was a good choice, they offer better cycle life and can cycle them to 80% capacity compared to 50% for normal Lead acid.

I disagree, they're over-hyped, over-priced, finicky, delicate things the only benefit of them people agree on is you can turn them upside down.
I'd rather a set of forklifts I could use the electrolyte as coolant but hey they were free so no complaints.

That 80% discharge thing is not true either.

Deleted User wrote: »

They do however need AGM specific chargers or charge controllers and will die early if used with normal lead acid charging equipment.

Yurp, I'm designing my own charge/distribution from off the shelf components. That'll be upgradeable to FLA at a later date.

Deleted User wrote: »

Not 100% sure about this but AGM required less voltage than regular lead acid.

Yeah they're non serviceable, can't top up the electrolyte so you can't charge them properly (above gassing voltage), it's the compromise of sealing a battery.

murphaph

What are the advantages/disadvantages of LA/Li-ion with respect to operating temperature? Tesla say you can mount their battery on an external wall...I considered my attic space but I think it will get far too hot up there in summer.

murphaph

murphaph wrote: »

What are the advantages/disadvantages of LA/Li-ion with respect to operating temperature? Tesla say you can mount their battery on an external wall...I considered my attic space but I think it will get far too hot up there in summer.

Jesus, don't install in the attic no matter what anyone tells you, it's your money !!!

While I'm sure it will tolerate it it will surely shorten it's life with hot sunny days.

Regarding mounting it on an external wall ? you'd probably get away with it in our climate where average winter temps hardly get below 5 degrees C in the day and -5 at night. Lithium can have issues below 20 Deg C. If the electrolyte freezes your expensive battery is dead.

keeping batteries at a happy temp around 20 deg C or a bit lower should ensure a longer life, Attic is a major no no and even while hot days are not that frequent it's too hostile an environment in my opinion, you'd be surprised how many days are too hot for a battery and if the battery is at a high state of charge this including heat will accelerate degradation even further.

Regarding mounting externally, well the specs should give a min and max temp to keep the battery, I would probably not expose it long term beyond 20 Deg C or below -10 but this absolutely depends on the specs and it may perhaps be the case it could have a battery heater which would reduce efficiency but is better than killing it.

The leaf battery for instance comes on at -17 Deg C and switches off at -10 now is they could heat it to 20 Deg C like the BMW I3 (with battery heater) or the Model S it would help speed up fast charging times, but this would be irrelevant for storage batteries because they don't need to charge fast.

If installing externally I would mount in a shady place where summer sun will not shine directly on it and preferably not above hot concrete or tarmac.

I would expect a Lithium storage battery in Ireland would be most happy out doors. or in a cool shed, only thing is sheds can roast in Summer too so keep this in mind.

It's unfortunate Irish people are forced to live in tiny houses in comparison to people on the continent. Little roof space for Solar PV and no cellar, when I go to Germany I really love the design of houses and the space they all enjoy, all the lovely greenery in every village with real trees and proper green spaces not just an empty green field like we have here, thought and effort is put into landscaping there. You will find small places and apartments too but I see way bigger houses than here and more than anything I love not seeing horrible housing estates everywhere, we really destroyed Ireland with housing estates with tiny houses and no design, plain and boring and they all look the same forcing people to live on top of one another and too many housing estates attracts too many thugs. Rant over lol.

Sir Liamalot

Sir Liamalot wrote: »

That 80% discharge thing is not true either.

Perhaps, but like a lot of things it's best to be cautious, in your case you got them 2nd hand so probably best to use 50%. And it depends on the quality of manufacturing. I would be sure if a battery comes from Tesla or Mercedes then it will be of the highest construction and highest quality cells used.

Nissan should get involved too because their current leaf battery in the 2014+ is proving to be extremely reliable and durable. And the 30 Kwh is better again.

The 60 kwh will be a dream !

Deleted User

De-rate lead acid ~1% per degree below 25°C. Uprate same above 25°C but there's a ceiling where they get stressed. Charge compensation +5mV per cell per °C below 25°C and -5mV per °C above.

Deleted User wrote: »

Perhaps, but like a lot of things it's best to be cautious, in your case you got them 2nd hand so probably best to use 50%.

Mad Lad you can't be believing everything you read on the internet. AGMs are non-serviceable FLA with a fancypants electrolyte rules for LA still apply.

I've another system running on 6V FLA that's approaching cycle 400 @ 10% - 30% DOD and they've more capacity now than when I bought them because they're conditioned.

Sir Liamalot

Sir Liamalot wrote: »

I've another system running on 6V FLA that's approaching cycle 400 @ 10% - 30% DOD and they've more capacity now than when I bought them because they're conditioned.

That's not a lot , 10-30% .

murphaph

Several senior Tesla managers have left recently and gone to Sonnenbatterie. Sonnenbatterie has stated that it intends to make a "major announcement" on the 25th of this month. Interesting times ahead.

josip

Powerwall has made it to Wales
It would be interesting to see the cost benefit analysis for the Welsh climate.

I suppose the powerwall would allow you store some energy to use during the day if you have no fit but if you have a FIT then the pay back on a powerwall would take years.

If I add up the cost of electricity, currently 8.4 C/Kwh night rate for charging the car, if I did all my charging at home of 30,000 Kms a year give or take then it would cost me at night rate , based on a consumption of 18 Kwh/100 kms , 453 € per year. Compare that to a 55 mpg diesel, 1,300 a year.

The rest of the house consumes roughly 6.5 Kwh daily, this was monitored before I got the car. So the car consumes roughly 5,400 Kwh over 30,000 Kms and the house roughly 2,100 Kwh or 7,500 Kwh total.

That's a big mother of a battery.

Of course the other part is that I get a lot of free electricity from public charging and also the free work charge point, and when I get the 161 Leaf with 30 Kwh battery (28 usable) it should get me all 140 Kms daily with ease and charged fully from the work charge point saving about 30-40 Euro's PM, not all my charging can be done at night due to working shift. Currently about half my charging is done in work.

I need roughly 15.5 kwh daily according to the energy monitor, some days 25 Kwh some days 7 depending on whether I'm off work or not.

So you're not going to generate this amount of energy in a day with a shockingly low 5.5 Kw/p of solar PV which is the max allowed to the grid on single phase, perhaps with a good wind turbine on a good site but wind turbine + installation is extortionately high in Ireland.

So maybe then the powerwall would take care of some of the excess considering you can only send 5.5 kw to the grid.

The solar PV calculators calculate I would need 8 or 9 Kw/P of solar PV for my yearly needs but this is if all my charging is done at home, on my days off shift then I need to charge at home.

I don't know, I can't see a case where the power wall makes sense ?

What was the cost including installation do we know ?

I suppose the powerwall would allow you store some energy to use during the day if you have no fit but if you have a FIT then the pay back on a powerwall would take years.

If I add up the cost of electricity, currently 8.4 C/Kwh night rate for charging the car, if I did all my charging at home of 30,000 Kms a year give or take then it would cost me at night rate , based on a consumption of 18 Kwh/100 kms , 453 € per year. Compare that to a 55 mpg diesel, 1,300 a year.

The rest of the house consumes roughly 6.5 Kwh daily, this was monitored before I got the car. So the car consumes roughly 5,400 Kwh over 30,000 Kms and the house roughly 2,100 Kwh or 7,500 Kwh total.

That's a big mother of a battery.

Of course the other part is that I get a lot of free electricity from public charging and also the free work charge point, and when I get the 161 Leaf with 30 Kwh battery (28 usable) it should get me all 140 Kms daily with ease and charged fully from the work charge point saving about 30-40 Euro's PM, not all my charging can be done at night due to working shift. Currently about half my charging is done in work.

I need roughly 15.5 kwh daily according to the energy monitor, some days 25 Kwh some days 7 depending on whether I'm off work or not.

So you're not going to generate this amount of energy in a day with a shockingly low 5.5 Kw/p of solar PV which is the max allowed to the grid on single phase, perhaps with a good wind turbine on a good site but wind turbine + installation is extortionately high in Ireland.

So maybe then the powerwall would take care of some of the excess considering you can only send 5.5 kw to the grid.

The solar PV calculators calculate I would need 8 or 9 Kw/P of solar PV for my yearly needs but this is if all my charging is done at home, on my days off shift then I need to charge at home.

I don't know, I can't see a case where the power wall makes sense ?

What was the cost including installation do we know ?

rolion

Offtopic
How did you came up with value of 5.5kwh maxim accepted sent up the "on-grid",please!?

rolion

rolion wrote: »

Offtopic
How did you came up with value of 5.5kwh maxim accepted sent up the "on-grid",please!?

I was off slightly, it's 5,750 watts on single phase.

It gets worse, they only allow 6,400 watts on 3 phase ? oh that's just ridiculous ! only in Ireland !

https://www.esb.ie/esbnetworks/en/generator-connections/micro_gen_connections.jsp

murphaph

Deleted User wrote: »

I was off slightly, it's 5,750 watts on single phase.

It gets worse, they only allow 6,400 watts on 3 phase ? oh that's just ridiculous ! only in Ireland !

https://www.esb.ie/esbnetworks/en/generator-connections/micro_gen_connections.jsp

Not true. In Germany the limit on a single phase can be even lower. Our network operator allows a max of 4,300W per phase unless you feed in symmetrically, ie into all 3 phases. Then our limit is 30kW or 10kW per phase.

I suspect the UK (with similar single phase domestic supply as in Ireland) has similar rules to prevent phases being overloaded and putting the network phases out of balance.

murphaph

murphaph wrote: »

Not true. In Germany the limit on a single phase can be even lower. Our network operator allows a max of 4,300W per phase unless you feed in symmetrically, ie into all 3 phases. Then our limit is 30kW or 10kW per phase.

I suspect the UK (with similar single phase domestic supply as in Ireland) has similar rules to prevent phases being overloaded and putting the network phases out of balance.

https://www.electricireland.ie/residential/help/micro-generation/electric-ireland-micro-generation-pilot-scheme

"Micro-generation covers small scale generators where domestic customers produce their own electricity and export the surplus onto ESB Networks LV System. This is subject to a rated maximum output of:

6kW when the connection is single phase
11kW when the connection is three phase"

freddyuk

murphaph wrote: »

Not true. In Germany the limit on a single phase can be even lower. Our network operator allows a max of 4,300W per phase unless you feed in symmetrically, ie into all 3 phases. Then our limit is 30kW or 10kW per phase.

I suspect the UK (with similar single phase domestic supply as in Ireland) has similar rules to prevent phases being overloaded and putting the network phases out of balance.

In UK it is 16amp maximum (3.7kw) and then you need DNO permission and/or a G59 certificate and possible witness testing. They often refuse any export as we have a lot of solar farms so the capacity is all gone in some areas.

murphaph

Deleted User wrote: »

https://www.electricireland.ie/residential/help/micro-generation/electric-ireland-micro-generation-pilot-scheme

"Micro-generation covers small scale generators where domestic customers produce their own electricity and export the surplus onto ESB Networks LV System. This is subject to a rated maximum output of:

6kW when the connection is single phase
11kW when the connection is three phase"

The 3 phase 11kW limit is low relative to Germany but the single phase 6kW limit is high and seems high relative to the UK too according to Freddy's post. I was simply highlighting that the limit is not "only in Ireland".

The difference with Ireland (and UK and presumably many other countries) is that much of continental Europe, more by accident than design I think) has 3 phase supply to domestic dwellings as standard. Nobody was thinking of feeding in electricity into the grid from micro generation 50 years ago.

It's the fact that dwellings typically only get a single phase that will always limit the ability for microgenerators to feed in without paying for an upgrade to 3 phase. I don't know if there's a technical reason for the 11kW limit on 3 phase in Ireland. That is low, though as almost nobody has a 3 phase supply at home, it is sort of irrelevant for most.

freddyuk

You can have 6kw single phase in Ireland IF you can get the planning because permitted development is restricted to 2.7kw.!! You need to pay a lot of euro to find out if you can have the permitted maximum which is another stumbling block to Irish micro generation. In UK the permitted planning law allows for the full authorised unrestricted capacity (4kw installed capacity) which kinda makes sense? Why is Ireland so against it?

4 Kw isn't a lot.

Probably because of the lack of investment in the Grid over the years ?

I think if enough homes had solar PV then they could at least eliminate the Coal power station, Moneypoint is it ? It generates roughly 20% of our electricity which is too much.

The other side is that Gas plants have to generate probably xx years to make a pay back ? so if there is more renewable energy then the need for Gas plants reduces ?