Re: Load balancing
"I have a 10MWh battery store near my house:"
"The project was awarded £13.2m from Ofgem’s Low Carbon Networks Fund"
At least 75% paid for by tax payers because it makes no economic sense.
A couple more interesting details have emerged about Tesla's “game-changing” home battery, and it remains a moderately limp competitor that's done wonders for market awareness. Courtesy of Bloomberg, the world gets an idea of what the retail from-the-installer price of the battery might look like (rather than the wholesale …
See also a separate project at:
Another justification I have seen for these is entirely independent of the renewable energy storage aspect.
A few MW (a few MWh) of 11kV-connected storage may allow a distribution network operator to avoid upgrading their distribution infrastucture.
Can't comment on the commercial validity but technically it sounds vaguely plausible. You've got X MW supplies into a district whose peak demand 3 years from now will be X+15%, and which from time to time already hits X+2%. Put in a grid-connected battery of X/10MW and you've avoided (for now) upgrading the supply to the area?
That was the premise quoted, anyway.
I was staying at a friend's place somewhat out the way in Australia a while ago, where mains utilities aren't a thing, so they get all their electricity from the sun and store it in what looked to me like a bigger version of regular leisure batteries. That provided enough electricity to keep everything running in the house well enough.
Are there any reliable comparisons around of how the Tesla specs match up to the solutions currently used in that type of environment?
This is an interesting development for us, as we're off grid. The idea seems sound to me, to have an all-in-one device that contains the circuitry to charge, invert, feed-in and feed-out. That's the interesting bit, not the battery bank or capacity.
FWIW, we have a 15kWhr bank, never taken below 50% SOC, as that kills the life. But we don't think of its capacity in kWHrs, as that's useless. Amp-hour rating is more important. Comments here about batteries with 300A capability are not too relevant, as these are for car starting conditions, not the typical requirements of deep cycling. And assuming you /get/ the full rating from a battery bank is also misleading, though admittedly non-lead-acid batteries are less affected by deep discharging.
We installed a desulphation unit, a simple device that puts a high frequency pulse across the terminals constantly, and that has keep the batteries sulphation-free for 6 years (touches wood.) Sulphation and over-deep discharge are the two killers of lead-acid batteries.
But our conditions, off-grid, are not really anything like those for which one assumes these Tesla power packs are designed. Our details just for interest...
"But we don't think of its capacity in kWHrs, as that's useless. Amp-hour rating is more important."
Yes, of course it is totally useless thinking about the actual amount of energy available rather than just the number of Amps :rolleyes: I suggest you go back to school, you need Amps and Volts together, one without the other is meaningless. Watt do you get from Amps and Volts? (clue in question.)
Gosh, a simple bit of information on real world experience shouldn't elicit such a response. But still, let me try to be a little clearer. If you are off-grid, then you have to take steps to ensure you do not over-tax any piece of the system, and one of those is the battery bank, which, if you abuse it, reduces the life of the most expensive component dramatically. Power comes in from wind and sun, and that you can see using an ammeter. Rough state of charge is given by the under-load voltage. We know we can use around 300 AHrs of a fully charged battery bank assuming no charging regime, before we start damaging the battery.
Now there is no point in doing the maths to tell us power input and output in kilowatt hours, as we have to concentrate on the two things easily measured. Yes, after 7 years of off-grid living, I do know one or two of the more basic formulae, but I was simply commenting on how things work in practice. I hope that makes things clearer.
If I'm missing some practical knowledge about managing a battery bank using kilowatt hours, I would very much like to know more, though, but if it's just ideal bench theory, well, that's a bit less helpful.
"We know we can use around 300 AHrs of a fully charged battery bank"
Is that a 72kWh battery bank able to supply those 300 Amps for an hour at 240V, or a 0.3kWh battery bank able to supply those 300 Amps for an hour at 1V? I think there might be a slight difference in size and cost between the two but they are both 300 Ah battery banks.
I didn't see a manual on Tesla's web site, but the Powerwall packs might only be usable in a grid-tied system from how there marketing fluff reads. The tiny amount of information available isn't enough to make an informed buying decision. I read another article that stated the Powerwall didn't come with an inverter. At this point, they are vaporware.
The best backup battery is likely to come as a kit for a used car pack that doesn't provide enough range anymore, but is perfectly serviceable for a home application. DIYr's are snapping up the used Prius NiMh packs since they are easy to refurbish and not as fussy as Li chemistry batteries.
Somehow I think that P.T. Musk is trying to forestall competition before the Gigglefactory is producing.
Hi interesting article and comments by lots of folk but that part you mentioned about no manual I enlarged one of the photos of musk battery packs .There is no control gear or inverter gear you only get the battery for that price, better look up Halfords for lead acid batteries .
Why buy this rubbish for home use when you can buy LifeP04 for close to the same price ?
Yes, it kickstarts the market but it is a pretty crap offering. Tesla lasts 10 years 'if you don't use it' whilst LifeP04 in the same rubbish scenario lasts 40 years !
The standard Lithium is built for lightness but until the hype was not really deemed sensible for home use.
And if you really are off-grid and rely on this technology to keep you powered up, you'll need a backup in case of failure (guarantees are nice, but they don't keep the lights on and if it takes a week to deliver a replacement to your remote, off-grid location ... ), or for those times when your "old" battery is being replaced.
The thing about multiple LA batteries is just that: you already have the makings of a resilient solution. Or at least one that can operate at reduced levels, rather than being a single all-or-nothing proposition.
So, as with all H.A. systems: computer or home, the cost of a truly reliable system is a multiple of the cost of a single purchase.
The tech makes sense for reduced weight. Such as cars, phones, laptops.
In terms of volume, not weight, the NiMH is close and can do more full cycles. My laptop is on it's 5th 14.8 V 5.2 AH pack, and is mostly used on mains, not off grid.
How much capacity does the 7KWH battery have after 700 cycles of 50% discharge (i.e. Off grid and using electricity every night, the sun don't shine)?
Weight or space isn't an issue for fixed solar applications, mobile mast or telephone exchange backup. Hence they use Lead Acid.
In Europe almost all the lead in Lead Acid batteries is recycled to make Lead Acid Batteries. The manufacturing cost and energy input to make Lead Acid batteries is far lower than the same capacity of NiMH or Lithium Ion. They are simple, and also with recycling much "greener".
"In terms of volume, not weight, the NiMH is close and can do more full cycles"
I like NiMH technology - it's actually a rechargeable hydrogen cycle with the hydrogen stored in mischmetall, very neat technically - but it uses an awful lot of nickel and cerium, which are not cheap and have lots of other uses. It's better to concentrate on lithium and aluminium technologies from the point of view of resource constraints - at least for the next 10 years.
I can see you've never been anywhere near a lead acid battery recycling plant.
Sadly, at least over here, there are no requirements to filter the air coming out of the plant. And I know a fellow that worked in one. And the kit they wore in there, the rules about tears in the suits made it pretty clear how "green" that air was.
I'll admit, at least they *are* recycling the stuff, and it makes it cheaper, but the acid is neutralized and tossed down the pipes around here. The dust from the grind/melt process and the off gasses from the "smelt out the plastic" routines are pretty damned nasty. The smelter output is run through filters, but the grinder room is open to the environment.
Not to defend Tesla in particular but rather to question people's expectations... I think that people have to stop branding the Powerwall battery a failure because it can't power all of a household's high wattage appliances at the same time.
If you're already off-grid, then you're probably already well aware that electricity usage has to be somewhat planned and you can't just wake up in the morning and fire up the toaster, kettle, oven, electric shower, hairdryer, curlers, washing machine and dishwasher simultaneously and to suggest that this battery, which is probably smaller and less robust than a lot of true off-grid'ers battery banks, should be able to do that seems rather unfair.
It's most valuable achievement seems to be raising awareness of the need for energy storage in a green energy dominated grid. Whether it's a good product seems rather less certain from the specs. I thought lithium cells were supposed to avoid the lead acid pitfalls of limited charge cycles and death by excessive discharge etc? Apparently not these...
Perhaps a more natural market for these sorts of mass-market, plug-and-play, all-in-one, certified and standardised solutions will develop as an integral part of a smart grid, controlled by the National Grid who would govern when and what wattage the Powerwalls would release to homeowners:- With the Grid sending out automated messages like "Calling all Powerwalls... calling all Powerwalls... calling all Powerwalls: The Greens haven't touched their lentil and bean soup today and so mighty fleets of wind turbines aren't quite spinning fast enough to generate enough electricity to meet demand. Can you all switch on and each reduce your house's draw from the grid by 500W using the energy you were able to store from your solar panels earlier when the sun was still shining out of the Greens' arses"
Musk could sell sand to some of the braindead Arabs. Even though his EVs and Powerbricks make no technical sense, some braindead people will buy them. That's easy money for Musk to extract so he'll continue to dupe the gullible.
Anyone with a clue can understand the false premise under which EVs and Powerbricks are being sold. But hey there is a sucker or two born every second so Musk should have no problem making a fortune.
There is a reason that UPSes mostly use old fashion lead acid batteries instead of lithium, lead is cheap, very very cheap. In fact lead is the very definition of a base metal. Lithium is favored in mobile applications because it's light, that matters to the phone in your pocket and it really matters in a car because the energy used to move a car is directly proportional to the mass of the car, for those of you who didn't take freshman physics the equation is
K = 1/2 * M * V^2, i.e.
Kinetic Energy = 1/2 * Mass * Velocity * Velocity.
So if you cut the weight of a moving vehicle by 50% you cut the energy used to get it to speed by 50%. However a battery pack that sits in your basement has a velocity of 0 so the weight doesn't matter as long as it doesn't exceed the load limit of the floor which in the case of a typical concrete basement floor is very very high. So the only factor that matters for a backup battery system is lifetime cost and that's an area where lead acid batteries are always going to beat lithium batteries because no metal is cheaper than lead, and the process for making a lead acid battery is dead simple. Also lead is really easy to recycle when it comes time to replace the batteries because it's melting point is so low as anyone who has ever soldered a wire or a pipe (before they banned lead solder) knows.
“The model puts out just 2 kilowatts of continuous power, which could be pretty much maxed out by a single vacuum cleaner, hair drier, microwave oven or a clothes iron.”
Such is the sorry state of science & mathematics in journalism these days that the above fool sentence was published. At least in the USA none of the above is used on larger than a 120V 15A circuit which is rated for 12A continuos duty (1440 Watts). Admit one can not run much more but to imply "maxed out" one is suggesting one is at or over the limits, not 72%.
"Such is the sorry state of science & mathematics in journalism these days that the above fool sentence was published. At least in the USA ..."
We don't all live in the USA. There are several devices in my house in the 2-3kW range that plug into the conventional circuit. (Furthermore our socket circuits are usually ring circuits rated at 30A).
Funny you should mention this as I have been on a Kettle Effiiciency program lately, after one of the kids (the one with an unfortunate congenital condition that makes a propeller stick out of the top of his head), asked about it.
Phase 1) The new kettle is glass see through with graduations on the side. I have gotten into the habit of working out exactly how much water I am going to use , and filling exactly. Added a few extra special marks like 1,2,3 tea mugs.
Phase 2) I now fill it from the hot tap whenever I can. **WTF???** you ask. Well changed the water system to solar. I might hook the electric element in the cylinder up, when the missus complains about getting a cold shower. Here we are one month from the winter solstice, and it still hasn't happened.
Phase 3) The kids came back from the op-shop with a big thermos. Now I am using 1 thermos as a tea pot, and another for boiling water when I make too much.
The nett result was 80% drop in power used by the kettle. Most of the energy went on boiling the same water again and again, and making endless cups of tea that get 50% drunk, then go cold. Saved a fair bit on tea as well. And mostly I have instant tea (properly drawn) and instant hot water - don't have to wait for the kettle.
The problem I have with such efficiency drives:
Multiply by time. The kettle might be stupendously powerful. But unless it's on for an hour at a time, it's not really worth counting. The more powerful kettles boil even quicker.
All your faffing about, if it boils ten litres a day, might say you a single unit of electricity. Maybe.
Sure, it's a lot of energy, but it's not the end of the world.
However, as pointed out, a quite jaunt in the shower might - on electric - be as powerful (or more) and last 15-20 minutes, for multiple people, multiple times a day. That's a lot more power.
All the messing about buying glass kettles and thermos and transferring from one to the other and taking only a little bit of water and so on and so forth... I can't justify the hassle.
And what you want could have been achieved easier with those taps that boil the water for you on demand, the same as the heating elements in the cheap coffee machines that can produce instant boiling water. Nothing is "kept warm". Nothing is heated unless it's to boiling point. And you heat only as much as you need to boiling point.
Two approaches, same cost-saving, one a luxury and convenient, the other messing about with thermoses and drawing lines on your kettle and educating your kids. And, actually, the one with the much higher temporary draw on the power supply, seems to make much more sense to me when you figure out the energy made to produce a glass kettle or vacuum-sealed glass thermos.
Hi not that I want to rain on anyone parade but don't ever drink water from a hot water storage tank . The water temperature is usually just perfect for legionnaires and other bugs to grow. Boiling the water will indeed kill them ,but that is boiling the water for 10 minutes not just for tea . While your immune system is good it wouldn't be so much of a problem but if you any other infections it's a different story.
It isn't about the minutiae of which battery from which supplier.
The interesting part is that Elon Musk, a proven tech innovator, has pointed out that renewable generation + battery storage is actually viable, and do-able.
Like him or not, people do listen to him - and like them or not, PayPal, Tesla and Space X have real working products.
The Tesla Power Wall will be a working, consumer grade product that people will buy, partly because of belief in Musk's vision (which is an altogether positive vision for CO2 reduction).
Tesla have open-sourced all the technology for others to build compatible products.
Credit where credit is due, and a big fat battery for fast charging in every garage would help kickstart the switch to electric transport too. Surprise, surprise!
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