Tesla to unveil home storage batteries

marcosdjcm

zeupater wrote: »

Of course, you have somewhere well over 60 square meters of southerly aspect window to place the panels in and don't mind it being pretty dark in the flat all summer ? .... and of course, you'll already have realised that you'll be running everything at ~12VDC !

Z

Yeah we probably should have had an electrician in the circle to make sense of it. But we were just basing it off pure kWh numbers from my last year's bills. It's likely heavily flawed.

And yep I don't mind the flat being dark in the day as I'm at work.

Martyn1981

Not a new idea to Japan, but new to Europe. Use your EV to reduce demand on the grid in the evening, then charge it up at night when demand is low.

Nissan wants you to use its Leaf EV like a Tesla Powerwall

The big unanswered questions are how much the V2G system will cost, and how well it can balance feeding your home against making sure your EV is still good to go at any time. Given the large capacity of the Leaf's battery (30kWh) vs. Tesla's Powerwall (7kWh or 10kWh, depending on the model), it's not the biggest issue, but it's unlikely to help much with range anxiety. The Nissan Leaf has a range of around 124 miles, making even a 80-percent charged car far less useful.

As for price, ENEL, through sponsored content, has previously pegged the cost of an V2G charger at around $900 -- a good deal cheaper than Tesla's $3,000 Powerwall system, although obviously that includes a battery.

Mart.

Martyn1981

Welsh home installs UK's first Tesla Powerwall storage battery

I assume this has been done in conjunction with SolarEdge as that's one of their inverters and management systems in the background.

Mart.

michaels

Martyn1981 wrote: »

Not a new idea to Japan, but new to Europe. Use your EV to reduce demand on the grid in the evening, then charge it up at night when demand is low.

Nissan wants you to use its Leaf EV like a Tesla Powerwall



Mart.

Might make real sense in places like Germany where thy have over deployed solar....

ed110220

michaels wrote: »

Might make real sense in places like Germany where thy have over deployed solar....

Over deployed? Do you have a reliable source for that?

There are lots of reasons why storage is a good idea beyond solar or even renewables. For example in traditional grid systems, the cheapest electricity tends to be produced by large power plants that cannot modulate their output easily. As demand rises, more and more expensive plants are brought online. This is why economy 7 and similar tariffs are available. If it were possible to economically store cheap energy when it is not otherwise needed and release it for use later instead of firing up expensive 'peaker' plants, there would be a great benefit.

zeupater

ed110220 wrote: »

Over deployed? Do you have a reliable source for that? ....

Hi

I'd guess that the reference related to the grid frequency problem which caused concern in Germany as installed capacity became more significant a few years back.

Grid balancing is really based on little more than maintaining frequency. Too little power to meet demand and mechanical generators start to labour so slow down causing the AC frequency to fall, too much and the generators start to free spin, so when frequency drops additional generation is brought on-line to meet the balanced target of 50hertz, then tweaked down again when the frequency rises too high. Solar inverters are designed to feed into the grid by matching existing conditions and have tolerance switching where they stop feeding AC if the grid conditions are beyond the accepted tolerances, which opens up a potential issue for the grid as the percentage of micro-generation increases. With too much micro-generation which isn't subject to central control there's the possibility that the available power causes the frequency to rise without control, which, when hitting the upper tolerance level, theoretically causes a substantial proportion of the micro-generation installations to register an out-of-tolerance condition at the same time and simply switch off, the knock on effect being an immediate massive shortfall in power generation, creating havoc across the entire grid ..... well that's the theory, so when the country with the highest percentage of pv started to approach a level where theory became an approaching threat, the inverter software control specifications were simply changed to ensure that micro-generation progressively ramped down as the upper frequency (50.2Hz) became closer .....

In effect, what was a potentially huge problem isn't anywhere near as huge anymore .... it's just that lots of articles are still based on outdated sources, which are regularly referenced by the 'worried' centralised generating corporates and many of their 'vested interest' supporters ... If it's an issue which has already been addressed, apart from blatant misinformation I see no reason why we see so much about it ...

HTH
Z

Ectophile

Martyn1981 wrote: »

Not a new idea to Japan, but new to Europe. Use your EV to reduce demand on the grid in the evening, then charge it up at night when demand is low.

Nissan wants you to use its Leaf EV like a Tesla Powerwall



Mart.

This is just asking for trouble. Imagine you've just had dinner. You now need to pop down the supermarket to buy food for tomorrow. But you can't - the battery on your EV is nearly flat because you used all the charge in it to cook the dinner.

The range on EVs is bad enough as it is without flattening the batteries every evening.

Martyn1981

Ectophile wrote: »

This is just asking for trouble. Imagine you've just had dinner. You now need to pop down the supermarket to buy food for tomorrow. But you can't - the battery on your EV is nearly flat because you used all the charge in it to cook the dinner.

The range on EVs is bad enough as it is without flattening the batteries every evening.

I don't think there will be any major problems. Have a think about it, and assume first of all that there will be a management system preventing the batts from going below a chosen charge.

Next think about the draw rate, possibly 1 or 2kW for an hour or two. These batts are designed to deliver massive power over a very short time, so low draws of 1 or 2kW will probably have no impact whatsoever on battery life - effectively free storage*.

Also, how much leccy is used in the cooking of dinner. Let's say a 3kW kettle for 5 mins = 250Wh. 800W microwave for 15 mins = 200Wh. Leccy hob, 1.5kW for 30 minutes = 750Wh.

Always remembering that you're not off-grid, you can draw another ~23kW from the mains, so again, presumably, limits can be set on kW and kWh. The car doesn't have to supply your needs, just supplement them.

'Just' 5m cars supplying 1kW for 2hours would pretty much remove the evening peak, and that's just domestic vehicles, their could be commercial vehicles such as buses, or industrial storage all willing to supply evening leccy if they are subject to time priced leccy.

Don't get me wrong, I'm sure there will be issues for some households planning to travel in the evening, but I'm sure the majority will be fine, then they have all night, with low demand and low prices to charge back up.

[Edit: * Just to clarify, I mean free storage in terms of battery costs, not leccy costs, nor system efficiency losses. You can price the cost of storage by dividing the batt price by the number (and size) of cycles. These small domestic kW and kWh draws will probably have no detrimental effect on batt life expectancies or performance as they'd barely be ticking over at such levels, compared to the harsh life they are designed for. M.]

Mart.

EricMears

Ectophile wrote: »

This is just asking for trouble. Imagine you've just had dinner. You now need to pop down the supermarket to buy food for tomorrow. But you can't - the battery on your EV is nearly flat because you used all the charge in it to cook the dinner.

The range on EVs is bad enough as it is without flattening the batteries every evening.

I guess it all depends on how soon after cooking the dinner you want to use your car and how far you want to go.

I'd probably still want to cook my main meal of the day at lunchtime (when there's free power) rather than doing so in the evening although I realise that may not be an option for everyone.

And (again speaking personally) I don't think I'd want to go very far from home between 8pm (when the grid peak has about finished and most people cooking in the evening will have started eating) and 1am (when I can start charging on E7.

If battery was prevented from discharging below a third full, I'd still have 30 miles of range left and don't envisage needing to go anything like that far most nights.

And of course if I knew I needed to make a longer trip at that time of the evening then I'd just unplug the car and opt out of supporting the grid that night.

almillar

But you can't - the battery on your EV is nearly flat because you used all the charge in it to cook the dinner.

So you set a minimum charge that the car won't go below. Problem solved. Lots of electric cars have a pre-heat function - this won't work below a certain charge either, so that it doesn't take range off you. I think you might have your sums wrong with cooking the tea. An oven plus a hob might take, what, 5kW to run? Run them for an hour. That's 5kWh. A Renault Zoe has a 22kWh battery.

And as Martyn1981 says, you've got more than a day's worth of charge in an electric car - motion is expensive - so even running the house in the evening wouldn't use too much, then you can get it back overnight at a cheaper rate.