Tesla unveils the Powerwall home storage battery

[HEXUS]

Charges from solar or at economy rate times, saves money, provides power outage buffer.

Read more.

[Biscuit]

Sounds... pretty reasonable actually. If you could realistically get your leccy bill close to £0, it would only take up to maybe 5-6 years(?) depending on your usage and house size to pay off your initial outlay and then you would still have 4-5 year warranty to lean on, optionally another 10 years.

I have my concerns about the construction of the battery and its environmental impact, but thats another story.

[Tabbykatze]

I can see a lot of people buying these to utilise night time electricity charges which are cheaper so that when they're using it during peak times they flip to battery to save money. A youtuber called "PhotonicInduction" did exactly that and apparently he was nearly paying nothing by selling back the electricity generated through other means and only consuming off-peak grid electricity when needed.

[DDY]

There's Photonicinduction on Youtube who charges lead-acid batteries during the night on the cheap tariff to use during the day. Works as backup power too;

https://www.youtube.com/watch?v=ka0MfipmdBw

[AlexKitch]

I have to wonder about the lifespan of the battery, and how expensive it would be to replace if it deteriorated

[dave2207]

Final paragraph: ".. State of California wants public utility companies to start storing 1,325 megawatts of energy by 2024 to minimise waste ..."
Energy is NOT measured in Mega-Watts! Energy is measured in Joules (or, if you must, kilowatt-hours kWh). You cannot store power - only energy.

[Corky34]

I'm no wizz when it comes to electricity but does the 5amp, 8.5amp max not matter when it's going through a DC-AC converter, what happens if you need to power something with higher amperage?

[LSG501]

So it's basically a giant UPS.... I've liked the idea ever since having solar panels (tesla are not the first) but the price is just too expensive compared to the savings, not mention things like life span etc.

They say 3000-3500 (no point doing currency conversion) + fitting and in some cases an ac/dc inverter (that can be £2000 if it's the same as a solar one). Think we had a quote of around £8000 for one that supported our usage and solar panels (4kw system).

Another thing was they were not actually uk quality assured (kite mark or whatever it is), they were perfectly fine supposedly but only EU quality checked

[watercooled]

Megawatt-hours is a thing too (or any other prefix of course), as I assume this means. But yeah, I don't know why energy is so commonly confused with power. It's bad enough that 'food' calories are actually kilo-calories.

About the batteries - I have to wonder if Li-ion is really such a great chemistry to use for stationary batteries. There was and is nothing wrong with using e.g. lead acid unless you're really short of space. For much less than a grand you can easily exceed 10kWh with a lead acid bank - a quick look on Amazon shows 110Ah batteries for £79. So that works out 8 batteries for just over 10kWh at £632, and that's retail price. Sure, you have the inverter and chargers too, but even so $3500 seems like a lot, and that's for the better-value 10kWh system.

Edit @corky: the current rating appears to be for the high voltage battery bank, not the inverter output.

[CampGareth]

Megawatt-hours is a thing too (or any other prefix of course), as I assume this means. But yeah, I don't know why energy is so commonly confused with power. It's bad enough that 'food' calories are actually kilo-calories.

About the batteries - I have to wonder if Li-ion is really such a great chemistry to use for stationary batteries. There was and is nothing wrong with using e.g. lead acid unless you're really short of space. For much less than a grand you can easily exceed 10kWh with a lead acid bank - a quick look on Amazon shows 110Ah batteries for £79. So that works out 8 batteries for just over 10kWh at £632, and that's retail price. Sure, you have the inverter and chargers too, but even so $3500 seems like a lot, and that's for the better-value 10kWh system.

Edit @corky: the current rating appears to be for the high voltage battery bank, not the inverter output.

I thought lead acid charging efficiencies were naff, i.e. you put in 500Wh and get 100Wh out, whereas lion it's pretty much 500 in 500 out?

[peterb]

That would be really useful in conjunction with solar PV cells for meeting peak demand during the day when peak demand exceeds the power generation of the cells at any given time, and meeting the background load during the hours of darkness.

[watercooled]

I thought lead acid charging efficiencies were naff, i.e. you put in 500Wh and get 100Wh out, whereas lion it's pretty much 500 in 500 out?

Lead acid are nowhere near that bad, even cheap batteries should manage >85% and well over 95% is attainable with the chemistry. Li-ion are more efficient but they're also massively more expensive. None are 100% efficient though.

NiMH are considerably less efficient though, but still >65%, nothing like the 20% you suggest.

Aside from a possible marketing push, I just don't see this as something ground-breaking, people have been using lead batteries for donkeys for this sort of thing but the current market seems to make it less economical than just exploiting silly-high feed-in tariffs.

Edit: I've just realised that $3500 doesn't seem to include the inverter either, so it looks even worse! I'm just wondering, what exactly is this supposed to do that isn't already possible for less money?

[devBunny]

A £3500, 10 km weekly cycle model and a $3000, 7 km daily cycle model.

So I have to charge the £3000 one by cycling for 7 km on my exercise bike every day but the £3500 one only needs a 10 km cycle once a week? Seems strange. Maybe I'm missing something.

[Chadders87]

Energy is measured in Joules (or, if you must, kilowatt-hours kWh). You cannot store power - only energy.

Absolutley, including Giga Watt hours (GWh) which is the size most energy firms report in.

[Inverted3ntropy]

Sounds... pretty reasonable actually. If you could realistically get your leccy bill close to £0, it would only take up to maybe 5-6 years(?) depending on your usage and house size to pay off your initial outlay and then you would still have 4-5 year warranty to lean on, optionally another 10 years.

I have my concerns about the construction of the battery and its environmental impact, but thats another story.

Biscuit, can you please elaborate that which disturbs you about the environmental impact of manufacturing of LIB?

[watercooled]

Biscuit, can you please elaborate that which disturbs you about the environmental impact of manufacturing of LIB?

The manufacture of the raw materials e.g. lithium, cobalt and nickel would be a good place to start reading.

I'm not arguing one way or the other; I don't claim to know the whole picture but from what I do know about the processes I think it's reasonable to have concerns.

For a lot of stuff which claims to be 'green', it's not always as simple as it first appears. For example, some product may consume less energy during its use but it's hard to draw conclusions about its 'greenness' without knowing about the energy consumed and environmental impact of manufacturing.