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[LordBucket]

www.teslamotors.com/powerwall

The news
So after a week or two of anticipation, it turns out that the Tesla Motors announcement was exactly what everybody expected it to be: a wall-mounted home battery to allow solar powered homes to go completely off grid by storing electricity generated during off-peak hours and using them through the night, when solar generation doesn't happen...because the planet's in the way.

$3500 for 10kw hours or electricity. Scalable. Up to 9 units can be snapped together for up to 90kwh of storage. As well as an industrial capacity unit with 100kwh of storage that they claim is inifinitly scalable. According to the video they already have an order for a 250 MEGAwatt hour installation, and there was discussion of using this to provide overnight backup power for entire cities.

Why does this matter?

One of the main weaknesses of solar panels is that they only generate power when light is hitting them. The sun is below the horizon for a lot of hours every day, and even when it's visible, peak usage hours are not the same as peak generation hours. And simply feeding the excess into the grid, while doable...is problematic, and not entirely scalable. The current grid is simply not designed to accommodate the way solar provides it power.

This potentially solves that problem.


Personally I think this is a reasonable solution. But I think it's a little early. For a long time,the bigger problem with solar has not been capability, it's been cost. Home solar systems still routinely cost $20,000 or more. Whereas the average home monthly electrical bill is only in the $80-$200 range. Even if you live in an expensive state like Hawaii, with a $190/month average, it can still take over a decade to break even on solar. In a more typical case it might be 20 years, close to the warranty period on most panels.

Solar still needs to be cheaper.

That said, it will become cheaper, and having a solution to the grid problem is helpful. This is probably a good move. Though it might take a few more years before it becomes very popular. If Swanson's law continues to hold, and the price of solar continues to drop by 20% for every doubling of total installations, that $20,000 installation will be $10280. At current rates, total worldwide installations are doubling slightly less often than every two year. About two and a quarter. So ~7 years to reduce costs in half. And if we're lucky, cheap and convenient batteries like Tesla's will speed up the installation rate. Even so, $10,000 plus $3500 will still take ten years to pay for itself in a more average-cost state like Florida or Nevada, and even longer in a cheap state like California.


I think we still have some years before this really takes off. But, it is coming.

[Zrk2]

Looks great, but most batteries are made in China, where there's basically no pollution regulation. What's the carbon output/unit energy stored when averaged over its' lifetime?

[Sergarr]

Problem here is that you need some mighty huge batteries to store that much energy.

[LordBucket]

I've been wondering why this hasn't been done yet

Human battery technology just isn't very good.

For example, a typical 40 pound $100 car battery has sufficient capacity to run a single refrigerator for only about an hour.


In Musk's presentation he likens switching the planet over to a purely solar/battery system to be a project of similar magnitude to building all cars currently on planet earth. You would need billions of those batteries he's selling. Which, like he points out, is not an unattainable goal. You could do that. Humanity might do that. It's not a bad or unlikely proposition. But it's not a trivial proposition. And only about a third of overall power use is residential. Pulling houses off the centralized power model is a lot easier than pulling factories and cities off.

[Zrk2]

I've been wondering why this hasn't been done yet

Human battery technology just isn't very good.

For example, a typical 40 pound $100 car battery has sufficient capacity to run a single refrigerator for only about an hour.

Well, running any sort of thermo-loop off DC power is inherently horribly inefficient. But still, your point stands.

[Reelya]

through the night, when solar generation doesn't happen...because the planet's in the way.

Punch a hole through the planet and you can have solar all the time, and no need to pay Tesla's exorbitant prices.

$3500 for 10kw hours or electricity. Scalable. Up to 9 units can be snapped together for up to 90kwh of storage. As well as an industrial capacity unit with 100kwh of storage that they claim is inifinitly scalable. According to the video they already have an order for a 250 MEGAwatt hour installation, and there was discussion of using this to provide overnight backup power for entire cities.

Not just overnight storage, instead of giving away excess coal-generated power overnight at cheap rates, it can be stored and sold at peak time for full price. This has several benefits: off-peak pricing drives up consumption, which drives up pollution emissions, since people deliberately run things during the off-peak period. Also, with good storage, generation capacity no longer has to cater to peak energy use, only average energy use. This means running plants at lower capacity and reduced need to buy new plants, and reduced need to buy energy from other cities, which has flow-on effects reducing peak generation needs across the country even if not every city does this.

[Ukrainian Ranger]

through the night, when solar generation doesn't happen...because the planet's in the way.

Punch a hole through the planet and you can have solar all the time, and no need to pay Tesla's exorbitant prices.

Pffff. Moving your house to the Sun will give you even more solar power!

[RedKing]

through the night, when solar generation doesn't happen...because the planet's in the way.

Punch a hole through the planet and you can have solar all the time, and no need to pay Tesla's exorbitant prices.

Pffff. Moving your house to the Sun will give you even more solar power!

Pfft. Still losing 99.9999999% of solar output to all those places your house *isn't*. The obvious solution is to build a Dyson Sphere of solar panels. All the solar power you could ever possibly need.*















*And you're going to need a lot for air conditioning, because inside that Dyson Sphere is going to get pretty toasty from all the captured thermal energy.

[Reelya]

We can use that thermal energy however in huge heat engines. Since space is damn cold, we have a heatsink capable of absorbing the heat.

And we have a perfect use for all the electricity of the sun: cosmic-grade bitcoin mining. We can stabilize a decentralized currency for the next 5 billion years. Take that, bankers!

[Bauglir]

... The thought of building a Dyson sphere for no purpose other than to run its own air conditioning just tickles me for some reason. At that scale you probably actually could manage the heat gradient necessary to drive a laser or something for heat disposal (it's still gotta go somewhere), so essentially you'd have constructed this incredible megastructure that serves no purpose but to convert solar output to a beam with tremendous amounts of waste. Although I suppose that could actually still be pretty useful.

[Reelya]

How about we make a sun-powered laser weapon that focuses total solar output on other star systems. I'm pretty sure we could vaporize entire planets around other stars if we pinpoint focused the sun's output.

Why take the risk of hostile E.T.s existing when we can blast every star system within 100 light years to dust?

[Helgoland]

You take pre-emptive warfare to a whole new level. I salute you, and would like to offer my services.

[Ukrainian Ranger]

Back to serious discussion

Followed the link...
For 100% solar powered house you want this

7 kWh $3,000
For daily cycle applications

not

10 kWh $3,500
For backup applications

Power
2.0 kW continuous, 3.3 kW peak

This means take two if you have conditioning and\or electric heating.

Honestly, I've been wondering why this hasn't been done yet. Seems so obvious that the problem with solar energy can be solved with a freaking battery for overnight. About time someone made one.

Most home systems be it diesel, solar or wind come with batteries included. For example my wind turbine system has 1.2kwh storage built in.

[mainiac]

Energy storage is a red herring tbh.  It's not a factor until we generate enough solar power to displace at least 30% or 40% of the grid.  We would need to spend years creating new solar panels at a much faster rate then we are right now to reach that point.

The system also makes use of needlessly flashy lithium ion technology which has the chief benefit of being denser then other systems.  That's an unncessary expense for a stationary application.  If I just google "car battery" and select the most popular item on the wallmart site I find this lead acid battery which has a cost of 21 cents per watt hour compared to 35 cents per watt hour with the Tesla system.  Now I know that's a very lazy comparison and not rigorous but I'm sure that a more rigorous study will show that you could have made an equivalent but bulkier lead acid battery system for less then the lithium ion system Tesla is promoting.  Lithium reserves are a lot bigger then we used to think and that's great news but it's still a very expensive commodity.  Of course Tesla wants to create new markets for lithium batteries so they can have economies of scale so they aren't going to be interested on slapping their name on the domestic battery solutions that other people have been selling for decades.

[GameBoyBlue]

The aluminum battery my techie friends have been sharing seems relevant.

https://www.youtube.com/watch?v=ZKIcYk7E9lU&feature=share