
Tesla Motors to Unveil Home and Utility Batteries April 30 - adventured
http://www.bloomberg.com/news/articles/2015-04-21/tesla-motors-to-unveil-home-and-utility-batteries-april-30
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kriro
Hope it'll be available in Europe. I'd like to store some photovoltaics
generated energy "because I can" (still get loltastic money for feeding it
into the grid, yay subsidies). Less reliance on the grid is good. I'm rooting
for decentralized power (I'm envisioning battery stores in communites that
form local grids) but there's obvious issues to be solved.

Very interested in the announcement, pricing etc.

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ghshephard
It will be interesting to see how this works in California. Everyone I know
who has Photovoltaics, also has a switch which is required to disable them the
instant the mains power goes down. The battery is still quite useful in that
scenario, but it would be even more useful if you could supply your house with
power from batteries, _after_ an event results in the grid losing power.

~~~
tempestn
That requirement (appropriately called "anti-islanding") is to avoid
islanding:
[https://en.wikipedia.org/wiki/Islanding](https://en.wikipedia.org/wiki/Islanding)

An alternative is to automatically disconnect your home from the grid in that
situation, rather than disabling the PV. This is referred to as intentional
islanding. (Although I suppose that could be disallowed in some jurisdictions,
for no good reason that I can think of. At the very least though, you should
be able to manually disconnect once the anti-islanding has kicked in, and then
fire the PV and/or battery-powered inverter back up.) Depending on your
equipment you may still have to shut down before reconnecting to the grid,
once grid power is back up. (Depends on whether your inverter is capable of
re-synchronizing with the grid, and again I suppose based on regulations in
your jurisdiction.)

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ghshephard
This sounds a lot like the ATS (Automatic Transfer Switch) which, is a
_massive_ switch that switches from Mains grid to generator during a power
outage in some of the buildings I've worked at (And scares the crap out of you
if you are in the same room when it switches over - very, very loud).

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brotchie
How feasible will it be to use 60+kWh of home battery storage for time-
shifting arbitrage (not pure arbitrage, but close enough)? Is it yet possible
for a consumer to get direct exposure to the spot electricity price for both
feed-in and feed-out?

It would be interesting a) What the payback period is on a strategy where you
charge when the spot price is low, and discharge when high, and b) How much
installed battery capacity would be required to eliminate this arbitrage? i.e.
what MWh of installed battery capacity would flatten the 24 hour across-grid
demand cycle.

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hyperbovine
I think most people would be happy to just charge the thing up via solar
during the day and use it at night.

~~~
ghshephard
It's the opposite though - during the night, you want to _use_ power from the
utility, when it's plentiful, and cheap (particularly if you have a TOU
contract).

The objective would be charge the battery up at _night_ from the grid, and
then use that power during the day + your solar power, when power is
expensive.

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nhaehnle
Once solar becomes widespread enough, the dynamic changes. In Germany,
electricity spot prices can be _lower_ around noon because of solar energy. A
quick Google search brings up this example:
[http://cleantechnica.com/2012/03/23/german-solar-bringing-
do...](http://cleantechnica.com/2012/03/23/german-solar-bringing-down-price-
of-afternoon-electricity-big-time-more-charts-facts/) (note that this already
happened in 2012!)

~~~
jimmcslim
Spot prices could even go negative, depending on the rules of the market.
That's certainly a feature of Australia's National Electricity Market (NEM)
which covers the eastern states. The price can drop to a floor of around
-$1000/MWh, so at these times the large generators are paying the network for
the privilege of keeping their running - which they are generally forced to
do, since such a period of negative prices doesn't tend to last long...
certainly not long enough to justify shutting a coal-fired turbine down and
then the expense of spinning it back up again.

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danans
It seems like the success of this has to come down to some kind of quality-of-
life value-add that is only realizable in homes.

Like how Tesla Model S's get their owners access to luxury, HOV lanes, and
public environmental bragging rights (presumably the buyers of a $100k car
aren't trying to save money on gas).

Otherwise, like some have noted, why wouldn't the utilities themselves do the
storage and avoid the round-trip power transmission losses?

The thing is, in the US, power outages are pretty rare and fixed pretty
quickly, so bridging outages doesn't seem like a major selling point. If the
customer really is the homeowner, I'm still wondering what the big life-value-
add is. It's not like home battery storage market has a luxury segment that
can be initially targeted as the Model S is in the car market. And

And I don't think that Elon is targeting geeks who want to set up power
arbitrage schemes in their homes.

EDIT: final point added.

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lerouxb
I'm really interested in how much this will cost.

In South Africa we're having rolling blackouts called "load shedding" because
we don't have enough power. Exactly why is a long and obviously controversial
story, but in short: Mega projects that were supposed to fill in the gaps are
being delayed, maintenance on existing infrastructure was delayed in the hope
that the new projects would come online in time, but that's now causing
cascading failures and maintenance cannot be avoided any longer, causing even
more outages..

The blackouts are zoned and 2.5 hours at a time. Here's Cape Town's map, for
example:
[http://ewn.co.za/assets/loadshedding/capetown.html](http://ewn.co.za/assets/loadshedding/capetown.html)

So we don't have grid power 24/7 anymore and our electricity prices (that used
to be some of the cheapest in the world) are now skyrocketing. So I would
imagine that many many people here might be in the market for something like
this at the right price.

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delta1
2.5 hours is extremely lucky, in my experience. Normally at least 4 hours and
often more like 6 - 8. One of my friends has been without electricity for the
past 5 days!

Totally agree that there is a big market here for the Tesla home batteries,
depending on the cost vs capacity. I am definitely in the market.

~~~
lerouxb
I think we're lucky in Cape Town, yes. "Maintenance festival" coming up,
though!
[http://www.sabc.co.za/news/a/79d21000481a5710803fc078423ca9a...](http://www.sabc.co.za/news/a/79d21000481a5710803fc078423ca9af/Eskom-
to-implement-maintenance-over-long-weekend-20152204)

I've actually been looking into playing with some LiFePO4 batteries and trying
to see how big of a UPS you can build for, say, R5000 or R10000. LiFe
batteries have longer lifetimes, are safer (less likely to catch fire or
explode), are less finicky about how they get charged (more like lead-acid),
seem to be potentially a bit cheaper, easier to use in multi-cell
configurations (cell-balancing issue related), etc. You can also source or
sink more current, so faster to charge/discharge. Downside is 14% less energy
density which is why they don't get used in laptops or smartphones and (in
Tesla's case) sometimes also not in cars. But that's not much of a downside
for (off-)grid storage..

Pretty sure there's a gap in the market there just waiting for someone to jump
into. And once you already have a giant battery it is probably that much
easier to convince yourself of covering your roof in solar panels, getting a
gas stove and disconnecting yourself from the grid entirely :)

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WalterBright
Many homes have natural gas powered generators that automatically kick in when
the power fails, as it often does (trees fall on the wires). Typical outage
times are 4 to 8 hours.

A system like this costs 5-10 grand.

I wonder if these home batteries would be a less expensive alternative.

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Animats
We'll have to wait for the numbers. Cost/KWh and lifetime number of
charge/discharge cycles are the numbers that matter. For fixed applications,
energy density isn't critical, as it is for mobile and cars.

If the big wind power people start buying these, it's real.

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mattbeckman
I was planning on using this year's unexpected tax refund to go solar.
However, I've been waiting all month for the announcement specifics/pricing
before making a move.

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DrStalker
I'm curious to see what (if anything) these batteries will do for users that
isn't already handled by a UPS.

Not that a cheaper, more energy dense UPS isn't already a win but the article
keeps focusing on the fact that the product is a battery, not what it will
actually be used for.

~~~
barrystaes
I'd say yes - a home battery could do what a UPS can, plus it can return power
to the grid.

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barrystaes
I wonder if these eventually would become be hydrogen based eventually. (or
already are..) No matter whether Tesla is actually working on home batteries,
i see a need for anyone invested in green energy. They could do greener than
LiPo ofcourse.

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JohnLen
Great innovation in technology and great products. Best combination of human
achievements for the world.

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esusatyo
I wonder how big of a market this is. I don't even know that many people who
owns a Genset.

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gnoway
I think there are some advantages. No gas fuel, no noise, maybe less
maintenance. Insurance vs. a genset should be different. I'm assuming you hook
these up with a bypass switch, so you effectively have a whole home online
UPS; this would eliminate brownouts and dirty/noisy power. I wonder if there's
a power factor advantage on the utility side as well.

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jpitz
Power factor advantage in what way? I would think a large battery charging
device would only lower a household's power factor.

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gnoway
Yes, but do you think there would be any benefit in it there being less
variability? Right now a utility deals with a bunch of random stuff drawing
power, presumably at different factors. I don't know what the right language
is to describe this, what I was thinking is that if everyone effectively had a
big UPS then that variability would be seen by the UPS, and the power company
would see a more uniform draw.

