Not so fast! Read the fine print. The battery stores power at 300-400 volts DC. So a completely new type of inverter is needed to give your house 230 volt pure sine wave AC. 99% of off grid houses run 12/24/48 volt inverters, so there's no way you can just buy this different battery technology and plug it into your existing off grid power system. Go and Google 400 volt dc to 230 volt ac inverter. There are none. When they develop them they will be $4000-$5000 each. So great idea with the battery technology, just need to see it through with the rest of the technology package.
t_naki,
May 20, 1:19pm
It does say that it has a DC to DC converter to manage power flow so it possibly stores power at a higher voltage and then converts it down to be used. Need more details to be sure.
timbo69,
May 20, 1:26pm
Im sure its simpler than that. They arent gonna "set" people up for something like that.
timbo69,
May 20, 1:27pm
Perhaps more details for an electrician - I would say its pretty user friendly other wise why would they bother?
pauldw,
May 20, 2:00pm
I heard on radio that a single unit had limited output capacity eg you could run a toaster or electric jug in the kitchen but not both at the same time. More module can be installed if you can afford them.
t_naki,
May 20, 2:37pm
I do not know why they would do that but like two9s says you cannot invert 400VDC to 230VAV so you would need to do something. Remember that you are looking at a marketing website, they are hardly going to make it look complicated. The fact that they have missed out the inverter is the biggest clue there might me more to it than what they are making out.
hilt_dwane,
May 20, 6:49pm
I sent that link to the guy who sold us our solar system and asked for his comments. This is the reply I got: A couple of things to keep in mind from Tesla's announcement are that the Gigafactory will not be completed until 2017, and that the 10kWh Powerwall only has a lifespan of 50 cycles. It is not designed for daily recharging.
The development, while exciting, is slightly misleading in terms of cost. Inverters are not included in the pricing, nor installation or the price of the various consents that are required to store electricity.
Rest assured, solarcity will keep all existing customers up to date of our battery initiative which will be launching in the future. But it will only be at a time when we can confidently bring to market a product that provides the best solution for New Zealanders at an appropriate price point.
timbo69,
May 20, 7:31pm
Watch the video and read the specs - some of what they say is true some is not. I really dont believe the 50 cycles claim - what would be the point of this? and they are available to American's later this year.
timbo69,
May 20, 7:33pm
Perhaps but Tesla as a company have shown they are not out of the normal mould - their electric cars are on the cutting edge of the technology. Time will tell.
pestri,
May 20, 7:36pm
Until you can guarantee 24/7365 solar to recharge you'll still need to be on the grid.
brycer,
May 20, 7:50pm
You should be a politician! Just quote out of context. "Powerwall comes in 10 kWh weekly cycle and 7 kWh daily cycle models." "10 kWh $3,500 For backup applications 7 kWh $3,000 For daily cycle applications and ten year warranty on both"
macman26,
May 20, 8:03pm
Most grid tie solar inverters now operate at 400VDC so that won't be an issue. You just need one that is not Grid tie or this function can be turned off.
timbo69,
May 20, 8:23pm
Not true - the sun will never shine 24 hours a day, that's the idea of batteries and the whole point of this thread. some people already run of solar - its just limiting - I would expect most are supplemented by gas or the grid.
pestri,
May 21, 2:53am
Said batteries have an 8 hr service life. am I wrong? 8 hours is a long way short of 24/7/365. am I right?
And then having rubbished my point you conclude that most are supplemented by gas or grid. QED
timbo69,
May 21, 3:04am
Most current system are supplemented - this new setup is a small but meaningfull step away from that.
Where do you get 8 hours service from ? They have 7 and 10 kw/h - they stop when you use then up Could be minutes or months
pestri,
May 21, 3:37am
Correct. most systems are supplemented, so one remains on the Grid. QED . AGAIN
ryanm2,
May 21, 3:37am
I think in the future the idea from Tesla is to have 2 Tesla cars, there batteries are 85kw each. Drive one, charge the other at home via solar, get home, use the remaining power, then swap. Elon Musk is a clever chap, maybe inverters etc will be released soon. These powerwall batteries had something like 38,000 pre orders in the states alone, selling out all production until mid 2016.
This^^^ Not complex and should be a low cost basic "string inverter". But it would need to be grid tied - if the home was still connected to the grid. So long as the minimum battery voltage stays above about 325V DC, can supply 230V RMS Ac sine wave. Very efficient too (2% losses).
t_naki,
May 21, 4:45am
True but that is grid tied not storage systems. Storage systems are mostly 12V, 24V or 48V. It is probably not a major issue, should it prove be more efficient to store at a higher voltage and technology will follow but at the moment the inverter for this system will most likely be the hinge pin in the economics of the system.
t_naki,
May 21, 4:47am
If you are going to invest in batteries surely you would do better to go off grid and if needed have a back up generator. That is where the real savings will be, when you don't have to pay the lines company supply charge.
pestri,
May 21, 3:00pm
Edzackery
mm12345,
May 21, 3:54pm
Yep. Was discussed on Nat Radio last week - as part of the inevitable consequence of people (retail customers) reducing electricity use, supply charges have gone up to offset that loss of revenue. If many people start disconnecting from the grid, then they'll also have a valid argument to ramp up supply charges even more, as the costs for maintaining the network aren't going to go down (or if so - then not by much), but those costs will have to be divided up between fewer and fewer customers. Offsetting that is that if demand falls for electricity from the grid, then the price "per unit" should fall. I'd love to be able to guess the future. Tesla's technology is great, but lithium mining/processing capacity is tiny at present. It would be too bad if there was a global effort and trillions of dollars invested to increase that capacity 100 or 1,000 times or whatever would be needed, only to find that someone else could produce alternative storage systems far more cheaply out of common materials. Seem to read about it every day - "new battery technology just around the corner" - but it hasn't happened yet.
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