Tesla Powerwall

[CougTek]

Read Ars Technica's report here.

They won't ship it internationally before next year. Too bad, as I would have reserved one this morning.

Who's in? It's certainly not very expensive for the power it can store. Anyone who thinks it is should take a look at industrial UPS battery packs. At 3500$, IMO, it is a steal.

 

[jtr1962]

I'm seriously considering it along with an installation of solar panels.

 

[jtr1962]

While we're on the subject of price, raw batteries cost more than a complete Powerwell unit will sell for. For example, here is a 640Wh LiFePO4 cell selling for $370. 10kWH worth would be nearly $6,000, and that's without any additional electronics needed to interface to 120VAC. Often not having a means to store power for use when the sun isn't shining is a showstopper for solar power. One or two of these could take care of that. A pair could power several air conditioners or electric heaters running overnight, for example.

 

[mubs]

Awesome. In much of the rest of the world, these kinds of things are a necessity. Imagine replacing polluting and expensive diesel gensets with these!

 

[Handruin]

I like the idea and the price sounds obtainable for what it offers. At the very least it's one hell of a whole-house UPS assuming instantaneous transfer of power is possible in power-outage situations.

 

[ddrueding]

Still holding out just a little bit for the Solar/Battery/EV package (I feel it will become an even better value proposition soon), but I did recently double my holdings in TSLA and SCTY

 

[time]

Unfortunately, I would need two for night-time coverage and four for a rainy day, but this sounds like a major announcement. I'm impressed.

 

[Clocker]

No competition for a natural gas whole house generator, which is what I would want.

 

[LunarMist]

"All of the Powerwalls and power packs are connected to the Internet," Musk said.
I don't like that.

Obviously there is a good market for the batteries in areas with relatively short outages, but generators are cheaper and run much longer if you have the space for installation.
I wonder how much extra power is needed on standby, especially in the winter. I also wonder about the safety. I can just see them bursting into flames and burning a house down.

 

[Clocker]

Also, if you want to use the idea of this reducing your electricity cost to your local utility during the day (during peak usage time) and having it recharge at night....I believe you have to have one of the 'Smart' electric meters installed on your house that can track your usage by time of day. We don't have those around here yet, so it makes absolutely no sense for me. I have not done the math, but I doubt the business case for that usage idea works anyway, based on the price, unless there is a huge difference between peak and off peak electricity rates.

 

[jtr1962]

I tend to think the main use for these would be in conjunction with solar panels rather than shifting time of use. We don't have smart electric meters, either, but the economics might work if we did. Right now we're paying about $0.30/kW-hr flat rate. That includes the delivery charge. Now if peak demand rates were something like $0.20/kW-hr higher (just a guess), you'll need to shift 17,500 kW-hrs for the device to pay for itself. If half your current use is peak time, and you use about 1,000 kW-hr/month, the payback time would be 3 years. So yes, this could make sense for time shifting electrical usage depending upon your peak versus off-peak rates and overall electrical usage. A lot of peak time use is air conditioning in the summer. It might be worth it for that alone.

That said, at the rates we're paying for power in NYC, solar power combined with one of these is already economically viable. I'm figuring $20K total for an installation which would work for us once you count rebates. After that our power is free. We pay about $4K annually for electric. A payback time of 5 or 6 years sounds good to me.

 

[ddrueding]

How did you get $20k? Including storage? I was putting it closer to $40k ($30k solar, $10k batteries)

 

[jtr1962]

Just a rough estimate. Also, the rebates cover something like 40% IIRC, so the system might cost $35K before rebates. Your average power usage might be higher than mine. I'm sizing mine for roughly 1500 kW-hr month average. Based on my location, I would need a 10 to 12 kW system. In any case, the payback time looks reasonable given that electric rates are only going up.

 

[Clocker]

Wow. Electricity is expensive over there. Here are my bills for the past year in my 2100 SF Ranch.

Billing Period	Description	Meter Reading	Days Billed	Usage	Amount Billed	Payment Due	Payment Due Date
Mar 10, 2015 - Apr 7, 2015	Residential Electric Service	20062 Actual - 19305 Actual	28	757	$111.07	$111.07	Apr 30, 2015
Feb 9, 2015 - Mar 10, 2015	Residential Electric Service	19305 Actual - 18612 Actual	29	693	$101.39	$101.39	Apr 2, 2015
Jan 7, 2015 - Feb 9, 2015	Residential Electric Service	18612 Actual - 17669 Actual	33	943	$137.33	$137.33	Mar 3, 2015
Dec 4, 2014 - Jan 7, 2015	Residential Electric Service	17669 Actual - 16653 Actual	34	1016	$147.87	$147.87	Jan 30, 2015
Nov 3, 2014 - Dec 4, 2014	Residential Electric Service	16653 Actual - 15715 Actual	31	938	$142.92	$142.92	Dec 29, 2014
Oct 3, 2014 - Nov 3, 2014	Residential Electric Service	15715 Actual - 14882 Actual	31	833	$126.78	$126.78	Nov 26, 2014
Sep 4, 2014 - Oct 3, 2014	Residential Electric Service	14882 Actual - 14104 Actual	29	778	$118.78	$118.78	Oct 29, 2014
Aug 4, 2014 - Sep 4, 2014	Residential Electric Service	14104 Actual - 13063 Actual	31	1041	$158.75	$158.75	Sep 26, 2014
Jul 3, 2014 - Aug 4, 2014	Residential Electric Service	13063 Actual - 12070 Actual	32	993	$151.13	$151.13	Aug 28, 2014
Jun 3, 2014 - Jul 3, 2014	Residential Electric Service	12070 Actual - 11246 Actual	30	824	$125.62	$125.62	Jul 28, 2014
May 5, 2014 - Jun 3, 2014	Residential Electric Service	11246 Actual - 10530 Actual	29	716	$109.26	$109.26	Jun 26, 2014
Apr 8, 2014 - May 5, 2014	Residential Electric Service	10530 Actual - 9816 Actual	27	714	$109.44	$109.44	May 29, 2014
Mar 10, 2014 - Apr 8, 2014	Residential Electric Service	9816 Actual - 8460 Actual	29	1356	$207.71	$207.71	May 1, 2014

 

[jtr1962]

Yeah, it is pretty pricey here:

From Date	To Date	Elec Use (Kwh)	Elec Demand (Kw)	Con Ed Electric Bill Amt	ESCO Electric Supply Amt	Gas Use (Therm)	Con Ed Gas Bill Amt	ESCO Gas Supply Amt	Total Bill Amt
03/27/2015	04/27/2015	810	0.00	$128.60	$107.75	7	$26.17	$4.63	$267.15
02/26/2015	03/27/2015	1,250	0.00	$179.48	$170.59	6	$23.84	$3.79	$377.70
01/27/2015	02/26/2015	1,290	0.00	$191.33	$190.39	8	$26.77	$5.37	$413.86
12/24/2014	01/27/2015	1,420	0.00	$209.11	$217.85	8	$29.07	$5.36	$461.39
11/24/2014	12/24/2014	1,440	0.00	$204.41	$198.48	7	$25.63	$5.07	$433.59
10/23/2014	11/24/2014	1,260	0.00	$191.30	$162.81	7	$26.87	$5.05	$386.03
09/24/2014	10/23/2014	790	0.00	$124.60	$107.09	6	$24.12	$4.86	$260.67
08/25/2014	09/24/2014	1,340	0.00	$204.37	$156.69	5	$23.48	$4.01	$388.55
07/25/2014	08/25/2014	1,380	0.00	$216.19	$175.71	5	$24.04	$4.07	$420.01
06/25/2014	07/25/2014	1,820	0.00	$281.56	$243.89	7	$25.94	$6.24	$557.63
05/27/2014	06/25/2014	1,510	0.00	$241.74	$190.5	6	$24.15	$6.05	$462.44
04/25/2014	05/27/2014	670	0.00	$115.52	$88.58	7	$27.25	$6.68	$238.03
03/27/2014	04/25/2014	760	0.00	$116.90	$109.31	7	$25.52	$5.87	$257.60
02/26/2014	03/27/2014	1,250	0.00	$177.72	$251.22	6	$24.14	$4.85	$457.93
01/27/2014	02/26/2014	1,290	0.00	$149.74	$352.00	8	$27.10	$6.38	$535.22
11/22/2013	01/27/2014	2,760	0.00	$405.87	$381.59	--	--	--	$787.46
12/24/2013	01/27/2014	--	--	--	--	10	$31.77	$7.14	$38.91
11/22/2013	12/24/2013	--	--	--	--	6	$25.73	$4.13	$29.86
10/23/2013	11/22/2013	930	0.00	$136.21	$115.01	7	$25.76	$4.98	$281.96
09/24/2013	10/23/2013	820	0.00	$124.86	$102.45	7	$25.16	$5.59	$258.06
08/23/2013	09/24/2013	1,300	0.00	$199.25	$165.50	7	$26.92	$6.37	$398.04
07/25/2013	08/23/2013	1,380	0.00	$202.25	$164.01	6	$23.99	$5.58	$395.83
06/25/2013	07/25/2013	1,910	0.00	$283.07	$235.29	7	$25.80	$6.52	$550.68
05/24/2013	06/25/2013	1,180	0.00	$179.89	$150.10	6	$24.69	$5.57	$360.25
04/25/2013	05/24/2013	610	0.00	$97.34	$75.16	7	$25.21	$6.18	$203.89

It doesn't help that it's an older house which leaks heat like a sieve, even with double-pane windows. I'm thinking of blown-in foam insulation to help in that area. I've heard they need to make a few holes in the wall for that.

 

[ddrueding]

It seems my electricity is more than either of you. I can't find a handy export like that, but I use about 1mwh/month and it costs me about $300/month. Cost averaged to $0.40kwh this month. This is with everything but the water heater and clothes dryer running on electric.

They need to make a hole in each stud bay to blow in insulation (two if there is a fire break). If you are considering any kind of remodel, having the sheetrock demo'd, insulated, replaced, textured, and the walls painted isn't that expensive.

 

[Clocker]

It seems my electricity is more than either of you. I can't find a handy export like that, but I use about 1mwh/month and it costs me about $300/month. Cost averaged to $0.40kwh this month. This is with everything but the water heater and clothes dryer running on electric.

They need to make a hole in each stud bay to blow in insulation (two if there is a fire break). If you are considering any kind of remodel, having the sheetrock demo'd, insulated, replaced, textured, and the walls painted isn't that expensive.

Just did a copy paste of my electric company website.

 

[ddrueding]

Mine either does monthly charts for a year that don't have numbers unless you hover over a bar (one bar at a time) or exports hourly data for a week to CSV. It also has usage and pricing in two different CSV exports. Pretty obvious they don't want you to actually use the data.

 

[Stereodude]

Electricity will cease to be cheaper at night if enough people start using batteries to shift their usage to night time. Further, around here the price doesn't change based on the time of day for residential use.

 

[Clocker]

Right but I believe the rate is lower for some tier of monthly use. After that it goes up to something like 16 cents per kwh. It's been a while since I checked the actual rates.

 

[snowhiker]

Electricity will cease to be cheaper at night if enough people start using batteries to shift their usage to night time. Further, around here the price doesn't change based on the time of day for residential use.

This.

The reason the utilities offer lower cost off-peak power is to reduce daytime demand, thus preventing the necessity of building more power plants to meet daytime peak demand. If enough shift occurs through battery usage the cheaper rate goes away and the "cost savings" part of the argument for such a system goes away.

Some early adapters may recover the cost of their system, but the people who install their system a week before the utility discontinues discount rates for off-peak power are going to be pissed and they'll never recover their cost.

There my be other good reasons for such a system but if cost savings are your primary reason you may be sorely disappointed.

 

[Howell]

Well, the page refreshed and ate my post. It was really good so I'm not surprised.

Short version, I can't see a personal use case that makes these economically feasible especially if you can feed power back to the grid. Utilities who need a way to store excess power generation will be the canaries.

Luckily and unfortunately I pay about $.10/ kwh so I'm not sure it will ever be viable for me to play with.

 

[Howell]

Also although my place is not very energy efficient the climate is temperate and my usage is well below average for my 1100sq-ft (no gas).

Forbes is bullish for personal use but bearish for utility use.

 

[ddrueding]

Since they are all internet connected, they could do more interactive time-shifting than just daily. I can see a model where the power company effectively leases local storage from you that they can manage in real-time. This could be really valuable to them.

 

[Howell]

It doesn't help that it's an older house which leaks heat like a sieve, even with double-pane windows. I'm thinking of blown-in foam insulation to help in that area. I've heard they need to make a few holes in the wall for that.

The key thing to stop is air movement; convection is a bigger deal than conduction. Foam any holes in the attic/ceiling and then floor basement (unless your basement is encapulated and conditioned).

 

[Howell]

Since they are all internet connected, they could do more interactive time-shifting than just daily. I can see a model where the power company effectively leases local storage from you that they can manage in real-time. This could be really valuable to them.

Even if that were possible it just shifts the capital cost to the homeowner. The homeowner needs an initial reason for investment.

 

[Bozo]

I've installed heating and hot water systems that only ran at night. The "on-off" switch was in the electric meter. The homes had two 120 gallon hot water heaters and a 400 gallon hot water storage tank for hot water base board heat. The heaters ran overnight(7 PM to 5 AM) and stored it for use during the day.
According to the power company, in the evening they have more than enough capacity because a lot of industry and the malls and stores close. Even the hospitals electrical demands drops by 60+%.
The customers paid a hefty surcharge for using to much electric during the day, but had a huge discount electric use at night.

 

[Howell]

Interesting, Bozo. I wonder what percentage of the US has a different rate at night.

 

[LunarMist]

Interesting, Bozo. I wonder what percentage of the US has a different rate at night.

I don't.

 

[Clocker]

Interesting, Bozo. I wonder what percentage of the US has a different rate at night.

It's probably just what is called 'interruptable service'. For example, if I wanted to, I could have my AC unit placed on a separate meter that is controlled by the power company. During times of high load, they can turn it off (remotely) if they want to. For me giving the power company this power over my usage, they would give me a discounted rate on the power that my AC unit uses.

 

[LunarMist]

It's probably just what is called 'interruptable service'. For example, if I wanted to, I could have my AC unit placed on a separate meter that is controlled by the power company. During times of high load, they can turn it off (remotely) if they want to. For me giving the power company this power over my usage, they would give me a discounted rate on the power that my AC unit uses.

We have that here, too. I opted out, but the robot keeps calling me.

 

[ddrueding]

Interesting, Bozo. I wonder what percentage of the US has a different rate at night.

It is one of the options made available to me. I can have it follow a predefined 24-hour cycle or adjust in real-time based on their availability. Their website will even tell me how much each of the plans would have cost me last year to help me choose.

 

[Bozo]

I have interruptible service on my ac. It only shut off the compressor during high loads.
The systems I installed actually disabled the hot water devices and the electric cloths dryer during the day.
The owners had an emergency override. But they paid a huge premium for using it.
I don't know if the power company even offers that package anymore.

 

[ddrueding]

Thinking about it, I probably have $4k of UPSes in my house already that are collectively less capable than this thing.

 

[Howell]

It would help to only buy the inverter once.

 

[LunarMist]

It's only 2000W output?

 

[Handruin]

That 2K Watt sustained output is an interesting spec on the unit. It might be why they can offer a 10 year warranty so that these units can last the duration of the warranty. The PowerWall is $3500 then the DC/AC inverter might run around $2000, then of course the installation. I'll guess maybe $500 to install the unit making this a $6K investment.

 

[LunarMist]

That 2K Watt sustained output is an interesting spec on the unit. It might be why they can offer a 10 year warranty so that these units can last the duration of the warranty. The PowerWall is $3500 then the DC/AC inverter might run around $2000, then of course the installation. I'll guess maybe $500 to install the unit making this a $6K investment.

Well, it's not a 20KW generator for sure. Perhaps they could be used in some sort

 

[ddrueding]

Running a bank of them could make the sustained rate more reasonable for other applications, but if you are time-shifting, that seems reasonable enough.

 

[LunarMist]

Running a bank of them could make the sustained rate more reasonable for other applications, but if you are time-shifting, that seems reasonable enough.

It looks like the 7KWH version is for the daily use, but the 10KWH model is only good for about 500 cycles altogether.