Anyone keeping an ear on Tesla today?

[russ]

Current SoCal Edison TOU-D-A super off-peak vs. on-peak differential is $0.35, so using your example it is about $6,400 over 10 years if you charge at it night, so it can be made to look more attractive to some potential buyers...

CORRECTION: $0.35 is summer only, $0.25 for winter, so overall less than I stated above

The utilities are so stupid they haven't thought of this? Nope - if it is real (questionable today) it is a far bigger thing for them than any home owner. They can buy wholesale power from the hydros in Oregon/Washington for not much at night - maybe 30$ per mW and sell it as peak power for several hundred per mW.

[SunEagle]

Current SoCal Edison TOU-D-A super off-peak vs. on-peak differential is $0.35, so using your example it is about $6,400 over 10 years if you charge at it night, so it can be made to look more attractive to some potential buyers...

CORRECTION: $0.35 is summer only, $0.25 for winter, so overall less than I stated above

I am sure there are some areas of the US that using battery power during the higher Tier times may make it worth while. Problem is setting up the "switching" system to go between grid and battery at the correct times. Could get complicated if someone in the household didn't follow the "energy usage plan".

[donald]

I am sure there are some areas of the US that using battery power during the higher Tier times may make it worth while. Problem is setting up the "switching" system to go between grid and battery at the correct times. Could get complicated if someone in the household didn't follow the "energy usage plan".

There's undoubtedly a software piece to the Tesla system we haven't seen yet. I'm sure there is an embedded linux system in that box that can be wifi or cell connected.

But if a solar home is using most of what is generated during the day, a battery will never make much sense. I'm sure the percent of residential solar generated that goes to the grid is well know.

[pleppik]

The utilities are so stupid they haven't thought of this? Nope - if it is real (questionable today) it is a far bigger thing for them than any home owner. They can buy wholesale power from the hydros in Oregon/Washington for not much at night - maybe 30$ per mW and sell it as peak power for several hundred per mW.

Tesla also announced utility-scale battery systems, so yes, apparently someone did think of this.

They didn't give pricing for the utility systems, but it's probably safe to assume that the price per KW for utilities is lower than the $300/KW they're charging for the residential systems.

At $300/KW for utility-scale batteries, there's studies for California and Texas that show batteries are a cheaper alternative to building gas-fired peakers.

[J.P.M.]

There's undoubtedly a software piece to the Tesla system we haven't seen yet. I'm sure there is an embedded linux system in that box that can be wifi or cell connected.

But if a solar home is using most of what is generated during the day, a battery will never make much sense. I'm sure the percent of residential solar generated that goes to the grid is well know.

On what do you base your certainty ?

[russ]

On what do you base your certainty ?

BS and blather

[hub]

Truth be told... I'm actually awaiting for more news of Enphase's battery system. Last I heard was that it was going to be modular and expandable. Unless the pricing of the batteries are going to be cheap and I can figure out how to add more panels to justified going off grid, I don't see myself using batteries that soon.

I like what they unveiled. The fact that its modular, scalable to 50KwH/rack, w/10 year warranty I don't see anything better out there this year.

[Sunking]

I like what they unveiled. The fact that its modular, scalable to 50KwH/rack, w/10 year warranty I don't see anything better out there this year.

It is not out there and there are better already out there.

[donald]

On what do you base your certainty ?

Well, that electricity is metered. The 7kwh system is based on the buyers ROI. Their sales projection would be partly derived from estimating the size of this group. Anyone with a solid net metering contract is not part of this group.

I'm thinking 7kwh is the actual system capacity. I'm thinking the 7 and 10 systems have the same amount of internal storage. They only gave one weight - 100kg.

[Sunking]

I'm thinking 7kwh is the actual system capacity. They only gave one weight - 100kg.

So what does that mean Donald. I bet you have no clue. I give you a hint. It is not good.

[donald]

So what does that mean Donald. I bet you have no clue. I give you a hint. It is not good.

Which part?
The 100 kg means the marketing people wanted a weight, and the engineers said we don't have one because it is not finished. So they gave a max estimated weight and rounded to a nice even number.

The same internal capacity means that it is a 10-12kwh system if we were to add up the actual cells. If 7 and 10 were 100% DOD figures, we would see two pack weights.

It's all good, because unlike you, Tesla has actual years of experience building these types of battery systems.

[Sunking]

Which part?
The 100 kg means the marketing people wanted a weight, and the engineers said we don't have one because it is not finished. So they gave a max estimated weight and rounded to a nice even number.

The same internal capacity means that it is a 10-12kwh system if we were to add up the actual cells. If 7 and 10 were 100% DOD figures, we would see two pack weights.

It's all good, because unlike you, Tesla has actual years of experience building these types of battery systems.

I told you did't have a clue. It means 70 wh/Kg. Even a cheap Chi-Com LiFePo4 has 100 wh/Kg density. It means they are using a very cheap battery with low energy density. The EV batteries run 200 to 240 wh/Kg. Top of the line Pb batteries get 70 wh/Kg.

Tesla does not publish what part of that 7 Kwh is usable. Only meaningful spec they have and it is very poor for a Lithium battery is specific energy is very low of C/3 or 2 Kw continuous, and 3 Kw burst aka C/2. All Lithium batteries I know of can discharge at rates in excess of 1C continuous. They published just enough info to be very suspicious if you know what to look for and you have no idea what to look for.

[donald]

As I said, if the two models weigh the same, all of the 7kwh is likely usable and the it is not a 7kwh "battery". It a battery system rated to provide 7kwh daily.

You keep talking like the Tesla product is a battery. It is not. It's a battery system. A BMS, cooling system, and probably a charge controller. Plus some sort of regulation on the output side. Does it have a fan? Heat sinks? You criticize conjecture, and now your guessing at what percent of the weight is battery. If not necessarily a negative if they have formulated a lower density battery compared to their EV product.

If the warranty matches the specs, it doesn't matter if the box contains cat piss and oregano.

[Mike90250]

As I said, if the two models weigh the same, all of the 7kwh is likely usable and the it is not a 7kwh "battery". It a battery system rated to provide 7kwh daily.

You keep talking like the Tesla product is a battery. It is not. It's a battery system. A BMS, cooling system, and probably a charge controller. Plus some sort of regulation on the output side. Does it have a fan? Heat sinks? You criticize conjecture, and now your guessing at what percent of the weight is battery. If not necessarily a negative if they have formulated a lower density battery compared to their EV product.

If the warranty matches the specs, it doesn't matter if the box contains cat piss and oregano.

Actually, the Warranty has fine print, and in the fine print, is the Givith and Takeith away parts. It likely has a data logger too, since it's got to have thermal management smarts. And somewhere is a DC-Dc converter, does it manage the 400VDC pack voltage to 50V for off grid or what. But it's the data logging that will get 'ya, because it will count the 100%-0% excursions and the ones in-between, and they will get you for the pro-rating and service call labor. (well, that's the way everyone else does warranty).
Even 10Kw is barely enough for a very small, efficient off grid house, I generally burn 7Kwh in the winter and 12Kwh (adding the water pumps) in the summer. So the 10Kw may just hold me overnight, but when Joe suburb homeowner has a grid failure and his air conditioned spa shuts off 3 hours later, he's not going to be happy with his Tesla battery.

http://arstechnica.com/information-technology/2015/05/01/teslas-new-powerwall-home-battery-will-cost-3500-for-10kwh-units/

[rwb1921]

Everyone is missing the most important part of the battery system information:

"The key thing for the Powerwall on the consumer side is it’s beautiful, it fits on the wall, you can put it on the outside wall of your house," Musk told journalists. "It's only about 6 inches thick and a few feet across and a few feet tall."

That sells it without all the unnecessary technical specs, who needs them

My son was texting me last night saying are you getting one.......................