Tesla Powerwall, The Specs, Numbers, and Implementation Absolutely Brilliant

[Sunking]

The rumor I heard is that they changed the internal series/parallel cell wiring to allow for higher discharge rates at the battery level.

That is impossible. A 1 gallon tank is a 1 gallon tank no matter what shape it is in.

A 7 Kwh battery can be

350 volts @ 20 AH
175 volts @ 40 AH
87 volts @ 80 AH
44 volts @ 160 AH

If you understand the physics, then you know wit is pure BS. If you do not know, you drank the Kool-Aide and will believe anything. When you keep changing the story and specs means you have vaporware.

[Mike90250]

The rumor I heard is that they changed the internal series/parallel cell wiring to allow for higher discharge rates at the battery level. They realized that it would be more useful to have more power for a shorter period of time than to string out the power for longer. .....

Nope. If they rewire internally, then the voltage will go down. You can't magically move some wires, and then get more power. It had to be a software change, or printer error.

[Cosmacelf]

Yes, yes, I know the relationship between series/parallel, voltage amperage, etc. I didn't put a lot of thought into the rumor, just relaying it. There are many ways of organizing approx. 680 cells to generate 350v, some ways will maximize maximum amperage draw better than others.

[Sunking]

. There are many ways of organizing approx. 680 cells to generate 350v,

No Sir there is only one way. 85S8P is the only way it can work with 680 cells to get 350 volts. There is no other combination that could possible work.

[donald]

Some cost guidance from Tesla's CTO last week puts the cost of lithium ion at "about $100/kwh by the end of the decade". I think the argument that most solar installs in a few years will include some storage is reasonable. Personally I wouldn't pay $3500 for 10kwh of battery backup. But I would probably pay $1500-$2000.

[ButchDeal]

Some cost guidance from Tesla's CTO last week puts the cost of lithium ion at "about $100/kwh by the end of the decade". I think the argument that most solar installs in a few years will include some storage is reasonable. Personally I wouldn't pay $3500 for 10kwh of battery backup. But I would probably pay $1500-$2000.

keep in mind that what they are initially doing does not have any backup capability, just load shifting to help with time of use. The inverter just has a set of clamps on the main lines to monitor consumption, and manages the inverter output to match consumption.
There is no way to disconnect from the grid and work independently. That would take more equipment and cost more.

[donald]

keep in mind that what they are initially doing does not have any backup capability, just load shifting to help with time of use. The inverter just has a set of clamps on the main lines to monitor consumption, and manages the inverter output to match consumption.
There is no way to disconnect from the grid and work independently. That would take more equipment and cost more.

You have it backwards for the U.S.
The first powerall to ship is the 10kwh, and is for backup. Musk reiterated this at the Edison Institute last week.

[SunEagle]

You have it backwards for the U.S.
The first powerall to ship is the 10kwh, and is for backup. Musk reiterated this at the Edison Institute last week.

I agree with you. The 10kWh unit was designed for backup but can only be cycled about once a week. Which is ok (but expensive) for an emergency power source unless you live in a area that gets lots of power outages.

[Sunking]

I agree with you. The 10kWh unit was designed for backup but can only be cycled about once a week. Which is ok (but expensive) for an emergency power source unless you live in a area that gets lots of power outages.

More money that you know what to do with, or a green Kool-Aid drinker.

[ButchDeal]

You have it backwards for the U.S.
The first powerall to ship is the 10kwh, and is for backup. Musk reiterated this at the Edison Institute last week.

That might be so BUT if you are planning to add a Powerwall to a SolarEdge inverter you don't have a backup solution without adding quite a bit of equipment. The SolarEdge system can easily be adapted to have time of use shifting with a software update and set of clamps to measure consumption. To get backup capability you will need a bit more equipment at minimum to disconnect from the grid and probably a sub panel for emergency loads... so a bit more money.

[donald]

That might be so BUT if you are planning to add a Powerwall to a SolarEdge inverter you don't have a backup solution without adding quite a bit of equipment. The SolarEdge system can easily be adapted to have time of use shifting with a software update and set of clamps to measure consumption. To get backup capability you will need a bit more equipment at minimum to disconnect from the grid and probably a sub panel for emergency loads... so a bit more money.

Everyone adding a proper generator connection does a transfer switch and often circuit control. It is not expensive. Especially if the electrician is into the main panel anyways installing the inverter. In the U.S. there are UL approved devices that work by simply redirecting the hot wire of each circuit to be controlled into the generator/battery powered sub panel. In this setup the main panel is completely without power when the generator/battery is energizing selected circuits in backup mode. It is a simple and safe solution.

[tehan]

It is a simple and safe solution.

I agree. In the past, off-grid inverters have been much more expensive than grid-tied inverters. This seems to have convinced some people that off-grid is hard. It isn't. It will be interesting to see if the niche off-grid manufacturers (e.g. Outback etc.) can survive the coming onslaught from SolarEdge, Enphase etc..

[lkruper]

Everyone adding a proper generator connection does a transfer switch and often circuit control. It is not expensive. Especially if the electrician is into the main panel anyways installing the inverter. In the U.S. there are UL approved devices that work by simply redirecting the hot wire of each circuit to be controlled into the generator/battery powered sub panel. In this setup the main panel is completely without power when the generator/battery is energizing selected circuits in backup mode. It is a simple and safe solution.

I am looking at Reliance Controls which comes pre-wired, but it allows the circuits not being re-directed to function normally. Can you share the device to which you refer? I am simply looking for a manual transfer switch for a small portable generator.

[donald]

I am looking at Reliance Controls which comes pre-wired, but it allows the circuits not being re-directed to function normally. Can you share the device to which you refer? I am simply looking for a manual transfer switch for a small portable generator.

I've used Reliance, it's the most common in the U.S. Be sure to get the right one for your generators power cord plug.
A transfer switch without the secondary panel works too. Just kill the circuits on the main panel that shouldn't be powered while using the generator.

[lkruper]

I've used Reliance, it's the most common in the U.S. Be sure to get the right one for your generators power cord plug.
A transfer switch without the secondary panel works too. Just kill the circuits on the main panel that shouldn't be powered while using the generator.

I did not see one that takes a 110v power cord (I have a Smarter Tools 1600w inverter generator) so I was going to have a 110v male to 30 amp 4 prong female made up that makes two prongs live at the 30 amp end.