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

[tehan]

Can you quote a Code section supporting this?
Would that mean that I could not use a commercial high voltage UPS in my home?

690.71B. There are exceptions listed there too which I guess Tesla (and your UPS) may fall under.

[Mike90250]

I understand there is a very small base of off-grid users who are upset that Powerwall does nothing for them. .....

So wrong. sigh....

I do not know what your background in solar is, but it's apparent, that you have none.
There is a large base of educated users whom are upset that the powerwall is a poor product with a lot of hype behind it.

Some Grid Tie systems use high voltage DC but the powerwall does not have an integral charger, so that would have to be purchased separately. It may pass NEC by the fact it's a sealed "box" with no accessible parts.

[inetdog]

Actually NEC code doesn't allow residential batteries over 50V at all. .

Can you quote a Code section supporting this?
Would that mean that I could not use a commercial high voltage UPS in my home?

[tehan]

It will not go away. All the electrical codes and rules change when you go higher than 50 volts. Lot mo money involved.

Actually NEC code doesn't allow residential batteries over 50V at all. So it's not completely clear how Tesla plans do get UL approval for Powerwall, but I presume they have a plan. It seems Powerwall works the same way the battery in the Tesla car works: it won't deliver any current unless a normally-open relay is closed by some external controller (i.e. the inverter). This is a significant fail-safe improvement over existing batteries and I suspect overcomes any objections on safety grounds. Oh and it costs virtually nothing - it's just smart engineering.

[Sunking]

I understand there is a very small base of off-grid users who are upset that Powerwall does nothing for them. There's a guy on the Tesla forum who rants about this daily. But the on-grid manufacturers (i.e. 99% of the PV industry) have been using high voltage DC for some time. And as storage is added to the on-grid mix I suspect that 48V DC is just going to go away.

It will not go away. All the electrical codes and rules change when you go higher than 50 volts. Lot mo money involved.

[SunEagle]

I'm thinking about it. I enjoy hearing other people's opinions, especially those critical of the product, and they are very much contributing to my decision making process.

I'm looking at installing a PV system for about $3.50 per watt. But I live in Texas where electricity is cheap and net metering not very favorable (I can net energy cost, but not distribution cost). So even with local and federal incentives the economic case is marginal. Adding Powerwall to the system will increase cost by about $1 per watt, but it provides an important secondary benefit as a grid backup system. It's hard for me to place a value on this, but it isn't small given that I can't run a generator here so I have no other backup options.

I believe I understand your needs for a secure backup power source where generators are not an option.

One of the reasons I have both generators and batteries is to provide a power source for my mother in law's oxygen machine. That needs to work at night even if the grid is down.

You have limited choices and none are cheap. I hope energy storage prices come down and you find a way to feel safe and secure with your choices.

[tehan]

So I gather you are going forward and getting one of the Tesla batteries for your home. That is your choice to make and money to spend. I wish you luck.

I'm thinking about it. I enjoy hearing other people's opinions, especially those critical of the product, and they are very much contributing to my decision making process.

I'm looking at installing a PV system for about $3.50 per watt. But I live in Texas where electricity is cheap and net metering not very favorable (I can net energy cost, but not distribution cost). So even with local and federal incentives the economic case is marginal. Adding Powerwall to the system will increase cost by about $1 per watt, but it provides an important secondary benefit as a grid backup system. It's hard for me to place a value on this, but it isn't small given that I can't run a generator here so I have no other backup options.

[tehan]

The battery pack is about 300VDC There is no base of installed off-grid systems based on 300VDC. So it's all new vaporware.
And I don't have 24/7 internet (needed for Tesla to control the pack) No reason for off-grid to need internet connection.

I understand there is a very small base of off-grid users who are upset that Powerwall does nothing for them. There's a guy on the Tesla forum who rants about this daily. But the on-grid manufacturers (i.e. 99% of the PV industry) have been using high voltage DC for some time. And as storage is added to the on-grid mix I suspect that 48V DC is just going to go away.

[tehan]

Tesla Owners are not off-grid. have internet, and more money then they have common sense. They drank the Kool-Aid

I know that is what you meant, I just said it for you.

I was pretty sure that's what he meant, but thank you for the translation!

[Sunking]

Glad to hear you admit it.

I like it.

[Sunking]

And I don't have 24/7 internet (needed for Tesla to control the pack) No reason for off-grid to need internet connection.

Tesla Owners are not off-grid. have internet, and more money then they have common sense. They drank the Kool-Aid

I know that is what you meant, I just said it for you.

[Mike90250]

Fatally flawed how exactly? I don't believe in playing the credentials game but you can assume I know a little more than they teach in school science class.

Odd comments. A quick Google search suggests there are 180,000 off-grid homes in the US. That's a tiny market of no interest to Tesla. The use cases are time-shifting (for which the daily cycle pack is suitable) or grid-failure backup (for which the weekly cycle is more than adequate). I suspect the vast majority of Powerwall customers will also install a PV system so will already have all the other necessary equipment. And seriously, internet? You think the people who are going to buy this don't have internet?

The battery pack is about 300VDC There is no base of installed off-grid systems based on 300VDC. So it's all new vaporware.
And I don't have 24/7 internet (needed for Tesla to control the pack) No reason for off-grid to need internet connection.

[SunEagle]

Odd comments. A quick Google search suggests there are 180,000 off-grid homes in the US. That's a tiny market of no interest to Tesla. The use cases are time-shifting (for which the daily cycle pack is suitable) or grid-failure backup (for which the weekly cycle is more than adequate). I suspect the vast majority of Powerwall customers will also install a PV system so will already have all the other necessary equipment. And seriously, internet? You think the people who are going to buy this don't have internet?

So I gather you are going forward and getting one of the Tesla batteries for your home. That is your choice to make and money to spend. I wish you luck.

[tehan]

The grid tie version was only allowed to cycle 1x a week. the other 6 days, it's useless. That makes for a lousy investment.

The off grid version was too small to be very useful, so several units would have to be installed.

The $3K sales price was battery pack only, ignoring the mandatory charger, inverter and wiring box. And the 24/7 internet connection.

Fatal flaws in my book.

Odd comments. A quick Google search suggests there are 180,000 off-grid homes in the US. That's a tiny market of no interest to Tesla. The use cases are time-shifting (for which the daily cycle pack is suitable) or grid-failure backup (for which the weekly cycle is more than adequate). I suspect the vast majority of Powerwall customers will also install a PV system so will already have all the other necessary equipment. And seriously, internet? You think the people who are going to buy this don't have internet?

[Mike90250]

Fatally flawed how exactly? I don't believe in playing the credentials game but you can assume I know a little more than they teach in school science class.

The grid tie version was only allowed to cycle 1x a week. the other 6 days, it's useless. That makes for a lousy investment.

The off grid version was too small to be very useful, so several units would have to be installed.

The $3K sales price was battery pack only, ignoring the mandatory charger, inverter and wiring box. And the 24/7 internet connection.

Fatal flaws in my book.