Tesla Motors Announces a New Home Battery • Hacker News Board

Re: Tesla Motors Announces a New Home Battery

#171

Post by jacquesm » Tue, Feb 17, 2015, 5:22 PM UTC

XorNot wrote: post #136

jacquesm wrote: post #73

Earlier quoted context omitted.

Tesla batteries retail for $30K@85KWh, so approximately $350/Wh, Lead-acid deep discharge is about $10000/100KWh, so approximately $100/Wh. That's a pretty large gap.

Might want to check your numbers there. $10,000 / 100 kWH == $0.10 per Wh. Which you absolute cannot get in any market. If you could, everyone would do it because the supply cost per kWh including replacement would beat regular power company power. EDIT: Just went back over my old calculations for this. The basic problem is that you trade off against the cost of peak electricity, not your solar. So you can essentiall…

Too late to edit, that should have been KWh of course.

Re: Tesla Motors Announces a New Home Battery

#172

Post by jacquesm » Tue, Feb 17, 2015, 5:22 PM UTC

tlrobinson wrote: post #154

jacquesm wrote: post #109

Earlier quoted context omitted.

There are some ways around that limitation. The reason it exists in the first place is so that the power company can safely power down their lines without installations such as yours feeding power back into the lines that are supposedly safe. This on the off chance that you'll end up electrocuting a line-man, which makes good sense. Of course, since your puny little solar installation is incapable of powering a subst…

"you're going to have to undo all of this" Why can't "all of this" be packaged into one idiot-proof box with connections to the grid, your off-grid system, and your house?

Depending on local variations in electrical code it can be. But check with a licensed installer familiar with your local code.

Re: Tesla Motors Announces a New Home Battery

#173

Post by brudgers » Tue, Feb 17, 2015, 5:23 PM UTC

balabaster wrote: post #139

brudgers wrote: post #105

Earlier quoted context omitted.

Such regulations provide several types of protection to the public commons. Another group of people who are protected are firefighters. In a typical residential installation the power meter also serves as the service disconnect. Response protocols include pulling the meter before many other life saving and property preserving operations. Live equipment and conductors operating from a second source downstream of the m…

Am I missing something? When you trip the breaker, the power is still on as far as the box in your house - unless it's shut off by the power company, it's just off inside the house. When you have alternative energy sources that include batteries, the same thing applies. The power from your batteries still runs through your box/breaker (via an inverter), and onward into the house. If you shut the box off, the power is…

In a typical US installation, the connection between the utility service and the dwelling service is made at the meter box. The meter forms the physical connection. When it is pulled, utility service is cut.

Secondary sources of electrical power such as solar panels, batteries, etc are connected downstream of the meter, i.e. connected to the load side from the perspective of the utility provider. Pulling the meter disconnects utility service but does not disconnect the secondary sources of electrical power. The dwelling therefore remains energized [and that's the point of installing such systems].

The difficulty in deenergizing the system presents a hazard. Finding and identifying the various disconnects takes time and is subject to error: who knows what was done for convenience or through poor planning or plain old stupidity.

Even if there is a disconnect for a grid of solar panels this only deenergizes the load side of the grid. Panels exposed to sunlight remain energized. Similarly lead acid batteries maintain an electrical potential when disconnected from the load side.

Re: Tesla Motors Announces a New Home Battery

#174

Post by joezydeco » Tue, Feb 17, 2015, 5:23 PM UTC

tlrobinson wrote: post #154

jacquesm wrote: post #109

Earlier quoted context omitted.

There are some ways around that limitation. The reason it exists in the first place is so that the power company can safely power down their lines without installations such as yours feeding power back into the lines that are supposedly safe. This on the off chance that you'll end up electrocuting a line-man, which makes good sense. Of course, since your puny little solar installation is incapable of powering a subst…

"you're going to have to undo all of this" Why can't "all of this" be packaged into one idiot-proof box with connections to the grid, your off-grid system, and your house?

You mean like a generator transfer switch?

http://www.generac.com/all-products/transfer-switches/home-b...

Re: Tesla Motors Announces a New Home Battery

#175

Post by psaintla » Tue, Feb 17, 2015, 5:29 PM UTC

Filligree wrote: post #52

psaintla wrote: post #50

Why is living off the grid the main objective here? I live in a suburban area that occasionally has power outages. Right now I'm considering the purchase of whole house generator but if I could have a battery instead I'd do it.

You can have a battery instead. You can get a battery right now; lead-acid will work just fine, if we're talking power outages of an hour or less. House-sized UPS systems are a thing. An expensive thing, mind you, though I don't know how expensive.

Yeah, I looked into that and last I checked it is prohibitively expensive. If this is a viable alternative I can see two great uses.

1.) Whole house UPS 2.) A way to take advantage of significantly lower night time electric rates.

Re: Tesla Motors Announces a New Home Battery

#176

Post by brudgers » Tue, Feb 17, 2015, 5:29 PM UTC

balabaster wrote: post #144

davegardner wrote: post #99

Earlier quoted context omitted.

The same issue exists with grid connected solar panels. My solar panels are designed to stop working whenever there is a power outage. This is a legally mandated requirement here and is very annoying when it happens on a beautiful sunny day. A solar panel installer told me that if I add a battery backup to my installation, then at least it'll still charge the batteries during a power outage.

This is the dumbest mandate I have ever heard of. Part of the installation of such power systems should have a mandate that in order for an off-grid power system to be connected to your box, your breaker to the grid must be off before you can enable your off-grid system. Why isn't there a mandate for this? It seems like the mandate was written entirely to protect the power company's profits hiding behind a thin veil…

In the US, rural electrification was largely complete 75 years ago. Urban electrification infrastructure dates back even longer. In all that time, intensity of use has increased.

There's a lot of bailing wire and duct tape...or overhead power lines and wood poles if you prefer...in the grid. It's grown based on small decisions over many years. People won't put up with six years of service interruptions while big chunks are rebuilt and debugged...nor will they be happy to underwrite the cost of doing so.

Re: Tesla Motors Announces a New Home Battery

#177

Post by jacquesm » Tue, Feb 17, 2015, 5:30 PM UTC

balabaster wrote: post #139

brudgers wrote: post #105

Earlier quoted context omitted.

Such regulations provide several types of protection to the public commons. Another group of people who are protected are firefighters. In a typical residential installation the power meter also serves as the service disconnect. Response protocols include pulling the meter before many other life saving and property preserving operations. Live equipment and conductors operating from a second source downstream of the m…

Am I missing something? When you trip the breaker, the power is still on as far as the box in your house - unless it's shut off by the power company, it's just off inside the house. When you have alternative energy sources that include batteries, the same thing applies. The power from your batteries still runs through your box/breaker (via an inverter), and onward into the house. If you shut the box off, the power is…

That you might not be there when you need to go to island mode or that you might not even be aware that the grid is down because you and a bunch of neighbours are capable of sourcing enough power that your 'off grid' detection mechanism fails.

There are solutions for this, it costs a little bit of money and depending on local regulations it may or may not be allowed.

So yes, you can override this and if you mechanically disconnect from the grid then you are typically allowed to operate your installation in island mode. But if you get caught backfeeding the grid when the grid is down then you will more than likely lose your hookup.

Most cheap/light inverters need an external power source to sync to and will automatically shut down if the grid is not available for synchronization purposes, which makes them compliant with the demands of the utilities. If you want to go to island mode you'll need a system that is considerably more expensive (batteries, load based inverter rather than generation capacity based) than one that can't.

Re: Tesla Motors Announces a New Home Battery

#178

Post by jacquesm » Tue, Feb 17, 2015, 5:32 PM UTC

innguest wrote: post #148

balabaster wrote: post #144

Earlier quoted context omitted.

This is the dumbest mandate I have ever heard of. Part of the installation of such power systems should have a mandate that in order for an off-grid power system to be connected to your box, your breaker to the grid must be off before you can enable your off-grid system. Why isn't there a mandate for this? It seems like the mandate was written entirely to protect the power company's profits hiding behind a thin veil…

It's BS as you rightfully detected but that doesn't stop the State cheerleaders above from giving us 1001 reasons why this is bad and we must protect the lives of electrical workers, firefighters, and even the lofty goal of protecting the hand-wavy "public commons" itself! Yeah, it's not the power company's fault for endangering the lives of their workers, it's our fault, you and I regular Joes, for daring to want el…

Either your sarcasm tags are missing or you're just simply dead wrong.

I set up a fairly beefy solar/wind powered system in an off-grid configurations specifically not to have to deal with the red tape, installation and insurance requirements of being 'on grid' and I don't regret that but all of those requirements, inspections and gear made perfect sense from an electrical point of view and from a safety point of view.

Re: Tesla Motors Announces a New Home Battery

#179

Post by CamperBob2 » Tue, Feb 17, 2015, 5:33 PM UTC

innguest wrote: post #148

balabaster wrote: post #144

Earlier quoted context omitted.

This is the dumbest mandate I have ever heard of. Part of the installation of such power systems should have a mandate that in order for an off-grid power system to be connected to your box, your breaker to the grid must be off before you can enable your off-grid system. Why isn't there a mandate for this? It seems like the mandate was written entirely to protect the power company's profits hiding behind a thin veil…

It's BS as you rightfully detected but that doesn't stop the State cheerleaders above from giving us 1001 reasons why this is bad and we must protect the lives of electrical workers, firefighters, and even the lofty goal of protecting the hand-wavy "public commons" itself! Yeah, it's not the power company's fault for endangering the lives of their workers, it's our fault, you and I regular Joes, for daring to want el…

This doesn't make any sense. There are almost certainly provisions in the law for backup generators to be connected to the service panel with a transfer switch, either manual or automatic. The idea is that when the generator is powering the house, the powerline service is completely disconnected, and vice versa. This is standard stuff, part of every electrical code I've ever heard of.

If a state legislature doesn't allow backup power to be supplied to a home or business with an NEC-compliant transfer switch, there should be some kind of judicial recourse. I'd spend some quality time with an attorney before taking "No" for an answer.

Re: Tesla Motors Announces a New Home Battery

#180

Post by wooster » Tue, Feb 17, 2015, 5:33 PM UTC

brudgers wrote: post #23

So, where does lithium come from? It comes from the Earth, of course, but it doesn't require strip mining or blowing the tops off mountains like other resources do...most often, lithium is found in briny underground ponds. The liquid is pumped out and left to dry in the sun. TANSTAAFL https://duckduckgo.com/?q=lithium+pond+photos&iax=1&ia=image... Mining is mining. There isn't a "green" form. Tearing holes in the ear…

"The big problem is the water...and it will run downhill from the Andes and wherever else Lithium is mined and into the Ocean."

Except for the geography which prevents that from happening and is why that area has giant salt flats:

http://en.wikipedia.org/wiki/Salar_de_Uyuni