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

[Mike90250]

RoadGlide you said (way back at beginning)

kWh = (Amp x Volts) / 1000

Actually, it's Kw x hours - KWh

1,000 of anything, is represented as 1K (the K replaces 3 decimal points, M replaces 6 decimal points)

So a 700 wh battery is also called a .7Kwh battery.

[Willy T]

The Tesla brand is more readily associated with mobility than with staying at home. However, the manufacturer is now bringing its battery technology to the market for stationary power storage. Together with the inverter manufacturer Fronius, the Californian company is going to be marketing the Tesla Home Battery in Germany and Europe starting in the fourth quarter of 2015.
The move is a response by the partners to the growing interest in electricity storage systems that significantly improve the availability of solar power for own-consumption. The storage technology, which is already used in electric vehicles, will now be combined with inverter and smart meter technology from Fronius. The inverter that will be used is the Fronius Symo Hybrid, which also supports the Fronius Solar Battery already on the market. The Tesla Home Battery will also be suitable for installation on a wall.
Division manager Martin Hackl at Fronius sees the collaboration as a step towards a fully renewable energy supply: "Tesla, a world leader in the field of electric mobility, is an ideal partner on our way towards being able to use solar power twenty-four hours a day." The two companies have already been working together for some time in the automotive business area: Tesla uses Fronius welding systems for manufacturing its S and X models.
The combined storage solution from Fronius and Tesla will be available in the fourth quarter, but Tesla has announced that it will already begin selling stationary storage under the name "Tesla Energy" in the USA this summer. The Powerwall storage system is offered with storage capacities of 7 and 10 kWh and is designed for use with solar power and as a backup solution.
Ralf Ossenbrink

I guess this tells it all and who was right and who was wrong.

[Bala]

Or pull out the iphone and press the "GEN" button.
There's not a lot of off grid being built in California that can't easily run an electric kettle or toaster without the generator.

I have seen articles in magazines on systems where people say they have x system running a lot of stuff.

Yes systems will generally run almost whatever you want,

I could run a lot more off my batteries at night but then they would not likely still be in good order after almost 9 years of service.

The claims are really meaningless IMHO as we have no idea how long the batteries last.

[Sunking]

You are mistaken about off-grid system tax credit eligibility:



My emphasis.

I stand corrected.

[RoadGlide]

Did you read it? Dual use like solar and grid connected. That would be a hybrid system.

Yes I did. What is your point? I'm not assuming a credit on the battery's just the actual array and the ancillary equipment which I can get under current regulations.

To be sure - am fairly certain I can get a credit for the whole shebang - that would be icing on the cake. If not I'm still ahead of the game. Calling yourself a Solar Fanatic while bashing Solar just doesn't make sense.

[Ian S]

Did you read it? Dual use like solar and grid connected. That would be a hybrid system.

You are mistaken about off-grid system tax credit eligibility:

Federal Tax Credit

Amount: 30% of system cost, including all equipment, materials and installation costs
Maximum Incentive: There is no maximum credit for systems placed in service after 2008.
Qualifying Installations: Both grid-tied and off-grid solar and wind systems apply. The home served by the system does not have to be the taxpayer’s principal residence.

My emphasis.

[Ian S]

Sunking - I think you may be mistaken...battery systems do qualify (but there are limitations) according to the IRS.

http://www.renewableenergyworld.com/...es-limitations

The system in that article is still connected to the grid but I believe you are right that off-grid systems qualify for the tax credit.

[Sunking]

Sunking - I think you may be mistaken...battery systems do qualify (but there are limitations) according to the IRS.

http://www.renewableenergyworld.com/...es-limitations

Did you read it? Dual use like solar and grid connected. That would be a hybrid system.

[RoadGlide]

Well worth the price, and I doubt your neighbors will not pay one penny for your system. Stand Alone Battery systems do not qualify last time I checked.

Sunking - I think you may be mistaken...battery systems do qualify (but there are limitations) according to the IRS.

http://www.renewableenergyworld.com/rea/news/article/2013/04/irs-confirms-that-batteries-qualify-for-the-energy-tax-credit-but-imposes-limitations

[organic farmer]

'Tax Credits' are one thing.

'Tax write-offs' are a different thing.

We have been using the costs of going off-grid as tax write-offs.

[Sunking]

I'll check with my CPA but from what I understand you can qualify for the tax credit if conventional power is available but you elect not to use it. There is utility power available at my site but they want 60K to bring it my home.

Well worth the price, and I doubt your neighbors will not pay one penny for your system. Stand Alone Battery systems do not qualify last time I checked.

[RoadGlide]

I don't believe you can get any FED tax credit for an "off grid" system. You better check with your CPA on that one.

Also whatever you have estimated to build your off grid system I guarantee you have forgotten something and it will cost you more. You will also be spending a lot of time baby sitting the batteries.

There are a number of people on this forum that live totally off grid and they might jump in and provide you with some costs and details of their systems.

I'll check with my CPA but from what I understand you can qualify for the tax credit if conventional power is available but you elect not to use it. There is utility power available at my site but they want 60K to bring it my home.

Understand that I may be underestimating total cost however I have a contractor background and will be doing most of the work myself hiring out subs where appropriate.

As far as babysitting the batteries - this is my retirement project so I should have enough time to make sure they don't get fubared.

[RoadGlide]

I can only assume you are thinking 48 volt battery with two 80 amp charge controllers. A 1200 AH battery is a bit to small with 9000 watt panel. You would be adding water weekly and splashing electrolyte everywhere. You cannot replace electrolyte and that destroys the battery. Minimum size required is 1500 AH, and that only gives you 14 Kwh per day usable.

Sunking - not quite sure of your calculations, specifically where you get 14kWh usable. From my understanding a 1500 Ah bank @ 48V gives me 72kWh per day. Assume your 14kWh usable is being based on a 20% DOD.

The way I am looking at it is that the array will be able to provide all the power I need on a typical day while at the same time charging up my battery bank and thus I would have 14kWh after the sun goes down and very little worries.

I do see your point on a larger battery bank though.

[SunEagle]

Have thought carefully about going totally off the grid. Right now I use about 23 kWh per day in a house that is not nearly as efficient ( all electric appliances etc.) as the one I am designing which will incorporate gas fired appliances (dryer, oven, water heater, radiant heat, etc.)

A 9 KW array capable of generating 1200+ kWh per month (40kWh per day) with a 1200 amp hour battery bank will set me back about 35k before tax credits. Another 5k for a generator and I won't have to worry about cloudy days. In other words I could install an off grid system w/ generator backup for about 30k after tax credits i.e. half of what the utility company wants just to bring power to my house.

Of course I won't be able to fire up a tig welder in the middle of the night (If I needed to I could always fire up the generator). However I don't see any issue with using it during the day as the above array should be able to provide the necessary power while at the same time still charging my battery bank.

I don't believe you can get any FED tax credit for an "off grid" system. You better check with your CPA on that one.

Also whatever you have estimated to build your off grid system I guarantee you have forgotten something and it will cost you more. You will also be spending a lot of time baby sitting the batteries.

There are a number of people on this forum that live totally off grid and they might jump in and provide you with some costs and details of their systems.

[bberry]

Off grid you generally dont have electric kettles, toaster and cant just light up the workshop and do a bit of welding or run a compressor anytime.

......

Or pull out the iphone and press the "GEN" button.
There's not a lot of off grid being built in California that can't easily run an electric kettle or toaster without the generator.