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Re: The Rise of the Personal Power Plant

Unread postPosted: Fri 02 Dec 2016, 09:54:29
by GHung
baha wrote:I ordered my Tesla Powerwall 2.0 yesterday. I will be installing PV at the same time. 15 kW-hr of storage and 5 kW of PV production will make me grid independent. Duke power can then shove all their power plants up their coal ash.

I feel better:)


Congrats, Baha. I'm sticking with tried-and-true (and cheap) lead-acid batteries. My main concern is the Powerwall's high voltages, and I still don't trust newer battery tech that much, especially the ridiculous numbers of cells required.

Re: The Rise of the Personal Power Plant

Unread postPosted: Sun 04 Dec 2016, 08:26:22
by vtsnowedin
baha wrote:I should say I went thru the Tesla training. The powerwall 1.0 has over 18,000 lithium cells about the size of a AA. Each one is housed in a steel box and is charged and discharged individually. There is a water cooling jacket for each cell and an individual cell can fail without affecting the others. The battery bank voltage is actually 48 Vdc and a DC to DC converter is used to produce the 400VDC required by the inverter.

Pretty cool stuff

Water cooling jacket? Filled with antifreeze I hope. What are the temperature limits?

Re: The Rise of the Personal Power Plant

Unread postPosted: Sun 04 Dec 2016, 09:01:13
by Shaved Monkey

Re: The Rise of the Personal Power Plant

Unread postPosted: Sun 04 Dec 2016, 10:41:27
by Tanada
baha wrote:50/50 glycol/water cooling fluid. Specs say -4 to 122 F. Suitable for outdoor installation but I would think you better keep it inside in VT :) I plan to install it inside to avoid the heat in NC.


For ICE motors you can vary the ratios of Glycol and Water to 70/30 g/w and get better cold performance limits. Does your owner manual allow those kind of adjustments for the powerwall?

Re: The Rise of the Personal Power Plant

Unread postPosted: Sun 04 Dec 2016, 11:33:36
by vtsnowedin
It will be interesting to see how much heat it gives off while being charged.
Mounted on an inside basement wall it might be a major contributor to the winter heat load and require outside venting to keep from increasing AC loads in summer.

Re: The Rise of the Personal Power Plant

Unread postPosted: Sun 04 Dec 2016, 13:26:52
by vtsnowedin
baha wrote:@Tanada - Now way! I doubt the cooling system is field serviceable, the batteries are not. Tesla is very particular about it's design. An ICE engine has loads of overcapacity where the Tesla is minimal design for efficiency. More glycol means more viscosity and lower heat carrying capacity. That throws the pump sizing and radiator (4" square) out of whack.

@VT - I will also be interested to see how the thing behaves. I don't think it will produce much heat. The size of the cooling system says that. And heat represents lost power so they will work to reduce it. They recommend it to be installed where it will mostly see indoor temps. Then the cooling system doesn't run as much. I think their more concerned with heat than cold,
overheating is a bad thing for Lithium:)

Well if all it needs is a 4"X4" radiator it would not be a concern. Be sure to post some pictures when it is installed and keep us informed of your results.

Re: The Rise of the Personal Power Plant

Unread postPosted: Sun 04 Dec 2016, 13:41:02
by GHung
baha said; I waited until the Powerwall was ready because I will not "give" kw-hrs to Duke power. If they will pay me, fine. Otherwise I will set up a fountain in the front yard that burns any excess power I produce.


I have two dump loads for surplus PV output; a 450 gallon hot water tank and a 5000 BTU AC unit in the master suite for cooling/dehumidification. Dumps are controlled by my charge controllers. I generally like to use surplus PV in real-time doing household chores, laundry, dishwasher,, stuff like that. Having an off-grid system with separate charge controllers and inverters gives me a lot of versatility and redundancy that most folks wouldn't want to fool with. Then, again, the only single point of failure is the battery set. I can lose two inverters and three charge controllers and still have a functioning system for critical loads.

Then again, again, I haven't had a single critical failure in 18 years. When people ask me about solar system reliability, I ask them to name things they rely upon every day, which have been in service 24/7/365 for well over a decade, that haven't failed at some point or needed regular maintenance. It's usually a very short list.

Re: The Rise of the Personal Power Plant

Unread postPosted: Mon 05 Dec 2016, 12:55:52
by KaiserJeep
I find myself wondering if the Tesla Powerwall 2 is even usable sans it's Internet connection. Musk has a way of shipping products and then revising the vehicle (or in this case the device) software one or more times via his mandatory network connection.

I would not mind paying for network access, especially if it were my only monthly utility charge. But having the box in the garage experience a fault and not be able to phone home about it is kinda scary.

But part of the dream I have is a completely conventional appearing home, with a solar roof that hides it's true nature, and a Passive House certification. No utility connections (except network if available) and little need of owner tweaking.

Re: The Rise of the Personal Power Plant

Unread postPosted: Tue 20 Jun 2017, 12:50:39
by Outcast_Searcher
baha wrote:I waited until the Powerwall was ready because I will not "give" kw-hrs to Duke power. If they will pay me, fine. Otherwise I will set up a fountain in the front yard that burns any excess power I produce.

Finally my home is a showcase for solar power. I have solar hot water collectors on the roof, a solar air heater on the south wall, a solar 30 amp battery charger in my shop, and soon a ground mounted solar array out back. I also have 4 - 4x10 hot water collectors I am going to use to drive an underfloor radiant heating system. BTW - I have already renovated my house to passive house standards.

Very cool. Congrats on your success and example with this.

I hear you on not wanting to let your power utility have free power even while they shaft your community to the extent they can buy the laws to allow, while maximizing their profits.

One thought/suggestion. If you have lots of excess power sometimes which you can wall off or limit (i.e. a circuit to access only "reserve" batteries when the weather/forecast is good or something like that?) , perhaps you could let friendly neighbors charge an EV for free now and again? Favors build great neighbors. Having neighbors who actively support each other is a very nice thing. (This was common when I was a kid. In cities now, not so much).

My next door neighbor is leaving for a couple weeks. I suggested I park my car in his driveway frequently, to help make it look like someone is home to anyone who doesn't know my car (i.e. from outside the neighborhood). He appreciated it. (I stay up most of the night and am around a lot by day, so I'm not too concerned about it looking like I'm not home).

Several years ago when my water line broke, he insisted my plumber attach his water supply to my house via a washing machine hose so I could have water (It worked great. I had almost normal water pressure). Then he adamantly refused to let me pay him something for the water and said "Please just let me be a good neighbor".

As I get older, I find such friendly relationships increasingly nice to have.

Re: The Rise of the Personal Power Plant

Unread postPosted: Wed 21 Jun 2017, 08:08:25
by Ibon
baha wrote:I can either give power to the grid or not. I have decided to give it away for now. It will go straight to my neighbors houses without them even knowing.


Our neighbors are too far away and we are dumping 70% of our 7.6kw on a daily basis from our hydro system.

Channels 1 and 2 of the dump load from our load controller are burning off unused power heating water. When we finish our last cabin we are planning on sending these two channels to a 2500W heating element that will be part of a hot tub we will make out of tropical hard wood left over scraps. We are planning on putting this right in the middle of a garden area with 10 hummingbird feeders.