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Tesla Solar Cells

09/01/2017 10:17 AM
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Guru
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#1

Re: Tesla Solar Cells

09/01/2017 11:15 AM

I might should start considering a roof job on my work shop, but I still have not worked out the storage aspect. I like having more storage power and energy than less.

Not ready for that giant Li+ battery pack out back, or even a molten silicon device.

I think I would rather have the molten silicon in my back yard, as it might be safer.

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#2
In reply to #1

Re: Tesla Solar Cells

09/01/2017 11:25 AM

I have your solution

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#3
In reply to #2

Re: Tesla Solar Cells

09/01/2017 12:25 PM

Yes wind is big business here in West Texas.

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#5
In reply to #3

Re: Tesla Solar Cells

09/01/2017 12:46 PM

don't install one in your backyard, the treehuggers will flip out if a dumb bird flys into one of the blades

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#6
In reply to #5

Re: Tesla Solar Cells

09/01/2017 1:28 PM

How about this one:

VAWT involute spiral design

I liked what I saw on this link: Loads of practical information also. Bird that gets too close to the spirals can still fly right in and take a joy ride, come out the other side unscathed. The guy wires spinning around could be an issue still, AFAICT.

All the heavy generating gear is at ground level, a real plus for an older gentleman.

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#9
In reply to #6

Re: Tesla Solar Cells

09/01/2017 2:09 PM

Check these out. They are pretty bird-friendly, since they are seen by wildlife as a solid, unmoving object. And available in small packages for residential use.

Kohilo Wind

They did a presentation at our local IEEE PES meeting, and we were quite impressed.

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#11
In reply to #9

Re: Tesla Solar Cells

09/01/2017 3:09 PM

I took the bait, and made a contact request.

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#12
In reply to #11

Re: Tesla Solar Cells

09/01/2017 3:33 PM

sucker

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#13
In reply to #12

Re: Tesla Solar Cells

09/01/2017 3:41 PM

As well we recall what P.T. Barnum is credited with "There is a sucker born every minute".

But there also what Dad taught me: "Boy, don't be the first to buy the new stuff, but when you are in competition, don't you be the last."

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#21
In reply to #13

Re: Tesla Solar Cells

09/05/2017 1:54 PM

There is no evidence Barnum ever said that.

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#22
In reply to #21

Re: Tesla Solar Cells

09/05/2017 2:04 PM

I thought you might be the one to call me out on that poorly thought out answer. Dern it, flat-broke, and busted again.

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#16
In reply to #6

Re: Tesla Solar Cells

09/02/2017 5:19 AM

Agree - also like what I see, but I sincerely hope that the science behind the idea is better than the grammar describing it.

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#17
In reply to #6

Re: Tesla Solar Cells

09/02/2017 4:21 PM

I agree with you, I want nothing to do with maintaining a gearbox/generator mounted on top of a tower.

From what I've read, the contention between VAWT and HAWT enthusiasts seems to be as polarized as religion or politics. One site will say one is obviously superior and the next will say the other is. I think the consensus is that HAWT is more efficient for steady winds but VAWT more useful with light, varying winds.

Any kind of wind turbine slows moving air down, extracting some of its kinetic energy. Extracting all of the kinetic energy would mean the air would come to a stop, obviously impossible for more air to enter. Albert Betz worked out that the maximum energy that can be extracted is 59.259259....% or 16/27. My understanding is that the common 3 blade wind turbines achieve about 70-80% of Betz limit.

https://en.wikipedia.org/wiki/Betz%27s_law

Of course, for the amateur, the difficulty of installing and maintaining a generator/gearbox on a tower (HAWT) trumps the lower efficiency of a VAWT.

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#18
In reply to #17

Re: Tesla Solar Cells

09/03/2017 7:05 PM

As an old timer once told me, or something to this effect.

You can only pass so many so many ft/lb hours of energy through a gearbox its lifetime. How you alot them is what matters.

I found it to be oten same lines as modified engines. They can only burn so much fuel in their lifetime. How fast you burn through that fuel is what will determine the life expectancy.

The more power you put through something the shorter the lifespan and with wind power it's likely they will see running hours in conditions that no engine or electric motor would subject them to.

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#20
In reply to #17

Re: Tesla Solar Cells

09/05/2017 8:50 AM

There is another way to use tall tower, and HAWT: At the top of mast is the rotor with a hydraulic pump that produces high pressure.

At the bottom is the hydraulic LP accumulator, the HP accumulator, the hydraulic motor/generator, and an LP booster pump (if needed).

Almost all the heavy stuff ends up at the bottom. One has to have a coaxial LP, and HP hydraulic line with rotating seal glands also.

Some astute engineer might be able to work out a sealless rotating system (for HAWT aiming), but I have not seen it.

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#4
In reply to #1

Re: Tesla Solar Cells

09/01/2017 12:38 PM

Molten silicon? Wow, is it that hot in Texas?

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#7
In reply to #4

Re: Tesla Solar Cells

09/01/2017 1:38 PM

Not usually. Mesquite wood we don't let get that hot when we are cooking, it ruins the ribs and brisket.

Molten silicon has to be heated electrically, and has a significant heat of fusion, and a considerable heat capacity above the melt temperature. That lends itself well to a high power density.

molten silicon and TPV

I read somewhere, can't find it right now, the energy density can be north of 10 MWh/m3 as thermal, and the TPV can be optically tuned using special mirrors for several selected bandwidths of optical radiated energy down into the infrared, resulting a net theoretical conversion efficiency of >80%. Thus far, no one is really making it over the 50% barrier by much, but >70% is clearly reachable with present knowledge, technology. This far surpasses every other means for storing energy, except for maybe pumped hydro, but even that with its high efficiency cannot match molten 1400 °C silicon for energy density.

The best scheme for utilizing this in a grid-connected system is very near the distributed renewable source(s). Harvest off-peak, and back generate during peak demand, high price times. Instantly dispatchable also.

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#15
In reply to #7

Re: Tesla Solar Cells

09/01/2017 4:55 PM

Aren't you subject to Carnot efficiency when you convert heat back into electricity? So if you heated silicon with a large mirror array, would the overall efficiency (electricity out/sunshine in) be as great as a solar array?

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#19
In reply to #15

Re: Tesla Solar Cells

09/05/2017 8:44 AM

Carnot efficiency is related to thermodynamic engines. Truly there is an upper limit of energy conversion at any temperature for an optical process of converting light to electricity, but it seems to have more to do with processes in the semiconductor materials involved, selection of band, rejection of other radiated energy back into the source, etc.

Certainly, I am not the one that reported the estimated and achieved efficiency thus far. The theoretical efficiency in this case remains at 82%. Practicable efficiency at this point has not quite reached 70% if my recollection is accurate. Workers in Madrid seemed to be very optimistic that with multiple band selection, they can surpass the 70% barrier handily.

Whether using direct heating, or electric heating, the efficiency of heating the material (silicon) is pretty doggone high.

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#8

Re: Tesla Solar Cells

09/01/2017 1:53 PM

On an unrelated note, for a former resident such as myself it's heartening to see Buffalo's shuttered steel mills repurposed like this.

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#10
In reply to #8

Re: Tesla Solar Cells

09/01/2017 3:00 PM

Anything to stir the slumbering chords of industry is a better sound than the dead, cold silence that has prevailed for the last several years, or was that decades?

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#23
In reply to #10

Re: Tesla Solar Cells

09/08/2017 2:16 PM

Locals still talk about the Lackawanna/Bethlehem Steel days--that plant closed in 1982. It was more or less downhill from there but the future looks a little brighter these days.

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#14

Re: Tesla Solar Cells

09/01/2017 4:50 PM

Meh.

I'm putting my money into my used oil burning diesel co-gen set.

Cheap, as reliable as any wind or solar is and will give me both cheap electricity and winter heat a the same time.

Being used oil collection network has now passed my annual heating only usage by double I have to start doing something with it. My fall collection run will probably put me on the high side of 6000 gallons on hand going into winter with a ~1000 gallon anticipated usage.

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