Solar Powered Generator

Buff-horns · November 30, 2005

http://www.treehugger.com/files/2005/10/sunball_-_the_w.php

Buff-horns · November 30, 2005

Thanks for the kind comments about our SunBall. Here is a bit more info.

The cells we use are triple junction which means they convert ALL the solar spectrum (200nm thru 1,800nm) into electricity. That means they convert UV, light and IR into electricity.

The Fresnel lens material is optical acrylic, is 2mm thick and absorbs less than 1% of the solar energy, thus very little heating in the lens. The lenses passes almost all the UV, light and IR into the hungry triple junction cell below. The material will not discolour and or degrade. It is very stable and designed for this function.

There are 20 lens & cell combinations per 1m2. This means each lens & cell combo handles 50 watts of solar energy on the top side of the lens. About 49 watts passes through the lens and onto the triple junction cell which converts 35% (~17 watts) of the total solar spectrum into electricity. That leaves the cell with a heat load of 49 - 17 = 32 watts which is dissipated onto 900cm2 of 3 mm aluminium heat sink. The max cell temp rise above ambient is 10deg C. The SunBall heat load is 0.03W/cm2 as compared to a flat panel at 0.09W/cm2. Also the passive hemispherical aluminium heat radiator is in the shade as the SunBall is always pointing at the sun. It is also very easily cooled by passing breezes.

The Spectrolab triple junction cells have a heat derating on ONLY -0.04%/deg C. That 13.8 times less efficiency loss than silicon solar cells (-0.55%/deg C).

Combined with the dawn to dusk tracking the SunBall delivers very significant late hot summer afternoon energy whos timing overlaps peak network loads. The SunBall is a much more cost effective way to deal with electricity network peak loads and their very costly investment requirements.

Heating water is better done with a SunBall minus the lenses and triple junction cells and fitted with a 1m2 circular solar hot water heater. Our calcs suggest we will get over 200% increase in hot water generation due to the dawn to dusk tracking. More on that product later.

Please feel free to take this discussion and your questions further either here or on the SunBall discussion group (link on the web site).

The SunBall will change forever the way we generate electricity on the planet.

Regards,

Greg Watson

Pond Life · December 13, 2005

Very interesting reading.

Let me just clarify this in case I've been confused by the techno babble.

This product is claimed to produce 330 watts of power in one hour in strong sunlight ?

I've just installed flat panels purchased in Thailand, Each panel is approx 0.8 sqm & produce 50 watts each, the solar ball seems to blow these panels away.

Has anyone got a Solar Ball in Thailand that could verify these claims ? I'd honestly like to see one in action. I know I sound sceptical but I would be happy to find out its true.

astral · December 13, 2005

Very interesting.

What about the cost including the shipping and import duty to Thailand??

Please keep us updated.

chownah · December 13, 2005

Very interesting reading.
Let me just clarify this in case I've been confused by the techno babble.

This product is claimed to produce 330 watts of power in one hour in strong sunlight ?

I've just installed flat panels purchased in Thailand, Each panel is approx 0.8 sqm & produce 50 watts each, the solar ball seems to blow these panels away.

Has anyone got a Solar Ball in Thailand that could verify these claims ? I'd honestly like to see one in action. I know I sound sceptical but I would be happy to find out its true.

<{POST_SNAPBACK}>

The term 'watt' is a unit of power just as you say...but it sounds like you are confusing 'watt' with 'watt-hour'. A solar panel generating 330 watts every instant for a period of one hour generates 330 watt-hours. A watt is the measure of how fast work can be done...a watt-hour is the measure of how much work is done. An analogy would be that a watt is like speed and watt-hour is like distance....speed x time = distance.....watts x time = watt-hours. If you wanted to lift a heavy weight a certain distance then it takes as much work to do it fast or slowly....that is to say it takes the same number of watt-hours to lift the weight. If you want to raise it quickly you need a motor with a lot of power...that is to say a large watt rating because watts is the measure of how fast work can be done and more watts will do the work faster and the weight will be lifted faster.

Not wanting to throw too much technical stuff at you all at once but for solar panels you need to know if they are talking about peak watts or average daily watts. Solar panels that do not track the sun will have a large peak at one part of the day and really low wattage at other times. The Ball thing is said to track the sun which means that if it does a good job of this it will be operating near peak power for most of the day and thus give you more energy or ability to do work. Daily watt-hour ratings would be good but this would vary alot depending on time of year and latitude...etc. so its easier for them to list their peak power and let people muddle throught as a best they can in comparing panels.

Enough for now...dinner time.

Buff-horns · December 13, 2005

comments on the sunball >>>>>>>>>>

http://www.greenandgoldenergy.com.au/

Comments on Sunball - the World's First "Solar Appliance"?

I will take 10 just get them over to the US asap.

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Posted by: Jason at October 31, 2005 12:32 PM

Wow this makes my day! I thought fresnel lenses would only be used on commercial utilities. It's great to see that they may decentralize this technology.Fresnal lenses get really hot--I hope that there method of dispersing the heat makes it usable for the rest of us. This is really important with that kind of increase in efficiency.

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Posted by: Jimcoli at October 31, 2005 12:51 PM

A heat diffuser? Why not use that energy to boil water and run a generator, producing even more electricity? Or use it to provide hot water or heat to a home?

And the only downside: It still doesn't solve the problem of LPG or propane for my cooktop. And, no, I will not voluntarily use an electric range.

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Posted by: Icelander at October 31, 2005 01:56 PM

I used to work as a grip for television and film lighting. A Fresnel lens is used to transform a point light source to a distant light source by spreading out the beam, more like the light from the sun where the beam is more or less divergent, depending on the focal length you choose. To foucs a beam, a lens more typical of an elipse light is used, similar to the kind found in magnifying glasses and field glasses which yield convergent beams. The source article you cite says "wide lense" and doesn't specify the type. Given their characteristics, the later type is probably in use.

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Posted by: Jerry Carter at October 31, 2005 02:01 PM

Jerry Carter, is sorta right, there are Concave mimicking Fresnel lenses (like you see in the back windows of RV's and some trucks) and Convex mimicking lenses that work like a magnifying lens, i have a nice 3.5' one that i can melt stone with in the hot Southwest US Sun,

i do wonder about acrylic Fresnel's what with the propensity for UV breakdown, and sand pitting/scratching. id be surprised if it worked for more than 2 years here.

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Posted by: Adric at October 31, 2005 02:17 PM

Icelander: if the solar cells get too hot, their efficiency will decrease. I don't know how cool they have to be kept, but I have a hunch they like to be kept below the temperature of boiling water. Also, adding a water cooling system to these machines would make them much more complex and at least a little more expensive.

I share Adric's concern about how well the material of the fresnel lens will stand up to UV exposure.

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Posted by: Ike at October 31, 2005 03:18 PM

Looks interesting, but man do they have to de-clutter their website.

All I wanted to know: approximate wattage output per SunBall (yes, I know it will vary; just a ballpark).

Answer? Nowhere to be found after ten minutes of determined searching, which is far more than someone less, uh, determined would have given the task.

(By the way--treehugger webmaster person? I like ellipses, and the fact that your comment engine prohibits their use is annoying. Any idea why?)

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Posted by: Ian Wood at October 31, 2005 04:02 PM

From their Sunball calculator, they claim that in the south of spain you could get 545 kWh per year per ball, which averages out to about 60W (daily cloudy+sunny+night+day average). South of spain, of course, a good location.

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Posted by: Anonymous at October 31, 2005 05:19 PM

Even if the fresnel lens lasts only 2 years (but i'm sure it will be longer), the point is plastic fresnel lenses are cheap PV cells are expensive. This ought to give more power with less solar cells.

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Posted by: jimcoli at October 31, 2005 07:17 PM

From the technical breif:

1 solar ball = 370Wpeak

they have calculators too to find out how many you need depending on your azimuth. I'd need about 20 of them for my not so efficient house (~800kWh/mo). The nice thing is with local utlility rebates for solar (as long as a local installer carries these) i would only pay $200 a piece for these; $4k to power my house on solar? i'm sold!

Most of the good info is found by clicking on the "products" link on the left.

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Posted by: dave at October 31, 2005 07:28 PM

I'd be a lot more likely to buy one if the concentrated solar power was used to run a Stirling engine instead of a photoelectric cell. Why concentrate all that heat on a solar cell that loses efficiency as it gets hotte), when you could power a stirling engine and generate quite a bit more electricity?

I know, that would be more complicated, more moving parts and all, but a stirling engine is pretty simple, and could easily be made with tough, long-lasting, easy-to-change parts, especially the seals and bearings and other parts that will wear fastest.

It already has light sensors and a motor to keep it following the sun, replacing the solar cell with a stirling engine wouldn't add that much more complexity, and the parts would be far cheaper to replace than those 'high-efficiency' solar cells.

I suppose the biggest problem would be noise. Stirling engines would unavoidably make more noise than a silent solar cell.

It's too bad, really. I'd LOVE to be able to put a series of such devices on my roof. It's a nice flat roof, gets lots of sunlight all year, etc. For a solar-cell setup, I'd have to buy a huge slab of very expensive solar panel all at once. With something like this, I could buy and install them one at a time as I had funds, and I'd also have a lot more leeway in where I put them. I could make far better use of space than if I have to place big contiguous slabs.

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Posted by: Ermine at October 31, 2005 09:18 PM

In full sun you get approximately 1.4 kW/m2.

In the article it states a 1cm2 cell with a lense capturing 500 times as much light operating at 33% efficiency.

Thus it would look like

(1400 watts/m2) * 500 cm2 * 0.33 / (10000 cm2/m2) = 23.33 watts.

Which is a remarkable amount of power from such a small cell but not particularly attractive at $160 0 AUD

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Posted by: Todd Allen at October 31, 2005 10:18 PM

Just 0.16%? Thats 4 times new york state!

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Posted by: Chris at October 31, 2005 10:37 PM

Why not the lens with a stirling engine?

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Posted by: Matt Mulligan at November 1, 2005 12:46 AM

similar track to these guys, check out the Sunflower solar concentrator.

http://www.energyinnovations.com/

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Posted by: Adam at November 1, 2005 01:27 AM

whatever happened to the idea of super-heating a liquid (like maybe alcohol) with a system like this to drive a small steam turbine?

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Posted by: k at November 1, 2005 04:30 AM

Regarding all of the stirling engine / turbine questions, there are people who do concentrated solar setups to run stirling engines and generate electricity: http://renewableenergyaccess.com/rea/news/story?id=38672

Note, however, that they do it with pretty huge dishes. My guess is that it's hard to scale the technology down to something that will easily go on a consumer's roof.

Also, existing solar modules don't need to be in a contiguous slab, each one just has to be somewhere that it gets good sunlight. As long as you've got an inverter that can handle different voltages, you can start with as little as one module and add more. A hypothetical solar-stirling device might be easier to integrate with a home's power system, but only if it output normal AC power right from the device.

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Posted by: Ike at November 1, 2005 11:46 AM

Hi Guys,