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Lion Kuntz
25th January 2007, 04:49
I know this forum is designed for, and populated by, people who are dealing with home-sized power issues, but Rob did post a greeting message when I signed up that posting message traffic can help him achieve his goal of getting 500 members into the forum.

I am always on the hunt for information and ideas for alternate power suitable for large projects, multi-story buildings with 100 living units, and downstairs public or commercial space. Your challenges are multiplied by a lot trying to crack this nut.

Now, I hope this isn't too far off-thread or off-topic, but I would like some review of possibilities.

First things first. I am pushing an idea, and my website has had 800,000 hits over 4 years, which started out from the assumption that BIPV (Building-Integrated PV) would be sufficient and affordable. Since I was starting from a blank piece of paper going into areas I didn't know if anybody had ever entered before me, there wasn't anywhere to go to get data handed on a silver platter.

I knew from long decades of experience that terraced buildings allow several roof deck layers to get light as patio decks, and that sloped shoulder buildings gave a smaller shadow profile onto neighbor's solar right-of-way then box shaped buildings.

I think we can all agree that it is un-neighborly to shade your neighbor's solar panels or even their building if you can design better.

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I used some 3-D ray tracing software to make pictures of what the sun would do on these kind of buildings. I liked the results I saw. I expanded the concept further and further.

Ultimately I got way over my head, personally. Design of multi-megawatt 24-hour power supplies is nothing I had any real background for.

Now, four years into this, I think I know what has to happen.

Basically, PV must be incorporated into the building like never before in history, to the point that PV is actually created in the building as part of the whole utilities services of power, heat, cooling and cooking gas with H2-PV, meaning PV power stored as hydrogen for non-sun-production hours.

Conceptually it's easy: plug a PV bank module into a reversible fuel cell module, and voila! In reality there are all kinds of sticky technical details.

The sticky details are in the Balance of System, more than anywhere else, so that's why I picked this forum section to post.

I think the kind of issues involved could make for an interesting discussion going over months, but that's just what I think, and depends heavily on other people thinking so too.

The basic parameters of the problem are outlined in some sample chapers of an uncompleted e-book. See http://ecocity.us for details.

The typical city block that I paced off in several cities was around 2.5 acres, or the international land area unit of the hectare (10,000 square meters). Of course there are more blocks that vary from that idea, especial in subdivisions that favor cul-de-sacs, so that it's really nothing more than a starting place to begin thinking about it. If the people didn't object to shaded roofed-over outdoor patio decks, the theoretical maximum PV power from polycrystal comes out to 1.3 megawatts per peak sunny hour. In the sunny southwest people might prefer shaded decks, and they get 6 full peak hours without tracking.

As you can imagine, this is not your backyard DIY installation.

Is this anything people want to talk about in their spare time?

If it's not right for here, this forum, Rob will say so, but I have a couple of new forums that I just started where we could move it in that case.

The optimistic numbers are not achievable for several reasons, but even half that much energy, say 650 kilowatts/peakhour is still heavy duty to think about. It is more than enough to make PV through the Electromagnetic Casting furnace process. An EMC furnace process 30 kilograms of silicon per hour (best state-of-the-art) and uses 12 kW/kg for 360 kWhs per hour. It would take 67 days for one of those furnaces to cast the polycrystal silicon to roof the building. (Yes, I know there is more to it than just that.) :cool:

Still, think about it. One building makes an essential part of the PV in two months to equip a similar building. If the building shell was built and the power systems installed while the interiors were being finished out, the building could devote almost every watt of power to the PV operation before the people moved in. By the time the building was populated the PV system would have paid off it's debt for it's own initial PV system by producing PV grade polycrystal ingots of marketable value. The two months, or 67 days, was predicated on non-storage of energy. With storage and 24 hour operations the casting of 10,000 meters of PV grade net silicon is 17 days.

Rummaging around I came upon some expired patents that show a pathway this can happen:

* 4588571 - Filed Apr 19, 1984 - Heliotronic Forschungs-und Entwicklungsgesellschaft fur Solarzellen- Grundstoffe mbH - Process for the purification of silicon by the action of an acid

* 4457903 - Filed Mar 1, 1983 - Heliotronic Forshungs und Entwicklungsgesellschaft fur Solarzellen Grundstoffe mbH - Semicontinuous process for the production of pure silicon

* 4572812 - Method and apparatus for casting conductive and semiconductive materials

There is a ton of Balance-of-System issues before anything real could happen, but these are starting places to talk it out.

David Hart
25th January 2007, 19:18
Hi Lion,

Check out http://www.greenandgoldenergy.com.au/ - tracking, concentrating solar PV. The system can scale from DIY to megawatt deployment.

Lion Kuntz
25th January 2007, 23:19
Hi Lion,

Check out http://www.greenandgoldenergy.com.au/ - tracking, concentrating solar PV. The system can scale from DIY to megawatt deployment.

There's any numbers of good choices out there but all of the ones under patent are at the mercy of the patent owner. A no-patent, open-source design using plenty "good enough" technology based on 20 year old stuff comes in as the winner.

PV is made of the same stuff as beer cans and beer bottles and costs the same as beer cans and beer bottles whenever it is made in the same quanity of volumes as beer cans and beer bottles. 30 cents a square foot, 2.5 cents a watt, is the natural price for PV. The out of pocket costs to put PV on every rooftop of America is $200 per capita.

Anyway, concentrators or naked PV, you still have the same issues I noted above about the balance-of-systems. A 24 kW system is still 8 times larger than a $5,000 3 kW grid-tie inverter can handle.

The bottleneck is not sunlight-to-electricity, but DC-to-grid at costs that match the high-volume bulk PV costs.

Grid-tie was opposed by all utilities for long times, so it wasn't pursued by inventors with no market to sell to. The patents are all new and will last a decade or two.

It requires an open-discussion of principles and circuits and combinations that are unpatented, public domain, or invented in public by input from many people so that no one inventor can stake a claim to monopoly on it. It also means not stepping on the toes of existing patents. It would be better if there were 20-year old expired patents, because then it would be clear that no new patents are being stepped on, since the same invention cannot be patented twice by two different people.

The Whole H2-PV Economy may be delayed for years by this bottleneck when everything else is completely solved.

Now if anybody has an old book that shows a good useful easy & cheap to mass produce pure-sinewave inverters from 20 years ago, that ends a lot of anxiety, since whether it was ever patented or not, ANYTHING published more than a year ago but never patented, or anything published and/or patented more than 20 years ago, is free-for-all.

By cheap to manufacture, I mean in the context of cheap abundant PV, not in the context of the present energy price structure. It takes 16 kWhs to electrolyze one kg of aluminum out of alumina. It takes one square foot of PV to do that in 242 days, or 242 sq.ft to do it in one day, or 1.8 acres of PV to do that in one minute. The more PV you have, the more energy to make the infrastructure faster to make more PV faster.

Silicon and aluminum are two of the top four elements on Earth surface. You hardly even have to dig for them, they are laying literally on the surface.

In fact, they are so common and so joined that you could probably make both together out of the same raw material, say kaolinite Al2.Si2.O5(OH)4, at the same time in one combined process. There's an equal measure of Si + Al in that. That's for people of the future -- for us, we don't have the luxury of time to invent whole new industrial process from scratch, and we don't have the luxury of cheap abundant power because we burned it commuting to Walmarts instead of investing it 30 years ago WHEN IT WAS CHEAP and abundant. H2-PV should have been finished 20 years ago and is barely started in 2007. There's no more time to fritter looking for the perfect answer when plenty "good enough" is already here. Not doing it is literally TALKING US ALL TO DEATH.

Anyway, back to Balance-of-Systems.

Joe Blake
28th January 2007, 19:12
Just a couple of brief comments. At present PV cells aren't really designed to handle excess heat. Rather than trying to build PV's which handle heat better, why not add on an "extra layer" to capture the heat and use that? So the building energy is PV plus waste heat. Just having living people in a building generates waste heat. That heat can generate hydrogen.

Once you've done that, then you can start increasing the amount of light by strategically scattered reflectors. Recycling old CD/DVD's is feasible here. Just trim them to hexagonal shape with a Stanley knife or paper guillotine, and you increase their light reflecting surface area.

Whenever I can capture sufficient spare time, I'm going to see if I can build a steam generator using old CD's mounted on pieces of PVC pipe.

I don't know how long it would last, but at least the CD's are useful in this second incarnation. Better than taking up landfill space I suppose.

Joe