Sunday, April 19, 2009

eco: solar heating means green jobs!

Our solar photovoltaic panels sit there making a dollar or two of electricity every day for us. Zero maintenance, besides occasionally wiping the grime off the panels.

As I intimated, solar heating is another story. After only two years the solar tubes on our roof stopped providing domestic hot water, so we had to turn on the back-up electric strip heater in one of our storage tanks to get hot water. A 50-gallon electric kettle is a very expensive way to get hot water, requiring far more electricity than our solar panels generate.

It was difficult to find anyone willing come and service it. (Our general contractor fired the original designer/subcontractor Bill Reyno and we wound up in legal mediation with the contractor over delays and non-functioning system.) Solar electric is just a bit of mechanical fabrication and some parts wired together; however, solar heating is tubes, wires, pipes, pumps, fittings, solder, valves, expansion tanks, electronic controllers, solenoids, and heat exchangers. There's no standardization, every contractor does it differently, and no one wants to take on responsibility for someone else's design with which they disagree. Everyone who's ever looked at our system has responded "I wouldn't do it that way..."

Finally Luminalt sent some people out. They figured out one of the pumps wasn't working. They had to isolate that pump, drain the system, dismantle it, find a lump of solder inside gumming on the mechanism, refill the system, replace a pressure valve, charge the system with glycol, test everything out. Two and a half guys, two days, $1100. Have no doubt that being environmental means green jobs for Americans! Better yet, the business end seems a little disorganized and they've yet to send me a bill!
158 degrees Temp from Solar!tank at 129 degrees!
Since Luminalt fixed it, we've been getting much hotter water, maybe because they replaced a pressure valve with a higher pressure one.
The rightmost temperature gauge in the first pic shows 158 degree glycol mixture from the solar tubes, and after pumping through a heat exchanger, the top sensor in the second pic shows 129 degree drinkable water in the first tank. It's magic!

On a sunny spring day we're getting more hot water than we need or use, which makes me dream about sending some excess heat to our radiant heating system to heat our house. The system was designed to do that, but that has never worked for a litany of design flaws too depressing to recount. Moving heat around is fiddly and depends on careful system design and installation.
Luminalt installer with Solamax tubes
Three out of the 40 Solamax Direct Flow Evacuated Solar Energy Collector tubes in this picture have condensation on the inside, so they ought to be replaced. I called the distributor SolarThermal, and the guy laughed. If they send these tubes out by UPS, a box of glass shards will arrive on my doorstep. I'd have to pay $300 for a special pallet load to be trucked to my door. That's why most solar installers use flat plate collectors or Mazdon tubes, which are not as efficient but a lot easier to transport.

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Saturday, August 9, 2008

eco: drying with solar wind power

I showed our first-generation low tech solar wind photonic membrane evaporator, here's its replacement saving money, avoiding pollution, and reducing wear and tear.

clothes drying on laundry trees by Kris Borchardt
Even lower tech than before, but the two laundry tree sculptures by Kris Borchardt are functional art.

And here's lower-tech indoor clothes drying technology for $13.
Pull-out end of retractable clothes dryer lineBusiness end of retractable clothes dryer line

If you put clothes in a dryer during the summer, you're crazy.

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Wednesday, March 5, 2008

eco: solar wind photonic membrane evaporator

I wrote about having both kinds of solar panels. (Quick update: The solar heat panels do heat our domestic hot water, but our overall heating system is still a busted inefficient disaster...)

I neglected to mention our third solar system, a proven hybrid technology that takes advantage of wind power as well. Here's a picture of one end of this engineering marvel:
solar photonic wind dryer
Unlike our other solar systems that cost many thousands of dollars, this cost about $25, and a ham-handed DIY disaster was able to install it in an hour. All the parts are available on dusty shelves at Ace Hardware: clothesline cord, two special reels, two hooks, and a nifty line tensioner. And it worked perfectly. Anyone who doesn't install one of these is throwing money away. (Update: Some people don't understand: this is a clothes line so you can dry your clothes for free without running an energy-consuming appliance.)

Despite its excellent technical features, it didn't fit in with our garden landscaping. (We still have a miniaturized version strung across our utility room.) Here's an early look at its replacement:
laundry trees by Kris Borchardt
Two laundry tree sculptures by Kris Borchardt, in the process of installation.

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Sunday, July 31, 2005

eco: solar progress uphill

Harnessing solar energy economically is the great engineering challenge of our time. My partner and I are putting solar thermal and photovoltaic on our new house, but we'll spend US$ tens of thousands of dollars (after tax breaks) just to save $100 a month in in electric and heating bills. It's an emotional and spiritual decision, not a rational economic one. But if someone can drive the cost per watt or BTU so low that putting in solar becomes an easy way to Make Money Fast, the market will take over.

Energy Innovations, founded by Idealab dot-com incubator guy Bill Gross, has thought so hard about this, it's inspiring.
  • They're focused on a great mission: "Our immediate goal is to reduce the payback time for a solar system so that it becomes a sensible and logical investment to electricity users around the world."
  • They're focused on a great market: the billions of square feet of roofs of commercial buildings that just lie there, unused, baking in the sun.
  • They're focused on cost over technology. Read their entire Innovations section, especially the "Lessons Learned". They looked at Stirling cycle engines, servo-controlled "petal" mirrors, big heliostat arrays, Fresnel lens concentrators, ... and abandoned them because they couldn't get them cheap enough in a short timeframe.
Yet even with all that focus, it is still so damn hard. Solar cells with reasonable efficiency cost money, so you concentrate sunlight on them with cheap mirrors, but then you have to track the sun with a mechanism that costs money. The more you concentrate, the more you can spend on exotic solar cells, but then you have more mechanical engineering. And the concentrated sunlight bakes the solar cells: you could try to capture that thermal energy but that raises cost and compexity, so you have to come up with a cooling system. The tradeoffs are everywhere.

There are other companies with big ideas: cheap PV films, PV coatings, nano-scale concentrators, etc. While these efforts that could change the fate of the Earth get a few millions in venture funding, the 2005 US energy bill gives around $6 billion dollars in tax breaks to carbon-spewing global-warming smog-creating oil, ethanol, and coal producers.

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