Horace Heffner wrote:
The significant development is the *replacement* of building materials with solar active materials. In looking at the economics it is only the *incremental* cost for solar that counts. The cost of the roofing materials replaced can thus be deducted from the true cost. In addition, solar elements can have much longer lifetimes and storm viability as compared to roofing shingles or even rooftop mounted panels.
I do not know about the long life. Cells lifetimes are limited by scratching and discoloration of plastic cover, and the cell materials breaking down from exposure to sunlight and heat. (The thing is placed in bright sunlight, after all!) My guess is that the roof will last much longer than the cells.
The cells degrade over time, not all at once. I recall some years ago the half-life was about 7 years.
I doubt that roofers will be able to replace only the solar cell part, and not the whole roof tile.
Roof tiles like this are very common in Japan. I have not seen any solar ones. Thin, flat panel solar cell arrays are common in southern Japan, as I have mentioned here. Japanese builders and roofers have been mounting equipment on roofs for 50 years. Solar heaters are extremely common. In some towns with southern exposure just about every house has one. The older ones had a large cross section to the wind, yet they seldom fall down or cause problems. Although at friend's house one of them flew off during a typhoon and crushed the neighbor's garage. It had been up there for decades. It was probably held with corroded clothes-hanger wire, knowing my friend.
I have seen many of them installed with chickenwire and bubblegum style building code violations, which is not uncommon in the countryside in Japan, where buildings often remain standing out of force of habit. Yet they seem to survive the annual typhoons. You see a lot of shoddy & dangerous construction in rural Japan. People casually detonating explosives and accidentally driving heavy equipment off the road into a 2-meter drop, since the roads often lack guard rails. One of them drove a bulldozer off a 50 meter drop and miraculously survived. Heck, I have seen 70-something county workers replacing traffic signal lights from the back of a truck, on a step-ladder, placed on a tottering pile of plastic shipping containers (which are ubiquitous in the countryside). They don't use wimpy cherry-picker trucks. Rural Japan would give an OSHA official a heart attack.
My friend with the flying solar water heater was a National University Professor, as you would expect. All National Universities in Japan that I have visited are held together with chickenwire and bubblegum. When they finally tore down Mizuno's building in the Nuclear Engineering Dept. a few years ago, I doubt they had to give it more than a firm push. It looked like a house of cards to me. It was literally splitting in half, with a gap of ~10 cm on the second floor and windows so skewed they had not closed in years. As they were tearing it down they found it was so full of radioactive garbage they had to declare it a hazard area, which greatly delayed the project and increased the cost. When it was finally down they found it was built on an important Ainu archeological site. None of which surprised me or Mizuno.
- Jed
