Let the sun shine in
For the last year, I have been living in an apartment with solar hot water. I have seen the water heaters from a distance, on roofs surrounding my office, but never had a chance to get up close and personal until I stopped by the 8th floor hotel room of a visiting friend last weekend. Kunming is known for its effective use of solar technology, but very few Kunming residents ever get a close look at these things unless they are purchasing one, or happen to live on an 8th floor. (Most apartments here are only 7 stories, since they do not have elevators, anything more would be excessive).
When apartment hunting, the bathroom was always my deal-breaker. I expected a western toilet (even though they’re hazardous to your gastrointestinal health) and I DEMANDED hot water. Shockingly, a number of rental options lacked any heated bathing options. A few had electric or gas water heaters installed in the bathroom: sleeping-bag sized rusty metal monoliths that provide scalding water and a palpable explosion/electrocution threat. At least 70% provided solar hot water, generally referred to in Chinese as “solar capacity” or 太阳能
There are definite quality differences in the heaters from apartment to apartment. Some hold their heat through two cloudy days, others start cooling after 18 hours or so. Some can give you a hot shower after only two or three hours of sun, others need 6 or 7 hours to recover from a cloudy spell. I’m lucky enough to have a very effective unit (not sure of brand, it’s on my roof).
There are many rumors circulating about the use of solar water heaters here in Yunnan, and particularly in Kunming, but I can’t find any confirmation for the most persistent one, which is that Kunming city supposedly has the highest solar energy use of any city in the world. Kunming was a project site for a Global Environment Facility (GEF) and UNDP joint project on renewable energy, and is home to one of the 3 major research bases for solar energy:
Yunnan Normal University Solar Energy Research Institute (Chinese, and a fussy load)
A bit more about the units being used here, courtesy of this story from June 06 in PlanetArk:
All have the same basic design, a row of sunlight-capturing glass pipes angled below an insulated water tank. The key to the demand boom, even in the freezing northeast and chilly western deserts, is the vacuum separating the inner tube with its energy-trapping coating from an outer tube. Sunlight travels freely through the glass tubes but the heat it generates is trapped inside the central one where it can be transmitted to water. “The vacuum prevents molecules carrying heat away, as there is no direct contact between inner and outer tube,” Huang said. The heaters are also easier to produce than better known electricity-generating panels. Himin’s workers making these wear white overalls and hair caps, in rooms sealed to visitors. But downstairs, water-heaters roll off a production line in open warehouses filled with the clanging of giant metal presses, the roar of painting machines and open flame of glass-handlers.
There are quite a few companies producing these units here in Kunming, websites in Chinese here and here. I would love to hear more from anyone who knows about the solar water heater industry in Yunnan province, particularly what kind of research is being done on cost, market adoption, or extrapolation to other cities/regions.