Kunming Heats Up as China's "Solar City"

Ryan Hodum – June 5, 2007 – 5:00am

Traveling across China, it's hard not to notice a unique and environmentally benign technology that has been gracefully integrated into urban buildings and other structures. As solar hot water heaters have grown in prominence over the last 30 years, they are now visible almost everywhere, atop hutongs (traditional alley complexes) in Beijing, on modern apartments in Shanghai, and in farming communities in rural Lijiang.

The heaters consist of a series of cylindrical glass tubes, mounted at an angle, connected to a large water storage tank. Mainland China is now home to as much as 60 percent of the world’s solar hot water heating capacity, and the total installed capacity of the heaters in the country is estimated at 30 million households, according to Eric Martinot, a renewable energy expert and Worldwatch Institute senior fellow based in Beijing.

But it is clear that one city stands out as China's aspiring "solar city", and that is Kunming in the western province of Yunnan. Although Kunming is more often referred to as the "City of Eternal Spring" due to its moderate climate, as one travels toward the city's central district, it is virtually impossible to avoid the glare reflecting from water tanks atop nearly every apartment complex. More than half the city's 4.7 million inhabitants use the solar heaters, according to Sangte Li, CEO of Sangte Solar, a successful manufacturer and distributor of the units in Kunming.

As China's urban population continues to grow each year (by nearly 50 percent in 2007), many apartment renters now expect to get a solar hot water unit along with traditional amenities. "The technology is so cheap it has become commonplace for everyone to have," explains Li. "Most people consider it an included expense as part of their total energy bill.... A solar hot water heater is viewed as a standard appliance by most urban Chinese dwellers."

Sangte Li says the units can be relatively inexpensive to install, with the average heater costing only 1,600 yuan (about US$200). The affordability and prevalence of the units is attributed to the low cost of domestic manufacturing, a competitive market, and plentiful solar resources throughout China. Over the last three decades, the industry has matured as a result of the implementation of government incentive programs, revised building codes, and product certification centers.

The technology is simple and practical. Sunlight passes through an outer glass tube and heats an absorber tube inside; a vacuum in the glass prevents any loss in temperature. A heat pipe then carries the collected energy to the water storage tank, where the liquid is heated. Because the glass tube has a high thermal conductivity, it is able to transfer large amounts of heat with a marginal rise in temperature.

The earliest Chinese models were derived from European technology, but the modern all-glass evacuated vacuum tube used today throughout much of the country was developed and patented by professors at Tsinghua University in Beijing. An average unit is about as wide as a bathtub and roughly 1.5 meters tall. The heated water is used mainly for showers and for washing dishes and clothes.

Kunming is home to many experts in the solar field. The Solar Energy Research Institute at Yunnan Normal University, founded in 1971, consists of four laboratories specializing in solar photovoltaic, solar thermal, biomass energy, and environmental engineering. Through technology cooperation and personnel training, the Institute has played an important role in establishing the solar energy industry in the province. In addition, the Chinese government authorized the formation of three National Solar Water Heating Testing Centers in 2002, one of which is housed at Yunnan Normal. The center provides free testing services to the solar industry to assist in product certification.

One of the more interesting dynamics of China's solar hot water heating market, according to Sangte Li, is the relationship between unit manufacturers and apartment developers. The nationwide construction boom parallels the largest increase in solar hot water heater installations in China's history. Most contracts are bid on the market through a formal competitive process, but Li has obtained much of his work through previous relationships, noting that entire apartment contracts are won based on friendships and a certain level of charisma. He says the market is saturated with solar hot water companies—there are over 2,000 today—making it difficult to differentiate one from the next. "The ability to engage developers and contractors is paramount in this industry," Li observes.

As for Kunming's status as China's premier "Solar City," it will need to remain at the cutting edge of this technology to retain this distinction. The city of Rizhao in northern China, with over half-a-million square meters of solar water heating panels, is quickly gaining notoriety in this renewable technology as well. Competition between universities in Beijing, which have patented the evacuated vacuum tube solar heater, and Yunnan University may be enough to spark the next wave of innovations throughout the country.