The low-carbon patent exhibition is held in Chongqing, November 7.

A thin board about the size of a laptop holds a series of circuits with a layout so elaborate that it looks more like a set of miniature building blocks than a component in a lighting system.

The circuit board developed by Hiten, a Chongqing-based high-tech maker of light-emitting diode (LED) lamps and solar photovoltaic systems, is innovative enough that it has been granted five patents and is prominently displayed at a low-carbon patent exhibition held in the southwestern metropolis on Nov 7.

Liu Ting, sales manager of the company, told China Daily that the board links LED lamps and solar batteries in such a way that it provides more efficient power storage and capacity to convert even low light to energy.

"Our solar cells do not just absorb sunlight as a source of power, but catch any light," Liu said, a feature especially useful on cloudy or rainy days, which are common in Chongqing.

Once the battery is fully charged, the circuitry orders it to stop absorbing energy to avoiding overcharging.

At the same time, the board judges the strength of natural light and accordingly adjusts LED brightness, Liu said.

"We do not sell single LED lamps or solar cells," Liu said. "What we provide is a lighting system of LED lamps, the control device, solar batteries and technological solutions."

She said her company's technical team offers on-site and tailor-made circuit designs at the request of clients.

Also inspired by Chongqing's wet weather, a grain dryer developed by local cooking utensil company Xinghuo was first designed for use in the rainy season.

But even on fine days, the dryer helps shorten time in the sun needed by harvested crops before storage, said Tang Xianlin, head of the company's marketing department.

Made of two steel cylinders - one for burning straw and another for emission collection - and a 2.3-meter-long tank, the system is convenient to use in rural areas, Tang said.

Similar inventions by Xinghuo's overseas peers are generally much larger and used for far more volume, ranging from scores of to hundreds of tons.

Priced at 46,000 yuan, the locally made grain dryer is more suitable for domestic volumes and budgets, Tang said.

With a patent secured, the dryer is on the promotion list from the Ministry of Agriculture, meaning farmers can receive a government subsidy, making the price even lower, he said.