Yuchai which has built China's largest roof solar PV power station has managed to convert sunlight collected on plant roofs into electricity to satisfy the enterprise's production demand and to sell the rest to the country.

In 2012, the "grid-connected generation project of Guangxi Yuchai Machinery Group Co., Ltd. ("Yuchai's new energy PV power station)" undertaken by Guangxi Yuchai New Energy Company passed the inspection by an organization designated by the Ministry of Finance and began to go into trial operation.

PV modules are arranged neatly on plant roofs

Yuchai's new energy PV power station can save standard coal by over 10,000 tons, carbon dioxide emission by 25,000 tons, sulfur dioxide emission by 750 tons, nitride emission by 37 tons and dust emission by 5,800 tons annually. PV power generation produces no pollution like gas, liquid and solid waste, and can be integrated with rooftop buildings without occupying land resources. Thus, the project will yield substantial environmental and social benefits.

Challenge: two months from construction to trial power generation

At the commanding heights of all project zones, you can see PV modules about 1.6 meters long and about 1 meters wide arranged in good order on roofs; entering the plant, you will find the inverter installed neatly on the edge of the verge of the plant or in positions not affecting the plant's original layout, which will not degrade the overall appearance of the plant. The design staff must have racked their brains before installation.

Li Xiaochuan, person in charge of the engineering technologies and construction of Yuchai's new energy PV power station and assistant to manager of the manufacturing improvement department, told the reporters that many factors were taken into account before design: project implementation should not affect production site, safety civilization, overall appearance and logistics smoothness, PV modules should be most efficient in power generation, module installation should be safest and module maintenance should be easiest, other equipment like inverter, combiner box and cable should be selected under the principles of minimum investment and economic operation assurance, and the project must be completed within the time prescribed by the Ministry of Finance, thus a lot of equipment was designed, produced and installed on site, and installation was concurrent with design. It can be seen that the project was difficult.

The construction period coincided with the rainy season and the temperature was high. PV module installation on roofs is aerial operation not allowed after night falls, thus workers of the new energy company often had to continue working against stuffiness after showers and in scorching suns. It took only two months from the construction to trial power generation of Yuchai's Golden Sun project with an installation area of 420,000 square meters and an installed capacity of 30MW, which is undoubtedly a severe challenge for Yuchai's technical workers who without previous knowledge of PV power generation in terms of scale, technology and construction period.

According to sources, Yuchai's new energy PV power station has a perfect communication monitoring system including data acquisition module and computer monitoring equipment. Operation parameters like generation capacity, voltage, current and frequency as well as environmental parameters like illumination intensity, ambient temperature, wind speed and wind direction can be transmitted to the monitoring system via RS485 interface, thus accomplish full automatic and unattended operation and monitoring of the PV power station. The PV station is currently one of China's most advanced distributive PV power stations.

Demonstration: Build roof PV power generation project with the largest installed capacity in China

Roof solar PV power stations are not fresh abroad. Germany starting early in this field worked out a "roof program" in 1991. With the strong support of a series of national policies, Germany's PV industry remains vigorous and Germany has played a world leading role in solar PV module installation and manufacturing.

In China, Golden Sun Demonstration Program with the heavy duty of launching the domestic PV market rolled out in 2009. After years of implementation, national financial subsidy policies play a vital role in the early development of China's PV power generation industry. As a national Golden Sun demonstration project in 2011, Yuchai's new energy PV power station exactly emerged in this context. According to the need of the national energy strategy and the situation of industrial development, the country has perfected and adjusted the relevant policies for PV generation. For example, encouragement and support policies for distributive PV power generation have begun to change from early subsidy into post subsidy, and relevant preferential policies for grid connection have been defined.

After going into operation, Yuchai's new energy PV power station has generated over 21 million kilowatt-hours. Despite acquisition of a substantial national subsidy, given the influence of unstable factors such as winter, rain, overcast and equipment failure, the period of cost recovery of the station is expected to be long.

Referring to the above-mentioned problems, Zhou Sunhai, vice president of Yuchai Group, said, "Yuchai's Golden Sun project is an emerging energy project actively encouraged and supported by the country, the company will start with supporting national new energy project construction and build a roof solar PV power station with the aim of generating power with the clean and renewable energy--solar energy to yield substantial social benefit, it is believed that economic benefit will come with social benefit.

Yuchai's new energy PV power station is a roof PV power generation project which has gone into operation with the largest installed capacity in the country to date. The capacity of the power station has exceeded the total capacity of National Golden Sun projects previously acquired by Guangxi. The project's official operation is of great demonstrative significance to Guangxi's efforts to explore increase of the capacity for continuous energy supply, thoroughly push forward building energy conservation and promote the integration of PV buildings, and has provided precious for the construction of large distributive PV power stations in the country. Its social value is inestimable.

(Chen Xiaoxiao/Ma Xuechen)