The Dunhuang city of Northwest China's Gansu province is really a remote location with arid climate, but with fantastic solar resources. With clear skies and sunshine of 3247 hours or more per year, this location is ideal for large scale solar plants. I visited a 10 MWp PV power plant developed by CGN Solar Energy Development Co (CGN SEDC) in the Qili town of Dunhuang City in February 2012. The plant is connected to China’s northwest national grid and expected to generate and supply more than 18,000 MWh of electricity to the grid. This means a good expected Plant Loading Factor (PLF) of about 20.6%.
The project site is located at 400 N latitude and features 10 sets of PV generation systems, each of which includes two sets of 500 KW generation units. The PV modules are rated at 230 kWp each and the system features a 500 kW inverter, which delivers electricity to the grid with a 35 kV line. The plant has been in operation since December 2010 and has seen better than expected PLF.
The China Guangdong Nuclear Power (CGN) Group is traditionally a nuclear power plant developer/operator and a state owned entity in China. In recent years it has been focusing on renewable generatrion sources such as Solar, Wind and Hyrdo as well. What struck me during the plant visit is that the company has laid a good emphasis on test-bedding new technologies and ‘trying out’ different options to support its R&D in this area. E.g. some of the module sets are fixed with sun tracking systems, while others are on fixed mountings. There is also a special area in the plant where small scale CPV units and other PV technologies are being tested.
The control room is located within the plant and has a few technicians mainly for monitoring and troubleshooting. However the plant operations are really very quiet and maintenance free. Having seen many petrochemical and fossil based generator plants in my life, a visit to a solar plant always fascinates me as to how quiet and serene the operation is. No noise at all and there is hardly any operators required in the field. During our visit in the morning (around 10 am), the ambient temperature was sub zero (-20C) and the sunlight was still quite bright. To some extent, I was in disbelief that the plant is running quietly and producing a good 40-50 thousand kWh of electricity every day (enough to supply more than 1,500 homes in the US), until I saw the actual numbers from the control room and the power meters. I was thinking to myself, this is how the future of energy generation should be: noise-free, pollution-free, very low operation intensity and practically maintenance-free.
The main challenge for the plant tends to be dust and sand accumulation on the panels, which may lead to a 15-20% drop in generation efficiency. Its difficult to use water to clean the panels as water is scarcely available in the region and also with sub-zero temperatures in the winter, there could be icing issues. The sun-tracking systems (partially deployed in the plany) tend to provide 20% better output from the panels, but are also costlier, take longer time to install and add to the maintenance costs especially with the sand and dust affecting the moving parts.
The State Council, China's cabinet, has set a strategic target to build a million-kW level solar power base in Dunhuang by 2020. The reasons are obvious as this region enjoys one of the best un-blocked solar irradiation in the world and had vast arid land available. The prices of Solar PV are coming down substantially with many China based manufacturers coming on board. China has more than 400 PV companies and produces more than 23% of the world’s PV panels, most of which are exported. However the local utilization and installtion of PV power plants is on the rise and China's overall solar power capacity is expected to reach more than 10 gigawatts by 2015. The success of CGN SEDC’s DunHuang PV power plant is certainly a good testament that such numbers are achieveable. The city of DunHuang, which is famous for the Mogao Caves (Caves of thousand Buddhas), may soon become famous for its large scale grid-connected Solar power plants.
Photo: Arrival at the Dunhuang airport
Photo: Solarika’s Nilesh Jadhav at the Dunhuang PV power plant
Photo: A front view of the 10 MW Dunhuang PV power plant
Photo: A side view of the 10 MW Dunhuang PV power plant
Recreated from original blog post authored by Nilesh Y. Jadhav at Solarika.org