Dazzling Solutions for a Sunnier Future
Dazzling Solutions for a Sunnier Future

Making solar power more effective has been a conundrum for renewable energy providers everywhere. CLP China found a dazzling solution in the form of mirror-like reflective materials to boost their output.

Coming up with a bright, innovative idea is hard enough. Breaking through with that idea and making it a reality can be harder still.


That has been the experience of the solar industry in China. With a decline of state subsidies in recent years, tapping the potential of solar power stations to increase their capacity and efficiency to compensate for the reduction in subsidies has been a key focus for the country’s power industry.


For years, researchers have explored how to reduce the cost of solar modules and improve the energy conversion efficiency of cells, which left limited room for further areas of research.


Finally, however, a new approach was taken by looking into what could be done to increase the amount of light radiation on solar panels to improve their generation efficiency. CLP China’s Sihong Solar Power Station developed a solution that was simple but smart: The use of mirror-like reflective materials.

Reflecting on a breakthrough discovery

The 93MW Sihong Solar Power Station in Jiangsu province is situated in an area with abundant water and has adopted the innovative model of solar-fishery integration, with solar panels installed above a fish farm. The panels are built in rows with a space between them to allow sunlight to reach the water.


The team looked into installing reflective devices in the gaps between rows of solar panels to reflect more sunlight onto the panels. The reflection, or scattering, of sunlight helped increase the amount of radiation on the rear row of solar panels, thereby increasing their generation capacity and efficiency. 


The project team went to great lengths to find the best installation mode and structure and the most suitable reflective film materials, as well as examining the return on investment. 

In the pilot phase, three types of 1.25 metre-wide reflective film were tested: Aluminum foil insulation film, mirror aluminum, and tin sheet. They were each installed on a group of solar panels to be compared with a control group. The team found the best way to install the reflective device was to place it at an angle of 80° to 140° to the solar panel. 


After analysis of the daily and cumulative power generation data of the three types of materials, the team discovered the most cost-effective material was mirror aluminum placed at a fixed angle of 120° to the solar panel. Data showed it increased power generation by between around 8.5% and 14%. 


The reflective devices were installed on 1MW of solar panels at Sihong Solar Power Station in 2019 with the objective of achieving an 8% increase in power generation capability and boosting generation by 100MWh a year. 

The design of solar panel reflective device
The innovative use of a reflective device, at an angle of 120°, has resulted in an increase in power generation.​

With an investment cost of RMB400,000 per MW, the project team estimates a payback on investment period of three to four years. CLP China is meanwhile considering expanding the installation of the reflective devices to an additional 5MW to 10MW of solar panels in the near future.


The innovation was awarded with a National Utility Model Patent by the National Intellectual Property Administration in August 2020, and a detailed study of it was published in the national journal Popular Science in the same year.

Robots rise to the dusting challenge

Thorough, regular maintenance is critical to ensure the operational efficiency of solar power plants – and the impact of dust on panels should never be underestimated.


Dust on solar panels can reduce the reception of sunlight, resulting in a decrease in solar radiation received by the panels and a lowering of their output, directly affecting the overall power generation of the plant. 


To make cleaning more effective, Sihong Solar Power Station uses robots to mop dust from the panels. The project team conducted multiple rounds of investigations and research before installing seven automatic cleaning robots on a pilot basis in late 2017. 


More than two years of data collection and analysis found that regularly cleaning the solar panels with robots helped improve their efficiency by an average of 3.17%. 

Automatic cleaning robot on a solar panel
A white, rectangular-shaped cleaning robot wipes the dust from solar panels, sparing workers from risky work above water.

Encouraged by its initial success, the team has deployed a total of 62 automatic cleaning robots across 10MW of solar panels since September 2020. 


A single row of panels in the selected installation area covers a long span of 360 metres, and each row of cleaning robots can provide cleaning across two areas, which maximises the cleaning efficiency of a single robot and reduces the investment cost.


The robot cleaners are now in full operation, taking over the risky work of cleaning solar panels above water and improving site safety. They are expected to help increase the generation capacity of the 10MW of solar panels by about 400 MWh every year, reducing carbon dioxide emissions by an estimated 400 tonnes which is equivalent to the planting of some 17,000 trees. The robots will soon be installed on a further 10MW to 20MW of solar panels at the plant.


With an average of more than 2,300 hours of annual sunshine at Sihong, the use of innovative reflective devices and cleaning robots are helping the plant make an impressive contribution to the creation of clearer, bluer skies above China.