Office of Technology Transfer – University of Michigan

Thermal Management System for Solar Photovoltaic Installations

Technology #2019-185

Questions about this technology? Ask a Technology Manager

Download Printable PDF

Categories
Researchers
Andrej Lenert
Managed By
Jeremy Nelson
Senior Licensing Specialist, Physical Sciences & Engineering 734-936-2095
Patent Protection

US Patent Pending

For all commercial photovoltaic (PV) solar panels, the performance of these devices decreases as the operating temperature is increased above 25 °C. In the sunny, dry climates that are ideal for PV installations, the average operating temperature of the panels is ~49 °C and their performance suffers accordingly. Presently, the common practice for megawatt-scale PV arrays in the United States is to rely on passive convective airflow to cool the panels, which has limited effectiveness. 

Mostly passive system for continuous cooling and improved panel efficiency and lifetime

Researchers at the University of Michigan have developed a radiation-assisted PV thermal management system (“RAPT”) that continuously maintains the operating temperature of the PV panel at a constant temperature only slightly above (+7 °C) the ambient temperature of the panel’s surroundings at peak solar times to prevent the deterioration of solar panel performance. The system accomplishes this by (a) deploying a novel cooling radiator between the rows of tracking solar arrays and (b) storing excess heat generated during the day so that radiative cooling occurs continuously throughout the night and day.

The radiator system uses an emitter and a thermally insulating, selectively transparent cover to scatter oncoming solar radiation with wavelengths >8 µm while simultaneously allowing infrared heat to pass through from the emitter. Using liquid coolant and a storage tank, excess heat from the PV panels is transported away from the panels and either radiated into the atmosphere or stored for nighttime radiative cooling. As an additional benefit, the system will moderate the rate of temperature decrease of the panels during the cooler nighttime, mitigating the damage to the system from thermal cycling.

The RAPT system has the potential to decrease the average panel operating temperature by 15-20 °C while buffering the temperature swings. This will translate into a 6-8% increase in panel power output and efficiency (calculated for a crystalline Si solar panel). RAPT would also improve panel reliability and extend the panel lifetime to >30 years, which would surpass Department of Energy targets. Using a levelized cost of electricity (LCOE) calculator developed by the National Renewable Energy Laboratory, the anticipated efficiency gain and prolonged lifetime is worth over $50/m(or ~$0.25/W), even when accounting for the slightly elevated operation and maintenance costs it would require.

Applications

  • Utility-scale solar photovoltaic (PV) installations
  • Especially effective for PV installations in arid regions such as the American Southwest
  • Buildings and rooftops
  • Wireless infrastructure

Advantages

  • Continuously cools PV panel through day and night, moderates temperature swings 
  • Increases PV panel efficiency by 6-8%, increases lifetime to >30 years
  • LCOE benefit of over $50/m2(or ~$0.25/W)
  • Particularly benefits bifacial solar panels for an additional 5-10% relative increase in efficiency