Session: 17-01-01: Research Posters

Paper Number: 150579

150579 - Comparative Experimental and Theoretical Study of Temperature Rise for Freestanding and Masonry Embedded Solar Cells 

With the implementation of the net zero building legislation in the United States, the use of building-integrated photovoltaics (BIPV) is rapidly increasing. Masonry building envelopes incorporating solar cells are one of the emerging BIPV alternatives. Among other advantages, incorporating PV within a cement block is envisioned to help reduce PV operation temperature due to the block’s capacity to absorb and store heat. In turn, this is anticipated to enhance the power output of the solar cells and reduce their degradation rate, as both decrease with higher operating temperatures. This study investigates experimentally and theoretically the thermal response of a PV integrated into a cement block and compares it to that of a free-standing PV to predict differences in annual power outputs and degradation rates. Two identical solar cells, one free-standing and the other attached to a concrete block, were instrumented with thermocouples to monitor the temperature on the front and the back of the cells. In addition, the concrete block had thermocouples embedded within it. Outdoor experiments were conducted over several days during summer and fall to understand the temperature response of each system for varying outdoor conditions. The standalone PV was mounted at 38° facing south, the optimum PV tilt angle for Albany, NY, while the PV on block stood vertically facing south. The results show that the surface temperature of the PV on block remained significantly lower than that of the standalone PV as outdoor temperature ramps up from morning to mid-day values. As an example, the maximum temperature difference between the two systems was as high as 13°C during a hot summer day, when outdoor temperature increased from 20°C in the early morning to 34°C by late afternoon. This confirms that the cement block is effective in storing the heat absorbed by the attached PV, reducing its operating temperature for these ambient conditions. However, once the rate of ambient temperature diminished, the temperature of the standalone PV stabilized, as the time constant of this system was relatively small. In contrast, the cement block temperature continued to increase, while remaining below that of the freestanding PV. The PV-only setup was observed to cool fast when direct sunlight was obstructed by the cloud cover or when wind speed picked up, while the temperature of the PV on the block remained more stable. The standalone PV also maintained a lower temperature than the other system during the cooler hours of the night. In both systems, the difference between the front and back temperature of the PV was small due to its low thermal resistance. Using outdoor data as a guide, finite element modeling was then employed to quantify temperature differences under more realistic conditions, specifically assuming backside conditions of the cement block that incorporate the constant indoor temperature seen in applications. This theoretical data was then used to estimate the associated differences in annual power output and degradation rate between the two systems.

Presenting Author: Diana-Andra Borca-Tasciuc Rensselaer Polytechnic Institute

Presenting Author Biography: Diana-Andra is a professor in the Mechanical, Aerospace, and Nuclear Engineering Department at Rensselaer Polytechnic Institute, which she joined in 2006. She received her B.S. in Physics from Bucharest University, and her M.S. and PhD. in Mechanical Engineering from the University of California at Los Angeles.

Authors:

Ozioma Ozioko Rensselaer Polytechnic Institute
Patrick Quinlan Solablock Inc.
Jason Laverty Solablock Inc.
John O'connor Solablock Inc.
Diana-Andra Borca-Tasciuc Rensselaer Polytechnic Institute