Session: 03-02: Innovative Building Material and Technologies

Paper Number: 157640

157640 - Effects of Ground and Diffuse Solar Illumination on the Performance of Luminescent Solar Concentrators With Asymmetric Light Transmitting Interface 

Abstract: 

The need for improved and aesthetically pleasing solar energy harvesting technology is to increase in the coming years around the world due to states and countries implementing clean energy legislation. One such technology, Building Integrated Photovoltaics (BIPVs), is used to harvest solar energy on-site in order to reduce CO2 emissions from buildings. Yet, BIPVs show a decrease in performance as Photovoltaic (PV) cells are positioned away from their optimal orientation. Luminescent solar concentrators (LSCs) have been investigated as a method to improve BIPVs’ overall performance and appeal by concentrating light towards a small area PV cell through the opaque LSC matrix, as well as trap and redirect light that can be more efficiently converted to electricity by the PV cell through the use of luminescent species. Even with these improvements, however, LSCs have shown reduced performance due to multiple factors, one of which is from escape cone losses.

To mitigate these types of losses, an Asymmetric Light Transmitting (ALT) interface has been incorporated into the top surface of the LSC to trap photons within the matrix. This interface allows for all diffraction orders of light to transmit in the forward direction while trapping higher diffraction modes from escaping through backward transmission. A previous study on direct light interaction with ALT LSCs showed improvements in energy production during the winter months. With this, the goal of this research is to further characterize and predict the energy production of a planar ALT interface LSC at vertical orientation with diffuse and ground light interaction for use in less optimal solar conditions.

A multi-scale model was developed for simulating light transmission and propagation through the ALT interface LSC. Using COMSOL’s Multiphysics Wave Optics Module, transmission properties of the ALT interface are implemented into an in-house Monte Carlo (MC) ray tracing code to model the propagation of light through the LSC with this specific interface. An annual energy production estimation is then performed using the results of the MC code in an in-house energy estimate code that uses local solar irradiance data in conjunction with the open-source PV modeling code, PVlib. A comparison of the annual energy production of the ALT LSC and plain interface LSC was performed for two locations, Albany, NY and Phoenix, AZ, for a vertically oriented LSC.

Results were calculated at the maximum power point (MPP) to investigate the electrical energy production capabilities of the two types of LSCs discussed under diffuse and ground solar illumination. The ALT interface LSC showed improvements in energy production during the months of November, December, and January, with December showing the largest increase of 11.6% compared to the plain interface LSC in Albany, NY. For Phoenix, AZ, the ALT interface LSC improved in performance during the month of December, with an increase of 1.0% in energy production when compared to the plain interface LSC. When compared to the improvements in energy production for the ALT interface LSC under direct light conditions, the ALT LSC improved in performance by 32.2% in Albany, NY and 6.7% for Phoenix, AZ. Thus, the ALT interface would be more beneficial in increasing the energy production of the LSC under direct solar illumination.

Presenting Author: Hannah Arnow Rensselaer Polytechnic Institute

Presenting Author Biography: Hannah Arnow is a PhD candidate in the Mechanical Engineering Department at Rensselaer Polytechnic Institute in Troy, NY. Her research focuses on improving Building-Integrated Photovoltaics through Luminescent Solar Concentrators integrated with Asymmetric Light Transmitting Interfaces.