QUANTIFICATION OF THE PASSIVE COOLING OF PHOTOVOLTAICS USING A GREEN ROOF

Open Access
Author:
Witmer, Lucas Turner
Graduate Program:
Energy and Mineral Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • Jeffrey Brownson, Thesis Advisor
Keywords:
  • microclimate
  • green roof
  • photovoltaic
Abstract:
An energy balance model of a Green Roof Integrated Photovoltaic (GRIPV) system has been created and analyzed in a transient system simulation, using a FORTRAN code base in the TRNSYS energy system simulation tool. Comparative analyses relative to a thermally integrated equivalent system on a conventional roof, using TMY2 data from cities in each of the nine U.S. geographic regions defined by NOAA, resulted in a small efficiency gain (0.08-0.55%) in terms of power output. The GRIPV model verified a neutral or slightly positive influence to the power production with thermal integration between green roofs and PV arrays in an integrated environment. It has been observed that the slight efficiency gains occur during the peak heat of summer when electricity networks are most strained and most likely to fail, slightly alleviating this risk. Additionally, the dual use of available roof space, employing both a photovoltaic array as well as a green roof, provides a means to increase the value proposition of photovoltaic (PV) roofing systems by over 100% from a net present value of $59/m2 for a conventional system to a net present value of $131/m2 for a GRIPV system in Pittsburgh, Pennsylvania. The model that has been developed here enables a comprehensive design for green roof integrated photovoltaics.