Performance investigation of zero-building-integrated photovoltaic roof system: A case study in Egypt

The concept of zero-energy buildings was developed due to the high cost of electricity and the availability of renewable energy. This study presents detailed design steps for a zero building using a grid-connected photovoltaic (PV) system with a battery to supply the load demand for a building in Egypt (31.0409 degrees N, 31.3785 degrees E). In the system design, the sizes of the system components are determined, including the sizes of the PV cells, batteries, chargers, and controllers, such that they fulfill the load requirements. Maximum power tracking is designed to achieve maximum utilization of solar energy. In addition, a cooling model for the PV system is introduced to increase its efficiency. The PV performance with and without the thermal absorber is theoretically investigated and compared using a three-dimensional conjugate heat transfer model. A coupled thermal-electrical iterative model is also used to estimate the system's hourly performance. Findings show that increasing the cooling flow rate for the proposed PV system from 0 L/min to 1 L/min significantly decreases the temperature of the PV module from 60 degrees C to 41 degrees C at a solar radiation of 650 W/m(2). The theoretical results show that using the PV thermal technology at a coolant flow rate of 2 L/min /module generates the highest electrical power along with enough thermal energy for residential building heating. The outlet warm water from the cooling process has been used household uses to achieve a zero-building theory. This thermal energy can also be used in floor heating radiant systems with high energy efficiency and good thermal comfort. Furthermore, the proposed system can sell 33.5 and 61.9 kWh energy to the grid per day in summer and winter, respectively. (C) 2020 The Authors. Published by Elsevier B.V. on behalf of Faculty of Engineering, Alexandria University.