Performance Evaluation of an Advanced Roof Integrated Solar Hot Water Heating System and Roof-Mounted Solar Photovoltaic Power System in New Home Construction

Abstract

The performance of a building integrated solar domestic water heating system and roof mounted PV system in a residential dwelling located in the Phoenix area was evaluated for a 12 month period. The solar domestic hot water heating system installed was a preproduction prototype RITH (Roof Integrated THermosiphon) system. The RITH is a thermosiphon system that fully integrates into the roof to achieve the same profile as a skylight when seen from the street. The PV system consisted of two SAE 300 DG/50 modules, each having a 300 watt dc rating, and a GC-1000 1 kW inverter to produce 0.5 kW AC power at STC (standard temperature conditions). Both systems were installed on a Calex Homes model home in the Phoenix area on a south facing part of the roof. Both systems were mounted directly to a 5/12 pitch roof and, therefore, tilted at a 22.6° angle. Since both units were mounted on an unoccupied model home the domestic hot water (DHW) load was modeled to simulate a typical family of four living in the Phoenix area. The solar domestic water heating system was sized to meet ∼70% of the annual hot water needs for a typical Phoenix family of four using 80 gallons of hot water per day. The PV system was connected directly to the grid without any battery storage and was intended to offset household electrical demand. Data are presented for both the actual and predicted performance of the solar domestic water heating and PV systems for the 12 month monitoring period.