Abstract :
Indirect benefits of rooftop photovoltaic (PV) systems for building insulation are quantified through measurements and modeling.
Measurements of the thermal conditions throughout a roof profile on a building partially covered by solar photovoltaic (PV) panels were
conducted in San Diego, California. Thermal infrared imagery on a clear April day demonstrated that daytime ceiling temperatures
under the PV arrays were up to 2.5 K cooler than under the exposed roof. Heat flux modeling showed a significant reduction in daytime
roof heat flux under the PV array. At night the conditions reversed and the ceiling under the PV arrays was warmer than for the exposed
roof indicating insulating properties of PV. Simulations showed no benefit (but also no disadvantage) of the PV covered roof for the
annual heating load, but a 5.9 kWh m 2 (or 38%) reduction in annual cooling load. The reduced daily variability in rooftop surface temperature
under the PV array reduces thermal stresses on the roof and leads to energy savings and/or human comfort benefits especially
for rooftop PV on older warehouse buildings.
2011 Elsevier Ltd. All rights reserved
