Can rooftop photovoltaic energy storage systems be insulated

Results show that installing PV systems with electrical storage and insulating roofs in the refurbishment scenario provides a cost-effective way to improve the thermal performance, while covering a large portion (55–80%) of annual energy and electrical needs.

Building rooftop solar photovoltaic (PV) arrays coupled with electrical storage are a demonstrated means for addressing building energy use since roof areas are often unobstructed to solar radiation and freely available for such utilization, .

The energy reduction was lower in the apartment complex (55% starting uninsulated and 57% starting with a low insulation) where the rooftop is a smaller part of the overall building heat transfer envelope. The authors recognise that energy savings deriving from roof insulation and those from PV generation are not equivalent due to timing.

The authors recognise that energy savings deriving from roof insulation and those from PV generation are not equivalent due to timing. Insulation ensures uniform savings throughout the day, while savings deriving from PV depend on solar radiation and day-hour.

Savings from insulation and PV from primary energy were 63.1% when combined with electrical storage. In relation to the impact of shading, cooling was reduced by 11.3% (Table 6, 827 kWh/year savings) in uninsulated multi-family roofs.

When adding PV systems with the roof initially uninsulated, net savings range from 55% (apartment complex) to 80% (single-family). Shading from stand-off PV arrays reduced summer cooling loads by 17% in uninsulated apartment complexes and provided large predicted improvements in comfort to upper floor dwellings next to exposed roofs. 1.