14% of Australians live in apartments, predominantly in urban centres, yet few of these have PV systems, despite high levels of PV deployment on separate and semi-detached residential buildings. Increased PV deployment on apartment buildings represents a valuable market opportunity for the PV industry, which would allow apartment dwellers to obtain the financial benefits of using PV to offset electricity bills. PV on apartment buildings could also help relieve network congestion, as it is a good fit with commercial loads commonly found in urban areas, and might therefore benefit network operators as well as households.
Some recent high-density residential developments incorporate a PV system for each residential unit, or an embedded network serving all units. However, in existing apartment buildings, as well as physical and other barriers to PV installation, legal arrangements can create additional difficulties for individual rooftop PV systems and there may be specific technical and economic barriers to the installation of embedded networks. In these cases, installing PV to supply common property demand (sometimes a high proportion of total building demand) may present a simpler retrofitting opportunity.
Common property load varies significantly between apartment buildings and may include lighting for common areas, and carparks; lifts; water heating and pumping for centralised hot water and pools; air conditioning and ventilation. Its characteristics and diversity are not well understood, with a 2008 DEWHA report identifying the need for further research into communal area energy use in high and medium density housing. Common property energy is typically purchased on behalf of all unit owners by the Owners Corporation, often on commercial tariffs with high ratios of demand to volumetric charges.
The authors present preliminary findings from a study that utilises the 30-minute common property electricity demand data for 25 apartment buildings in the Sydney metropolitan area. Daily and annual demand profiles are examined and PV systems modelled for each building, sized both for available roofspace and to ensure high levels of onsite consumption. The economic viability of these PV systems is explored using existing retail tariff structures. The findings highlight the potential opportunity for PV to assist in meeting common property load in medium- and hi-rise apartment buildings, and the additional opportunity to supply individual unit loads or sell energy to third parties in medium-rise buildings.