Wattwatchers monitoring helps UNSW-led study into solar PV for energy consumers in apartment buildings

One in 10 Australians live in apartment buildings, and apartments make up a third of all new dwellings, but currently many of them are missing out on the rooftop solar boom.

Free-standing houses traditionally have dominated the world-record residential rooftop PV roll-out in Australia: there are now 2 million solar households, which is 21.6 percent of all households, with up to 50 percent penetration in the highest uptake areas.

Apartment buildings, by comparison, have lagged behind for a number of reasons, including limited roof space on a per occupant basis, and the complexities of managing ownership and sharing benefits across multiple tenants, mixed rental and occupant-owned accommodation, common property areas and strata committees, and regulatory barriers such as metering requirements for billing.

Energy use in apartment dwellings averages less than half that of houses, but it’s more variable than household loads – especially in regard to how apartment block loads ‘peak’.

In 2017, researchers at the University of New South Wales (UNSW), with funding support from Energy Consumers Australia (ECA), began a study to better understand how more solar PV could be deployed in multi-tenant apartment buildings.

To see how electricity is being used at typical unit blocks, they deployed Wattwatchers cloud-enabled monitoring devices in four apartment buildings in the Greater Sydney area, covering mains connections, common property area loads and individual apartments.

Armed with highly-granular data, they were able to model different approaches to adding solar PV to apartment buildings of varying sizes – numbers of apartments and numbers of floors in each building. They modelled: common property only; individual behind-the-meter; shared behind-the-meter; embedded networks.

This month, December 2018, the UNSW team led by PhD candidate Mike Roberts revealed preliminary findings from their year-long study, with the full report to be published in 2019. Roberts, with academic colleagues at the UNSW Centre for Energy and Environmental Markets (CEEM), also have presented related findings to the Asia Pacific Solar Research Conference in 2018, in a paper called ‘An analysis of Australian rooftop solar potential on residential buildings’.

The ‘solar potential’ opportunity they see in apartment buildings across Australia is 2.9-4 GWp, which is a lot. But how to unlock it in the more complex residential operating environment of apartment buildings?

Wattwatchers data helped the UNSW team to map energy use in individual apartments and Common Property (CP) areas.

Preliminary observations from this UNSW project include:

  • Using solar PV for common property areas-only may be a ‘best suited’ option, especially where available roof space is very limited
  • Solar PV contributing 1-1.5kW per apartment may add value to embedded networks
  • Shared behind-the-meter solar PV of 1-1.5kW per apartment may also be competitive
  • Battery storage doesn’t yet meet return-on-investment thresholds

Roberts said that full analysis of the dataset from the Wattwatchers monitoring was still a work in progress.

‘Although we know apartment residents are missing out on solar, there is very little hard data available about their energy use,’ said Roberts.

‘Using Wattwatchers meters to collect 12 months of granular load data across each of these buildings allows us to get some interesting insights into how best to share the costs and benefits of solar PV. We’ve just started analysing the data and will make the full dataset available for other researchers to use.’

FOOTNOTE: Wattwatchers Director of Communications and Community Networks, Murray Hogarth, participated in a panel session at UNSW on December 3, as part of a presentation of the preliminary findings from the apartment buildings project.