Researchers from Adelaide University said facing rooftop solar panels east and west instead of north will allow households to maximise their energy self-sufficiency and reduce the use of non-renewable energy sources imported from the grid.
Changing the direction panels are facing so that on-site renewable energy generation better matches the load can also reduce unwanted solar exports in the middle of the day, helping improve grid stability.
Solar panels are usually mounted facing the equator to maximise annual energy yield but researchers Kirrilie Rowe and Peter Pudney said the power generated by these systems generally do not match traditional residential loads.
“A typical residential load profile has a peak in the morning and a larger peak in the late afternoon or evening, whereas power generated by PV panels facing the equator peaks in the middle of the day,” they said, adding that “by orienting panels in different directions it is possible to minimise the shortfall between load and generation.”
The researchers analysed data from more than 70 separate dwellings and a 42-apartment building across three years. The properties are all located in South Australia which has become one of the world’s most advanced renewable energy power systems. Solar and wind supply more than 70% of the state’s annual generation and more than 54% of homes have rooftop solar installations.
The widespread adoption of PV and subsequent solar generation has reduced midday demand, but high usage persists in the morning and afternoon, creating pronounced peaks at these times.
In addition, high solar generation and exports in the middle of the day can push distribution network voltage over acceptable limits with South Australia’s distribution network service provider taking steps to limit residential PV exports to the wider grid.
The researchers said changing the direction panels are facing is one solution to counter this characteristic ‘duck curve’ profile.
“We have shown that below around 1.4 kW for separate dwellings and 1 kW for apartments, panels facing north maximise annual self-sufficiency,” they said. “Beyond this size, optimal panel orientation is increasingly more east and west to maximise self-sufficiency.”
With most new rooftop solar installations in Australia now exceeding 10 kW, the researchers said the orientation of the panels should be considered.
“The initial panel placement to minimise shortfall is mostly north, because there is enough load in the middle of the day to use the generated power,” they said. “However, as PV size is increased, greater self-sufficiency is obtained by removing panels from the north and adding them to the northwest and northeast, and then east and west or east and northwest.”
“Optimal orientations for PV power above 1.4 kW per dwelling are never north.”
The study findings were presented in the article “Orienting PV panels to maximise self-sufficiency in residential communities,” published in ScienceDirect.
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