Adelaide study: past a few kilowatts, face the panels east and west
Victoria Shinder2 min readResearchers at Adelaide University argue that orienting rooftop solar east and west rather than north lets Australian households use more of what they generate and eases pressure on the grid. pv magazine reported the study on 23 September 2026.
The reasoning starts from a mismatch. Kirrilie Rowe and Peter Pudney note that a typical residential load profile peaks in the morning and, more strongly, in the late afternoon or evening, while equator-facing panels peak in the middle of the day. Orienting panels in different directions can minimise the shortfall between load and generation, and reduce unwanted midday exports.
The finding is quantified: below around 1.4 kW for separate dwellings and 1 kW for apartments, north-facing panels maximise annual self-sufficiency. Beyond that size, the optimal orientation is increasingly east and west.
The data comes from more than 70 separate dwellings and a 42-apartment building across three years, all in South Australia — where solar and wind supply more than 70% of annual generation and more than 54% of homes have rooftop solar. Widespread PV has cut midday demand while morning and afternoon usage persists, producing pronounced peaks; high midday generation and export can push distribution voltage past acceptable limits, and the state's network operator has taken steps to limit residential exports.
What it means
The result inverts the default advice, and the threshold is what makes it actionable. Maximising annual yield and maximising self-sufficiency are different objectives, and they pointed the same way only while systems were small enough that everything generated was consumed. Above a couple of kilowatts the surplus is the problem, and a lower total yield that lands at the right hours beats a higher one that cannot be used or exported.
Note what the objective function is before transplanting the number. These households face export limits and a tariff structure that makes midday generation worth little. Where export is paid near retail rates and the network is unconstrained, annual yield is still the right target and north still wins.
South Australia is the useful part for everyone else: at 70% wind and solar with half the homes generating, it is running the conditions other grids are heading towards. The orientation question arrives when hosting capacity binds, not when penetration is high in the abstract.