Method Recovers Rooftop Solar Tilt and Azimuth
Researchers estimated panel orientation from DC power data alone, testing the approach on 17 commercial rooftop systems in Australia.
Updated on Nov. 5, 2026 in Energy
Researchers developed a method that recovers the tilt and azimuth of rooftop photovoltaic arrays from operational power data. On unshaded systems, the method recovered tilt to within about 2° and azimuth to within about 4° median error.
Why it matters
Accurate orientation data is essential for estimating electricity generation and detecting faults in solar systems. Installation records are often missing or incorrect, and site inspections are impractical for large PV portfolios.
The method was tested on 17 commercial rooftop systems in Australia, recovering tilt to about 2° and azimuth to about 4° median error on unshaded arrays. Shading raised azimuth error sharply, and the researchers have not yet made the approach robust to inverter clipping or tripping.
The players
University of New South Wales
A public research university in Sydney, Australia, with a large solar energy research program.
Chinese Academy of Sciences
China's national academy of sciences and a major institution for scientific research across many disciplines.
The details
The method uses only DC power recorded at five-minute intervals per MPPT, plus site coordinates, and selects periods with high direct irradiance and sufficient morning and afternoon measurements. An optimization algorithm identifies the orientation that best matches measured output while adjusting effective system capacity to account for losses. The findings were published in Solar Energy.
Timeline
Operational data was collected from the rooftop systems in 2025.
The research findings were published on November 5, 2026.
The Big Picture
Conventional clear-sky modeling built with the pvlib library produced median tilt errors of 10° to 12° and azimuth errors of 48° to 62° compared with ERA5-based results on unshaded systems. The new power-data method cuts those errors to roughly 2° and 4°, a substantial narrowing of the gap between modeled and actual orientation.
Solar owners and installers may be able to verify system orientation from routine power data rather than costly site visits or missing paperwork. More accurate orientation estimates can also improve forecasts of how much electricity a rooftop array will produce.
The takeaway
Orientation data that once required a site visit can increasingly be inferred from the power a system already produces. Solar operators with incomplete installation records may find this kind of analysis a practical way to fill the gaps.
Further reading
For broader context on how solar installations are reshaping power generation, explore Energy.
