Household generation below a salesperson’s forecast is not by itself proof that modules breached their performance curve. Annual energy depends on solar resource, orientation, shade, soiling, temperature, mismatch, inverter clipping, grid availability and downtime. The performance document may instead compare a module’s measured output with its warranted nameplate percentage under defined conditions.
Build a safe evidence ladder:
- Export daily/monthly generation and alarm history before an app reset or account transfer.
- Photograph serial labels and visible damage from a safe location; do not walk the roof.
- Compare inverter production with the utility/generation meter, accounting for different measurement points.
- Note changes: new shade, construction, long outages, cleaning, component replacement or loss of one string.
- Ask a qualified technician for a written fault isolation: module, connector/cable, inverter, meter, grid, design or maintenance.
- If claiming module performance, obtain the test method and result required by the manufacturer instead of inventing a home test.