PV string drift, three years on

String-level yield data is noisy on any given day and unambiguous over three years. Drift that looks like weather in April is clearly degradation by the third winter.

The operators who win are the ones who kept the history and looked at the slope, not the snapshot. The worst inverters announce themselves long before they fail outright.

That is the case for capturing readings you do not yet know you need — the analysis that matters is the one you run years later.