The metrics that matter
The headline number is performance ratio (PR) — energy actually harvested versus what the sunlight that fell on the array should have produced. PR normalises for the weather, so it exposes losses within your control: a well-built Kenyan system holds ~0.75–0.80, and a drift below that flags soiling, shading or a fault. Specific yield (kWh per kWp) lets you compare your system to its design expectation and to other sites. String or MPPT-level data is the most powerful diagnostic — an identical string lagging its neighbours localises a fault instantly.
Beyond energy, a dashboard watches inverter status and faults, availability (was the system actually up?), and — on hybrid systems — battery state of charge, cycles and temperature. Alerts turn all of this from a report you never read into a notification that reaches you before a small problem becomes a season of lost generation.