There are two kinds of installer: the one who learns about a fault when the customer calls, furious about a high bill, and the one who calls the customer to say it has already been fixed before they noticed. The difference is monitoring. It is the heart of any O&M plan and the basis of after-sales satisfaction.
What to really monitor
Looking at "how much it generated today" is not enough. Track generation vs expected (compared with the day's irradiance), performance per string/MPPT (one string out of line signals a problem), inverter status and fault codes, voltage and current and, when available, module-level data (with microinverters and optimizers). The secret is to compare against the expected baseline, not against the previous day.
Alerts that prevent losses
Set alerts for zero generation (inverter off or tripped), persistent performance drops (soiling, shade, PID/hot spots), recurring faults and disconnections and one string underperforming the others. A system that stops on a Friday and is only noticed the next month means weeks of lost generation — the alert pays for monitoring on its own.
Turn data into relationships
Use monitoring as a commercial tool: send periodic reports showing the savings generated (customers love it), warn proactively about drops and use the data to suggest cleaning, maintenance or expansion at the right time. Well-communicated monitoring becomes proof that the customer made the right choice — and brings referrals.
Monitoring signals and what they indicate
| Signal | Likely cause | Action |
|---|---|---|
| Zero generation | Inverter off / breaker tripped | Check and restart |
| Gradual drop in generation | Soiling / shading | Cleaning / tree trimming |
| One string below the others | Module or connection fault | Inspection and thermography |
| Recurring inverter faults | Overheating / grid issues | Technical diagnosis |
| Performance drop with a hot module | Hot spot / PID | Assess the module |