Monitoring is the cheapest maintenance tool
You do not need to visit the roof every day to know whether a solar plant is behaving normally. A few minutes of regular monitoring can reveal downtime, repeated alarms or gradual performance changes much earlier than waiting for the electricity bill.
Most modern grid-tied inverters provide a local display, mobile app, web portal or datalogger. The exact interface varies, but the same core information is useful across brands.
The four things to watch
1. Daily energy
Daily energy shows how much electricity the plant produced during the day. Compare it with recent days under similar weather, not with an arbitrary fixed target.
2. Current power
Instantaneous power helps show whether the plant is operating at that moment. A low value can be normal early in the morning, late in the evening or under clouds.
3. Alarm and event history
Repeated grid, insulation, temperature or DC-input alarms are often more informative than the total generation number. Record exact codes and times.
4. Monthly and yearly totals
Longer-term totals help identify gradual changes that daily weather can hide. They are also useful for comparing the same season year to year.
Learn the normal daily curve
On a clear day, many systems show a gradual rise in power during the morning, a broad peak around midday and a gradual decline later.
A plant will not always produce a perfect curve, but unusual shapes can be useful clues:
- repeated vertical drops may indicate inverter trips or grid events;
- a regular dip at the same time can indicate shading;
- a flat-topped curve can sometimes reflect inverter clipping or operating limits;
- a long missing period may indicate downtime or a communication gap.
The graph is evidence, not a diagnosis by itself.
A blank app does not always mean zero generation
Monitoring depends on communication. Wi-Fi, internet, datalogger power or cloud-server issues can interrupt the app even when the inverter continues producing.
If the app is blank, check the inverter’s local display or energy counter if it can be done safely. Electricity-meter export data can provide another cross-check.
This distinction prevents unnecessary service calls for a communications problem.
Set a simple monitoring routine
For a residential plant, a practical routine can be:
- glance at generation several times a week;
- check alarms whenever output looks unusual;
- record monthly totals;
- compare the same month with previous periods;
- note cleaning dates, faults and grid outages.
Commercial and larger systems may require more frequent monitoring and structured reporting depending on operational requirements.
What data should you save?
Keep screenshots or exported data when a fault occurs. Useful evidence includes:
- exact alarm code;
- time and duration of the event;
- daily generation before and after the event;
- power curve for the affected day;
- DC input or MPPT values where the portal provides them;
- grid voltage if available.
This can significantly shorten troubleshooting.
When monitoring should trigger action
Investigate when you see a sustained reduction that cannot be explained by weather, repeated inverter shutdowns, one string behaving abnormally, recurring zero-generation periods or a sudden change after electrical or rooftop work.
If the plant is producing but the portal is unreliable, fix the monitoring path. If the plant itself is underperforming, move to technical diagnosis.
For low-output troubleshooting, see why your solar system may be generating less electricity.