Solar System Monitoring: What to Track and How to Catch Problems Early
By Team Faseeh Lall
A solar system does not have to stop producing electricity completely to have a problem.
An inverter can go offline while the rest of the system continues operating. Communication with the monitoring platform can fail. One section of an array can produce less than expected. A gradual performance decline can continue for weeks before the property owner notices anything unusual on the electricity bill.
That is why solar system monitoring is an important part of long-term photovoltaic system management.
Monitoring gives homeowners, businesses, and solar asset managers visibility into how much electricity the system is producing, whether equipment is communicating correctly, and whether current performance is reasonably consistent with expectations.
But simply having a monitoring app is not enough.
The real value comes from knowing what to monitor, which changes matter, and what action to take when the data indicates a problem.
The U.S. Department of Energy notes that PV monitoring platforms can help owners identify and address system-performance problems in real time and can provide information on availability, performance, alarms, maintenance activity, and even the financial impact of lost production.
What Is Solar System Monitoring?
Solar system monitoring is the ongoing collection and review of photovoltaic performance data.
Depending on the equipment and monitoring platform, owners may be able to see:
Daily energy production
Monthly and lifetime production
Current power output
Inverter status
Individual inverter performance
Module or string-level data
System alerts
Communication status
Historical production trends
Meter information
More advanced commercial monitoring systems may also incorporate weather data, expected-performance models, system availability, maintenance tickets, and financial calculations.
The purpose is not simply to create a dashboard full of numbers.
Monitoring should help answer a much more useful question:
Is the solar system operating as expected, and if not, why?
Why Solar Monitoring Matters
Solar photovoltaic systems can operate for decades.
During that time, equipment ages, environmental conditions change, communications fail, inverters develop faults, wiring can be damaged, and surrounding vegetation or new structures may change shading conditions.
DOE specifically identifies maintaining effective monitoring systems as important because staff changes, lost passwords, misplaced documentation, equipment problems, and system aging can otherwise make it harder to understand long-term PV performance.
Without monitoring, underperformance may remain unnoticed.
A homeowner may discover the problem only after receiving an unexpectedly high electricity bill.
A commercial property owner may not identify an underperforming rooftop until a monthly or quarterly review.
For systems that generate Solar Renewable Energy Certificates, lower solar production can also mean less qualifying generation available to support SREC creation.
Monitoring therefore protects more than visibility.
It supports better maintenance, faster issue detection, energy savings, and long-term asset management.
What Should You Monitor in a Solar System?
A useful monitoring strategy focuses on several indicators rather than one number.
1. Total Energy Production
Start with how much electricity the system produces.
Most monitoring platforms show daily, monthly, annual, and lifetime energy generation.
Owners should become familiar with the normal production pattern of their systems.
Solar production naturally changes due to:
Weather
Cloud cover
Seasons
Available daylight
Temperature
Shading
For that reason, one low-production day usually does not prove that something is wrong.
Look for patterns.
A sustained unexplained decline is much more meaningful than comparing one cloudy day with one sunny day.
2. Actual vs. Expected Production
Knowing that a system generated 40 kWh today does not automatically tell you whether that number is good.
You need context.
The system's actual output should be compared with a reasonable performance expectation based on factors such as:
System capacity
System design
Orientation
Historical production
Solar resource
Seasonal conditions
Weather
DOE's assessment of 75 federal PV systems compared measured production with modeled production and evaluated metrics such as system availability and performance ratio.
This illustrates an important monitoring principle:
Production data becomes more valuable when it is compared with what the system should reasonably be producing.
SAMS follows a similar approach by comparing actual production with expected system performance rather than simply checking whether the installation is technically online.
3. Inverter Status
The inverter deserves special attention because inverter problems account for a significant portion of PV system downtime and maintenance activity.
DOE notes that a large share of downtime and maintenance in photovoltaic systems is associated with inverters.
Your monitoring platform may show:
Whether the inverter is online
Current output
Fault codes
Warning messages
Communication status
Historical errors
A repeated inverter fault should not simply be ignored because the system eventually restarts.
Recurring faults may indicate an underlying issue that requires inspection or maintenance.
4. Communication Status
Sometimes the solar system is producing correctly but the monitoring platform stops receiving data.
This creates an important distinction:
A monitoring outage is not automatically a production outage.
The communication problem may involve:
Internet connectivity
Wi-Fi
Cellular communication
Gateway hardware
Monitoring software
Inverter communications
Meter connectivity
However, a communication failure should still be investigated.
When the data disappears, the owner loses visibility into whether the system is actually operating correctly.
That means a communication problem can hide a separate technical problem.
5. System Availability
Availability measures whether the system or key equipment is capable of operating when it should be available.
A system may have good annual production overall but still experience repeated outages.
Monitoring availability can reveal these interruptions.
For example, an inverter that goes offline for short periods several times per month might not immediately create an obvious annual production collapse.
But repeated downtime can accumulate.
DOE identifies availability as one of the key performance indicators that PV monitoring platforms can report.
6. Alerts and Fault Notifications
A useful monitoring platform should help identify abnormal conditions.
Depending on the equipment, alerts may indicate:
Inverter shutdown
Communication loss
Ground fault
Low production
Meter problem
Equipment error
Other abnormal conditions
DOE notes that monitoring platforms can issue alarms by email or text so system operators can respond to conditions requiring attention.
But notifications are only useful if someone reviews them.
A dashboard generating hundreds of ignored warnings is not an effective monitoring program.
There should be a clear response process.
7. Historical Production Trends
Historical data can help owners distinguish a sudden fault from a gradual performance problem.
Useful comparisons include:
This month vs. the same month last year
Current season vs. previous seasons
Similar weather periods
One inverter vs. another inverter
One property vs. comparable portfolio properties
Historical comparison should still be used carefully because annual weather conditions vary.
The goal is not to expect identical production every year.
It is to identify meaningful patterns that deserve investigation.
Solar Monitoring App vs. Professional Monitoring
Many modern solar systems include a manufacturer app or online portal.
These tools can be very useful.
They allow homeowners to see production, review basic system information, and sometimes receive fault alerts.
But there is a difference between having access to monitoring data and actively managing system performance.
An app may tell you that production dropped.
It may not always tell you:
Why it dropped
Whether the change is normal
Whether a technician is needed
Whether the problem is communication-related
Whether cleaning is justified
Whether an inverter fault is recurring
Whether production loss is financially significant
Professional solar monitoring adds interpretation and follow-up to the raw data.
SAMS MD's current monitoring service, for example, reviews production, compares actual output with expected performance, monitors inverter and communication problems, and guides the next step when the system requires attention.
What Can Cause Solar Production to Drop?
A production decrease does not point to one universal problem.
Possible causes include:
Inverter Problems
An inverter may shut down, reduce output, or develop recurring faults.
Communication Issues
Production may continue physically while monitoring data disappears.
Soiling
Dust, bird droppings, pollen, and other contaminants can affect panel surfaces.
Shading
New vegetation, nearby construction, or other changes may create shading that did not exist when the system was installed.
Wiring or Electrical Problems
Damaged wiring, connections, or other electrical faults can affect system output.
Module Damage
Cracks, hot spots, water intrusion, or other module problems may require professional inspection.
Meter Problems
Incorrect or missing meter information can affect the reliability of performance records.
Monitoring helps identify the symptom.
Inspection and technical diagnosis identify the cause.
How Monitoring Supports Preventive Maintenance
Monitoring and maintenance should work together.
A traditional reactive approach waits for the owner to notice something obvious.
A monitoring-based approach can identify abnormal performance earlier.
The workflow becomes:
Monitor → identify abnormal behavior → investigate → inspect → repair → verify recovery
This is more useful than performing maintenance without performance context.
For example, cleaning solar panels simply because six months have passed may not be necessary.
If monitoring shows that production is consistent with expectations, cleaning may not currently provide meaningful value.
On the other hand, unexplained performance loss combined with visible heavy soiling may justify cleaning sooner.
Monitoring helps make maintenance more targeted.
Remote Solar Monitoring for Commercial Portfolios
Monitoring becomes even more important when an owner manages multiple solar properties.
A commercial asset manager cannot physically inspect every site each day.
Remote monitoring provides centralized visibility into portfolio performance.
It can help answer:
Which properties are underperforming?
Which inverters are offline?
Which sites have communication failures?
Where are open issues concentrated?
Which properties need technicians first?
NREL's O&M guidance emphasizes that monitoring strategy should reflect the size and financial importance of the asset and that data quality, presentation, and transparency are central to effective monitoring.
For commercial portfolios, standardized monitoring can also make site-to-site comparison easier.
How Solar Monitoring Supports SREC Performance
For systems participating in SREC markets, monitoring has an additional financial role.
SRECs ultimately depend on eligible solar generation.
If a system is not producing electricity because of an unresolved fault, that period of lost generation may also reduce the amount of production available to support certificate creation.
Monitoring does not increase the number of SRECs beyond what the system legitimately generates.
Instead, it helps protect the production behind them.
The relationship is straightforward:
Healthy system → qualifying solar production → eligible certificate generation
A system that underperforms unnoticed for an extended period may therefore lose both energy production and potential certificate value.
This connection is particularly relevant to SAMS MD because its service model combines solar system performance management with SREC-focused support.
What Happens When Monitoring Detects a Problem?
Detecting a problem is only the first step.
A clear issue-resolution process should follow.
1: Confirm the Data
Determine whether the unusual reading is genuine or caused by a communication problem.
2: Compare With Expected Performance
Check whether weather, seasonal conditions, or other normal factors explain the change.
3: Review Equipment Status
Check inverter alerts, communication status, meters, and available system information.
4: Determine Whether Inspection Is Needed
If the cause cannot be confirmed remotely, a professional inspection may be required.
5: Coordinate Maintenance or Warranty Support
Depending on the diagnosis, the system may require repair, installer involvement, manufacturer support, cleaning, or other corrective work.
6: Verify Performance After Resolution
Do not close the issue simply because a technician visited the property.
Monitoring should confirm that normal production has returned.
How Often Should You Check Solar Monitoring?
There is no universal monitoring frequency appropriate for every system.
A homeowner with a relatively small rooftop installation may not need to study the dashboard every day.
A commercial portfolio with significant energy and SREC exposure may justify much more active monitoring.
DOE recommends checking operational indicators frequently, reviewing periodic reports, and acting on underperformance identified through the monitoring process.
The better principle is:
Monitor often enough that meaningful production problems do not remain unnoticed for long periods.
For homeowners, automated alerts combined with periodic review may be sufficient.
For businesses and larger portfolios, professional ongoing monitoring may provide greater value.
What Makes a Good Solar Monitoring Program?
A strong monitoring program should provide more than graphs.
It should create actionable information.
Important characteristics include:
Reliable production data
Clear system baselines
Equipment status
Useful alerts
Historical trends
Easy reporting
Documented response procedures
Access to qualified maintenance support
Verification after corrective work
DOE also recommends considering data quality, reporting, system continuity, third-party data access, cybersecurity, and the ability to maintain monitoring hardware and software over time.
For commercial owners, data ownership and access should also be considered.
If an installer or monitoring provider changes, the owner should understand how historical system information will remain available.
Common Solar Monitoring Mistakes
Monitoring technology cannot protect a system if it is poorly managed.
Common mistakes include:
Never Checking the Monitoring Platform
Some owners stop logging in after the first few months.
Production problems can then remain unnoticed.
Looking Only at the Electricity Bill
Utility bills can provide useful context, but changes in electricity consumption can make them a poor standalone measure of solar-system health.
Reacting to One Bad Day
Weather creates normal short-term production variation.
Look for meaningful patterns.
Ignoring Communication Errors
Missing data does not always mean zero production, but it removes visibility into system health.
Resetting Faults Without Investigation
Repeated equipment errors should be diagnosed rather than simply cleared.
Detecting Problems but Not Following Up
Monitoring without issue resolution is incomplete.
The goal is not to identify more alerts.
The goal is to restore and protect solar performance.
Solar Monitoring as Part of Long-Term Asset Management
Monitoring becomes most valuable when it connects with the rest of the solar-management process.
That includes:
Inspections
Preventive maintenance
Corrective maintenance
Cleaning decisions
Warranty coordination
SREC management
Financial reporting
Long-term equipment planning
The monitoring platform provides the visibility.
Asset management provides the process for acting on that visibility.
For example:
Monitoring detects inverter failure → issue is investigated → warranty coverage is checked → repair is coordinated → monitoring confirms recovery.
This is a much stronger approach than treating each service as a separate activity.
When Professional Solar Monitoring Makes Sense
Professional monitoring may be useful when:
You do not regularly review your solar dashboard
Your system has recurring faults
Production has declined unexpectedly
You own multiple solar properties
The original installer no longer actively monitors the system
SREC production depends on reliable generation
You need someone to coordinate action when problems appear
You want ongoing performance visibility rather than reactive repairs
For many solar owners, the greatest value is not another app.
It is having someone responsible for reviewing the data and deciding what happens next.
Final Thoughts
A solar monitoring system should do more than tell you how many kilowatt-hours your panels produced yesterday.
Effective solar system monitoring helps owners understand whether their photovoltaic system is performing as expected, detect inverter or communication problems, identify unusual production changes, and make better maintenance decisions.
The process becomes even more valuable when monitoring is connected with inspection, issue resolution, warranty coordination, and long-term asset management.
The key principle is simple:
Do not wait until your solar system stops working completely before paying attention to its performance.
Monitor production.
Compare it with reasonable expectations.
Investigate sustained changes.
Respond to meaningful alerts.
And verify that performance returns after problems are resolved.
That ongoing visibility can help protect energy production, financial savings, and the long-term value of the solar asset.