How to Use UNI-T UT381PV for Rooftop Solar Panel Inspection Malaysia
How to Use UNI-T UT381PV for Rooftop Solar Panel Inspection Malaysia
Content
A rooftop solar system may produce less power than expected even when the panels appear to be operating normally. The cause may involve weak sunlight, incorrect panel orientation, high panel temperature, shading, contamination or an electrical problem.
The UNI-T UT381PV Solar Irradiance Meter helps solar installers and maintenance technicians record the environmental and installation conditions that affect photovoltaic system performance.
Start with a Visual Inspection
Before taking measurements, inspect the solar panels and surrounding area for visible problems.
Check for:
- Dust, leaves or bird droppings on the panel
- Shadows from trees, antennas or nearby buildings
- Cracked glass or damaged panel surfaces
- Loose mounting structures
- Damaged cables or connectors
- Signs of overheating near junction boxes
- Panels installed at visibly different angles
The UT381PV provides measurement data, but it does not replace a complete visual and electrical inspection.
Measure Solar Irradiance
Position the UT381PV so that its sensor is exposed to the same sunlight as the solar panel being inspected.
The instrument measures solar irradiance from 0 to 1400 W/m². Record the irradiance while checking the electrical output of the PV system.
If solar irradiance is low because of cloud cover, a reduced electrical output may be normal. If irradiance is strong but the system output remains unusually low, further investigation may be required.
Possible causes include:
- Dirty solar panels
- Partial shading
- High panel temperature
- Incorrect panel angle
- Loose or damaged connections
- Panel mismatch
- Defective bypass diode
- Inverter or string problem
For meaningful comparison, take the irradiance and electrical readings as close together as possible because sunlight conditions can change quickly.
Check the Solar Panel Temperature
Attach the supplied suction-cup temperature probe securely to the panel surface.
The UT381PV can monitor panel temperature together with ambient conditions. This is important because a solar panel can become significantly hotter than the surrounding air.
High panel temperature may reduce electrical output even when the available sunlight is strong. Technicians should therefore avoid judging panel performance using irradiance alone.
Record:
- Solar irradiance
- Ambient temperature
- Panel surface temperature
- PV voltage
- PV current
- Time of measurement
- Weather conditions
These readings provide better context when investigating low solar generation.
Verify the Panel Inclination
Place the UT381PV against the panel or use the mounting bracket to check its inclination angle.
The instrument provides an inclination measurement range from −90° to +90°. Compare the measured angle with the installation design or the expected mounting angle for the project.
Incorrect inclination may affect how much solar energy reaches the panel throughout the day. It can also indicate an installation inconsistency when panels within the same array are positioned at different angles.
Check the Panel Azimuth
The UT381PV includes an azimuth measurement function from 0° to 360°.
Azimuth indicates the horizontal direction that the solar panel faces. Use this function to confirm that the panel orientation matches the installation plan.
Before relying on the azimuth reading:
- Perform compass calibration when required
- Keep the instrument away from strong magnetic fields
- Avoid measuring beside large metal structures where possible
- Allow the reading to stabilise
- Repeat the measurement for confirmation
Incorrect orientation may reduce the amount of sunlight captured during important parts of the day.
Record the Measurement Data
The UT381PV can store up to 12,800 sets of measurement data. Its recording interval can be adjusted from one second to 60 minutes.
Bluetooth connectivity with the UNI-T iENV mobile application allows technicians to review and manage field measurements more conveniently.
Consistent records are useful for:
- Comparing different solar strings
- Documenting installation conditions
- Monitoring performance changes
- Supporting maintenance reports
- Comparing readings before and after panel cleaning
- Investigating customer complaints about low generation
Avoid Common Measurement Errors
For more consistent results:
- Do not cover or shade the irradiance sensor
- Position the sensor in the same plane as the solar panel
- Wait for weather conditions to stabilise
- Take comparison readings within a short period
- Ensure the temperature probe has proper surface contact
- Calibrate the compass before critical azimuth measurements
- Do not compare readings taken under very different sunlight conditions
The UT381PV measures environmental and installation conditions. Additional electrical instruments may still be required to check PV voltage, current, insulation resistance and I-V curve performance.
Suitable Users in Malaysia
The UNI-T UT381PV is suitable for:
- Solar installation contractors
- Rooftop PV maintenance teams
- Facility management departments
- Solar farm technicians
- Electrical contractors
- Renewable-energy consultants
- PV testing laboratories
- Commercial and industrial building operators
For assistance selecting the UNI-T UT381PV Solar Irradiance Meter for rooftop solar inspection in Malaysia, contact MTM Precision.
MTM Precision Sdn Bhd
Showroom & Service Centre: No. 29-1 & 29-2, Jalan Bandar 18, Pusat Bandar Puchong, 47160 Puchong, Selangor, Malaysia
Tel: 03-8080 7172
WhatsApp: +6016-660 7346
Email: mtmpre@yahoo.com
Website: www.mtmpre.com.my
30 Sep 2026
