A hot spot in your solar panel is both an efficiency drain and a fire risk. Thermal imaging finds them fast — from ground level, rooftop, or drone. Here's the Singapore-specific playbook.
Singapore's solar PV capacity has grown rapidly — from HDB rooftop installations under SolarNova to large commercial arrays on warehouse and factory rooftops across the island. Most of these systems are inspected visually (looking for obvious physical damage) and electrically (checking IV curves and string voltages). What most operators miss is the most valuable inspection method: solar panel thermal imaging in Singapore's conditions reveals hot spots, failing bypass diodes, cracked cells, and soiling patterns that neither visual nor electrical testing catches early enough.
A hot spot is not just an efficiency problem. In severe cases, a hot spot in a module can reach temperatures exceeding 150°C — enough to ignite the EVA encapsulant or backsheet, turning a rooftop asset into a fire source. SCDF has documented PV-related fire incidents in Singapore, and thermal inspection is the most effective single prevention measure.
Singapore's equatorial climate creates a specific set of PV degradation drivers:
Key Stat
Singapore receives approximately 1,850 kWh/m²/year of solar irradiance — well above the global average. This means PV panels in Singapore accumulate UV and thermal stress faster than equivalent systems in Europe or temperate Asia. Annual thermographic inspection is not over-cautious; it is appropriate for the operating environment.
Each solar panel contains three bypass diodes, one protecting each of three cell strings. When a diode fails short-circuit, the string it protects becomes reverse-biased and dissipates energy as heat. Thermally, this appears as one third of the panel being significantly hotter than the surrounding two thirds — a clear, geometric warm zone following the internal cell string layout. Delta-T typically 30–60°C above adjacent panels. This is a critical fault requiring module replacement.
Cell cracks appear as irregular warm zones that don't follow string geometry. A single cracked cell may show a 15–30°C elevation over surrounding cells. Multiple cracks create more complex patterns. Finger cracks (from foot traffic or hail) are common on accessible rooftops in Singapore — maintenance workers stepping across panels is the most frequent cause. Thermal imaging reveals cracks that are invisible to the eye, especially under the EVA layer.
A bird dropping, patch of moss, or accumulated dust over individual cells creates localised shading. The shaded cell operates in reverse bias, dissipating energy as heat. The thermal signature is a small, intense hot spot at the exact location of the soiling — often just one or two cells showing 20–50°C elevation while surrounding cells are normal. The fix is cleaning, not replacement — but uncleaned soiling hot spots cause permanent cell damage over time.
Pro Tip
If you find a soiling-related hot spot during thermal inspection, clean the panel and re-scan 24–48 hours later (during similar irradiance conditions). If the hot spot disappears, the cleaning resolved it. If it persists at a reduced temperature, the cell has already been partially damaged. If it persists at the same temperature, the cell is cracked, not just dirty.
When one string in a panel produces less current than its neighbours (due to internal resistance differences or partial shading), the lower-performing panel in the string appears cooler during full-sun imaging — it's producing less power and therefore generating less heat. This is the counterintuitive pattern: cold panels in a string context can indicate underperformance, not health. Compare string currents electrically to confirm.
The junction box on the back of each panel houses the bypass diodes and output connections. Junction box faults — water ingress, corroded contacts, failed potting compound — appear as hot spots at the rear of the panel, concentrated at the junction box location. Singapore's rain ingress means junction box seals fail faster than in dry climates. This is also a fire risk location since junction boxes contain combustible potting materials.
Key Stat
IEC 62446-3, the international standard for PV thermographic inspection, classifies a delta-T above 20°C as a Class 3 (critical) defect requiring immediate investigation and corrective action. At Singapore's irradiance levels, hot spots meeting this threshold are not uncommon in systems older than 5 years that have not been regularly inspected.
For residential rooftop arrays and low-rise HDB installations, a ground-based survey with a 320×240 or higher thermal camera can identify severe hot spots from a distance. This is practical, fast, and requires no access equipment. Limitations: oblique viewing angle reduces temperature measurement accuracy, and small faults on distant panels may fall below resolution. Best for: initial screening to identify panels warranting closer investigation.
Walking the rooftop with a thermal camera and imaging each panel from 0.5–2 metres provides the most detailed results. You can see individual cell-level faults and image junction boxes directly. Limitations: requires safe rooftop access, appropriate fall protection, and cannot be done quickly on large arrays. Best for: small to medium commercial arrays (up to 50kWp) and detailed diagnostic inspection following ground-level screening.
A thermal camera mounted on a commercial drone is the most efficient method for large arrays. A 200kWp commercial rooftop system can be surveyed in under an hour. Images are captured at a consistent altitude, angle, and speed, producing a systematic image set that covers every panel. In Singapore, commercial drone operations require a Permit to Fly (PTF) from CAAS for operations in controlled or restricted airspace, which covers most developed areas. Factor permit lead time into project planning.
Solar PV thermal inspection must be performed during daylight, under stable irradiance above 600 W/m² (a good sunny Singapore afternoon), with the system operating at normal load. Clouds cause rapid irradiance changes that make temperature readings inconsistent — wait for stable sunshine or use irradiance logging to identify stable periods in the data.
Scan from east-facing panels in the afternoon (when west sun is direct) and from west-facing panels in the morning. Perpendicular angle to the panel face gives the most accurate temperature measurement — oblique angles introduce reflection error.
Unitest carries the full range of thermal imaging cameras suited to solar PV inspection, from ground-based surveys to drone-mountable options. For Fluke's thermal camera range, including models with the resolution and thermal sensitivity needed for PV work, see our Fluke Industrial product range. For a full survey-ready setup with calibration documentation, our SAC-SINGLAS calibration lab provides certificates your O&M reports can reference. To discuss the right tool for your PV asset portfolio, contact our technical team.
Solar panel thermal imaging in Singapore is not optional maintenance — it is risk management. With Singapore's UV intensity, humidity, and growing rooftop PV stock, hot spots develop faster than in temperate climates and carry real fire risk if left undetected. Annual thermographic inspection, combined with IV curve testing and visual checks, gives your PV system the full health picture. The cost of a survey is a fraction of one module replacement — and a vanishingly small fraction of a rooftop fire.
What temperature difference indicates a failing solar panel in thermal imaging?
The IEC 62446-3 standard classifies PV defects by delta-T relative to surrounding cells: 0–10°C difference = monitor, possible soiling or shading; 10–20°C = significant defect, schedule inspection; above 20°C = critical defect requiring immediate investigation. A bypass diode failure causing one third of a panel to be inactive typically shows 30–60°C above surrounding cells — unmistakable even with a basic thermal camera.
Can I inspect solar panels with a thermal camera from the ground?
Yes, for rooftop residential and HDB arrays. A 320×240 camera with an appropriate telephoto lens can identify severe hot spots from 5–15 metres below. However, ground-level inspection has limitations: you cannot view panels at a perpendicular angle from below (oblique angles reduce temperature measurement accuracy), and small localised hot spots may be below resolution at long distances. Rooftop access or drone inspection gives more reliable results for formal condition reports.
How often should Singapore solar panels be thermally inspected?
SolarNova guidelines and best practice recommend annual thermographic inspection of PV systems. Singapore's equatorial environment (intense UV, high humidity, salt-laden air near coastal areas) accelerates cell degradation and module soiling compared to temperate climates. Systems in their first five years should be surveyed annually; older systems or those showing performance drop should be surveyed every six months.
What causes hot spots in solar panels?
The main causes: (1) bypass diode failure, where one of the three diode zones in a panel short-circuits and creates a reverse-biased region that dissipates energy as heat; (2) cracked cells, common after hail, foot traffic, or thermal stress cycling; (3) soiling, where bird droppings, dust, or biological growth shade individual cells; (4) manufacturing defects such as poor soldering or delamination; (5) shading from adjacent panels, obstructions, or nearby structures causing partial string bypass.
Do I need a drone for large-scale solar PV thermal inspection in Singapore?
For large commercial rooftop arrays (>50kWp) and ground-mount systems, drone-mounted thermal cameras are significantly more efficient. A drone survey can cover a 200kWp system in 30–60 minutes that would take a ground team a full day. EMA (Energy Market Authority) and CAAS (Civil Aviation Authority of Singapore) require appropriate drone operator licences and airspace notifications for commercial drone surveys in Singapore.
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