About the Hotspot Risk Scoring
Hotspot risk scoring assesses the probability and severity of thermal hotspots developing on solar panels — localized overheating that permanently damages cells and reduces output. Hotspots are caused by partial shading, soiling on a subset of cells, cracked cells, reverse-biased cells, or poor-quality manufacturing — and can degrade a panel's output by 5–30%.
How to calculate it
- 1Identify risk factors: partial shading (tree, pole, chimney), regular heavy soiling (bird droppings on localised areas), known cracked-cell batches, high-irradiance location.
- 2Score each factor: shading (high/medium/none), soiling type (uniform/localised), module age and known QA issues.
- 3Assign a hotspot risk score. High-risk systems benefit most from thermographic (IR) inspection.
- 4Plan IR inspection: thermal drone or handheld IR camera under full irradiance (>600 W/m²) and low wind. Look for hot spots > 20°C above adjacent cells.
- 5Remediate: clean soiled cells, bypass shaded strings, replace cracked/reverse-biased modules.
Worked example
A 10-year-old rooftop system in Chennai, partially shaded by a new water tank, and with irregular cleaning (bird droppings on south-facing edge). Risk score: HIGH. IR inspection reveals 3 modules with 40–60°C hotspots on reverse-biased cells. Replacing those 3 modules recovers ~3% of system output.
What you can calculate
- 0–10 risk score
- IEC 62446-3
- Inspection intervals
- Low/High/Critical
Standards & references
Frequently asked questions
How do I detect hotspots in my solar system?
The most reliable method is thermal infrared (IR) imaging under clear-sky full-sun conditions. Drone-based IR surveys can cover a large rooftop or ground-mount array in minutes and produce a heat map showing individual cells. For residential systems, handheld IR cameras (rentable at ₹2,000–5,000/day) can cover 10 panels in an hour. Visual inspection can detect badly discoloured (browning) encapsulant but misses early-stage hotspots.
Can bypass diodes prevent hotspot damage?
Bypass diodes (one per ~20 cells, typically 3 per module) activate when a cell reverse-biases due to shading, redirecting current around the shaded sub-string. This limits the power dissipated in the shaded cell but does not eliminate hotspots — the bypassed cell still heats up when carrying current in reverse bias. Bypass diodes also degrade over time and can fail open, removing their protection. Regular IR inspection catches failed diodes.
Does hotspot damage void the panel warranty?
Hotspot damage caused by external factors (shading, soiling, physical damage) is generally NOT covered under the manufacturer's product warranty. Hotspots from manufacturing defects (cell cracks from handling, poor busbar soldering) are typically covered under the 10–12 year product warranty if identified and documented promptly. IR inspection at commissioning and year 1 provides baseline evidence for warranty claims.
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