In partnership with
How Marketers Are Scaling With AI in 2026
61% of marketers say this is the biggest marketing shift in decades.
Get the data and trends shaping growth in 2026 with this groundbreaking state of marketing report.
Inside you’ll discover:
Results from over 1,500 marketers centered around results, goals and priorities in the age of AI
Stand out content and growth trends in a world full of noise
How to scale with AI without losing humanity
Where to invest for the best return in 2026
Download your 2026 state of marketing report today.
Get Your Report
Solar panels are tested at 25°C and 1,000 W/m² irradiance. Philippine rooftops routinely reach 55-65°C during summer months. This gap between lab conditions and field reality costs Philippine solar owners significant annual energy production — but it's predictable and manageable.
Temperature Coefficient: The Key Number
Every solar panel has a temperature coefficient of power (Pmax) — typically -0.35% to -0.45%/°C for monocrystalline panels. This means for every degree above 25°C, output drops by that percentage.
Panel Temperature | Output Loss (at -0.40%/°C) | Real Output of 550W Panel |
|---|---|---|
25°C (STC) | 0% | 550W |
35°C | 4.0% | 528W |
45°C | 8.0% | 506W |
55°C (typical PH roof) | 12.0% | 484W |
65°C (hot summer) | 16.0% | 462W |
What Panel Temperature Is in Practice
Panel temperature = Ambient temperature + (NOCT - 20) where NOCT (Nominal Operating Cell Temperature) is typically 43-47°C. In Philippines at 35°C ambient: Panel temp ≈ 35 + (45 - 20) = 60°C. That's a 14% output reduction from rated power.
How Humidity Affects Panels
High humidity accelerates potential-induced degradation (PID), corrosion of junction boxes, and soiling from dust+moisture. Philippine coastal areas are particularly high risk. Mitigation:
Choose panels with IP68-rated junction boxes
Use panels with anti-PID certification
Ensure proper tilt angle (minimum 10°) for rainwater self-cleaning
Clean panels every 3-6 months in high-humidity, coastal areas
Minimizing Temperature Losses
Ensure ventilation gap: Minimum 100-150mm clearance below panels for airflow
Choose bifacial panels: Lower temperature coefficient available in premium bifacial models
North-facing panels: Run cooler than west-facing due to lower afternoon irradiance intensity
Account for losses in your estimate: Use 85% of STC output as realistic Philippine production
The SolarEnergyPH Estimator applies Philippine-specific temperature derating automatically in its savings calculations.
Engr. Jason Morales — Founder, SolarEnergyPH