The temperature coefficient significantly affects solar panel performance in hot climates by indicating how much the panel’s efficiency decreases as its temperature rises above the standard testing temperature of 25°C (77°F).
How Temperature Coefficient Affects Solar Panel Performance
- Definition: The temperature coefficient is expressed as a negative percentage per degree Celsius (e.g., -0.3%/°C to -0.5%/°C), reflecting the drop in power output for every degree Celsius increase in temperature above 25°C. For example, a temperature coefficient of -0.4%/°C means the panel loses 0.4% of its efficiency for each °C above 25°C.
- Performance Loss: As solar panels get hotter, their voltage output decreases more than any increase in current, leading to an overall reduction in power. Since solar panels in hot climates can reach operating temperatures of 50°C or even higher (sometimes up to 65°C or 70°C), this loss can be substantial. For instance, a module with a -0.41%/°C coefficient operating at 65°C can lose over 16% of its power compared to the 25°C baseline.
- Example: If a 260-watt panel has a -0.41%/°C temperature coefficient and the panel temperature reaches 65°C, power loss will be approximately 42.6 watts, reducing the output to around 217 watts.
Impact in Hot Climates
- In hot climates, solar panels regularly operate well above 25°C, sometimes reaching 50-65°C due to direct sun exposure and heat absorbed from roofing materials. This means their real-world efficiency is consistently lower than the rated efficiency at standard test conditions.
- Even small temperature coefficients matter over time, because heat-related losses add up, reducing annual energy yield. For example, a coefficient difference of 0.1% can translate into several percentage points in yearly energy production.
- Roof material and installation play key roles: heat-absorbing roofs (e.g., asphalt shingles) can raise panel temperature, worsening losses. Mounting panels with airflow underneath can help keep temperatures lower and mitigate efficiency drops.
Mitigation and Selection Strategies
- Choosing panels with a low (less negative) temperature coefficient improves performance in hot climates. Some advanced panels (e.g., from REC Group, Panasonic, Maxeon) offer coefficients as low as -0.24%/°C to -0.29%/°C, which translates into better heat tolerance and higher efficiencies under hot conditions compared to panels with coefficients closer to -0.4% or -0.5%/°C.
- Thin-film panels often have the lowest temperature coefficients (~ -0.2%/°C) but have other trade-offs in efficiency and cost.
- Design improvements such as thermally conductive substrates and mounting techniques that allow airflow can reduce operating temperature and power loss.
Summary Table
| Aspect | Effect in Hot Climates |
|---|---|
| Temperature Coefficient | Efficiency drops by ~0.3%-0.5% per °C above 25°C |
| Typical Operating Temp. | Panels can reach 50-65°C or more, causing significant losses |
| Power Loss Example | ~16% loss at 65°C for -0.41%/°C coefficient panel |
| Best Panel Choices | Low coefficient panels (-0.24% to -0.29%/°C) reduce heat loss |
| Installation Factors | Airflow and reflective roofing reduce temp and improve output |
In conclusion, the temperature coefficient is a crucial parameter affecting solar panel performance in hot climates. Lower (less negative) temperature coefficients result in less efficiency loss as temperatures rise, leading to greater energy yield and better economic returns in hot, sunny environments. Proper panel selection and installation strategies can help mitigate heat-induced losses and optimize system performance.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-the-temperature-coefficient-affect-solar-panel-performance-in-hot-climates/
