New Record on the House Roof: 2025-05-09

On May 9, 2025, our rooftop solar system set a new production record: 59.69 kWh in a single day — despite being limited to just 7 kWp inverter capacity!

The previous all-time high was 59.47 kWh, reached almost exactly two years earlier on May 3, 2023. But yesterday, conditions were ideal:

• Full sun throughout the day
• Mild temperatures around 20 °C
• Strong wind that kept the panels cool

This rare combination of sunshine, cool air, and constant airflow allowed the PV modules to operate at peak efficiency. Despite the inverter cap, the system delivered a specific yield of over 8.5 kWh/kWp — truly exceptional.

Our smaller west-facing studio system (4 × 410 W) also added 6.011 kWh, bringing the total daily production to an impressive 65.701 kWh.

A day to remember — and a perfect example of how cool, sunny, and windy spring days can outperform even the sunniest summer ones.

For more on how temperature affects solar panel efficiency, check out my article: Solar Panels and Temperature