What is the real-world energy density (W/ft²) homeowners achieve vs a comparably sited racked array, accounting for BIPV heat penalties and non-PV tiles—how large is the performance gap by climate?
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The real-world energy density of Building-Integrated Photovoltaics (BIPV) systems can be affected by several factors, including heat penalties and non-PV tiles. Here’s a breakdown of the key considerations:
Energy Density Comparison
Racked Arrays vs. BIPV Systems: Racked arrays typically have better airflow and cooling, which can lead to higher energy densities compared to BIPV systems. BIPV systems, on the other hand, can experience heat buildup due to reduced airflow, potentially reducing their efficiency.
Heat Penalties: BIPV systems can suffer from heat penalties, which can decrease their efficiency. Studies have shown that PV module efficiency drops by approximately 0.5% for every 1°C rise in surface temperature.
Real-world Solar Roof systems often deliver 10–30% lower energy density (W/ft²) than comparably sited racked arrays due to BIPV heat losses and space taken by non-PV tiles.
The gap is smallest in cooler, sunny climates and largest in hot regions where elevated temperatures further reduce PV efficiency.