A flat roof in winter might never clip. A tilted roof in June will clip for 4 hours a day. Ladybug PV calculates the clipping loss hourly. If your simulation shows flat-topped power curves at noon, your inverter is too small. If it never clips, your inverter is too big (expensive). 4. Ground Reflection (Albedo) The default albedo is 0.2 (green grass/dirt). But what happens when you put a bifacial panel on a white TPO membrane roof? Albedo jumps to 0.7.
But what about harvesting ?
Let’s dismantle the black box. How does Ladybug PV actually work, what assumptions is it making, and how do we move from kWh/m² to actual return on investment? First, a critical clarification for the purists: Ladybug PV does not perform its own cell-level semiconductor simulation. That would be computationally ruinous for an urban-scale model. Instead, Ladybug leverages the NREL PVWatts v8 API (or the local DC power model if you disable API calls). ladybug pv
Ladybug PV calculates the AC power as: If DC Power > Inverter Capacity, then AC Power = Inverter Capacity (Clamped) A flat roof in winter might never clip