We explain the calculations and terms used in m4chanical GES in a way decision makers can follow.
The ratio of actual energy to the energy expected under the same conditions. It gives an efficiency indicator independent of weather: output can be low on a cloudy day while PR stays normal. The dashboard computes energy-weighted PR only over intervals with irradiance of 100 W/m² or more, so dawn and dusk noise does not distort it.
PR = Σ P_actual / Σ P_expected × 100The theoretical AC power computed from installed capacity, measured irradiance and module temperature. Standard test conditions are 1000 W/m² and 25 °C; crystalline silicon module power falls as temperature rises.
P_expected = P_installed × (G / 1000) × (1 + γ × (T_module − 25))How much module power changes per 1 °C. The current model uses −0.4 %/°C, a typical value for crystalline silicon. For a real plant, the value from the module datasheet should be used.
γ = −0.004 / °CIf an inverter's output drops below 0.5 kW while irradiance is above 200 W/m², the interval is flagged as a critical inverter fault. The irradiance condition avoids false alarms at night or in heavy overcast.
P_actual ≤ 0.5 kW ∧ G > 200 W/m²If PR falls below the threshold (85% by default), an underperformance warning is raised. Possible causes include soiling, shading or hotspots; the actual cause is confirmed on site.
PR < threshold ∧ G ≥ 100 W/m²The difference between expected and actual power multiplied by duration for each 15-minute interval. An event's estimated loss is the sum over its intervals. It is an estimate and depends on measurement accuracy and the model.
E_loss = Σ max(0, P_expected − P_actual) × 0.25 hWant to see these calculations on your own plant data?
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