Mismatch loss between orientations

What this step does

The row measures the power lost when the strings of the two faces of east-west racking run in parallel at one voltage. Each face has its own maximum-power voltage, set by its irradiance and its cell temperature. The array's current at a voltage is the sum of the two faces' currents (1). The loss is the two faces' maximum powers less the maximum power of the summed curve (2). The row is present on east-west racking with the operating point on the array's I–V curve.

The math

1. Array current
2. Loss at a timestep

$$I_i(U_{mod}) = I_{E,i}(U_{mod}) + I_{W,i}(U_{mod}) \tag{1}$$ $$L_i = N_{inv}\left(\max_{U_{mod}} U_{mod}\,I_{E,i}(U_{mod}) + \max_{U_{mod}} U_{mod}\,I_{W,i}(U_{mod}) - \max_{U_{mod}} U_{mod}\,I_i(U_{mod})\right) \tag{2}$$

where

Symbol	Meaning	Unit
$I_{E,i}(U_{mod}),\ I_{W,i}(U_{mod})$	the current of one inverter's east and west strings at the string voltage $U_{mod}$ before the cable drop, after the flat derates, at timestep $i$	A
$U_{mod}$	the voltage at the modules. The string voltage before the cable drop	V
$L_i$	the power the row loses or gains at timestep $i$ over the whole system	W
$N_{inv}$	the number of inverters	—

Reading the number

A loss, negative, and zero when the two faces see the same light. Faces at 10° lose 0.03 to 0.05 % of the array energy over a year at Springfield, Phoenix and Sydney. The loss grows with the difference between the faces' voltages, so it is largest in the morning and the afternoon.

API

loss.orientation_mismatch

Symbols follow the symbol registry.