Inverter Loss due to max. input current

What this step does

The row measures the array energy lost when the array current exceeds the inverter's DC current limit. The inverter raises the array voltage until the current meets the limit. When the power limit also applies, the inverter holds the higher of the two voltages: Inverter Loss over nominal inv. power takes the loss down to the AC-limit voltage, and this row only the further loss when the current limit sets a higher voltage. Equation 2 holds for the Operating point on the array's I–V curve option of the Model tab's Inverter operating limits step. Under Cap the power, no I–V curve, the row is the maximum power times the share of the current above the limit; under Clip at the AC nameplate it is zero.

The math

1. Running total
2. Loss at a timestep

$$E_{after} = E_{before} - E_{row},\qquad E_{row} = \frac{\Delta t}{1000\,P_{DC}}\sum_i L_i \tag{1}$$ $$L_i = N_{inv}\left[P_{before,i} - U_{I,i}\,I_{max}\right] \tag{2}$$

where

Symbol	Meaning	Unit
$E_{before}$	the running total of the loss diagram before this row	kWh/kWp
$E_{after}$	the running total after this row	kWh/kWp
$E_{row}$	the row taken as a loss	kWh/kWp
$\Delta t$	the length of one timestep	hours
$P_{DC}$	the DC nameplate of the system	kWp
$L_i$	the power lost at timestep $i$ over the whole system	W
$N_{inv}$	the number of inverters	—
$P_{before,i}$	one inverter's array power before this row at timestep $i$	W
$U_{I,i}$	the voltage at which the array current equals the limit	V
$I_{max}$	the inverter's DC current limit	A

Reading the number

A loss, negative. Usually zero on utility and rooftop systems. It appears when an input carries more parallel strings than its current limit allows.

API

loss.inv_i_clip

Symbols follow the symbol registry.