Inverter Loss over nominal inv. voltage

What this step does

The array energy lost when the array's maximum-power voltage exceeds the top of the inverter's MPPT window, which happens with long strings in cold weather. With the operating point on the array's I–V curve (Model tab, Inverter operating limits step) the inverter holds the array at the top of the window. The step's other two methods do not model the top of the window, so this row stays at zero and that energy stays in the array output.

The math

1. Running total
2. Loss at a timestep

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

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	—
$P_{mpp,i}$	the maximum power of one inverter's array at timestep $i$, after the DC losses	W
$V_{max}$	the top of the inverter's MPPT window	V
$I(V)$	the current of one inverter's array at voltage $V$, from its current-voltage curve	A

Reading the number

A loss, negative. Usually zero on utility and rooftop systems alike; cold timesteps with long strings make it appear.

API

loss.inv_v_clip

Symbols follow the symbol registry.