Inverter Loss over nominal inv. power

What this step does

The array energy lost when the array could deliver more than the inverter's AC limit: the nameplate, lowered by the temperature derating and, unless the Losses tab shows the grid limitation on its own row, by the grid power limitation. The inverter moves the array away from its maximum-power point until the output meets the limit. The Model tab's Inverter operating limits step sets how the operating point moves. The Model tab's MPPT minimum loss row step decides whether the energy lost while the array voltage sits below the MPPT window counts here or in Inverter Loss due to voltage threshold.

The math

$$E_{after} = E_{before} - E_{row},\qquad E_{row} = \frac{\Delta t}{1000\,P_{DC}}\sum_i L_i \tag{1}$$

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

Reading the number

A loss, negative. The DC-to-AC ratio and the derating schedule set it. A ratio of 1.35 loses about 3 % over a year at a sunny site; a rooftop system with a ratio near 1.1 loses a few tenths of a percent.

API

loss.inv_p_clip

Symbols follow the symbol registry.