Module efficiency loss

What it is

A flat derate for modules that produce less than their nameplate, as a fraction of the DC power. A negative value means the modules produce more than nameplate, which is common when the manufacturer's tolerance is positive.

Typical values and how to get it

Minus a quarter of the positive tolerance window is a common convention: a 0 to +3 % tolerance gives −0.75 %. Flash-test statistics give it exactly. If not given: 0: no module quality loss.

How it is applied

$$P_{\text{after}} = P_{\text{before}}\,(1 - f_{\text{qual}})$$

where

Symbol	Meaning	Unit
$P_{\text{after}}$	the array DC power after this derate	W
$P_{\text{before}}$	the array DC power before it	W
$f_{\text{qual}}$	this input as a fraction; negative for a gain	—

API

dc_losses.quality_loss — sent as a fraction, negative for a gain

Symbols follow the symbol registry.