Mismatch loss, modules and strings

What this step does

The power lost because the modules of a string, and the strings of an inverter, do not share one maximum-power point. The module mismatch and the string mismatch combine into one flat fraction of the array energy.

The math

$$E_{after} = E_{before} - L_m,\qquad L_m = \left[1 - (1-m_{mod})(1-m_{str})\right] E_{before} \tag{1}$$

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
$L_m$	the row as a loss	kWh/kWp
$m_{mod}$	the module mismatch loss input, a fraction	—
$m_{str}$	the string mismatch loss input, a fraction	—

Reading the number

A loss, negative. With the common design values, 2 % for the modules and 0.15 to 0.5 % for the strings, it is about 2 to 2.5 % on utility and rooftop systems alike. The two inputs alone set it.

API

loss.mismatch

Symbols follow the symbol registry.