Array nominal energy (at STC effic.)

What this step does

The row opens the energy cascade. It converts the effective irradiation into energy at the module's rated efficiency, as if every module ran at standard test conditions. Per kilowatt of nameplate it equals the effective irradiation in kWh/m², because one kWp of modules produces one kW at 1,000 W/m². The rear side of a bifacial module is added by the next row.

The math

$$E_{nom} = \frac{N\,P_{nom}}{P_{DC}}\,\frac{H_{eff}}{G_{ref}} \tag{1}$$

where

Symbol	Meaning	Unit
$E_{nom}$	the array nominal energy	kWh/kWp
$N$	the number of modules in the system	—
$P_{nom}$	the module nameplate power at standard test conditions	W
$P_{DC}$	the DC nameplate of the system	kWp
$H_{eff}$	the effective irradiation on the collectors	kWh/m²
$G_{ref}$	the reference irradiance of the standard test conditions (1,000 W/m²)	W/m²

Reading the number

A total, positive. The site's sunlight, the tilt or tracking and the irradiance rows above set it. A common range is 1,400 to 2,700 kWh/kWp a year for a utility plant and 1,100 to 1,900 kWh/kWp for a rooftop system.

References

1. IEC 61724-1:2021, Photovoltaic system performance, Part 1: monitoring (performance ratio and yields)

API

loss.array_nominal

Symbols follow the symbol registry.