Solar PTC Rating (not the STC) - What is PTC and How is It Used?
Share
When looking closely at PV module datasheets you will see some list PTC Rating and some do not. Most do list STC ratings – as the Standard Test Condition it is just that: the standard.
So what is PTC rating on a solar module and how is it used?
PTC is often referred to as PVUSA Test Condition, but more explicitly it is Photovoltaics for Utility Scale Applications Test Condition. Meaning the normal expected PV condition expected on a utility scale project. The rating is determined by calculating a regressive power output (linear) as the irradiance, wind, and temperature change in near STC conditions; with irradiance showing the strongest correlation to output power.
So what is PTC rating on a solar module and how is it used?
PTC is often referred to as PVUSA Test Condition, but more explicitly it is Photovoltaics for Utility Scale Applications Test Condition. Meaning the normal expected PV condition expected on a utility scale project. The rating is determined by calculating a regressive power output (linear) as the irradiance, wind, and temperature change in near STC conditions; with irradiance showing the strongest correlation to output power.
The idea here being that to determine the actual power output of solar panelsthat would be expected in a real world scenario. There is considered potential irregularities and uncertainty in the model with the multiple variations each with their own measurement errors and irregularities. But generally speaking it is helpful measurement to determine an expected output once installed.
How to Calculate PTC Rating for PV Modules:
The California Energy Commission provides a great resource for PTC ratings for most solar panels. Download the current list under PV Modules.