How to Choose a Pyranometer: A Must-Know Guide for PV Professionals
Many factors affect photovoltaic (PV) power generation, among which
solar irradiance is the core determinant. A pyranometer is a key instrument
specifically used to measure solar irradiance. So, what types of pyranometers
are there, and what are the differences between them?
According to the international standard ISO 9060:2018, pyranometers
are mainly divided into two categories: thermopile-based and
photodiode-based.
A thermopile pyranometer measures irradiance by detecting the
temperature difference between the sensing surface (thermoelectric
junction) and the instrument body (reference junction). Its working principle
is as follows:solar radiation is absorbed by the thermopile sensor →
temperature rises → a thermoelectric voltage is generated → output voltage is
proportional to irradiance.
A photodiode pyranometer, also known as a silicon pyranometer, uses
silicon photodiodes or photovoltaic cells as photoelectric receivers. Under
illumination, it generates a photocurrent, which is proportional to solar
irradiance.
What are the specific differences between these two irradiance meters,
and how should you choose in practical applications? The table below clearly
illustrates this.
As shown in the table above, the two types of pyranometers differ
significantly in performance characteristics. Thermopile pyranometers offer
higher accuracy and classification levels, making them suitable for professional, high-precision monitoring scenarios, but they are relatively
more expensive. Photodiode pyranometers, while slightly lower in accuracy
and stability, feature faster response times, better spectral matching with PV
modules, and lower cost, making them more suitable for large-scale
deployment in PV power plants.
What kind of scenarios do you typically work in? Which type of
pyranometer do you prefer? Feel free to share your thoughts in the
comments.