# PV Metrology

PV metrology summarises the various aspects of measurement in the field of photovoltaics. Metrology is the science of measurement, embracing both experimental and theoretical determination at any level of uncertainty in any field of science and technology [bipm.org]. Many aspects of the measurement of solar cells and solar modules (PV devices) are covered in the IEC 60904 and IEC 61853 series of standards and in the IEC 60891 standard. This wiki describes many measurement methods that are also described in these standards. In most cases, the aim is to determine the power or the energy generated in a period of time (energy yield) of PV devices as accurately as possible. As these values depend on many parameters, the measurement conditions for which the results apply must be precisely defined. So-called Standard Test Conditions (STC) exist for pure power measurements. For standardised yield calculations, the "Energy Rating" even defines ambient conditions for an entire year. How the associated measurements are carried out without lasting a whole year is explained on the relevant pages of this wiki.