Indeed, after months of working, we have developed a reference PV cell dedicated to the calibrations and sent it to FRAUNHOFER CalLab, (laboratory for PV cells and PV module measures, internationally accredited ilac-MRA).
The reference PV cell has undergo to two-stage process, that has allowed to achieve a measure with an uncertainty of only 1.3%.
A Reference PV cell calibrated with that accuracy is a distinctive factor: it decreases the uncertainty during our adjustments operations. On the market, usually, a PV Cell pyranometer is adjusted with an uncertainty much greater than only 1.3%!
By September 2015 also the calibration of other manufacturer sensor’s will be done by using that reference PV cell.
Glossary of metrology terms:
Uncertainty = is the mathematical notation of margin of error of a measurement. When explicitly stated, express the range of values that enclose the true value. Tipical denotation is:
measured value (±uncertainty)
Accuracy = of a measurement system, is the degree of closeness of values measurated of a magnitude to that magnitude’s true value
Calibration = “operation that, underspecified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication” (← JCGM 200:2008 International vocabulary of metrology )
Adjustment= “set of operations carried out on a measuring systemso that it provides prescribed indications corresponding to given values of a quantity to be measured” (← JCGM 200:2008 International vocabulary of metrology )