Measurement and analysis of the step response of pyranometers requiring second-order correction

• Published in: Solar energy Vol. 49; no. 4; pp. 309 - 313
• Main Authors: Shen, B., Robinson, A.M.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.10.1992; Elsevier; Pergamon Press Inc
• Subjects: 140100 - Solar Energy- Resources & Availability; 990200 - Mathematics & Computers; BENCH-SCALE EXPERIMENTS; CALCULATION METHODS; CALIBRATION; Earth, ocean, space; ENERGIA SOLAR; ENERGIE SOLAIRE; ERRORS; Exact sciences and technology; External geophysics; FREQUENCY RESPONSE TESTING; GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; Geophysics. Techniques, methods, instrumentation and models; INSTRUMENT DE MESURE; INSTRUMENTOS DE MEDICION; MATHEMATICAL MODELS; MEASURING INSTRUMENTS; MODELE; MODELOS; PYRANOMETERS; Radiation; RADIATIONS; SINGLE EXPONENTIAL CORRECTION; SOLAR ENERGY; SOLAR EQUIPMENT; SOLAR RADIATION; STELLAR RADIATION; STEP FUNCTION; TESTING; THERMAL MODELS; Weights & measures; Pyranometer; Second order equation; Experimental result; Instrumental response; Instruments; Differential equation; Solar radiation; Time constant; Corrections; Step function
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/0038-092X(92)90010-8

We have measured the time response of Kipp and Zonen CM-5 pyranometers to a step function of radiation and observed that the pyranometer output varied significantly from a single exponential function of time. Using a multi-exponential function to fit the experimental data, we extracted the two dominant exponential components of the signal to obtain the analytic function describing the pyranometer response. A thermal model of the pyranometer has been developed, whose response displays the observed time behaviour. The model was applied to correct the time response error of the pyranometers subject to a step function of incident radiation, and compared with a single exponential correction scheme.