부산대학교 도서관

In this work, we introduce and analyze a new cost-effective solution to measure the directnormal irradiance (DNI) without the need of a sun-tracker. While the state-of-the-art setup tomeasure the DNI is comprised of a pyrheliometer assembled on a sun tracker, the EKOMS-90 [1] (formerly known as MS-05 [2]) measures DNI based on the MS-093 sunshineduration measurement concept [3,4] which doesn’t require a solar tracker to align the sensoraperture with the sun disk, presenting a relatively lower cost solution for sensor networks tomeasure DNI. To measure DNI the MS-90 sensor body is set up with a fixed tilt optimized according tothe location latitude. The direct beam is reflected to the sensor head by a 45˚ tilted rotatingmirror. Each revolution of the mirror has a period of 15s, reflecting the direct beam radiationto the sensor head once every period. A pyroelectric detector then measures the signal pulse,which is proportional to DNI. We present a comprehensive study of the EKO MS-90 measurement accuracy. Toquantify the measurement error of this new sensor we compare the MS-90 DNImeasurements with reference pyrheliometers assembled on a sun tracker measured at two testsites, EKO in Tokyo, Japan, and at the National Renewable Energy Agency (NREL) inColorado, USA. The MS-90 DNI data is acquired continuously every minute since February2017 at EKO, and since October 2017 at NREL. The preliminary results show for both test sites that the cost-effective MS-90 sensorsmeasure the DNI with deviations from the reference within ±5%, for solar zenith anglessmaller than 75˚ and DNI values higher than 700W/m2. Larger deviations practically within±10% are observed for greater incidence angles and lower DNI values depending on seasonaleffects. [1] J.M. Pó, K. Hoogendijk, I. Chiba, A. Akiyama, W. Beuttell, Direct Normal IrradianceMeasurements Using a Tracker-Less Sunshine Duration Measurement Concept, in 35thEuropean Photovoltaic Solar Energy Conference and Exhibition, pp 1676 – 1678,2018 [2] M. Sengupta, A. Habte, C. Gueymard, S. Wilbert, D. Renné, Best practices handbookfor the collection and use of solar resource data for solar energy applications: Second edition.NREL technical report, NREL/TP-5D00-68886, pp 3-27-28, 2017 [3] MS-093 Sunshine duration sensor manual, EKO Instruments, accessed January2019 [4] WMO, 2008, Guide to Meteorological Instruments and Methods of Observation,seventh edition, Annex 1.B, subscript point 5, and 8.1.3 [ABSTRACT FROM AUTHOR]