DNI Estimation Procedures for the Assessment of Solar Radiation Availability in Concentrating Systems

Towards Implementation CSP Technology in Malacca Part. 1: DNI Assessment in Alor Gajah

“…Though accurate datasets of GHI are available for many sites, still efforts are required to fully characterize the DNI resource [12]. In this study, the map in Figure 5 illustrates the geographic distribution of average yearly total DNI of the four experimented sites in Alor Gajah [15].…”

“…Since measurements of global and diffuse irradiance have good accessibility and availability, the present paper aims at clarifying to the extent such data can be used for deriving DNI data hourly by observing on-site using solar flux meter [12]. DNI on site for AG1 shows in Figure 6 explained a good agreement between the result obtained on-site and result mapping by SolarGIS that simulates the area of AG1 will give the results at the range of 1000-1100 kWh/ m²/year [4].…”

“…As direct radiation has a geometric behaviour, the horizontal direct irradiance comes from DNI multiplied by the cosine of the zenith angle. Hence, the assessment of DNI is vital for the study of both concentrating and flat-plate solar systems [12]. Besides, solar collectors are built to utilize the solar radiation.…”

“…Unfortunately, the tricky part of indirect evaluation of DNI is that pyranometers can be affected by several sources of uncertainty, which should be properly considered. The uncertainty of DNI defined by Padovan as (2) [12].…”

“…Alternatively is to indirectly derive DNI from the measurements of global and diffuse horizontal irradiance. The diffuse irradiance is measured with a shaded pyranometer and the best way is to occult the solar disk with a ball driven by a sun tracker [12].…”