Ramp rate analysis for forecasting operations in Singapore

The aggregate global horizontal irradiance (GHI) found as the carefully quality controlled mean of 25 radiometric ground stations belonging to the Solar Energy Research Institute of Singapore (SERIS) is assumed to represent the total solar power generation potential for Singapore. Analysing 1,323,459 quality controlled 1-min aggregate GHI measurements (between 2013-05-01 and 2019-12-09), the maximum absolute observed ramp down event from 1-min to the next was 197 Wm
^-2
representing a 26% reduction; the maximum absolute observed ramp up event was 219 Wm
^-2
, representing a 39% increase. The lag time period ( tL) was then extended from 1-min through to 300-min to find the maximum observed delta between any time t and the measurement taken at t+tL. The maximum ramping event increased with increasing tL. Ramp down events are more severe in Singapore, reaching nearly a 900 Wm
^-2
reduction with a lag time greater than an hour; this is due to regular convective cloud systems in the afternoon. For lag times of 5, 10, 15, 30 and 60-mins, the maximum observed ramp up events were 337 Wm
^-2
(52%), 362 Wm
^-2
(122%), 460 Wm
^-2
(163%), 595 Wm
^-2
(192%) and 707 Wm
^-2
(325%), respectively. The maximum observed ramp down events were 356 Wm
^-2
(40%), 439 Wm
^-2
(62%), 560 Wm
^-2
(67%), 711 Wm
^-2
(81%) and 882 Wm
^-2
(88%), respectively.