Abstract:
Photovoltaic (PV) power generation units located in
tropical or equatorial sites frequently experience low-lying, dense
cloud cover; and are thereby exposed to rapid real time changes in
irradiance. Commonly referred to as cloud transients, the changes
lead to short duration power variations and substantial reduction
of output from individual units. The paper proposes pessimistic (or
worst-case) analytical assessment of power variation statistics at a
PV generation unit, as well as the consequent drop in output power.
Statistical estimates are introduced for worst-case short duration
mean output power, its temporal variability, and the associated
power change distribution. The metrics are verified against ensemble estimates from field studies conducted in Brazil and India.
Statistical estimates have the advantage of exclusive parametric dependence on optical air mass, which makes them applicable across
diverse geography and climate. They can therefore be used for
quick evaluation of short duration performance as well as comparative studies, both at existing as well as prospective PV generating
stations
