REF: S. Hosseini, B.M. Goortani, M. Niroomand, Instantaneous Responses of on-grid PV Plants to Changes in Environmental and Weather Conditions, International Journal of Renewable Energy Research, 6(4) 1296-1306 (2016).
The operation of an on-grid, 20 KW, PV, pilot plant is analysed. The instantaneous environmental variables and weather conditions including solar irradiance, temperature, wind speed, and clouds are recorded and analysed, simultaneously along with plant responses including PV module temperature, generated power, current, and voltage. The power decreases with increasing ambient temperature. Increasing solar irradiance increases the temperature difference between modules and ambient. Instantaneous energy and exergy efficiencies during three different days, representing sunny, partly cloudy, and cloudy days, are further calculated. The energy efficiency varies between 5.76% and 15.53%, while that of exergy varies between 4.84% and 15.73%. For cloudy days, the exergy efficiency is higher than that of energy, while for a sunny day it is in reverse. Another important parameter affecting the generated power is partial shading on PV modules, particularly during early mornings and late afternoons. The shading changes from 3% to 9%, because of small azimuth and elevation angles. It was
found that partial shading of 4.73% on PV modules may result a significant power decrease of 52.3%. A new algorithm based on Fuzzy Logic is proposed to overcome these power decreases under partial shading.
Keywords PV cell; instantaneous respond; exergy and energy efficiency; partial shading.