DETERMINATION OF YEARLY PERFORMANCE AND DEGRADATION RATE OF ELECTRICAL PARAMETERS OF AMORPHOUS SILICON PHOTOVOLTAIC MODULE IN MINNA, NIGERIA

ABSTRACT

There is need for accurate knowledge of performance, degradation rate and lifespan of photovoltaic (PV) module in every location for an effective solar PV power system. Outdoor degradation analysis was carried out on amorphous silicon PV module rated 10 W using CR1000 software-based Data Acquisition System (DAS). The PV module under test and meteorological Sensors were installed on a metal support structure at the same test plane. The data monitoring was from 09:00 to 18:00 hours each day continuously for a period of four years, from (December 2014 to November 2018).The experiment was carried out near the Department of Physics, Federal University of Technology, Minna (latitude 09o37'N, longitude 06o32'E and 249 meters above sea level). The sensors were connected directly to the CR1000 Campbell Scientific data logger, while the module was connected to the logger via electronic loads. The logger was programmed to scan the load current from 0 to 1 A at intervals of 50mA every 5 minutes, and average values of short-circuit current, (Isc), open-circuit voltage, (Voc), current at maximum power, (Imax), voltage at maximum power, (Vmax), power(P) and maximum power(Pmax) obtained from the modules together with the ambient parameters are recorded and logged. Data download at the data acquisition site was performed every 7 days to ensure effective and close monitoring of the data acquisition system (DAS). At the end of each month and where necessary, hourly, daily and monthly averages of each of the parameters-solar irradiance, solar insolation, wind speed, ambient and module temperatures, and the output response variables (open-circuit voltage, Voc, short-circuit current, Isc, voltage at maximum power, Vmax, current at maximum power, Imax, efficiency, Eff, and fill factor, FF) of the photovoltaic modules were obtained. Annual yearly averages of the performance variables were carried out to ascertain the performance, degradation rate and lifespan of the module. The module performance for the four years of study was compared with Standard Test Condition (STC) specifications. The maximum power achieved at 1000W/m2 for the four years of study were 0.652W, 2.186W, 2.078W, and 1.812W representing 6.52%, 21.86%, 20.78% and 18.12% of the manufacturer’s 10W specification. Module efficiency at 1000W/m2 for the four years of study is 2.25%, 7.56%, 7.19%, and 6.27% respectively as against the manufacturers STC specification of 33%. Accordingly, Module Performance Ratios for the PV module investigated were 0.07, 0.23, 0.22 and 0.19 respectively. For the Rate of Degradation (RoD), it was observed that Open-Circuit voltage (Voc), Short-Circuit Current (Isc), Power-Output (P), Maximum Power (Pmax), had an average yearly degradation rate of 0.73V, 0.010A, 0.040W, 0.050W respectively for the four years of study. To also determine the lifespan of the module, an empirically determined statistical model given as YEAR = 3.36 - 0.237 Voc (v) - 71.5 Isc (A) + 8.07 Power (W) was fitted to the observed data to predict the lifetime of the module at any given year.