DETERMINATION OF YEARLY PERFORMANCEAND DEGRADATION RATE OF ELECTRICAL PARAMETERS OF A MONOCRYSTALLINE PV MODULE IN MINNA, CENTRAL NIGERIA

ABSTRACT

There is a need for accurate knowledge of the performance, degradation rate, and lifespan of the photovoltaic (PV) module in every location for an effective solar PV power system. Outdoor degradation analysis was carried out on a mono-crystalline PV module rated 10 W using the CR1000 software-based Data Acquisition System (DAS). The PV module under test and meteorological Sensors were installed on a metal support structure on the same test plane. The data obtained was monitored 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 Physics Department, 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 is 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), the voltage at maximum power,(Vmax), power and maximum power 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, the voltage at maximum power, Vmax, current at maximum power, Imax, efficiency, Eff, and fill factor, FF) of the photovoltaic modules were obtained.Yearly averages of the performance variables were obtained 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 are 0.711W, 1.82W, 0.50W, and 0.22W representing 7.11%, 18.39%, 5.0% and 2.25% of the manufacturer’s 10W specification. Module efficiency at 1000W/m2 for the four years of study is 3.30%, 10.12%, 3.98%, and 2.82% respectively as against the manufacturer's STC specification of 46%. Accordingly, Module Performance Ratios for the PV module investigated were 0.072, 0.22, 0.087, and 0.061respectively. For the Rate of Degradation (RoD), it was observed that Open-Circuit voltage (Voc), Short-Circuit Current (Isc), Power-Output (P), and Maximum Power (Pmax), has an average yearly degradation rate of 1.06V, 0.002A, 0.082W and 0.142W representing 4.9%,0.30%,0.56%, and 1.4%respectively for the four years of study. The lifespan of the module was also determined through an empirically generated statistical model given as YEAR =4.60 -0.603Voc (v)-6.83Isc(A) +1.75 Power (W) was fitted to the observed data to predict the lifetime and yearly performance status of the module at any given year.