Upper-limit solar photovoltaic power generation: Estimates for 2-axis tracking collectors in Nigeria

• Published in: Energy (Oxford) 2016-01, Vol.95, p.504-516
• Main Author: Njoku, H.O.
• Format: Article
• Language: English
• Subjects: 2-axis tracking; Accumulators; Collectors; Latitude; Maximum PV generation potential; Photovoltaic cells; Seasons; Solar cells; Solar photovoltaics; System performance ratio; Tracked PV collectors; Tracking; Tracking (position)
• ISSN: 0360-5442
• DOI: 10.1016/j.energy.2015.11.078

Energy generation by solar PV (photovoltaic) systems can be improved by incorporating tracking mechanisms, with the highest improvements resulting from 2-axis tracking. Peak energy generation levels (from PV collectors with 2-axis tracking) have been determined in this study, for locations in Nigeria. The spatial domain of interest was discretized into a grid of 1° latitude by 1° longitude cells. For each cell, monthly average daily irradiation on horizontal surfaces and ambient temperatures were obtained from the web-based NASA meteorological data service. With these, irradiation on tilted surfaces, system performance ratios, rp, seasonal and annual energy generation potentials, E/Pk, and improvements in energy generation potentials, ΔE/Pk, were determined. An approach for estimating rp is suggested, which accounts for effects of varying temperature and insolation levels on performance. rp values obtained by this approach are conservative relative to the fixed value of 0.75 which is presently in common use. The highest seasonal E/Pk (446–648 kWh/kWp) and ΔE/Pk (32%–62%) occur in the December-January-February season, and the least (249–590 kWh/kWp and 10%–26%, respectively) in the June-July-August season. E/Pk generally increased with latitudes. The additional E/Pk obtained with tracking (20%–40% annually) could offset additional costs due to tracking. •Energy generation estimates for solar PV systems with 2-axis tracking are presented.•System performance ratios at 5 sites, obtained with 3 different models are compared.•Energy generation potentials, E/P_k, are determined for Nigerian locations.•Gains in E/P_k compared to the outputs of non-tracking collectors are also obtained.•Highest E/P_k are obtained in the DJF season and at high latitude locations.