Wind and solar resource complementarity and its viability in wind/PV hybrid energy systems in Machakos, Kenya

Abstract

Integration of intermittent renewable energy resources provides the potential to mitigate the impact of the variability of independent sources. The intermittent nature creates stability, reliability and power quality problems in power grids. Wind and solar energies are the most viable resources whose complementarity could be deployed in the development of hybrid renewable energy systems to enhance their performance. In this study, wind-solar resource complementarity is investigated to establish its viability in hybrid energy systems in Machakos, a rural-urban town whose geographical location is 1°31′S, 37,016′E in the Eastern region of Kenya. The study findings could be fundamental in energy planning and developments in the area to provide more flexible and dependable hybrid energy systems which would supply energy services under constantly changing conditions. Ground measurements included PVGIS simulation and experimental tools installed at a height of 20 m. Weibull's distribution model and energy potential of wind resource are investigated to characterize wind resource for energy generation. The Wind distribution revealed a positively skewed profile with scale (c) and shape (k) parameter values of 2.68 m/s (≈ 3.0 m/s) and 1.9 at a mean wind speed of 2.47 m/s, respectively. The findings revealed a wind power density of 17 W/m2 at an average wind speed of 3.0 m/s. Further, an annual solar insolation of 2130 kWh/m2 with monthly average of 178 kWh/m2 translating to daily insolation of 5.8 kWh/m2 at an installation capacity of 1 kWp is reported. The months with minimum and maximum solar insolation were July and March which recorded monthly averages of 145 kWh/m2 and 213 kWh/m2 translating to a daily average of 4.7 kWh/m2 and 6.9 kWh/m2, respectively. The understanding gained from this study could be useful to the renewable energy research community and can be extended to stakeholders in PV and wind energy systems for micro grids and utility applications.