Building integrated wind turbine are considered as part of a group of technologies that are suitable for domestic micro-energy generation. Darrieus and Savonius turbines work efficiently in the urban environment at low wind speed, the Savonius rotor is self-starting and creates high torque but has low efficiency, while the Darrieus rotor is very efficient but does not self-start easily. Thus, the combination of these rotors as hybrid system would help to improve the overall efficiency of the wind turbines. The aim of this paper was to design, fabricate and experimentally investigate the performance of hybrid Vertical Axis Wind Turbine (VAWT) on residential buildings. A building model with gable rooftop was design and fabricated for use in testing of the hybrid VAWT. The height of the hybrid VAWT was paced at Y = 150 mm above the rooftop. The results obtained from the studies showed that the hybrid VAWT mounted on the building rooftop yield up to 63% more energy compared to the bare-hybrid VAWT (without building). Similar improvement in performance of the hybrid VAWT is also observed in the rotational speed, mechanical power and the coefficient of torque, where the building integrated hybrid VAWT outperformed the bare-hybrid VAWT. Thus the results indicate that urban buildings are suitable for the mounting of the hybrid VAWT.

Solar flares are known to produce fast Corona Mass Ejections (CMEs) that can lead to the occurrence of different classes of geomagnetic storms. Severe geomagnetic storms can generate disturbances in the magnetosphere and the ionosphere that can affect communication channels; by disrupting Satellite and navigation systems, such as GPS, Galileo, Compass and GLONASS. During intense Solar flares, enhancement in the ionospheric electron density usually occurs, leading to the absorption of the High Frequency (HF) signals by the ionosphere. Enhancement in the Very Low Frequency (VLF) radio waves (3 -30 kHz) usually takes place during solar flares. This phenomenon is called Sudden Ionospheric Disturbance (SID). These SIDs serves as an opportunity for the tracking of solar flares using VLF. In this study, the diurnal variation of the VLF signals transmitted from six locations selected from USA, Australia and Japan were used to monitor SIDs. The signals were received using the 0-50 kHz frequency receiver (Super SID Monitor) installed at the Kebbi State University of Science and Technology (KSUST), Aliero, Nigeria (latitude: 12.31°N and Longitude: 4.50°E). The diurnal variation of the VLF signals alongside some magnetic indices (Dst, kp, and ap), solar wind speed and density as well as the solar flux index (f10.7) for the month of February, 2020 was investigated. Results from this study reveal that; the VLF amplitudes appeared to be stronger when the lowest level of the geomagnetic activity was recorded across all stations on the quietest day of the month. During this day, the intensity of the signals received vary across the stations, ranging from 2*10 4 to 4*10 7 dB. During the disturbed period, decrease in the Disturbance Storm Time (Dst) index was observed to have two minimum excursion with values of -31 and -33 nT, thus indicating a weak geomagnetic storm (-30-50) event. Consequently a gradual increase in the solar wind speed with a peak value of 520 km/s, significant decrease in the VLF amplitude ranging from 50 -7*10 5 dB was observed during the weak geomagnetic storm, on 19 February, 2020. It is also evident from this study that the intensity/strength of the VLF signal and its pattern of propagation are greatly affected by the geomagnetic storm. In spite of the changes in the VLF amplitude observed, there was no trace of solar flares during the weak geomagnetic storm. This therefore suggests that not all classes of geomagnetic storms are connected to solar flares.