# Introduction he more noticeable benefits of usable electric power include: improved health care, improved education, better transportation systems, improved communication systems, a higher standard of living, and economic stability. Unfortunately, almost 33% of the world's populations live without usable electrical power (Osama & Egon, 2007). Most of the non-electrified regions are found in developing countries (Phuangpornpitak & Kumar, 2007). Nigeria is one of the developing countries that most of its population lives without usable electricity. Many of the rural areas of Nigeria have not benefited from these uses of electricity in the same proportion as the more populated urban areas of the country (Akinboro, et al 2012). These rural areas can be electrified either by extending the grids of the existing power systems or by constructing isolated new power systems, which are alternative energy sources. Electrifying these remote areas by extending grid system is difficult and costly. Some of the rural areas that were electrified Like Mubi, Adamawa State, experience unreliable power supply characterized by low voltage and incessant power cuts often without warning or even apologies to consumers (Medugu & Markus, 2011). The fluctuating power supply causes problem to electronics appliances used at homes. House occupants are forced to use fossil fuel generators. These fossil fuel generators do not only create noise but contribute to global warming. As the current international trend in rural electrification is to utilize renewable energy resources; solar, wind, biomass, and micro hydro power systems can be seen as alternatives. Among these, combined wind and solar systems are becoming more popular for stand-alone power generation applications, due to advances in renewable energy technologies and subsequent rise in prices of petroleum products. Research and development efforts in solar, wind, and other renewable energy technologies are required to continue improving their performance, establishing techniques for accurately predicting their output and reliably integrating them with other conventional generating sources (Oji et al, 2012). (Prasad & Natarajan, 2006), presented a new method for optimization of a wind-PV integrated hybrid system. (Nelson et al, 2006) performed an economic evaluation of a hybrid wind/photovoltaic/fuel cell generation system for a typical home in the Pacific Northwest. (Grinspan et al, 2006) presented the development of a Savonius rotor configuration which is simple in design, fabrication and maintenance, and is suitable for small-scale rural application. (Mojola, 1985), examined the performance characteristics of the Savonius windmill rotor under field conditions. In order to reduce the need for fossil fuel leading to an increase in the sustainability of the power supply, wind and solar energy systems in stand-alone or hybrid forms are thought to be ideal solution for residential electrification due to abundant solar radiation and significant wind distribution availability in Mubi. Thus, in this research, hybrid renewable power generation system integrating solar and wind resources is to be designed and modeled, to electrify a residential house and its surrounding. A hybrid Photovoltaic-wind power generation system is proposed to supply electricity to a residence. The Hybrid Renewable Power Generation System (HRPGS) is a system aimed at the production and utilization of the electrical energy coming from more than one source, provided that at least one of them is renewable (Gupta, 2008). Residential generating systems harnessing wind and solar energies are seen as a potential answer to individual energy concern. The integration of renewable energies such as solar and wind are the best solution for feeding the mini-grids and isolated loads in remote areas. # Hybrid Power Generating System A hybrid power generating system is a system in which two or more supplies from different renewable energy sources are integrated to supply electricity. The hybrid used here is based on Photovoltaic (PV) modules and wind turbine. # a) Wind Turbine Energy available in wind is basically the kinetic energy of large masses of air moving over the Earth's surface. Blades of the wind turbine receive this kinetic energy, which is then transformed to useful mechanical energy, depending on end use (Mathew, 2006) Air of mass m (kg) moving with speed v (m/s) has a kinetic energy given by (Patel, 2006;Mathew, 2006): ???? = 1 2 ???? 2(1) The power P in moving air is the flow rate of KE per second. Thus the theoretical power in the moving air is giving by (Patel, 2006): ?? = 1 2 ?????? 3 (2) Where ?? is the density of the air stream, A the area of the wind captured. The most accurate estimate for wind power density in W/m 2 is that given by eqn (3) (Getachew, 2009) P A = 1 2 . 1 n . ? ?? j .v j 3 ? n j=1 (3) Where n is the number of wind speed readings and ? j and ?? j are the j th readings of the air density (kg/m 3 ) and wind speed (m/s) respectively. The swept area, A depends on the dimensions of the rotor. For a horizontal axis turbine of rotor diameter d, the swept area can be given by (Patel, 2006): ?? = ???? 2 4 (4) For a vertical axis turbine of maximum rotor width w and rotor height h, the swept area can be approximated by (Patel, 2006): ?? = 2 3 ???(5) The air density ? depends on pressure and temperature. It can be expressed as (Patel, 2006): ?? = ?? ???? (6) Where p is air pressure (Pa) and R is the specific gas constant (287 Jkg -1 K -1 ) and T is air temperature in K. If we know the elevation Z' (m) and temperature T at a site, then the air density can be calculated by (Mathew, 2006). ?? = 353 .049 ?? ?? ??0.034 ??" ?? ?(7) If pressure and temperature data are not available, the following correlation may be used for estimating the density (Getachew, 2009) ?? = 1.225 ? (1.194 * 10 ?4 ) * ???(8) a) PV Cells The complex physics of the PV cell can be represented by the equivalent electrical circuit shown in Fig. 1. The diode current is given by the classical diode current expression ?? ?? = ?? 0 ??????? ? ???? ???? ?????? ? ? 1?(10) constant, K is Boltzmann constant (1.38×10 -23 J/K), T is temperature on absolute scale K. Thus, the load current is given by the expression ?? = ?? ?? ? ?? ?? ? ?? ??? (11) ?? = ?? ?? ? ?? 0 ??????? ? ???? ???? ?????? ? ? 1? ? ?? ???? ?? ?? ?(12) The last term is the leakage current to the ground. In practical cells, it is negligible compared to I L and I o and is generally ignored. The maximum photo voltage is produced under the open-circuit voltage. Again by ignoring the ground leakage current, eqn 11 gives the open-circuit voltage as follows ?? 0 = ?????? ?? ???? ? ?? ?? ?? 0 + 1?(13) III. # System Description and Design Implementation The solar -wind with power generation system is designed as shown in Fig. 2. The generating system has a DC bus which combines the DC output of the PV module, the DC output of the wind turbine, and a battery. The AC bus combines the output of the inverter and the load. This parallel configuration requires no switching of the AC load supply while maintaining flexibility of energy source. When solar radiation falls on the solar panel, DC electricity flows. This electricity flows through the charge controller which regulates the DC energy for efficient charging. Similarly, when wind blows over the blades of the turbine, it turns the DC generator. The electricity generated is used for battery charging. The powers from the solar panel and the wind turbine add up when the two sources are at reasonable potentials. When the wind speed is below the cut-in point, and in a sunny day, solar energy takes over the charging. If on the other hand the wind speed is reasonably high and no solar radiation, especially at night, the wind turbine takes over charging the battery. Power inverter is then connected to transform the direct current energy of the battery into alternating current energy. ? It controls the modulation of the inverter through the feedback loop by adjusting the modulation current. This process helps to maintain a constant 220V across the load when the voltage of a fully charged battery drops from 14V to 10V IV. # Inverter Charge Controller and Control Unit Design The inverter is designed around the TL494 Pulse Width Modulation control Integrated Circuit which has an in-built oscillator among other features as shown in Fig. 3. The picture is shown in Fig. 4. Choosing C 4 to be 100nF and using eqn 14, R 3 is obtained as 100???(Alberkrack, 2002). # Global Journal of Researches in Engineering ( ) 4 3 2 1 C R f = (14) The 220VAC from the inverter output is rectified and dropped to a lower value by R 9 and R allowing a current of 0.2mA and a voltage of 2.5V at pin 1. R 9 and R 10 can be obtained using voltage divider as nearest preferred value of 1.0 ???. The error amplifier of the TL494 compares a sample of the internal 5V reference voltage to the voltage at pin 1 through R 4 and R 5 . The two resistors also set the gain for the amplifier to 11 and using R 4 to be 10K?, R 5 can be calculated using eqn 15 obtaining the value of 100 ???. # ( ) 4 5 1 R gain R ? = (15) R 8 and R 7 set the potential at pin 1 variable to 2.5V the error between pins 1 and 2 controls the pulse width modulation. C 5 filters the ripple from the rectifier and R 6 serves as feedback to the second internal error amplifier of the TL494. The output is referenced to ground through R 1 and R 2 which gives a voltage drop of 4.7V at 0.5mA. The battery charger/controller was designed using LM338 a 5A variable voltage regulator. The output voltage is set to 14V. The power supply to the on-board components was designed using LM317 variable voltage regulator. The power unit regulates the output to 10V over battery voltage variation of 11V to 14V. Complete innovation of the inverter with the accessories discussed is displayed in Fig. 5. # Global Journal of Researches in Engineering ( ) # Description of the Main Parts of the Wind Turbine A wind turbine consists of the following four main parts: the base, tower, nacelle, and blades, as shown in Fig. 6. The blades capture the wind's energy and spin a generator in the nacelle with the aid of an improvised gear box housed two gear system of ratio 1:6. The shaft with fewer gears was attached to the wind turbine rotor while the shaft with more gears was attached to the generator. The tail was cut to the shape shown in Fig. 6 for turning the turbine to the direction of the wind. The tower contains the electrical circuits, supports the nacelle, and provides access to the nacelle for maintenance while the base is made of concrete and steel and supports the whole structure. capacitive and resistive loads respectively. The efficiencies were determined from the ratio of full-load DC voltage to the no-load DC voltage. The control unit of the inverter was also tested and was in conformity with the design which was auto-switching (OFF for sun rises and ON for sunset). The battery's state of charge was 8.7V. The charger was connected at 8:12am and the corresponding voltage across the battery was measured at an interval of thirty minutes.Fig, 8 shows the graph of the voltage across battery against the corresponding time of the day indicating the three charging stages of the charge controller. The system is able to power a 3 bedroom resident containing 16 energy saving bulbs, 1 TV set, 4 fans and 2 computer system for 12 hours without draining the battery. # Discussion It was observed that wind and solar are complementary since sunny days are usually calm and strong winds are often accompanied by cloud and may occur at night. The inverter under capacitive loads draws less energy from the battery than resistive loads. This is practically indicated by a lower drain from the battery voltage. The graph of Fig. 8 shows how the battery rapidly charged from 8.7V to 10.39V within 30minutes indicating boost stage, and from 10.39V to 12.39V for two hours thirty minutes indicating the floating stage. While the last stage showed how the charging fluctuates indicating trickle mode. The charging of the battery by the wind turbine greatly depends on the rotational speed of the blade which in turn depends on the wind speed. The readings were obtained at low wind speed. The charger was able to add 0.77V to the battery's state of charge within two hours thirty minutes. The control unit switches ON the inverter once the solar plate could not detect any solar radiation and switches OFF once it detects it. # VIII. # Conclusion A hybrid power generating system consisting of a PV array and wind turbine with energy storage device and power electronic converter was designed and constructed to take advantage of the seasonal wind and sunshine. The design is achieved as an efficient and cost competitive system configuration so that hybrid power source can improve the life of people especially in rural areas where electricity is not stable or is absent. The efficiency of the designed electricity generating machine (inverter) is about 95% and 73% for capacitive and resistive loads respectively. The wind turbine performance showed a promising output, but there was a challenge with the generator at lower wind speed as can be seen from table 4.4 where only 0.77V was added to the battery's state of charge. This platform has been laid to harvest the wind energy and the abundant solar radiation availability in Mubi. The integrated solar-wind hybrid power generating system is environmentally friendly and maintenance free. ![Global Journal of Researches in Engineering ( ) F Volume XIV Issue IV Version I II.](image-2.png "T") 1![Figure 1 : A PV cell equivalent electrical circuits after (Duffie & Beckman, 2006) The current I at the output terminals is equal to the light-generated current L I less the diode current D I and the shunt-leakage current sh I . The series resistance](image-3.png "Figure 1 :") 2![Figure 2 : Block diagram of PV-Wind Hybrid Power Generating System a) The control unit plays two roles ? It controls the operation of the inverter. That is if it senses solar energy, it automatically switches off the inverter and allows only charging of battery. This also means that the control unit switches OFF the inverter during the day and switches ON at night.](image-4.png "Figure 2 :") 3![Figure 3 : Complete Circuit diagram of the Inverter Module/ Charge Controller and the Control unit.](image-5.png "Figure 3 :") 4![Figure 4 : Constructed Inverter and Charge controller Connecting an external capacitor C 4 and resistor R 3 to pins 5 and 6 control the oscillation frequency of the TL494.Choosing C 4 to be 100nF and using eqn 14, R 3 is obtained as 100???(Alberkrack, 2002).](image-6.png "Figure 4 :") 5![Figure 5 : The 500W Power Inverter after Casing V.](image-7.png "Figure 5 :") 6![Figure 6 : Shows the picture if the Integrated Electricity generating system in operation](image-8.png "Figure 6 :") 78![Figure 7 : structural frame of the wind turbine and solar panel](image-9.png "Figure 7 :Figure 8 :") © 2014 Global Journals Inc. (US) © 2014 Global Journals Inc. (US) Integrated Solar -Wind Hybrid Power Generating System for Residential Application Year 2014 © 2014 Global Journals Inc. (US) Integrated Solar -Wind Hybrid Power Generating System for Residential Application * Solar Energy Installations In Nigeria: Observation, Prospects, Problems and Solutions FAkinboro LAdejumob VMakinde Transnational Journal of Science and Technology 2 4 2012 * JDuffie WBeckman Solar Engineering of Thermal Processes. 3 rd ed New Jersey John Wiley and Sons, Inc 2006 * Study into the Potential and Feasibility of a Standalone Solar-Wind Hybrid Electric Energy Supply System: For Application in BGetachew 2009 * Ethiopia. Ph. D Dissertation. Ethiopia: Royal Institute of Technology, KTH * Design, Development and Testing of Savonius Wind Turbine Rotor with Twisted Blades AGrinspan Suresh USaha PMahanta DRao GBhanu Proceedings of 28 th National Conference on Fluid Mechanics and Fluid Power 28 th National Conference on Fluid Mechanics and Fluid Power 2006 * Computerize Modelling of Hybrid Energy System-part I: Problem Formulation and Model Development AGupta 2008 5 th ICECE * Wind as a Viable Source of electricity for fluctuation of electri power in Yola DWMedugu AMarkus Ozean Journal of Applied Science 4 1 2011 * Wind Energy: Fundamentals, Resource Analysis and Economics SMathew 2006 Springer-Verlag Berlin Heidelberg * On the Aerodynamic Design of the Savonius Windmill Rotor Mojola Journal of Wind Engineering and Industrial Aerodynamics 21 1985 * Unit Sizing and Cost Analysis of Stand-Alone Hybrid Wind/PV/Fuel Cell Power Generation Systems DNelson MNehrir CWang Renewable Energy 2006 3 * Utilization of Solar Energy for Power Generation in Nigeria JOji NIdusuyi TAliu MPetinrin OAdejobi AAdetunji International Journal of Energy Engineering 2 2 2012 * An Online Control Stretagy for DC Coupled Hybrid Power System OOsama OAEgon 2007 * IEEE Power Engineering Society General Meeting * Wind and Solar Power Systems: Design, Analysis and Operation MRPatel 2006 Taylor and Freinds Group Boca Raton London * PV Hybrid Systems for Rural Electricfication in Thiland NPhuangpornpitak SKumar Renewable and Sustainable Energy Reviews 11 7 2007 * Optimization of Integrated photovoltaic-Wind Power Generation System with Battery Storage ARPrasad ENatarajan Energy 3 1 2006 * Global Journal of Researches in Engineering