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The electricity in Gaza, Palestine, is limited and scheduled for 4-10 hours per day due to political reasons. This status represents a real problem for different sectors. This paper presents an effective solution especially for the energy supply problem in the residential sector by using an unconventional PV system which operates in stand-alone and grid-connected modes. The system includes a storage battery block with a proper capacity to secure for continuous power supply of a residential house with a daily energy load of 10 kWh. It was found that an unconventional PV system of 3.2 kWp and a storage battery block of 19.2 kWh will be able to cover the total daily energy demands of the house including the outlined electricity cutoff hours. The design of this system and specifics of its components are presented in this paper. The system was simulated by Matlab software, where the daily load curve, grid cutoff hours, and the monthly solar radiation are considered. The obtained simulation results show that the produced PV energy exceeds the load demands during nine months of the year, and thereby, a high battery state of charge (SOC) in the range of 73-84% is achieved. During the three months of the lowest solar radiation (Dec.-Feb.), the produced PV energy is equal to the load demand while the battery state of charge varies in the range of 40-49% which verifies the appropriateness of the proposed PV system. The daily energy yield of the PV system varies between 2.6 and 5.4 kWh/kWp in January and July, respectively, which corresponds to a performance ratio of 90% and 66.25%, respectively.

Correct matching between PV array and inverter improves the inverter efficiency, increases the annual produced energy, decreases the clipping losses of the inverter, and prevent to a large extent the inverter frequent shut downs during clear sunny days of high solar radiation and low ambient temperature. Therefore, this paper presents a new methodology for selecting the appropriate peak power of the PV array with respect to the inverter output AC rated power taking into account the local daily distribution of solar radiation and ambient temperature. In addition, the proposed methodology specifies the appropriate number of PV modules in each string and the number of parallel strings connected to the input of the inverteraccording to its specifications and to PV cell temperature. Mathematically modeling of system parameters and components are presented and used in the simulation to investigate the different scenarios. The paper presents also a case study using simulation to find the optimal matching parameters of a PV array connected to an inverter with the specifications: 6 kW rated output power, an input mpp voltage range of 333-500 V, 6.2 kW maximum input DC power, and an output AC voltage of 230 Vrms. Considering the local climate conditions in West Bank, the simulation resulted a peak power of 7 kW for the PV array, which is greater than the inverter output power by the factor 1.16. In addition, the obtained PV array consists of two parallel strings each includes 12 PV modules  connected in series  while each PV module is rated at 290 W. The output voltage of the PV arrayvaries between 359 V to 564 Vat minimum and maximum temperature of 10 ˚C to 70 ˚C respectively. This PV array-inverter combination resulted by simulation an annual yield of 1600 kWh/kWp and an energy of 11197 kWh which corresponds to an energy gain of 1591 kWh/year more than using a PV array with a peak power of 6 kW as the inverter rated power.

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Micro-Grid (MG) is a small-scale power network associated with Renewable Energy Sources (RES), EnergyStorage System (ESS) and local critical loads. MGs can either be connected to the main grid or operate stand-alone. Due to variable nature of RES such as Photovoltaic (PV) solar cells, ESS become necessary to maintain reliability of power supply to critical loads during islanded mode. During grid connected mode, ESS is used to support the grid or MG depending on the grid operator and energy management functions. On the other hand, the power converters interfaced ESS can be used to provide additional services to the main grid, such as reactive power and unbalanced compensation. This paper presents a control strategy for an Energy Storage Power Converter (ESPC) in MGs, in order to mitigate the negative effects of grid connected MGs working with highly unbalanced operation and poor power factor conditions. Simulation results have been carried out by using Matlab -Simulink software to verify the effectiveness of the proposed control scheme.