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Disadvantages of Solar energy

ELECTRICAL ENERGY SECTOR IN PALESTINE

Most of the electricity which is about 88%is carried from the IEC while a little part of electrical energy is produced locally limited to only 70 MW at Gaza power plant, and the remainder carried from Jordan which is estimated to 20 MW of electric power to supply Jericho and the power carried from Egypt are estimated to 25 MW to supply Rafah in the Gaza Strip.

WHY SOLAR NOT THERMAL IN PALESTINE?

• Thermal power plants also needs sources imported from Israel at high costs .

• Thermal require large spaces of land far away from the population and city centers.

SO Palestinian Energy Authority (PEA) HIS strategy aims to improve using RES to accomplish 10% of the total demand for electric energy, in other word aims to produce 130 MW of electricity by the year 2020 .

PEA indicates four major requirements to obtain the stated objective:

• selection of a RE plan which is required to be achieved by the year 2020
• signature of laws and schemes It is necessary to organizevarious issues among RE investors and electrical distribution companies.
• support professionals, engineers, and technicians to createadequate knowledge of utilizing modern technologies and learn about the views of different RE systems.
• provide adequate financial resourcesto support benefit from the RES and the selection of tariffs that can support the private sector to invest in this modern technology.

THE ELECTRICAL GRID IN PALESTINE

• To illuminate the electrical power network in Palestine :

IEC going to producingand provided most of the electrical energy of the West Bank from tow connecti onpoints the first one is 33 kV, and the second one is 22 kV.

• The electricity network is facing a problem from the increasing demand for electric energy in the West Bank,and this problem needs practical solutions, as it has established and distributed newcontact points with a 161 kV effort distributed in the form of four contact points with :

1) voltage of 161 /33kV in the southern areas of the West Bank, which is in thecity of Hebron.

2) In the middle of which is the city of Ramallah.

3) in the north of the West Bank and is in the cities of Nablus and Jenin in order to developthe performance and reliability of the transportation and distribution system.

IMPACT OF PV SYSTEMS ON ELECTRICITY DISTRIBUTION NETWORKS

• Many issues recommend the need to a sufficient knowledge of how several tariffs chemes affect to social welfare, PV adoption rates, and the overabundance distribution between the house.
• he issues include several impacts of PV systems on electricity distribution networks:

1) increased the electrical losses depending on the bidirectional of the power stream at the electrical grid.

2) voltage rising happens in the state of reversed power pointed via the source which makes the voltage drop negative and might affect inverter cutting from thecentral grid which performs loss of power produced while interruption duration .

3) high penetration of solar systems might affect on electricity distribution networks.

4) raise the negative influences on the network such as variations in PV production power due to the interrupted nature of RES affectedto many factors such as temperature, and sunshine irradiation.

• so the grown in the sector of household PV systems need modern and some modification on agrid facilities, Add to decreases utility revenues more than it decreases prices,so All of these things propose further difficulties for utilities Economically andtechnically .

SOLAR ENERGY POTENTIAL

• Solar energy investment is independent of IEC, is plentiful, and has a huge potential in Palestine, so it is the only secured and viable energy source inPalestine.
• the annual average of solar energy is 5.4 kWh/m2-day and a sun light duration of about 3000 hours/year.

UNIVERSITIES ROOFTOP PV SYSTEMS

The universities rooftop PV systems will give many advantages for the Palestinian economics:

• produce significant savings for the price of electricity bills to universities and coat portion of its expenses.
• bringing Palestine closer to energy independence and encourages its commitment to RE.
• creating knowledge of green energy in universities and making sustainable energy practices to Palestine’s teaching environment, so Installing PV systems on universities surfaces have two-way benefits:

1) the first trend is to contribute to and enhance the authority’s plans and strategies to reduce dependence on Israel in purchasing energy to support the distribution of electricity and Palestinian municipalities in reducing pressures and debt on them by reducing dependency on purchases and reducing losses as well as reducing electricity prices from what is done Buy it from Israel.

2) related to education for students, motivating them,setting a practical model for them to improve energy technologies, and helping students in universities also learn and study how electricity works, the benefits of RE and energy efficiency.

The Higher Education and Palestinian Ministry of Education emerged a national program to deploy solar PV systems on the rooftops of 500 public schools in Palestine having a total generation capacity of 35 MW, this program is based on a آNet Metering scheme

TARIFF SCHEMES USED IN PALESTINE

• Palestine has a special status with regard to the methods of obtaining electricity, buying, and selling, this is due to the fact that Palestine is an occupied and non-independent country, and this necessitates dealing with borders that it cannot exceed .
• The electricity cost selected to include varying expenses, such as maintenance and repair of electrical power grids, the cost of energy, and customer services. For this reason, the electrical distribution companies buy electrical energy from IEC and sell the kWh units at higher costs. and when we talk about PV projects interconnected with the grid, we must think with further modifications related to electrical tariffs must be specified by this companies, Feed-in Tariff and Net-Metering are the two schemes used in Palestine.

NET-METERING SCHEME

• Net-Metering scheme allows small scale renewable energy power producers to store the energy generated in times of overproduction, as solar energy during peak production, in the national grid and to balance out their consumption from the grid with stored electricity during other times of low energy production as in cloudy days and during night hours.
• Palestine Net-Metering scheme obliges the customers having PV systems to have a bidirectional kWh- meter,This meter measures the energy consumed from the grid when the PV generation is less than consumption and also measures the excess energy injected to the grid when the PV generation exceeds the consumption.
• With Net-Metering, the customers pay for the net electricity consumed over the billing period at the conventional rate. Providers may benefit from Net-Metering because, when customers are producing electricity during peak periods, the system load factor is increased .

The Palestinian Energy Authority (PEA) issued the Net metering scheme with two main items:

• The monthly excess PV energy injected in the grid after covering the load demand will be deducted by 25% for using the national grid which means that only 75% of excess energy will be credited for the following month.
• after one year the excess PV energy will not be accounted to the customer . Hence the customers have to manage their consumption in order to avoid losing the excess generated PV energy or to select suitable size of PV system that fits their annual energy consumption.

Stand-alone systems

Stand-alone systems

• A stand-alone PV system is any system incorporating PV modules and not having a connection to the grid. The simplest stand-alone system consists of a module supplying a load directly.
• Beyond a certain size of system a charge regulator is necessary to protect the battery from over-charging with subsequent reduction in life.
• This forms the basic DC PV system and is illustrated in Fig loads are added the charge regulator would also serve the function of protecting the battery from over discharging.

Grid linked systems

Grid linked systems

• Grid linked systems are sub-divided into those in which the grid acts only as an auxiliary supply (grid back-up) and those in which the grid acts as a form of storage or two-way supply (grid-connected).
• In these systems surplus energy flows into the grid and energy deficit is met from the grid.
• Alternatively, the grid connected PV system energy supply to the grid can be considered totally separately from building energy demand which is met from the grid. In grid back-up systems the grid could be unavailable at meeting the demand so a standalone AC system consisting of PV array, batteries and stand-alone inverter is used, with changeover to inverter output when the grid supply goes. In grid connected systems the grid is assumed to be available most of the time and a grid connected inverter converts the DC output of the PV array to 230 V or 400V 50Hz AC for direct connection to the grid supply without the need for a battery.
• The disadvantage of the system is the need for the presence of the grid for the inverter to function; if the grid fails then no energy is generated even at times of high radiance.

WE PREFER GRID CONNECTED PV SYSTEM

WE PREFER GRID CONNECTED PV SYS-TEMle

• Grid tied PV system is more reliable than other PV systems.
• No use of battery reduces its capital cost so we go for the grid-connected topology.
• If generated solar energy is integrated into the conventional grid, it can supply the demand from morning to afternoon(total 6 hours mainly in sunny days) that is the particular time range when the Solar PV system can be fed to the grid.
• As no battery backup is there, that means the utility will continue supply to the rest of the time period.
• Grid-connected systems have demonstrated an advantage in natural disasters by providing emergency power capabilities when utility power was interrupted.
• Although PV power is generally more expensive than utility provided power, the use of grid-connected systems is increasing.

The roof of the engineering building

The roof of the engineering building with solar panels

System simulation models on OUTOCAD

The inter-row spacing

Here are the steel structures of arrays :

MODUL DATA SHEET :

MODUL DATA SHEET

INVERTER DATA SHEET:

INVERTER DATA SHEET

DESIGN

PVsys RESULTS

System simulation models on OUTOCAD

SINGLE LINE DIAGRAM