A photovoltaic cell comprises P-type and N-type semiconducting materials with different electrical belongingss, joined together. The joint between these two semiconducting materials is called the “ P-N junction. ”
Sunlight striking the photovoltaic cell is absorbed by the cell. The energy of the captive light generates atoms with positive or negative charge ( holes and negatrons ) , which move about or switch freely in all waies within the cell.
The negatrons ( – ) tend to roll up in the N-type semiconducting material, and the holes ( + ) in the P-type semiconducting material. Therefore, when an external burden, such as an electric bulb or an electric motor, is connected between the forepart and back electrodes, electricity flows in the cell.
Information provided by Nisshin Electric Co. , Ltd.
hypertext transfer protocol: //www.apec-vc.or.jp/e/modules/tinyd00/index.php? id=74
( B ) Equivalent circuit and explicate the significance of each constituent relevant to a PV cell.
We can specify an electrical circuit that acts merely like our ideal solar cell, and pull its conventional diagram. It is merely a current beginning in analogue with a rectifying tube, the rectifying tube represents the P-N
Si junction. A current beginning is a device that produces a changeless current and in this instance the current is relative to the strength of the light falling on the cell. See figure 1.2 for the ideal tantamount circuit.
Figure 1.2 Ideal Equivalent Circuit.
Real solar cells have features that degrade their public presentation compared to the ideal. In peculiar, their wiring has some opposition to the flow of current. This is represented electrically by a resistance in series. Likewise, there is some opposition that is in analogue with the current beginning and rectifying tube that drains some sum of power from the cell. To be more complete, so, the tantamount circuit looks like the circuit in figure 1.3.
Figure 1.3 Realistic Equivalent Circuit.
hypertext transfer protocol: //chuck-wright.com/SolarSprintPV/SolarSprintPV.html
( degree Celsius ) Factors impacting the electrical end product.
The chief factors that affect the electrical end product are shadowing, location, orientation and soilure.
One of the biggest environmental factors impacting solar electricity production is shadowing. PV faculties are really sensitive to shadow. For illustration, if shaded by every bit much as a leafless tree subdivision, a PV faculty could lose up to 80 % of its end product. hypertext transfer protocol: //www.geosolution.com/solar_introduction.htm
Given that the photovoltaic cell produces electricity from direct Sun light it stand to ground that a PV panel installed in Florida will bring forth more energy over the class of a twelvemonth than an indistinguishable panel installed in Limerick.
Another factor that will impact the electrical end product of your array is the directional orientation of the faculties. When taking a location, a southern exposure will increase output as this will expose the PV panel to the maximal sum of sunlight. The tilt angle of the array will besides impact power end product.
Any dust or soil build up like dead foliages will cut down the electrical end product of the PV panel in a mode similar to shadowing.
( vitamin D ) Show utilizing a study how a PV renewable energy system is integrated on to a grid affiliated system including any control features.
Sketch of how a PV renewable energy system is integrated on to a grid affiliated system ;
Figure 1.4 PV renewable energy system integrated on to a grid connected system.
Research the fuel cell under the undermentioned headers:
( a ) The rule of operation and building.
A fuel cell is a electrochemical energy transition device, but unlike a battery, a fuel cell ne’er goes dead or requires reloading. The fuel cell is made up of three sections which are sandwiched together to organize the anode, the electrolyte, and the cathode. Two chemical reactions occur at the interfaces of the three different sections. The net consequence of the two reactions is that fuel is consumed, H2O or C dioxide is created, and an electric current is created, which can be used to power electrical devices, see figure 2.1 for the basic fuel cell building.
Figure 2.1 Basic fuel cell building.
( B ) Types of cell.
Fuel cell types are by and large characterized by the electrolyte stuff. The electrolyte is the substance between the positive and negative terminuss, functioning as the span for the ion exchange that generates electrical current.
While there are tonss of types of fuel cells, there are six principle sorts in assorted phases of commercial handiness, or undergoing research, development and presentation. These six fuel cell types are significantly different from each other in many respects ; nevertheless, the cardinal distinguishing characteristic is the electrolyte stuff.
1. Alkaline Fuel Cell ( AFC )
2. Molten Carbonate Fuel Cell ( MCFC )
3. Phosphoric Acid Fuel Cell ( PAFC )
4. Proton Exchange Membrane Fuel Cell ( PEMFC )
5. Solid Oxide Fuel Cell ( SOFC )
6. Direct Methanol Fuel Ce
Beginning hypertext transfer protocol: //www.nfcrc.uci.edu/2/FUEL_CELL_INFORMATION/FCexplained/FC_Types.aspx
( degree Celsius ) Fuel Beginnings.
Hydrogen is the current fuel of pick for all fuel cells. Some gases, such as N from the air, have merely a dilution consequence on the public presentation of the fuel cell. Other gases, such as CO and CH4, have different effects on fuel cells, depending on the type of fuel cell. For illustration, CO is a toxicant to fuel cells runing at comparatively low temperatures, such as the Proton Exchange Membrane Fuel Cell ( PEMFC ) . However, CO can be used straight as a fuel for the high-temperature fuel cells such as the Solid Oxide Fuel Cell ( SOFC ) . Each fuel cell with its specific electrolyte and accelerators will accept different gases as fuels and experience toxic condition or dilution. Therefore, the gas supply systems must be tailored to a specific type of fuel cell.
( vitamin D ) Sketch one type of cell and rubric to the full.
Research the micro turbine under the undermentioned headers:
( a ) The rule of operation and block diagram of agreement.
Micro turbines are little electricity generators used to make high-velocity rotary motion that turns an electrical generator.
In there simplest signifier micro turbines are really simple devices with merely 3 parts ;
A compressor to compact the incoming air to high force per unit area.
A burning country to fire the fuel and bring forth high force per unit area, high speed gas.
A turbine to pull out the energy from the high force per unit area, high speed gas fluxing from the burning chamber to turn the shaft of the electrical generator.
Most designs are single-shaft and utilize a high-velocity lasting magnet generator bring forthing variable electromotive force, variable frequence jumping current ( AC ) power. An inverter phase is used to bring forth suited 50 or 60 Hz AC power.
Most units like the one in figure 3.1 below come with a recuperator phase used to repossess some of the fumes heat and utilize it to heat the incoming air in order to increase the unit ‘s efficiency.
Figure 3.1 Micro Turbine Block Diagram.
( B ) Types of fuel used.
Most micro turbines burn natural gas, but can run on a assortment of other fuel types including propane and Diesel and some can run on renewable and waste fuel such as biogas.
( degree Celsius ) List one advantage and one disadvantage of this type of coevals.
Advantage: – Very simple design with few traveling parts necessitating really low care.
Disadvantage: – Low fuel to electricity efficiencies.
( vitamin D ) Difference between ‘simple-cycle ‘ and ‘recuperated ‘ operation.
In a simple-cycle micro turbine design all of the heat from the exhaust gasses coming from the combustor are expelled straight into the ambiance. In the recuperated design some of the heat from the fumes gasses is reclaimed and can be used to heat the incoming air to increase the efficiency of the micro turbine.
Micro turbine Efficiency
Unrecuperated ( simple-cycle ) 15 %
Recuperated 20-30 %
With Heat Recovery up to 85 %
Microturbines by Barney L. Capehart, PhD, CEM
College of Engineering, University of Florida
Last updated: 08-31-2010
hypertext transfer protocol: //www.wbdg.org/resources/microturbines.php
Research coevals systems under the undermentioned headers:
( a ) Essential differences between a Distributed Generation system and a Central Generation system.
In a cardinal coevals system electricity is chiefly produced at big coevals installations and shipped though the transmittal and distribution grids to the terminal consumers.
In a distributed coevals system electricity is connected straight to the distribution grid or produced following to its point of usage. Typically be described as small-scale electricity coevals.
( B ) The term “ Islanding ” and what jeopardies does it show for a distributed generator.
Islanding is the term given to depict a status where a distributed coevals generator continues to present power to a location even though the supply from the electricity provider has been disconnected therefore doing that location an “ island ” with power surrounded by a “ sea ” of unpowered consumers.
The chief jeopardy associated with islanding is that workers may presume that as there is no power coming from the distribution grid that the location is offline and this premise may expose the workers to possible electric daze jeopardies. For this ground, distributed generators must be able to observe islanding and instantly halt bring forthing power ; this is referred to as anti-islanding.
( degree Celsius ) The term “ Weak Grid ” and province possible impact on operation of air current generators.
Many air current farms are geographically distant and are connected to comparatively weak transmittal systems besides called a weak grid. The presence of air current farms in such weak systems raises serious concerns about the system stableness. Some of the most important challenges for air current coevals installations on such grids are voltage control, reactive power direction, dynamic power-swing stableness, and behaviour following perturbations in the power grid.
( vitamin D ) Draw a block diagram demoing the equipment necessary to command the synchronization
of a Wind Generator on the grid. Indicate typical electromotive forces at which the generator
operates and besides typical electromotive forces at the Grid interface in Ireland.