Learning the different features of a solar cell Essay Example

Learning the different features of a solar cell

School of Engineering

ENS4445-Sustainability and Renewable Energy

(LAB REPORT)

Different Features of a solar cell

Submitted by: Yousef AL-Ghannam -10184469

Done For: Dr.Octavian Bass

Abstract

Increase in demand for electrical energy at all levels of production has triggered research and exploration in other sources of energy. Majorly, solar PV has become the centre of interest in this research since it can be connected to the grid for commercial supply. For instance, many solar power farms and domestic solar PV modules have been installed across the globe that uses the solar power. Solar PV power has over time gained more popularity in generating green energy. Main focus has been centred on reduction of greenhouse gases (GHGs), and generating more electricity to meet the global demand that has increased with the increase in population growth. Analysing the components of a solar cell furnishes the researchers with relevant information that is useful in determining the quality, efficiency, rate of energy conversion and the best time and angle of solar irradiation.

Table of Contents

2Abstract

4Table of figures

5Nomenclature

6Introduction 1.

1.2. Electricity Generation Concept 6

7General questions 2.

9Experiment part 1 3.

Objectives 9

Equipment 9

Procedure 10

13Experiment part 2 4.

Objective 13

Experimental components 13

18Discussion 4.

Experiment 1: manual mode 19

Experiment 2: auto mode 20

22Conclusion 5.

25References

Table of figures

10Figure 1: Shorting the positive and the negative at the start of the experiment

11Figure 2: adjusting the current value

15Figure 3: automatic switching a cover sheet between the lamp and the solar panel

150Figure 4: power characteristic curve as the solar angle approaches 90

16Figure 5: voltage/current characteristic

20Figure 6: Angle 90ᵒ manual mode

21Figure 7: Auto mode characteristic

22Figure 8: characteristic for solar plates connected in series

19Table 1: Manual mode Angle 90ᵒ for single solar module

20Table 2: Auto mode

22Table 4: Two solar plates connected in series

Nomenclature

AC alternating current

DC direct current

mA milliampere

mV millivoltage

LT low transmission

  1. Introduction

Scientists have been committed to research on alternative energy and capture this ensure to substitute the CO2 emitting power generating options such like coal, and fossil fuel power plants. Majorly, alternative energy is focused on basis of reducing the greenhouse gases from the ambient and meets the global energy demand. However, solar power is the most abundant source of alternative energy that been underutilized for power generation. Moreover, compared to other sources of alternative energy solar power has very low maintenance expenses as well low fatalities in the area of installation. In fact, you can install solar modules in buildings and ensure that there are no fatalities or danger involved from the area they have been installed. Other alternative sources of renewable wind pose great danger to flying birds and planes. Therefore, more research on solar power is necessary to capture more information that most researchers will require in their quest to save the world from pollution (Augustin, 2012). This lab report has shown electric generation using the solar panel. In addition, this report explain how to have different positions of the lamp and angle of irradiation affect the amount of electric voltage and current generated using solar panel.

1.2. Electricity Generation Concept

An electrical device that converts light energy to useful electrical energy is known as Solar cell. Solar cell harnesses light energy from the sun to useful electricity using photovoltaic effect. It does so by using the incident photons of energy from the sun radiation to directly generate electricity. During a sunny day, crystalline solar cells receive direct sun and are heated, which makes atoms to vibrate and move faster, thereby creating an in built voltage. These are atoms are controlled by kinetic energy developed by the electrons and holes within the solar cell layers.

Solar cells are designed such that when heated by the sun’s radiation they consume more solar energy and create higher temperatures than in the ambient air. Normally, the standard solar temperature when the atmospheric temperature is Learning the different features of a solar cell 1 and the sun’s isolation isLearning the different features of a solar cell 2, it is betweenLearning the different features of a solar cell 3
(Lorenzo, 1994).

Different material types are used in building Solar cells, which demonstrate different efficiencies of the solar cell. These materials may include thermodynamic efficiency, which have efficiency based on charge carrier, conductive efficiency and reflectance efficiency. Usually, silicon solar cells have the best features when used in developing effective solar cells.

  1. General questions

What is solar energy?

Sun radiation reaching the earth is at varying intensity depending on the location and environmental factors in the region. Therefore, the radiant energy that comes from light and heat emitted by the sun is the solar energy. Solar power is used in a variety of ways such like thermal heating, passive solar, and solar electricity. However, the most utilized sources of electricity are photovoltaic and solar thermal.

The meaning of solar electricity and what does photovoltaic

The way of approach and source of energy defines the type of electricity. Therefore, solar electricity is electricity generated when solar cells in a solar panel trap photons from sun radiation and create electric charges (Castellano, 2010). Additionally, solar electricity uses photovoltaic technology from tapping sun’s radiation to generate electrical energy from light and light from the sun.

What is needed to feed solar electricity into the mains power grid?

Solar cells contained in the solar panels convert the solar energy tapped from the sun to DC voltage that can be store in DC batteries. Using AC inverters, the tapped and stored DC voltage from the sun is converted to AC, which is then connected to LT panel then to AC distribution box then AC energy meter to the main distribution board for stepping up for transmission to the mains power grid (Stephen, 2012).

How is a solar cell assembled?

Normally, a solar cell contains different layers made of different materials including a glass cover, front contact grid, anti-reflective coating, N-type silicon, P-type silicon, and back contact. However, these layers can either be connected in series or in parallel depending on the amount of energy requirements and use.

Advantages of solar electricity?

Main focus when investing in solar electricity is to lower pollution from greenhouse gases. Secondly, using solar power there are reduced electricity bills and it has a payback period after installation of the system

In what areas does solar electricity make the most sense?

Solar electricity will depend on certain factors including presence of sun hours, and absence of clouds in the sky. Therefore, solar electricity will generally make sense in area that have enough solar radiation and no clouds.

What are the disadvantages of solar cells?

Solar cells convert solar energy to DC power. Therefore, for you to get AC power you must user an inverter to convert the DC power from the solar panel. Moreover, solar cells must use the available solar radiation to generate electricity, thus, in low solar times the conversion rate is insignificant and hence no generation (Greg P. S., 2002). Finally, solar cells cannot generate electricity during the night since there is no solar radiation at night. Therefore, it is a must to have a storage facility to store the generated DC voltage for use during the periods of low sun.

Who is credited as the inventor of the solar cell?

Russell Ohl invented the silicon solar cell in 1941. Earlier solar cells, had energy lower conversion efficiencies that ranged lower than one percent.

When was the first solar cell created?

Bell laboratories built the first practical solar cell in 1954, led by Daryl chapin using silicon p-n junction which was diffused to reach 6 % efficiency.

The component that converts direct current into alternating current is known as an inverter.

What is built into an inverter for PV systems so that the maximum power of solar cells is achieved?

Basically, to achieve maximum power in solar cells, a DC-DC convertor is needed for this operation.

What types of solar cells are there? Which have the highest degree of efficiency? Which are the most affordable?

Generally, solar cells are made of four kinds including Signal Junction and Multijunction Concentration and GaAs, Crystalline Si Cells, and Thin Film Technologies, or Emerging PV. Single junction GaAs and Multijunction concentrators have the highest efficiencies (Jenny, 2003). However, Thin Film have low cost and hence affordable thus, it is popular for use homes but for people who have not enough space in their homes crystalline cells since they have higher conversion efficiencies and are more reliable.

  1. Experiment part 1

Objectives

This experiment is set to study the behavior of solar cells in relation to angle of radiance and changing current value manually by choosing manual mode. Additionally, the experiment determines the characteristics of voltage and current in solar power generation with varying angles of radiance.

Equipment

  • USB monitor board

  • PC Software

  • Solar panel

Procedure

  1. The two components were connected to the USB monitor board.

Firstly, the solar panel was connected facing the lamp radiation. Electricity values were to be represented on the PC screen using the Heliocentric Energies system GmbH – Clean Energy Trainer (PC software). Then the lamp was adjusted to about 50 cm to the panel to generate radiation.

Learning the different features of a solar cell 4

  1. In the USB monitor board we connected positive electrode to short the negative and switched on the lamp at the start of the experiment.

Learning the different features of a solar cell 5

Figure 1: Shorting the positive and the negative at the start of the experiment

  1. We adjusted the panel to about 900 after it had gained enough temperature to heat up. Manually, from the PC software we adjusted the current value, which was set between 0 – 200 mA while observing the output voltage value in the PC software.

Learning the different features of a solar cell 6

Figure 2: adjusting the current value

  1. We adjusted the angle of radiance to the solar panel and recorded the voltage output.

Question about the Experiments

How do the measurements behave depending on the tilt angle?

Depending on the tilt angle, radiation to the solar panel varies as the tilt angle changes. Moreover, as the tilt angle reduces from 900 towards 00, the amount of radiation reduces drastically lowering the output voltage. Consequently, as the tilt angle shifts from 00 towards 900 the output voltage increases.

How do the measurements behave depending on the intensity of the illumination?

Generally, output voltage for solar panels depends on the light intensity. When the light intensity increases voltage output for a solar panel increases, consequently, a decrease in light intensity leads to a decrease in voltage output.

What general statements can be made about the measurements with a continuously increasing intensity of illumination?

Generally, as the sunlight illumination increases to the solar panel, the output voltage increases drastically. Additionally, continuously increasing the illumination raises the voltage measurements until the maximum level at which the solar panel cannot generate higher than the set voltage rating.

What factors does the angle of irradiation depend on?

Generally, atmospheric elevation, earth’s magnetic field, earth rotation, length of path of radiation of the earth and atmospheric air mass are some of the characters that angle of irradiation depend on.

What contributes to shadowing?

When solar cells are connected in series, they tend to lower their voltage output this effect cause reverse bias on the cell. As a result series connections of the solar cells contribute to shadowing.

Comprehension questions about the Experiment

We only consider voltage values in the experiments. Why is the current value always the same?

Basically, when solar cells convert the solar energy from the sun photons are changed to electrons which are transmitted as a change in potential difference between the p and n junctions of a solar cell. Therefore, in solar cell experiment it is the potential difference between the p and n junction that varies while the current remain constant.

Is the generation rate of electricity equal daily all the year? Why or why not? What is the possible solution for this?

Sun hours are not constant throughout the year. Therefore, some days have low sun intensity and others have maximum sun intensity. This is attributable to cloudy days and nights when there is no sunlight. Thus, there is a need to have a battery bank to store the generated solar energy during solar days for use when there is no sun and during the nights.

What factor dose the ideal current yield depends on?

Current yield in a solar cell is always related to the p-n junction and it depends on the base collector voltage from the junction depending on the charge carrier.

What physical size can the current and voltage values of the solar module reach?

Solar modules produce a maximum power approx. 1.7 V and 145 mA when used with one 75 W lamp.

  1. Experiment part 2

Objective

This experiment is studies the voltage behavior with the varying current and angle of radiance.

Experimental components

  • Solar cell

  • USB data monitor

Procedure

  1. The connection of the components is similar to the previous connection but current values were applied automatically.

Learning the different features of a solar cell 7

  1. The radiation angle in this experiment is to start at 900 since we changed to automatic mode. We started the system at automatic mode and waited for the system to stop for a current improvement.

Learning the different features of a solar cell 8

  1. We put cover sheet between the solar panel and the lamp. To determine the performance of the solar panel with less radiation.

Learning the different features of a solar cell 9

Figure 3: automatic switching a cover sheet between the lamp and the solar panel

Question about the Experiments

When does the solar module provide maximum power?

Solar radiation depends on amount of intensity, angle of irradiance and shadow cover. Therefore, for maximum power generation, a solar module will require to have continuous solar radiation, direct solar radiation at angle near 900 to the solar source.

Learning the different features of a solar cell 10

Figure 4: power characteristic curve as the solar angle approaches 900

When does the solar module provide maximum power with a low intensity of illumination?

At approximately, 1.7 V and 70 mA and using one 75 W lamp and a film covering the solar module has a maximum power. In addition MPP has shifted and the angle radiation is approaching 900 to the mirror of the solar panel, the solar module increases the amount of power generated by the solar panel regardless of amount of intensity of illumination (Lorenzo 1994).

Learning the different features of a solar cell 11

Figure 5: voltage/current characteristic

What is a characteristic curve?

A graphical representation of two physical independent components is what is known as characteristic curve.

How is the maximum power point of the solar module calculated?

Using the characteristic curve, MPP is determined by determining the product of the measured voltage and current from the solar cells. Or, for a current/voltage curve, the rectangle that forms the largest area is the maximum power.

Has the MPP (Maximum Power Point) of the solar cell changed with a lower intensity of illumination? Can a generalization be made?

Yes. It can be generalized that lowering illumination intensity lowers the voltage thus charging the MMP.

Which graphic visualization is best suited for reading the MPP?

The characteristic curve.

Is the MPP constant? What does the MPP depends on?

MPP is not constant and It depends majorly on the illumination intensity

Comprehension questions about the Experiment

Does a solar cell behave similarly to other power sources, Such as batteries, when connected in a series and in parallel?

No, connecting the solar cells in series and parallel is not the same. When solar cells are connected in series cause shadowing in the solar cells (Stephen, 2012).

If one solar cell within a series of connected solar cells is destroyed, is a current flow interrupted?

Yes, destroying one cell terminates the current transfer and continuation to the consequent cell.

How could the problem from the Previous question be solved?

Such a problem can be solved using a bypass diode.

Is the efficiency of solar cell comparable with that of a diesel engine?

No, because diesel engine has an efficiency of 45 %. This is attributable to the fact that solar cell uses sun a source of energy while diesel engine uses biofuel for combustion.

How does a characteristics curve in the current/voltage characteristics curve behave if the resistance is doubled?

Doubling the resistance has no effect on the characteristic curve and it remains the same.

Known or estimated? How high is the annual energy output KWh of a photovoltaic system for an average single family home?

This is basically 3000 to 4000 kWh .

How many of the solar models used in the experiment are required to operate the following devices?

Number of solar modules

Computer

Car radio

Mobile Phone

Hair dryer

Light bulb

Can a light bulb be damaged if 20 more modules are connected in parallel than the number of modules calculated above?

No, adding modules supply an equivalent amount of output voltage, which is equitable to the bulbs’ rating.

  1. Discussion

In general, solar panel performance depends on the orientation to the direction of the sun. Thus, table 1 is an indication of the results for a solar positioned at an angle of 90ᵒ to the suns direction. From the results, when varying the current manually from the PC it varies the output voltage from the solar maintaining the angle of irradiance. Further this is illustrated in figure 4, a graph, when varying the current manually, voltage drops as the current increases. This implies that is a higher at which the panel develops resistance when the current is rose thus lowering the voltage output.

Experiment 1: manual mode

Basically, voltage depends on the rate of solar radiation, thus on varying the current in the manual mode affects both the output voltage and current from the solar PV module. In addition, maintaining the solar irradiation angle at 900 maintains the solar radiation constant. However, as the temperature increases on the module, the resultant voltage output decreases (table 1).

Table 1: Manual mode Angle 90ᵒ for single solar module

voltage (mV)

0

0

Learning the different features of a solar cell 12

Figure 6: Angle 90ᵒ manual mode

Experiment 2: auto mode

On adjusting the PC software to auto mode, the rate at which the current varies is automatically set, thus creating an automatic change in the voltage output. As the current increases, voltage generated due to shadowing caused by the connecting solar plates in series. On varying the current automatically with a transparent medium to cover the panels and connecting the panels in series, eventually the panels generate zero voltage. This is attributable to the blockage of the radiation reaching the surface of the panel. This is as indicated in table 3 and figure 8, where the voltage generated ultimately changes to zero.

: Auto modeTable 2

0

0

Learning the different features of a solar cell 13

Figure 7: Auto mode characteristic

On arranging the panels in series the output voltage does change at a decreasing rate. Thus, it is clear that when solar panels are connected in series develop a higher rate of resistance compared to the panels when connected in parallel (table 4). The characteristic curve for the solar plates connected in parallel there is an inverse relation between the current and the voltage (figure 8).

Table 3: Two solar plates connected in series

Learning the different features of a solar cell 14

Figure 8: characteristic for solar plates connected in series

  1. Conclusion

The data from the two experiments indicates that solar power is always depended on other environmental factors as well positioning of the solar PV module. From the experiments above, Solar PV performance depends on the rate at which solar radiation reaches the solar panel. In addition, the output from the solar PV module relies on the angle of irradiance. As the irradiance angle decrease from 900 so does the voltage reduce. It is notable from the experiments that solar intensity in a greater way affects the out from the solar panel. Generally, varying the external features around the solar PV module will have a direct effect on the resultant output from the module.

References

Augustin, M., & Castaner, L., (2012). Solar Cells: Materials, Manufacture and Operation. New

York: Elsivier.

Castellano, R., (2010). Solar Panel Processing, Paris: Archives contemporariness.

Greg P. S., (2002). Optoelectronics of Solar Cells. Washington: SPIE Press

Jenny, N., (2003). The Physics of Solar Cells. New York: Imperial College Press.

John, P., (1999). From space to Earth: the story of solar electricity. New York: Earthscan.

Lorenzo, E., (1994), Engineering of Photovoltaic Systems: Solar Electricity, Paris: Progensa.

Stephen, F., (2012). Solar Cell Device Physics. New York: Elsivier.