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1.1 Introduction
Given the current energy crisis and increasing need for sustainable energy. I endeavor to create a cost effective, small-scale electrical generator which could be used to power consumer electronics. Solar energy has proven its worth as an alternative energy source because it is low-impact and emission free. It has been implemented with much success for power grids with hundreds of acres of enormous solar concentrations. In the small-scale, solar energy has been harvested through the use of photovoltaic (PV) panels and have been used to power anything from an iPod to a residential home [1] .
Although PV systems are considered part of the green energy revolution, materials utilized for it construction (like silicon) are extremely dangerous to the environment and much care must be taken to ensure that they are recycled properly. PV cells also only utilize the energy stored in specific wavelengths of light and therefore have an approximate efficiency between 14-19%. Sunlight, however, produces immense amounts of heat which only serves to heat up the surface of the solar cell. Although there are some PV cells that have reached efficiency levels over 40% (world record is 41.6%), they are enormously complex and expensive.

Cell phones have become an extremely popular device in the entire world and it is easy to say they are part of our daily lives. In the year 2010 there was an estimate of over 4.6 billion cell phones worldwide and the number has been growing by more than a billion ever since; this translates to more than half the world’s population. Both the developed and the developing world countries are buying more cell phones, but it is in developing countries where the cell phone growth stays the strongest. However, cell phones need electric sources to charge their batteries in order to work, but there are people in developing and third world countries that find it hard to access electric sources. For example, one resident of a village in Tanzania describes how he takes all seven of the village‘s mobiles down to a nearby town with electricity to charge all seven mobiles. Obviously, this is quite different than what we see in the United States or other developed countries. Their inability to access a centralized power grid is due to either or the combinations of two things; the cost of constructing transmission lines to their homes, or the inability to construct transmission lines due to their location.In an attempt to provide an alternative means of charging to those unfortunate areas in third world and developing countries, a solar powered multiple cellphones charging booth is to be designed and constructed in this project. However, the focus of this project is specifically to design and construct a multiple cell phones charger powered by solar energy.

Solar power is the practical add-on to the existing sources of energy. It effectively supplements the current sources of energy. With intelligent designs, the solar cells can be integrated into the final consumer electronic or portable devices. This reduces the dependence of recharging these with the electricity, thus making this ideal choice for the locations where electricity may not be actually available. The solar panels are costly today but their costs are coming down to affordable levels. Also many a times the government aids are available especially for the remote areas [4] .
With the solar panels being available in various form factors, a range of consumer electronic devices making use of the solar panels are making entry into the market place and it is expected that this trend would continue in the future. As of now there are speakers, earphones, calculators and other small power consuming devices already available. The trend is to integrate the solar power in the small form factor that enhances the battery life and acts as an additional source of energy to supplement the battery power from other sources. As the efficiency of the solar panels and conversion would become better, a lesser area would be able to generate more energy and
eventually the solar charging may become the sole energy source in many consumer devices.

1.2 Aim and Objectives

The aim of this project is to design and construct a working solar powered multiple cell phones charging booth to charge a number of cell phones simultaneously.
The objectives are as follows:
i. To design a working solar charger circuit for the project.
ii. To arrange and solder the component according to the design circuit.
iii. To connect the solar charger circuit with the solar panel.
iv. To construct a well packaged housing for the project.
v. To test and evaluate the performance of the developed device.

1.3 Scope of the Project

The proposed project will be capable of charging 10 phones simultaneously.

1.4 Problem Statement

According to the International Energy Agency, in 2011 1.4 billion people around the world did not have access to electricity [3] . And most users of cell phone in rural areas find difficulty in charging their cell phones. Therefore this project is to overcome the problem and also to create a means of charging a number of cell phones simultaneously. The Solar cell phone charging booth runs solely on produced sustainable energy in the form of DC power. The project has no dependence on the power grid.

The system consists of Solar PV, a solar charge controller, USB port and cell phone battery. A solar charger is similar to the voltage regulator. It regulates the voltage and current that is coming from the solar panels and going to the battery [5] . My goal by the end of the semester is to have a product that provides safe, cheap, clean and reliable energy to under-privileged families, villages and areas of developing and third world countries.

1.5 Justification of the Project

Solar power is one of the widely available energy sources. It has been in focus worldwide and solar installations of capacities in megawatts order are reality today. The efficiency of the solar panels remains low even today and the requirement of ensuring highest efficiency outside the panel remains stringent. Thanks to this, several techniques have been deployed to harness the maximum energy, Maximum Power point tracking being one of them.
Consumer electronic devices typically need few watts and many of these devices/gadgets now use USB port for charging. The standardization to USB voltage presents opportunity to design more and more chargers that conform to this form factor and voltage requirements.Solar charging is slow and this presents another challenge of keeping the devices in the sunlight (daytime). This may not be always practical and hence there is a need to have battery backup solutions.
Solar USB chargers can be used to charge gadgets like mobiles, PMP, PDA’s and even e-book readers or any other devices that use a USB or mini USB interface. It can be especially useful during
• Conferences/All Day Meetings
• Camping trip /Picnic
• Power outages
• Natural disasters
• No access to power outlet
At present all the gadgets are charged typically with a 5V to 5.5V source (current could vary depending upon the capacity of the battery, typically limited to 500mA). Hence for charging the voltage provided to the gadgets should not be higher than the above mentioned voltage range.

1.6 Thesis Outline

This thesis consists of five chapters. Chapter One will discuss about the overview of the project, objective of the project, project scope and problem statement.
Chapter Two contains a detail description of the original setup. It explains about the concept used and the components that involved in the project.
Chapter Three includes the original designed circuit and its components. Also a complete analysis to the presented design will be given.
Chapter Four shows the experimental work and the practical testing results to the constructed circuit will be explained.
The last Chapter contains the detail description about conclusion and recommendation. It concludes the whole project and gives a future recommendation to make this project perfect.Also it explains the important merit of the project.

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