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APSC 100 213B Solar Powered Laptop
- Jacqueline Pageau
- Cole De Sa
- Brad Jordan
- Kieran Potter
- Jake Garvey
Design of a Solar Powered Laptop
APSC-100 Project Proposal
Group Number: 213B
Jacqueline Pageau 5998198
Cole De Sa
Brad Jordan Report Prepared For Faculty Sponsor: Dr. Pearse
Project Manager: Nabeil
Community Sponsor: Dr. Pearse
Date Submitted: October 16, 2009
One Laptop per Child is a non-profit organization that provides children in some of the most remote areas on earth with opportunities to meet their potentials by exposing them to a world of ideas. The organization has produced a laptop known as the XO laptop to be distributed to children in developing countries. Unfortunately the majority of these children have no access to electricity in order to power the laptops. Solar energy has thus been proposed as a convenient alternative to energy that requires a great deal of infrastructure. The problem remains as to how to effectively and inexpensively power the laptops using solar energy.
The proposal requires a solution to the stated problem. The project requires that a successful prototype be constructed and presented for evaluation.
A general understanding of the XO laptop itself and the science of solar panels is needed in order to find an optimal design for presentation. Through research, various necessary criteria for the solar system accompanying the XO laptop are evident. The criteria for the solar panels are portability, durability, low cost, and sufficient energy output.
The prototype is still to be determined, although much research has gone into the decision of what solar panels will be used and the connection of the panel to the laptop.
Table of Contents
Table of Contents 3
2.0 Problem Formulation 5
3.0 Design Considerations 6
4.0 How Solar Panels Work 8
5.0 Future Considerations 9
5.0 Economic Analysis 11
6.0 Conclusions 12
7.0 References 13
The XO laptop is an educational tool built to be distributed to poor children in underdeveloped nations around the world. As a result, it incorporates low cost, durable, and user friendly design elements in order serve as a practical tool for educating people in remote areas with little infrastructure and little money. One of its key design features is its low power draw: the XO laptop consumes less than 2 Watts of power(1). Despite this, it can be difficult for children to power the laptop due limited access to electricity. One of the possible solutions to the problem of charging the XO laptop in areas with limited access to electricity is solar charging option. Any design for a solar panel to charge the XO laptop must take into account the same criteria that the XO laptop itself does: it must be very inexpensive, durable, easy to use, and still fulfill the function of charging the XO laptop in a reasonable amount of time. Previous designs planning to power the XO laptop with solar panels are generally too expensive, not durable enough for the conditions, or do not provide enough power to charge the XO laptop quickly enough. Despite being impractical, many of these designs contained potentially useful elements. For example, one 10 watt at 21 volt photovoltaic cell design, despite being far too expensive for the XO laptop, incorporated a folding design in order to improve durability and practicality(2). The design for the XO laptop solar charging option will be developed through further analysis of previous designs as well as research and analysis into the advantages and disadvantages of various types of solar panels and designs. A design will be chosen which is able to charge the XO laptop in a reasonable amount of time while minimizing cost and being durable enough to withstand the elements and use by children. The design will also be easy to assemble with instructions that must be understood by people all over the world.
The problem of finding a solar power solution for the XO laptop considers the most effective way to power the laptop using solar energy while minimizing cost, and maximizing practicality. The task involves the consideration of the materials to be used, the simplicity of the design, the practicality and cost, and the development of user-friendly instructions to accompany the product. The main purpose is to design a system that outperforms previous prototypes while keeping the organization’s main principles in mind.
There are numerous issues to be addressed when deciding on the design of the solar panel system. To begin, the XO is a durable, kid-friendly product, and as such, the solar panel accompanying it must also be a durable learning tool. Due to the fact that the product’s targeted audience is youth in developing countries, the laptop must be able to withstand any accidental abuse, such as being dropped. Since solar cells can be very fragile, finding a suitable way to protect the solar panels is an important task and may be difficult with the given budget. Next, the solar system must be compact and portable, similarly to the laptop itself. This is once again in response to the known targeted audience. Small children are unable to carry heavy loads and thus a lightweight product is necessary. Furthermore, the XO laptop contains an unusual plug. A suitable plug must therefore be found or fabricated. If a supplier for the plug can be found, the plug must be inexpensive and readily available. Finally, the instructions, which will accompany the XO laptop and its counterparts, will be presented along with the prototype and should be simple and universally understood. People from various backgrounds will read these instructions and they must therefore be communicable to people who speak a wide range of languages. The problems outlined above are to be solved with a budget of $80 and within a period of 12 weeks. The low budget and short time period will make the completion of the task challenging, although the formulation of this problem will help in the development of a timeline and the purchase of an inexpensive solar system. The formulation of the issues to be faced is thus a necessary step in finding a suitable solar solution for the XO laptop.
There are a large number of factors to be considered when deciding upon a design for the solar panel to accompany the XO laptop. Such considerations include the portability of the laptop, its durability, the cost of the solar system, the style and creative aspect of the system, the XO’s energy needs and thus the power output of the solar panel, and finally the XO’s unusual plug.
To begin, many designs involving a case were considered for the solar panels themselves since this would keep the panel safe from harm, such as being dropped or kicked. An alternative to this option is the choice of a thin-film, flexible solar panel to be used to power the laptop. These panels can be rolled and are also very lightweight. Thin film panels are not rigid, and a case is therefore unnecessary. Eliminating this need reduces cost and produces a lighter result. Furthermore, cost is an important factor to be taken into consideration when choosing a suitable design. The budget for the prototype is $80.00, and the XO laptop itself is known as the “$100.00 laptop”. The design must therefore evidently be extremely inexpensive, with the panel itself costing no more than $50.00. There are a few options that would decrease the cost of the solar panel, such as buying many lower-wattage solar cells and wiring them in series to produce the necessary power output, and manually encapsulating the solar panels. In deciding to manually encapsulate the solar panels to be used, there is a high risk in terms of the improper choice of materials used, or a fragile and unstable end product. Another design consideration is the overall appearance of the solar panel. Many people associate certain objects with various brands. The XO laptop itself has a specific appearance and in turn the solar system accompanying the laptop should follow suit. A simple and clean design will be chosen for the prototype, and as such will mimic the XO laptop. Moreover, the XO is able to run off a mere 2 watts of power, although a higher wattage is necessary for the solar system in order to ensure the laptop is able to run and charge properly. An energy output of between 10 to 20 watts is thus desired. This could either be achieved with a single solar panel that provides the necessary energy output, or with numerous lower watt solar cells wired together in series that as a whole provide 10 to 20 watts of power. Finally, the XO plug is a non-standard plug. Finding the proper plug for the laptop and a supplier that offers the plugs at a low cost is fairly difficult. For this reason, constructing the plug becomes an option worth considering. In all, there are many factors to be considered when deciding on a suitable solar system design to power the XO laptop.
How Solar Panels Work
Each solar panel, or photovoltaic cell, is composed silicon wafers that are precisely cut to less than a centimeter in diameter. Silicon is used because of the fact that it has four of a possible eight valence electrons and so when two silicon atoms bond, the result has no charge. There are also more atomic reasons for the use of silicon but this is the main reason. The top of the wafer, which will be exposed to sunlight, is coated in phosphorus and then heated so as to diffuse the phosphorus into the silicon. As a result, when the elements bond, they complete the valence shell of eight electrons and they have one left over; therefore the side is negatively charged. Next, the wafer is covered with a very thin conductive grid. Following that, the bottom of the wafer is treated similarly to the top but with boron, which has three valence electrons. As a result, when the elements bond, there is one space remaining in the valence shell and so the bottom is considered positively charged. Next, the top of the wafer is exposed to sunlight and the photons from the sun give the extra electron enough energy to detach from the plate. As soon as the electron is detached, it is attracted to the positively charged molecules below. As the electron is drawn downwards, it must first cross the wires which produces an electrical current.
During the design and construction of the project, it is crucial to remember that any protective material that is used to cover the panel must enable photons to reach the cells. That being said, the nature of non-amorphous solar panels is to be quite brittle and fragile therefore the protection offered by the covering material can not be compromised.
Another characteristic of solar panels that must be considered during the design of the model is that there is a high possibility of over-heating. As a result, it could be beneficial for the design to include either a fan underneath the solar panel or an open channel for fresh air to pass through.
The main consideration for this project is the selection of the optimum solar panel that meets the specification requirements for the XO-1 Laptop with regard to compatibility. Additionally, the selected solar panel must be economically viable, to maintain the affordability, and consequently, the vision of the One Laptop Per Child project
The project plan outline is identified in Figure 1, with the main focus being the selection of the optimum solar panel for this project. It is intended that a commercial product be selected to interface with the XO Laptop, whereby all tolerances and specification requirements with respect to power, voltage, and amperage are adhered to.
Additional research is to be conducted to acquire basic electronics knowledge, which is necessary to facilitate the build phase. Research will also be carried out to identify possible solutions for effective connection of the solar panel to the laptop. Upon completion of the build phase of the prototype, testing is to be conducted to determine the efficiency of the power and solar performance, and if required re-design may then be addressed. Final design improvements will then be implemented to produce the optimum project design, including project documentation.
It is imperative that the final design allow for ease of manufacturing, as the intent is that documentation be provided to developing countries so as to facilitate local manufacturing of the solar solution. It has been identified that the documentation will utilize graphics rather than verbal communication, for ease of communicating assembly details in regions where the English language may not be utilized extensively.
Week 1 2 3 4 5 6 7 8 9 10 11 12
Project Team Information
Clinic 3 Workshop
Identify Project Objectives
Identify Project Constraints
Identify Specification Requirements
Research Basic Solar Technology
Analyze Previous Designs
Research Solar Panel Types
Submit Written Proposal
Select Optimum Solar Panel Type
Research Solar Panels Within Type
Select Solar Panel That Meets Specifications
Order Solar Panel
Acquire Basic Electronics Knowledge
Research Manufacturing Process
Order Connector Parts
Research Protective Case Options
Analyze Prototype Efficiency of Power
Planned Figure 1. XO Solar Laptop Group 213B Project Plan
5.0 Economic Analysis The solar panels are a cheap and inexpensive way to provide a learning experience for young children in underdeveloped countries. These laptops being able to be so cheap allows them to bought by government associations in bulk since they are so cheap providing many more children with new technology to give them a learning experience of a life time. Most kids in underdeveloped countries would never get to see a laptop in their lifetime or even a computer because in most places they do not have the advantage we usually take for granted which is electricity. We are providing them with an alternate power source for such an item is an amazing thing opening up many windows for the youth in underdeveloped countries. These kids will now be able to start typing learning how to spell and all the simple things a school can teach you all from this laptop. They can advance their education without going to school for those unfortunate enough who are not able to attend they can play on their laptops an connect to fiends laptops are start their own little network sharing information skills and will be able to practice basic typing skills. This product will be almost indestructible so once built it can power a laptop for life, allowing for a lower cost to the earth. We are removing a very small amount of material from the earth to provide and endless amount of happiness to children around the world. This project also helps the earth as we are taking in solar energy instead of the popular electricity. This allows also for a bigger market reaching to earth lovers who try to save the earth and do earth friendly items. This item may not be the best for those laptops but will definitely be the cheapest. This overall is an amazing thing taking 50 to 80 dollars worth out of the ground to provide one or two children with endless happiness and a major tool to education.
In order to solve the problem of providing a solar charging option for the XO laptop, a photovoltaic system will be designed to provide power for the XO laptop while being durable, easy to assemble, and inexpensive. In order to select the optimal design, further research will be done on previous designs and specific types of solar panels in order to find the most effective and inexpensive option. The solar panel will be selected approximately by the end of week six, and will then be ordered. Once all of the parts have arrived, a prototype will be developed and improved upon before a final design is obtained.
(1) XO Solar: OLPC”. The OLPC Wiki. February 2009.
<http://wiki.laptop.org/go/XO_Solar> (2) “Product News: OLPC”. The OLPC Wiki. February 2009.