Executive Summary: 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.
Design of a Solar Powered Laptop
APSC-100 Project Proposal
Group Number: 213B
Jacqueline Pageau 5998198
Cole De Sa
Date Submitted: October 16, 2009
To visit The XO Solar Solution project click here
Honesty Statement[edit | edit source]
"We do hereby verify that this written report is our own individual work and contains our own original ideas, concepts, and designs. No portion of this report has been copied in whole or in part from another source, with the possible exception of properly referenced material."
Introduction[edit | edit source]
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.
Problem Formulation[edit | edit source]
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.
Design Plan[edit | edit source]
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. 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. Furthermore, the overall appearance of the prototype should be taken into consideration. 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. 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 keeping these considerations in mind, and once a solar panel is selected, the group plans on finalizing the design of a case to hold the panel and the corresponding plug.
How Solar Panels Work[edit | edit source]
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.
Future Considerations[edit | edit source]
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.
Economic Analysis[edit | edit source]
One of the most important factors to be considered in the project is the identifying of a solar panel that meets the financial limitations identified in the problem. In order to meet our limited budget, a solar panel costing under $50 would be ideal. This would provide the group with an additional $30 remaining for extra materials needed for the project. In reality, a solar panel that would meet the specifications of this project and provide a workable solution is well above this price range. This is unrealistic for various reasons. First of all, the fact that the group is attempting to purchase a single solar panel as oppose to doing so in mass production results in a larger cost per unit. As seen in figure 2, costs are significantly reduced when purchasing a higher wattage panel as well as when purchasing in large quantities (3). Shipping costs are also an issue since many of the inexpensive panels are found outside of Canada and incur high shipping costs. It is evidently not economically viable to purchase a solar panel in which the shipping costs account for up to 30% of the cost of the panel itself. Moreover, the group is in need of a 10-20 watt panel. The cost per watt such a solar panel is larger than that of larger models. Clearly, one of the greater challenges will be finding a solar panel that meets the limiting requirements of the project.
The cost of construction and mass production of the final product could be significantly less expensive than the cost of the group's prototype. The cost of each solar panel, when in mass production, will be much lower than that of the single panel purchased by the group. Ideally, any additional costs will be limited by the assembly of the product locally. This will decrease total construction and shipping costs as well as bolster the local economy by creating jobs and income.
Brand Watt Min.
Quantity* US$/Unit US$/
EPV Solar 50 368 $92.50 $1.85
REC 220 30 $533.97 $2.43
BP Solar 175 60 $424.97 $2.43
BP Solar 190 60 $460.97 $2.43
REC 210 30 $512.48 $2.44
BP Solar 175 40 $447.97 $2.56
BrightWatts 140 20 $378.00 $2.70
BP Solar 190 20 $568.00 $2.99
Evergreen 205 28 $738.00 $3.60
Sharp 198 1 $777.06 $3.92
Kyocera 135 2 $625.00 $4.63
Mitsubishi 125 1 $595.00 $4.76
Figure 2: Solar Panel Cost Comparison
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.
(2) "Product News: OLPC". The OLPC Wiki. February 2009.
(3) "Solar Panels". EcoBusiness Links. November 13th 2008. <http://web.archive.org/web/20120626011055/http://www.ecobusinesslinks.com:80/solar_panels.htm>
10.0 Individual Contributions
In terms of individual contribution, Kieran completed the introduction and conclusion in this report, carried out research mostly concerning previous designs and produced the slide entitled "Previous Designs" in the oral presentation. Kieran also presented the slide "Design Considerations".
Jacqueline completed the design plan and problem formulation sections in this report as well as carried out research concerning various solar panel options for the prototype. She also completed and presented the research slide as well as the XO specifications slide. Jacqueline also completed many progress reports for the group.
Cole De Sa
Cole completed the future considerations section including the Gantt chart in this report. Cole also carried out research concerning the current specifications of the XO laptop. As for the oral presentation, Cole completed and presented the slides entitled "Next Steps" and "How You Can Help". She also assembled and submitted Team Assignment 1 for the group.
Jake completed the sections on materials and how solar panels work in this report. Jake also carried out research concerning different types of panels, specifically mono- and poly-crystalline panels. HE completed and presented the slides entitled "How Solar Panels Work" and "Our Goal". Jake also assembled and submitted Team Assignment 2.
Brad assembled and submitted the initial submission of the written proposal report. He completed the slide on design considerations for the oral presentation and carried out research concerning the wiring of the XO laptop.