Deployment Guide/Workbook
This is a workbook for estimating the cost of a large-scale deployment of One Laptop Per Child. It is a working document that reflects lessons learned from initial pilots and deployments. Additional ideas will be incorporated as we learn from each other.
The latest version is available in Microsoft Excel format: Deployment_Workbook.xls
Introduction
The One Laptop per Child (OLPC) Deployment Workbook contains six worksheets. There are two worksheets for use in planning: Country and School. The Country worksheet takes information about overall number of laptops and rough percentages of schools and provides a rough estimate of the costs. The School worksheet takes detailed information about a particular school and provides an estimate of the required infrastructure, power, and costs given different power scenarios.
These estimated costs depend on the accuracy of the system component costs specified in the Laptop Costs, Program Costs, and Other Costs worksheets. While the defaults provided are based on commercially available components, these must be updated to reflect current and local prices for these components before using this workbook to estimate costs.
How to use the workbook
- Download the workbook (see the top of this page)
- Determine local prices for items such as school servers, generators, wireless access points, wireless switches, the cost of running a Cat5 network cable or power cable for 30m in a typical school, and update the Other Costs worksheet.
- If estimating costs across the entire deployment, the Program Costs worksheet should also be updated.
- At this point, you can estimate costs across the entire deployment using the Country Expenses Estimate worksheet.
- If you want to see the estimated cost of a single school, and compare the costs of different methods of powering the laptops, use the Individual School Expenses Estimate worksheet.
Similar Workbooks
Similar spreadsheets are available from other sources. For example, the Global e-Schools and Communities Initiative has Total Cost of Ownership Tools which are more general and long-term.
Workbook Description
The workbook is a database of the cost (both in money and power) of system components, contained in the Laptop Costs, Other Costs, and Program Costs worksheets. The Country Expenses Estimate and School Expenses Estimate worksheets provide two methods of making expense estimates using that database. The Examples worksheet contains intermediate calculations used by the Country Expenses Estimate, and the Changes worksheet indicates what version of the workbook you have, and any recent changes.
Country Expenses Estimate
This worksheet calculates the estimated expenses for a one-time deployment in a country, estimating both the initial capital expenditure and the monthly technical operating expenses. It has two sections. The first contains information needed about the deployment, and the second shows the estimated costs of deployment.
To be filled by the Country
Total Number of Laptops
The total number of laptops, both to students and teachers, should be specified here.
Percentage of Laptops going where
This is a coarse description of the types of schools where the laptops will be deployed, grouped by size and source of power. Enter the percentage of laptops (not schools) which will be deployed to each group. Any remaining schools are assigned to the "large schools on the national grid" group.
Three sizes of schools are identified: those smaller than 50 students, those between 50 and 500 students, and those with more than 500 students. These groups were selected as the costs of a school are roughly linear within them.
The sources of power considered here are national grid, solar, generator, and individual solar panels (for small schools). Some of the variations in power distribution within the school supported by the School Expenses Estimate are not directly selectable in the Country estimate.
Percentage of Schools with Internet Connectivity
The types of Internet connections that will be used by schools in a country are specified here. Allowed options are:
- DSL - A DSL broadband connection
- VSAT - A satellite connection
- GSM - A cellular telephone data connection, GPRS, EDGE, or other (3G)
- Other - An alternative local method may be specified
- None - no Internet connection will be provided
What is needed for this estimate is the percentage of schools that will have each type of connection. Any schools not accounted for are assumed to have no Internet connection.
This input impacts the budget estimate in a variety of ways: the initial cost of the terminal equipment, and the power and monthly subscription cost of the connection. It does not impact the decision to have a school server or wireless network.
The local costs of each of these connectivity options, in terms of money and power, must be specified in the Other Costs worksheet.
Additional Usage Information
These are parameters about laptop usage which can greatly impact the price estimates of off-grid schools.
Laptop Usage
The number of times a laptop in the school will be charged in a day. To specify a usage model where laptops are continuously connected (both charging and operating) throughout the day, specify 2. Fractional values --- such as 0.5, indicating one charge every two days --- may be specified. This workbook assumes that if multiple charges per day are supplied to the laptops, they are supplied sequentially, not simultaneously (for example, using a multi-battery charger in addition to the laptop).
This value is typically 0.5 to 2. It should not be smaller than 0.33, which indicates that the student is only getting one charge per three school days. It should not be larger than the Infrastructure Usage divided by the Laptop & MBC Charge time (two hours, in System Constants in the Other Costs worksheet).
Laptops simultaneously charging
This is the percentage of the laptops in a school that will be charging (or connected to power) at any one time. This ratio should be 100% if all of the students are capable of plugging their laptops in simultaneously. This is used to estimate the peak power draw, necessary when estimating the required generators, inverters, and school power infrastructure.
This value is typically 60 to 100%. It must not be smaller than Laptop Usage (above) times Laptop & MBC Charge time (two hours, in System Constants in the Other Costs worksheet) divided by the Infrastructure Usage.
Infrastructure Usage
The number of hours in a school day that networking infrastructure and the school server are operated. It is surprising how little it costs to operate the infrastructure for longer periods of time, compared to the capital cost of installing it.
It is assumed in this workbook that infrastructure is turned off on the weekends. This may be altered by changing the Number of School Days
This value should be at least the Laptop & MBC Charge time (two hours, in System Constants in the Other Costs worksheet). It should not be larger than 24.
How much storage
The number of days of electrical power storage that is provided in solar powered schools. Fractional portions of a day (0.5, 0.2) may be specified.
This value is typically between 0 and 2
Hours of sunlight per day
The number of hours per day that the school receives sunlight acceptable for generating solar power.
This value is typically between 2 and 4.5
Estimated Deployment Expenses
This is a table showing the Capital and Operating expenses for the laptop and infrastructure costs. It is organized first with the costs by group of school, then the repair costs, the Internet connectivity, and the associated program costs.
The expenses (capital and operating) are also detailed into Laptop, laptop repair, networking, and power infrastructure.
The Examples worksheet contains the intermediate calculations whose results are reported here.
Total Estimated Capital Costs
This is the total estimated cost to deploy the indicated amount of laptops into schools of the the specified size, power, and connectivity.
Total Estimated Monthly Operating Costs
This is the total estimated cost per month to provide Internet connectivity and increased power to support laptops and associated infrastructure in the specified schools.
Estimated Total Number of Schools
This number is computed from the information given. If an accurate number is available, it should be entered here to improve the quality of the estimate.
Individual School Expenses Estimate
This worksheet calculates the estimated expenses for a particular school, illustrating the costs of different power generation and distribution schemes. It has two sections. The first contains six fields that describe the school, the remainder of the worksheet shows estimated power usage and costs.
To be filled by the Country
These are the variables that describe the school for which power and cost estimates are being made.
Number of laptops in the school
The total number of XO laptops deployed at the school, including teachers and students.
Internet Connectivity
How this school will be connected to the Internet. Allowed options are:
- DSL - A DSL broadband connection
- VSAT - A satellite connection
- GSM - A cellular telephone data connection, GPRS, EDGE, or other (3G)
- Other - An alternative local method may be specified
- None - no Internet connection will be provided
The local costs of each of these options, in terms of money and power, must be specified in the Other Costs worksheet.
Additional Parameters
These are identical to those described in Additional Usage Information for the Country worksheet. In this case they apply only to this school.
Suggested Infrastructure
This is information provided by the worksheet about the school infrastructure.
Number of Servers - The number of school servers that are recommended for this school, and its size. The number of servers is one in most cases. Even when two is specified, this may be viewed as encouragement to buy one server with twice the disk space and memory. The size of the server depends on the number of laptops being supported.
Number of Access Points - The number of 802.11 WiFi Access Points (APs) in a school is roughly determined by the number of laptops in the school. This laptop/AP ratio is assumed to be 50:1 for small schools, but increases for larger schools.
Number of Switches - The number of network switches required for a school. These are assumed to be eight port switches, with four ports providing power (for access points). The number required is determined by the number of access points.
Power Requirements
Laptops - This is the real power required for laptops in a school, expressed both as a peak power and the total power per day. The peak power, expressed in kiloWatts, is calculated as the number of laptops simultaneously charging in the school times the real power (in Watt Hours) required to charge a laptop, divided by the time it takes to charge. The total power, expressed in kiloWatt Hours per day, is the number of laptops in the school times the number of charges per day times the real power (in Watt Hours) required to charge a laptop.
Laptops (assuming XO power adapter) - This is the apparent power required for laptops in a school, expressed both as a peak power and the total power per day. This takes into account irregularities in the way that the power adapter consumes power. If a large number of them are the main consumers of electricity in a system, it is necessary to use the apparent power in estimating power requirements. The apparent power, expressed in kiloVolt Amps, is calculated as the number of laptops simultaneously charging in the school times the real power (in Watt hours) required to charge a laptop, divided by the time it takes to charge times the laptop power adapter's power factor. The total apparent power, expressed in kiloVolt Amp Hours per day, is the number of laptops in the school times the number of charges per day times the real power (in Watt Hours) required to charge a laptop, divided by the laptop power adapter's power factor.
Servers - This is the apparent power required for the School server, expressed both as a peak power (in kiloVolt Amps) and the total power per day (in kiloVolt Amp hours).
Networking - This is the apparent power required for the school networking infrastructure, expressed both as a peak power (in kiloVolt Amps) and the total power per day (in kiloVolt Amp hours). The networking infrastructure includes the 802.11 access points, the network switches, and any Internet access equipment (DSL/VSAT/GSM modem).
Peak Power Draw at this school
Specified in kiloVolt Amps. This is estimated as the power required to continuously power the server and networking infrastructure, plus that required to power the "Simultaneous Charging" portion of the laptops in a school. If multiple charges per day are supplied to the laptops, it is assumed that they are not supplied simultaneously.
Power per day required by this school
Specified in kiloVolt Amp hours. This is the total amount of energy required to operate the schools laptops and associated infrastructure for a single day.
Server
These are characteristics of the recommended School server:
Processor - A rough recommendation of processor speed
Minimum Memory (DRAM) - The minimum amount of memory (DRAM) the server should have.
Minimum Disk Storage - The minimum amount of disk storage that the server should have.
Estimated Costs
These are estimates of the infrastructure needed for each of a number of power source and distribution combinations.
With Grid Power
This is the detailed estimate for this school with a connection to the national power grid, using power strips and the XO power adapter to distribute power.
With Grid Power and XOP
This is the detailed estimate for this school with a connection to the national power grid, using the XOP (or equivalent) to distribute power to the laptops.
With Grid Power and MBC
This is the detailed estimate for this school with a connection to the national power grid, using the Multi Battery Charger (or equivalent) to recharge the laptop batteries.
The number of Multi Battery Chargers could be based on how many charges you required each day, how long people are in school to swap batteries and how many hours it takes the MBC to charge a battery. It is instead currently based on the Simultaneous_Charging ratio specified as a constant in the Other Costs worksheet.
With Solar Power
This is the detailed estimate for this school using a centralized solar system for power.
With Solar Power and XOP
This is the detailed estimate for this school with a centralized solar system, using the XOP (or equivalent) to distribute power to the laptops.
With Solar Power and MBC
This is the detailed estimate for this school with a centralized solar system, using the Multi Battery Charger (or equivalent) to recharge the laptop batteries.
With Generator
This is the detailed estimate for this school using a diesel/gasoline powered generator for power, and distributing the power using power strips and XO power adapters.
With Generator and XOP
This is the detailed estimate for this school using a diesel/gasoline powered generator, using the XOP (or equivalent) to distribute power to the laptops.
With Individual Solar
This is the detailed estimate for this school with a centralized solar system for the server and networking infrastructure, and individual solar panels for recharging the laptops.
Laptop Costs
This page details the purchase and delivery costs of the laptop. It includes an estimate of the repair costs over time.
Program Costs
No actual costs are currently listed on this page, but a number of items which may incur cost in a deployment are listed.
Other Costs
This worksheet specifies the equipment costs and power requirements used for estimates across the workbook. It contains all costs, other than those associated directly with the XO laptop (specified in Laptop Costs), or with the pedagogical aspects of a deployment (specified in Program Costs). While example prices are provided, actual prices quoted on the local market must be substituted before using this workbook for budget estimates. All prices should include shipping costs and duties.
Server and Networking
These are the local costs of server, wired and wireless networking equipment.
Internet Access
These are the local costs of Internet connectivity.
Power Infrastructure
XOP Distributed or Rack - This is the XOP Distributed power system for the laptops. It is a power supply which supports four or fivelaptops per node, and may be chained to simply accomodate more laptops. It includes a rack for creating a charging station for the laptops. This is an estimated price of $150 ex-works, and $15 shipping
Multi Battery Charger - This is the OLPC multi battery charging system for the laptops. It is a battery charger which charges up to fifteen laptop batteries at a time, and takes either an AC input or a DC input direct from an array of solar panels. This is an estimated price of $300 ex-works, with $50 shipping.
System Constants
Miscellanious constants having to do with typical laptop usage or server memory/storage requirements.
Examples
This worksheet contains an abbreviated version of the individual school cost estimates for the various example schools used in generating an estimate for a country deployment. These should only be changed in order to refine the country estimate. Use the School Expenses Estimate worksheet to experiment with school parameters.
Several school infrastructure parameters, such as the number of sunlight hours, the number of laptop charges per day, and the various types of internet connections are defined in common in the Country worksheet.
The costs of Internet connections are not present in these example school estimates. Their cost is represented separately in the country estimate, and their power is appropriately averaged and accounted for in the calculations on this worksheet.
Example #1: Small School
This is a school with 30 students. This sample point illustrates the higher cost of providing infrastructure to small schools.
Example #2: Medium School
This is a school with 200 students. This sample point is representative of a wide range of school sizes between the small school and the large schools (500 or more students).
Example #3: Large School
This is a school with 500 students. Our models do not take advantage of any economies of scale present in schools larger than this, making this an appropriate sample point.