Power Generation for a Diagnostic Laboratory and Patient Room in Abri, Sudan

Final Report

Sponsor: Engineers Without Borders at WSU Advisor: Dr. James Dolan P.O. Box 642910 Washington State University Pullman, WA 99164-2910

Mentor: Dr. Mohamed Osman

Team: Sam Guan Charles Renneberg Kylan Robinson (Team Leader) Takele Taffesse Vladimir Yerokhin

Duration: 8 January 2007 to 4 May 2007

Course: EE 416 Electrical Engineering Design Instructor: P.D. Pedrow School of EECS Pullman, WA 99164

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Table of Contents List of Terms................................................................................................................................... 3 Executive Summary........................................................................................................................ 4 Introduction..................................................................................................................................... 5 Background..................................................................................................................................... 6 Project Management ....................................................................................................................... 7 Results............................................................................................................................................. 8

Modeling, Simulation, and Engineering Analysis .............................................................. 8 Demonstration Prototype .................................................................................................. 20 Description of Final Design .............................................................................................. 23

Conclusion .................................................................................................................................... 26 Recommendations for Future Work.............................................................................................. 28 Acknowledgements....................................................................................................................... 28 References..................................................................................................................................... 29 Appendix A: Equipment Specification…………………………………………………………..31 Appendix B: User Manual ............................................................................................................ 34 Appendix C: Manuals and Specification Sheets........................................................................... 39 Appendix D: DC Load Analysis ................................................................................................... 40 Appendix E: Wire Sizing Chart .................................................................................................... 42 Appendix F: Solicitation Packet ................................................................................................... 44

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List of Terms A list of technical terms related to this project is presented in Table 1. Fuji uses these terms deliberately and has adopted them as a standard. Many of the terms have synonyms, but the team members have agreed to use these specific terms for the sake of consistency. Term Definition Abri The city in Sudan where the hospital is located. Array A group of interconnected solar modules. BOS Balance of system Cell A thin wafer of silicon that converts solar energy into electric

energy. Charge Controller A device that charges a battery bank and prevents them from being

charged or discharged too much. Data Logger A device used to store data related to the system’s performance. DOD Depth of Discharge EECS School of Electrical Engineering and Computer Science at WSU EKG/ECG An electrocardiogram device. EWB Engineers Without Borders. Field Junction Box The interface between the solar array and the inverter. HOMER A software package designed for modeling photovoltaic systems. Insolation Incoming solar radiation, measured in J/m2.

Inverter A device that transforms DC power into AC power. Irradiance A measure of instantaneous solar energy, measured in W/m2. Module A single unit comprised of many interconnected solar cells. Passive Cooling An air conditioning system that uses convection to control ambient

air temperature. Photovoltaic (PV) The process of converting light directly into electricity. Surge Current The amount of current drawn by a device Sudan A country located in northeastern Africa. WSU Washington State University (Pullman, Washington, USA)

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Executive Summary Members of Project Fuji worked with Engineers Without Borders at Washington State

University, Dr. Mohamed Osman of WSU's School of Electrical Engineering and Computer Science, Builders Without Borders, and Napata.org to design infrastructural resources for the hospital in Abri, Sudan. The hospital is located in a rural area and serves a population of 40,000. Due to a lack of electricity, the hospital is currently incapable of adequately serving the region. It is unable to preserve vaccines and medicines, operate sterilization autoclaves, or run other pieces of small medical equipment that perform blood and urine analysis. In the near future, the hospital plans to obtain more diagnostic equipment, such as X-ray, ultrasound, and EKG/ECG machines. When this equipment arrives, it must be connected to a reliable power source. If power cannot be supplied to the hospital equipment, patients will continue to travel more than 200 miles for proper treatment. Due to the location of the hospital and the nature of the load, photovoltaic power is a perfect solution for the hospital. The Project Fuji team was responsible for designing a feasible, adequate, and sustainable solar power generation scheme for the hospital. This report describes the steps the team took in designing their solution and discusses the results of their work.

During the project’s first semester, the Fuji team spent a considerable amount of time understanding the problem they have been given to solve. The team devoted itself to seeking out experts and professionals who could offer sound advice. Fuji formed relationships with photovoltaic companies, professors at WSU, and local hospitals. The team also consulted with members of EWB and shared ideas with a civil engineering senior design team from WSU that was designing a patient room and a diagnostic laboratory for the same hospital. Over the course of time, the Fuji team members learned to work together to complete tasks. They learned how to delegate responsibilities and use tools such as Microsoft Project to organize their efforts.

At the beginning of the spring semester, Fuji entered the design portion of the project. After meeting with their main mentor, Dr. Osman, the team had a much clearer concept of the responsibilities and the tasks ahead of them. The team participated in a video course dedicated to the design of photovoltaic power systems and interviewed the maintenance engineers of the local fire department and two area hospitals. Professor Mat Taylor was contacted and the team met with him to ask questions. Finally confident that they had enough background information, the team collaborated to establish a master Gantt chart that covers all activities for the remainder of the project.

To conclude the project, team members of Project Fuji performed the design tasks that resulted in a final product that is ready to be implemented in Sudan. Each team member focused on a different aspect of the design, but the group agreed to assist each other whenever it is possible. Different areas of responsibility included, but were not limited to, characterizing the load, choosing the inverter, selecting the batteries and determining their configuration, specifying a charge controller, investigating and choosing the solar modules, wiring and safety, and data logging. Concurrently with the design tasks, the team members solicited companies and organizations for donations of both equipment and funds. The goal here was to secure enough donations to build the team’s prototype. The prototype was built and presented at the annual WSU EECS poster competition, and Project Fuji was awarded Third Place for their efforts.

The next step for the team is to start obtaining money and supplies that can be used in the actual implementation of the hospital’s system. The team is very confident in this design and is dedicated to the goal of having it implemented in the Sudan hospital. This was an important

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project because it will allow people to have access to basic services that are often taken for granted. If implemented successfully, the Fuji design will help improve health and save lives.

Introduction The Project Fuji was proposed by Engineers Without Borders at WSU. Engineers

Without Borders is an international humanitarian organization with chapters across the nation. It is comprised of engineers of all fields, who want to use their engineering skills to do humanitarian work. This project consisted of a team of electrical engineers and a computer engineer finding a renewable energy solution for a health clinic located in Abri, Sudan (see Figures 1 and 2). At the end of the semester, the team presented a design plan along with a working prototype. The prototype was a miniature version of the actual system.

There are many options when it comes to renewable energy generation schemes. Among the most popular are solar, wind and hydro. Abri is located at 20.77°N 30.35°E, and the climate is arid with ample insolation year-round. After careful consideration, Team Fuji decided to use solar power [1].

The requirement of this project was to come up with a complete engineering blueprint of a solar power plant. The system was to be off-grid because currently there is no power available in Abri. The location of the site is remote; the nearest large city is Khartoum, Sudan, 391 miles away. Accordingly, the design needed to be durable and as maintenance-free as possible.

Figure 1. The Fuji team.

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Figure 2. Mid-day in Abri, Sudan.

Background Team Fuji explored many different types of renewable energy options before picking

solar power. Solar power has many qualities that are ideal for a site like Abri. The most important aspect of PV systems is that they consist of few moving parts. According to Siemens, a manufacturer of solar panels, this quality leads to increased reliability and decreased maintenance efforts [2]. A solar plant is the ideal solution for sites which have a high amount of insolation [3]. The climate for Abri is arid and dry. It gets plenty of sunshine throughout the year. In fact, the irradiation rating of Abri is close to 1000 W/m2, which is the standard used for rating solar modules.

In addition to areas of high isolation, PV systems are ideal in rural locations where power must be generated at the site of the load. Dr. Gisela Schneider, in her project located in rural Gambia, specifically credited the ability to generate onsite power to the success of her project [4]. A solar module is made up of many individual solar cells. These cells are made up of silicon. When these cells are struck by sun light, the electrons are “knocked” loose inducing a current. This current is sent to the charge controller to charge the batteries that act as energy storage. The batteries can only give out DC power. So the current coming from the battery is fed to an inverter which produces AC power. Solar is a very mature technology. It has been used worldwide. For example in Portugal, the government is planning to build a solar power station that covers 250 hectares and produces power for 130,000 households [5]. Recently, researchers at Boeing-Specrolab have produced a solar module which broke the 40% efficiency barrier, meaning that more energy is produced

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with a smaller amount of Silicon. This proves that solar generators could become the least expensive form of energy production in the near future [6].

Project Management In order to successfully finish this design project, members of the Project Fuji team had

to meet specific deadlines and budget their time carefully. At the beginning of the semester, everyone on the team worked together and tasks were completed one at a time. As the project progressed, though, time constraints made it necessary to work on multiple tasks concurrently. This was accomplished by delegating responsibilities to individual members of the team. A list of tasks and their deadlines was constructed, and team members were required to fulfill their responsibilities in a timely manner. Microsoft Project was used to schedule member tasks, and the resulting Gantt chart had over 140 tasks listed. In Figure 3, a simplified Gantt chart captures the main points of the master Gantt chart. This chart shows the major steps Fuji took during the design process and includes three refinements of the “Component Choice” task. The rest of this section explains some of the more important design tasks in greater detail.

Figure 3. Simplified Team Gantt Chart.

Load Estimation and Load Specification Estimating the load proved to be one of the most difficult issues for this project. Without an accurate estimation of the load, an efficient power generation scheme cannot be devised. The team first gathered data to determine what kinds of medical equipment are essential for a small hospital’s operation. This was accomplished by contacting and interviewing local (Pullman) medical professionals. Fuji then arrived at a load estimate by averaging the power consumption of various medical devices. On April 6, team mentor Dr. Osman instructed the team to specify the exact medical equipment the hospital would use as part of the final system design. The team revisited their estimations and changed measurements from averages to exact quantities. This increased the precision of the load estimation and therefore increased the efficiency of the design. Some estimation was still necessary, however, as the team had to approximate the time

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usage of each device. Appendix A provides a complete list of this medical equipment and the associated power consumption.

DC System Component The Fuji team had a number of options to consider regarding the type of power the

system would produce. The system could be designed to support AC loads, DC loads, or both. This was an especially important question when it came to hospital refrigerators. DC refrigerators are more efficient and robust, but transmitting DC power can be expensive due to the low voltage levels. In the end, Fuji decided to create a standalone DC system for the refrigerators, where the power is produced at the location of consumption.

Phase Definition Since the beginning of the project, Fuji team members had known that modularity and expandability was an important design requirement for the system. A phase-based implementation was considered in order to allow the power generation scheme to grow with the hospital and allow the project to proceed even if full funding has not yet been received. Fuji decided to specify the system in four distinct phases.

Poster Session Team Fuji was responsible for creating a presentation poster and demonstration prototype for the annual EECS poster session. This meant designing and implementing a scaled-down model of the complete system and printing out an academic-style poster that explained Fuji’s work.

Component Choice Over the course of the design process, Fuji modified the overall design description a number of times. Each time this occurred, a new system had to be formulated to meet the new requirements. The refinement stages consisted of selecting different batteries, solar modules, wires, charge controllers, communication managers, data loggers, and inverters to be installed at the project location.

Results

Modeling, Simulation, and Engineering Analysis

System Simulation A program called HOMER [7] was used during the design synthesis to simulate the use

of the photovoltaic system. HOMER simulates systems and creates a list of feasible system designs. First, HOMER lets you pick the equipment to be modeled. After the equipment is chosen, each element can be configured to match the desired specifications. HOMER automatically adds noise to the load to simulate the actual performance. The daily radiation and clearness data for a specific place on earth are based on a site’s latitude and longitude and are obtained through an internet database. After all the variables are loaded to the program, HOMER makes energy balance calculations for every hour during a full year. Figure 4 shows the program after it ran 672 simulations.

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Figure 4. HOMER software showing feasible system designs. After HOMER has evaluated each aspect of the system, it shows a list of designs that could be considered and sorts them by the least total net present cost. It also displays simulation results that show data like the amount of energy produced, battery discharge levels, and excess electricity produced. An example of this is shown in Figure 5. HOMER can also perform a sensitivity analysis in which it takes two specified variables and shows how changes in them affect the outcome. However, HOMER does not account for the effects of temperature on the photovoltaic array or the battery bank, which will degrade the performance of the components. It also does not account for the price of the system wiring.

The Fuji team also used simple online calculators to calculate things such as wire gauge size [8] and the number of batteries needed [9]. These results helped the team determine if the existing calculations are feasible.

Codes The team has analyzed the U.S. National Electrical Code. Although the project location is in Sudan, Africa the U.S. NEC is generally recognized as a good international reference. The most important section in the NEC is section 690 which is the section pertaining to solar power systems [10]. The NEC-690 describes the wiring and protection of the system. These codes are used by electricians for guidance. The Underwriters Laboratories (UL) is another set of guidelines that the team researched [11]. UL provides guidelines for the testing of all types of electrical equipment. For example, in order for a battery to be UL approved, it has to successfully go through a series of performance tests. The team plans to use only UL approved equipment so that the system will be UL certified.

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Figure 5. HOMER software showing simulation results for a particular design.

Another important consideration is that additional codes pertain to power that is supplied

to medical equipment. In particular, there are strenuous requirements for the quality and reliability of electrical power to equipment which touches a patient. The team researched these requirements and determined that they could not feasibly be met. Therefore, the team has specified that any medical equipment used at the hospital that touches a patient must be battery operated. This way, the device itself is responsible for the power quality and our system is only responsible for charging the device’s battery.

Peak Hours Estimation Solar module power ratings are rated based on universally standard weather conditions

including an ambient temperature of 25ºC and a solar irradiation of 1000 W/m2. This standard value is generally experienced in ideal conditions. In order to effectively size a PV system, a process known as peak hour estimation is utilized. This process results in an equivalent amount of time during a single day which the module will experience the standard 1000 W/m2. Typical conditions may result in an irradiation profile such as the one shown by the red line in Figure 6. The peak hours estimation process will produce the dashed green line in the same figure, and theoretically the area under both curves will be the same.

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Figure 6. Peak hours estimation process.

Since data related to the irradiation profile experienced in Abri are not available, the team

researched profiles of nearby towns and ultimately settled on calculating the number of peak hours from weather data which is available in Dongola, Sudan. The proximity of Dongola to Abri is shown in Figure 7.

Figure 7. Proximity of Dongola to Abri.

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Another software simulation program that was used is RETScreen[12]. Unlike HOMER,

RETScreen does not perform time series simulations. It is more focused on simulating and analyzing the cost of the system over time. RETScreen also has a very helpful tool in determining solar irradiance. The best source of irradiation data was made available through RETScreen. This program reported the average daily radiation experienced in each month, based on data from NASA’s Surface Meteorology and Solar Energy Data Set, and the North-South tilt angle of the array [13]. Table 1 describes the data associated with a 0° tilt angle (array is flat to the earth’s surface).

Table 1. Zero degree tilt angle data.

In this case, the system sizing would be conducted to provide ample power to the load in conditions of 5.08 kWh/m2/d. This is because the system must be sized to operate during the worst season (in this case December). One method of maximizing the lowest monthly radiation is to tilt the array toward the winter sun. By altering the slope of the PV array, Table 2 is compiled, within which it can be seen that a tilt angle of 18.5° provides the highest monthly low. The RETscreen data provided for a tilt angle of 18.5° are presented in Table 3.

In this case, the system can be sized around a substantially higher average daily radiation of 6.21 kWh/m2/d (which occurs in both July and December). In order to calculate the peak hours estimation from Table 3, equation 1 is used.

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Table 2. Comparison of tilt angles.

Tilt of PV Array Along N-S Axis

(°)

Lowest Average Daily Radiation (kWh/m2/day)

17 6.14 18 6.19

18.3 6.20 18.4 6.21 18.5 6.21 18.6 6.20

19 6.18 20 6.14

Table 3. Data associated with the ideal tilt angle.

×

=

day

hrsT

m

kW

daym

hrkW22

1)(

)(21.6

21.6=T

where: 1 kW/m2 corresponds to the standard irradiation value

(1)

Since the calculation of peak hours has such a profound effect on the sizing of the team’s system, this estimation was verified using a secondary data source. From Elagib and Mansell’s “New approaches for estimating global solar radiation across Sudan,” the yearly average daily solar radiation in Dongola was reported as 24.06 MJ/m2/d [14].

In order to estimate peak hours, the average irradiation had to be derived from the average insolation value, as is shown in equation 2.

14

=

×

=

222

5.278sec86400

1

)(

(sec)6^10*06.24

)(06.24

m

Wday

daym

W

daym

MJ

(2)

This statistic is the average irradiation over a 24 hour period. Using this figure, the

estimated peak output hours is calculated using equation 3.

( ) ( )hrsTm

Whrs

m

W ×

=×

22

1000245.278

7.6=T

(3)

Based on these calculations, the time that the city of Dongola experiences 1000 W/m2 of irradiation is concluded to be 6.7 hours. This is the value that was used to estimate the nominal power produced by the solar module array each day.

DC Transmission Analysis A complex Excel spreadsheet was created to determine the benefits of running a separate

DC transmission line for DC equipment. This spreadsheet takes into consideration the cost of another transmission line, inverter inefficiency, and the difference in price for the number of panels and batteries needed, and makes an assumption that DC equipment costs the same as AC equipment.

The benefits of a partial DC load are that the power consumed by the DC appliances is not affected by inverter efficiency. The cost of a DC load is that a separate transmission line must be set up to transmit that power and the voltage in this line would be lower than in an AC line meaning the gauge will be higher.

The analysis, therefore, is a cost comparison over a range of load values corresponding to the portion of the overall load which is DC. The cost savings are the greatest when these DC loads are run continuously because this minimizes the required continuous power rating of the transmission line and maximizes the power losses through the inverter. Therefore, the refrigerators will be converted to DC first (which accounts for up to 600 Watts, running 24 hours a day) and then other appliances from the equipment list, the longest running time of which is six hours. Table 3 and Figure 8 present the results of this analysis. Table 4 describes the assumptions and constants used in this analysis. Appendix D describes the individual steps in this analysis.

Based on the above analysis and customer preference, the team decided to use DC components in the design. The DC load components consist of two DC refrigerators and a DC freezer. Additional criteria used in this decision making process are described in Table 5. In order to decrease initial costs while maintaining an acceptable level of simplicity and reliability the team decided to design for an additional DC stand-alone system.

Load Characterization One severe obstacle to Project Fuji is that specific data related to the project’s

implementation are not available. For example, PV systems are sized to accommodate the load

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profile of the customer. However, for this project the profile is not available since the hospital is currently without power or equipment.

The specifications the team is particularly interested in are the maximum continuous power the load will draw at any given time, the average power the load will draw per day, and the maximum surge current the load will draw. The system can then be designed around these specifications.

Table 3. DC load analysis. DC Load (W)

DC Load (W*hrs/day)

Initial Cost Savings ($)

0 0 0 50 1200 123.47

100 2400 318.97 150 3600 525.67 200 4800 736.10 250 6000 947.41 300 7200 1158.02 350 8400 1366.86 400 9600 1573.05 450 10800 1775.77 500 12000 1974.24 550 13200 2167.57 600 14400 2354.83 650 14700 2331.10 700 15000 2298.90 750 15300 2256.68 800 15600 2202.54 850 15900 2134.15 900 16200 2048.55 950 16500 1941.95

1000 16800 1809.42 In order to determine a correct and feasible load the team has consulted several experts in

the medical field who provided information about the essential equipment of a hospital. Based on the information gathered the team constructed a list of equipment that is shown in Appendix A. Table 6 shows a summary of the load requirements for the AC system and Table 7 shows the load requirements of the DC system. Since the DC system does not require the use of an inverter, the only parameter of interest is the daily consumption.

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Figure 8. DC load analysis, graphical.

Table 4. Constants used in analysis.

Cost per panel ($) 745 Panel peak output (W) 167 Peak hrs per day 6.7 Cost per battery ($) 569 Battery capacity (W*hrs) 3660 Bank reserve (days) 4 Max. trans. power loss (%) 2 DC load voltage (V) 48 Delta of copper 0.0039 Resistivity of copper(rho) 6.787E-07 Max ambient air temp (°C) 40 Trans line dist (in) 3000 Trans line dist (ft) 250 Inverter losses (%) 20

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Table 5. AC/DC Decision Matrix.

Table 6. Load parameters, AC system. Characteristic Value Units

Continuous (peak) power 4,217 Watts Average daily load consumption 14,100 Watt(hrs)/day Surge current 34.7 Amps

Table 7. Load parameters, DC system.

Characteristic Value Units Average daily load consumption 2,000 Watt(hrs)/day

System Placement Analysis Since the hospital is comprised of several buildings, each housing a part of the overall

electrical load, a detailed placement analysis has benefited the design in terms of efficiency. Power must be transmitted from the solar farm to the individual loads and this transmission comes with associated losses dependant on wire gauge and the length of the line. Since the team has specified a maximum allowable voltage drop (3%), the longer the line is the higher gauge wire the team will need to use. This means that in order to minimize the required wire gauge and therefore the overall system cost the team will want to place the system in the “middle” of all the individual loads. However, since the loads are not all equal this process consists of weighted points and an analysis analogous to a center of gravity calculation. This method required estimation for placement of the medical devices. Figure 9, and Table 7 describe the results of this analysis. The DC load is located in a single building and therefore required no such analysis.

Center of Load = M

yxm

yx

N

iiii

cmcm

∑== 1

,,

Where: N = number of points mi = load at point i

<xi, yi> = coordinates of point i M = total load

(4)

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Figure 9. Center of load map of the hospital.

Table 7. Location data.

Coordinates

(meters) Load Location x y (Watts)

Load Description

1 12 8 97 Fans, lights 2 15.5 5 2572 Autoclave, water purifier, air filter, x-ray, IV pump

3 17 5 967 Centrifuge, EKG, ultrasound, fridge, pulse oximeter, UV air filter, laptop, printer, fetal monitor

4 21 5.5 97 Fans, lights 5 23 7.5 97 Fans, lights 6 28 11 97 Fans, lights

Total 3927

Wire Sizing The sizing of the wires needed to interconnect all the DC components was determined based on a 3% voltage drop. The tables used for this are provided in Appendix E. The AC wiring

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size was based on the rated amperage of the wire [10]. Table 8 and 9 show the wire size determined for both the DC and the AC system, and the maximum wire length that can be used.

Table 8. AC system wiring. Connected Components Wire Gauge Size Maximum Wire Length

For < 3% voltage drop PV to charge controller AWG 4 40 feet Charger controller to battery AWG 4 25 feet Battery to inverter AWG 2 28 feet Inverter to load AWG 12 NA / Rated for 20 Amps

Table 9. DC system wiring.

Connected Components Wire Gauge Size Maximum Wire Length For < 3% voltage drop

PV to charge controller AWG 10 28 feet Charger controller to battery AWG 8 32 feet Battery to load AWG 8 32 feet

Battery Sizing Energy storage is an essential part of a stand-alone photovoltaic system, especially if the

electrical load is to be powered at night. Currently, the most cost effective and reliable method for energy storage is batteries. The system must use the appropriate number of batteries to deliver sufficient power to the load at night and during bad weather conditions. Using the equipment list shown in Appendix A the total AC power consumption per day is estimated to be 14.1 kWh. Splitting that into four phases results in 3.5 kWh/d per phase.

Using a four day reserve and considering the 96% inverter efficiency, the amp-hours consumed each day for a single phase is shown in equation 4. Then, the total battery bank capacity for the four phases is shown in equation 5. The average discharge time for a 4 day reserve at 80% maximum discharge is then shown in equation 6.

dayphaseVAhefficiencyinvV

dayskWh//48@479.382

80.0*),(96.0*48

4*52493.3 = (4)

4phase*382.479Ah = 1529.92Ah @48V /day (5)

Time (hours) = hrsdays

AcidLeadeDischMaximum

hrsdayserve120

80.024*4

)%,80(arg%24*)(Re ==

− (6)

Therefore a 1530 Ah battery capacity would be required to provide 4 days of backup

energy storage at a discharge rate of 14.1kWh per day in a 48V system. Using 300Ah batteries, the number of batteries needed in parallel is then calculated with equation 7. Using 12 Volt batteries, the number of batteries in series is then shown in equation 8.

Number of battery needed = 6258

92.1529

)(==

Ah

Ah

BatteryAh

Capacity (7)

20

412

48 ==V

V

tageBatteryVol

ageSystemVoltbatteries (8)

Therefore the total number of 300Ah batteries needed for the design is 6 x 4 = 24

batteries. Similar calculations can be performed which show that the DC battery bank requires 4 of the same type of batteries.

Panel Sizing Team Fuji has two solar arrays in the design. One panel array is for the AC system and the other panel array is for the DC system. The team first examined the inefficiencies of the system in order to determine the amount of power that needs to be generated in order to run the load. This analysis is shown in Table 10.

Table 10. Inefficiencies in AC system. Power derating in AC array

Battery inefficiency 5% Charge controller inefficiency 5%

Temperature derating 3.5% Inverter inefficiency 30% Extra safety margin 10%

Total 53.5% The DC system has the same inefficiencies except for the inverter, so the total inefficiency of the DC array is 23.5%. In the AC system, Fuji designed four phases of implementation. The total requirement of the load is 14,100 Wh/day and the average power per phase is 3,525 Wh/day. Taking into account the inefficiency of the AC system, each phase of the solar array must generate 5,411Wh/day. Abri is characterized with a peak hour estimation of 6.7 hours (described above), so each phase of the array must provide a rated output of 808 Wh. In the DC system, the load estimation is 1,663 Wh/day. Using an inefficiency of 23.5% the array must provide 1,980Wh/day, or a rated output of 296 Wh.

Demonstration Prototype The prototype of this project represents a scaled-down version of the final project which validates the overall system and demonstrates its primary functionality. It demonstrates each of the key steps of transforming solar energy into usable electric power, and was designed to communicate Fuji’s progress and ideas to the academic community at WSU as well as the general public.

To demonstrate this functionality, various components were used together. A solar panel, two batteries, a charge controller, an inverter, an AC water purifier, a DC water pump, and lab-view were all used in the prototype system (see Figure 10 for configuration). The demonstration was required to be in-doors and so to simulate irradiation, the team placed a set of construction lights above the solar array.

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DC Water Pump

AC UV Water

Purifier

Solar ModuleCharge Controller

Batteries

Load

Inverter

50Ah

50 Ah

Light Source

Prototype Monitor

LabView

Fluke Hydra

Figure 10. The Fuji prototype.

First, the solar panel was energized using the two 500 Watt construction lights so that it

would provide a significant amount of current (see Figure 11). The power generated by the panel under these conditions was generally around 0.4 Amps at 13 Volts. This generated current then passed through a charge controller which regulated the battery (see Figure 12). Two Interstate brand batteries were connected in parallel to generate a capacity of 100Ah, at 12 Volts. A DC motor was run directly from the battery terminals and simulates the DC load. The inverter also converted energy from the batteries into 120 Volt, 60 Hz AC power which was supplied to the UV water filter simulating the AC load.

Some audience members suggested to the team that shipping would be a major concern. This advice was noted and is suggested as a future task. The team tried to clarify to the audiences how a small amount of shading affects the solar panel output power. By covering the solar cells it was possible to demonstrate how the power generated from the solar panel decreased in an un-proportionate manner. For example, by only covering one of the 33 cells the power output of the panel is actually cut by two thirds.

A program called LabVIEW by National Instruments was used to simulate data acquisition that will be implemented in the design. It is a program that can collect data from an outside source such as a multimeter via a serial port. Three types of data were monitored. They included the power to the load, module current, and battery voltage (see Figure 13). The design of the data logging schematic used for the team’s prototype is shown in Figure 14.

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Figure 11. The solar module and construction lights.

Figure 12. The prototype charge controller.

Figure 13. LabVIEW monitoring the prototype.

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Figure 14. The LabVIEW block diagram.

Description of Final Design After running the sizing analysis described above, and considering the cost vs. reliability vs. efficiency tradeoffs, the team specified a modular system consisting of four phases of implementation (Table 11) accompanied by an additional stand-alone DC system. This DC system will supply the hospital’s main refrigerator/freezer vaccine storage and is therefore defined as a critical load since the vaccines stored in this area will spoil in the event of a system failure. The AC system is defined as a non-critical load since system failures can be avoided by rationing equipment use during periods of low battery reserves. For increased reliability in the AC system, Team Fuji has specified an optional gas/diesel generator sub-system with two-wire auto-start capability.

Table 11. Implementation phases and their purposes. Phase Purpose

I Diagnostic Laboratory II Surgery and Sterilization III Office Equipment IV X-Ray and Refrigerator

The team also constructed a list of requirements that these two systems must

meet/provide. The list of quantitative requirements in presented in Table 12. Other qualitative

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requirements of the design include the collection of system use data, ease of installation, operation and maintenance, and minimal risk of system repairs. The system use data would enable future groups to renovate the design in order to maximize efficiency or increase load capacity. For example, after analyzing these data, a group may determine that the battery bank’s depth of discharge is lower than expected and therefore conclude that future expansions to the system would not require additional battery lines.

Table 12. System requirements. System Requirements Value System life 25 yrs AC system failure rate (non-critical load) < 1 failure per 1 yr DC system failure rate (critical load) < 1 failure per 6 yrs Maximum DOD – AC battery bank < 80% Maximum DOD – DC battery bank < 80% Nominal Inverter efficiency > 70% Nominal Charge Controller efficiency > 95% Panel production per day DC 2,000 kWh Panel production per day AC 14,100 kWh AC system energy reserve 4 days DC system energy reserve 5 days Max load power (cont.) expandable to w/o replacements* 6000 VA * above this power level certain BOS components must be replaced (i.e. trans. lines)

Based on analyses of the load characterization described and interface requirements

decided on by the team, the characteristics that will be required of the PV system components were determined. Tables 13, 14, and 15 list these requirements.

Table 13. Inverter and charger requirements. Inverter must operate at 48V input voltage Inverter must be able to supply at least 32.5 Amps for at least 250 ms Inverter must provide for a two-wire electrical auto-start of a generator Inverter must include over power detection at output to load Provide sensors to monitor the temperature of the batteries Inverter able to accept at least 175 Amps of input current Inverter must provide a sine wave output with maximum harmonic distortion of 5% Inverter output of 230 VAC at 50 Hz Inverter must provide at least 4000 W output power Efficiency at nominal load power of no less than 90% Charger must achieve maximum power point tracking [15] Charger must have voltage step-down capability to 48 Volts (24 for DC controller) Charger must include adjustable critical low voltage settings for battery bank

25

Table 14. Battery requirements.

Lead-Acid deep cycle flooded type Total storage capacity of the AC battery bank is 1700 Ah at 48V nominal Total storage capacity of the DC battery bank is 600 Ah at 24V nominal Battery bank must be expandable Maximum depth of discharge of the battery must be 80%(20% state of charge) AC Days of reserve (Autonomy) is 5 days DC Days of reserve (Autonomy) is 4 days

Table 15. Photovoltaic module requirements.

AC Panel configuration voltage must be at least 48 ± 5V DC Panel configuration voltage must be at least 24 ± 3V AC system must generate at least 14.1 kWh per day DC system must generate at least 2.0 kWh per day Minimum module efficiency of 10% Minimum 36 cells per a module Operating temperature range is -40 to 80 C UL 1703 approved

Based on the component characteristics described above, Table 16 illustrates the models

chosen for the system design components.

Table 16. Component definitions.

Component Manufacturer Model

number Inverter Outback VFX-3048E Battery (both systems) Concorde PVX-2580L AC system module Sharp ND-187U1F DC system module SolarWorld SW-165

The system schematic in Figure 15 describes the system the team designed in order to

meet the above requirements and objectives. A detailed equipment list complete with component costs is provided as Appendix A. Figure 16 describes the data logging scheme and equipment, as well as the grounding scheme. A complete user guide for the overall system is included as Appendix B of this report. Refer to this document for details on operation, routine maintenance, and troubleshooting of the system design.

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Figure 15. System schematic, basic components.

Conclusion Team Fuji has compiled a list of the medical equipment that will be sent to the hospital in

Abri, Sudan. The complete list of this equipment is available in Appendix A. Based on this equipment’s consumption characteristics and estimated daily use, the hospital is expected to consume approximately 15.6 kW hours per day. To put this number into perspective, consider that in the year 2000 the average American household consumed 25 kW hours per day [16].

In addition to this medical equipment, the hospital will receive a complete photovoltaic system which will supply the devices reliably over the next 25 years. In the event that grid power is brought to the town during this time, the system is able to work in conjunction with the grid by using it as a backup source. The system consists of two stand-alone components, one for supplying the DC devices located in a building on the north side of the hospital’s campus and one for supplying AC power to devices in multiple buildings on the south side of the campus. The AC system has been designed to supply power which meets the local standard of 230 Volts, at 50 Hz. The DC system has been designed to supply 24 Volt devices.

Funding sources and donors for this project are still being located and the design has been made modular to allow multiple phases of implementation as more donations are received.

27

Figure 16. System Schematic, data logging and system grounding.

Table 17 describes the costs of each phase in terms of both equipment (PV system components), and load (hospital’s electrical medical devices), as well as the total cost to implement the entire system.

Table 17. Summary of system costs. SUMMARY

Phase Equipment Load Phase Total

I $19,770 $9,367 $29,137 II $6,746 $2,803 $9,549 III $9,509 $1,218 $10,727 IV $9,022 $3,638 $12,660

System Grand Total $62,073

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Recommendations for Future Work To maximize the lifespan of the solar equipment, some of the components of the system

should be stored in an equipment shed that provides shelter from the environment. This shed needs to be cooled to ensure that these components are not adversely affected by high levels of heat. A passive cooling approach would work particularly well because it would not require electrical energy. Fuji recommends delegating the task of designing a passive cooling shed to another senior design group or Engineers Without Borders.

Team Fuji picked the DI-710-UHSB by DataQ as the monitoring system. It is a system that can monitor eight channels of current or voltage for 776 days when the data points are taken once every second. When the hospital decides to expand its operations to incorporate more pieces of electrical equipment, a photovoltaic system engineer should analyze this data to help decide the best course of action.

Team Fuji recommends buying and testing all equipment in the United States before shipping it to Sudan. Fuji believes this is the most reliable method of implementation. Sudan is a nation that is currently under economic sanction by the United States. Fuji is not certain if shipping equipment to Sudan is a legal and viable option. Fuji has asked Lorraine McConnell, Bio Safety Officer for WSU, to look into this matter. The investigation is ongoing and Ms. McConnell will notify Dr. Pedrow once the investigation concludes.

WSU prohibits anyone from Team Fuji to travel to Sudan and implement this project. In the event that this project is ready for actual implementation, Fuji recommends hiring an electrician or someone with a solid technical background in electrical engineering to carry out the implementation.

Acknowledgements The following people have graciously provided the team with information, suggestions,

and advice that have been invaluable to the team, and their interest and dedication is much appreciated:

Dr. Patrick Pedrow, WSU

Dr. Mohamed Osman, WSU Dr. Mat Taylor, WSU Mr. John Yates, WSU

Dr. Alexsander Dimitrovski, WSU Mr. Brad Cook

Professor Pedrow helped with constructive comments on the various aspects of the design

project as well as periodic reviews of team progress. Dr. Osman provided important insights into the Abri hospital and helped Fuji by specifying the project requirements. Mat Taylor’s expertise in photovoltaics was crucial in the verification of the team’s design. John Yates assisted the team with early input and by providing test and evaluation equipment used in the demonstration prototype. Alex Dimitroviski, shared his experiences and knowledge of power transmission with the team. Brad Cook helped the team in inverter selection and explained applicable medical codes.

29

References [1] C. Renneberg, K. Robinson, T. Taffesse, and V. Yerokhin, “Project Fuji Design Proposal,”

Design Proposal, Washington State University, Pullman, WA, USA, 2006. [2] Siemens Photovoltaic Video Series: World of Solar Electricity. [Videorecording]. Siemens,

2005. [3] A.M. Omer, “Overview of renewable energy sources in the Republic of the Sudan,” Energy,

vol. 27, pp. 523-547, 2002. [4] G. Schneider, “Oxygen supply in rural Africa: a personal experience,” International Journal

of Tuberculosis and Lung Disease, vol. 5, no. 6, pp. 524-526, 2002. [5] L. Haines, The Register Online, “Portugal builds world’s biggest solar plant,” June 2006,

www.theregister.co.uk. [Accessed Nov. 02, 2006]. [6] C. Kielich, “New World Record Achieved in Solar Cell Technology,” Department of Energy,

December 2006, http://www.energy.gov/news/4503.htm. [Accessed Feb. 27, 2007]. [7] HOMER, The Optimization Model for Distributed Power Available:

http://www.nrel.gov/homer, [accessed January 16, 2007]. [8] PowerStream http://www.powerstream.com/Wire_Size.htm, [accessed February 12, 2007]. [9] Solar Power Answers [Online]. Available: http://www.solar-power-

answers.co.uk/design.html, [accessed February 12, 2007]. [10] Mark W. Earley, National Electrical Code Handbook 1993, 6th ed., Engineering Science

Library: Natl Fire Protection Assn;, February 23, 2007.

[11] "Scope for UL 1741," November 2005. [Online]. Available: http://ulstandardsinfonet.ul.com/scopes/scopes.asp?fn=1741.html. [Accessed Feb. 12, 2007].

[12] RETScreen International [Online]. Available: http://www.retscreen.net, [accessed February 22, 2007].

[13] Earth Science Enterprise Program, NASA, “Surface Meteorology and Solar Energy Data

Set,” December 2005, [Online]. Available: http://eosweb.larc.nasa.gov/sse/RETScreen/. [14] Nadir Ahmed Elagib and Martin G. Mansell, “New approaches for estimating global solar

radiation across Sudan,” Energy Conversion and Management, vol. 41, pp. 419-434, 2000. [15] K. Kobayashi, H. Matsuo and Y. Sekine, “An Excellent Operating Point Tracker of the

Solar-Cell Power Supply System,” IEEE Transactions on Industrial Electronics, vol. 53, pp. 495-499, April 2006.

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[16] “Electrical Energy,” The New Book of Popular Science. 2000 edition. Grolier Incorporated, 1998.

31

Appendix A: Equipment Specification

PHOTOVOLTAIC EQUIPMENT Make and Model Unit Price Quantity Price

AC Conduit Adapter Outback FX-ACA $35 1 $35

Batteries (for AC load) Concorde PVX-2580L $569 8 $4,552

Batteries (for DC load) Concorde PVX-2580L $569 4 $2,276

Charge Controller (AC) Outback MX-60 $649 1 $649

Charge Controller (DC) Xantrex C-35 $119 1 $119

Communication Manager Outback HUB-4 $195 1 $195

Data Logging Equipment DataQ DI-710-UHSB $995 1 $995

DC Conduit Adapter Outback FX-DCA $45 1 $45

Inverter Outback VFX 3048E $2,345 1 $2,345

Inverter Breaker Box Outback PS2DC-175 $385 1 $385

Inverter Out AC Breaker Box Outback PS2AC50D $385 1 $385

Mounting Plate Outback PS2MP $129 1 $129

PV Modules (AC) Sharp ND-167U1 $745 6 $4,470

PV Modules (DC) SolarWorld SW-165 $755 2 $1,510

Remote Temperature Sensor Outback RTS $29 1 $29

System Controller Outback MATE $295 1 $295

Wire 12 Gauge $0.15/ft 1884 $283

10 Gauge $0.83/ft 50 $42

8 Gauge $2.19/ft 128 $280

4 Gauge $3.44/ft 130 $447

2 Gauge $5.43/ft 56 $304

Phase One Total: $19,770

Batteries (AC) Concorde PVX-2580L $569 4 $2,276

PV Modules Sharp ND-167U1 $745 6 $4,470

Phase Two Totals: $6,746

Batteries Concorde PVX-2580L $569 4 $2,276

Charge Controller (AC) Outback MX-60 $649 1 $649

Inverter Outback VFX 3048E $1,995 1 $1,995

Inverter Breaker Box Outback OBDC-175 $119 1 $119

PV Modules Sharp ND-167U1 $745 6 $4,470

Phase Three Totals: $9,509

Batteries Concorde PVX-2580L $569 8 $4,552

PV Modules Sharp ND-167U1 $745 6 $4,470

Phase Four Totals: $9,022

Photovoltaic Totals: $45,047

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LOAD DEVICES Make and Model Power (W)

Consumption (kWh/day)

Isurge (A) Price

Centrifuge Drucker 614B 120 0.2 1.6 $272

EKG/ECG GE MAC 1200 5.85 0.0 0.1 $2,300

Ultrasound Terason 2000 150 0.6 2.0 $1,700

Fetal Monitor Viasys Elite 100 EN35R 1.8 0.0 0.0 $734

Water Purifier Solardyne UV-1 system 12 0.0 0.2 $459

UV Air Filter Hygeair 40-0188 40 0.4 0.5 $350*

Lights (4) Spectrum Arco 6 104 0.6 1.4 $120*

Portable Fans (3) Revel BF12 90 0.9 1.2 $45*

Pulse Oximeter Mediaid 5340 50 0.1 0.7 $135* AA battery charger (Ni-MH)

RadioShack 23-043 10 0.0 0.1 $30

Refridge (8.1 cu. Ft.) SunDazer DCR225 50 0.4 N/A $1,074 Refridge (8.1 cu. Ft.) SunDazer DCR225 50 0.4 N/A $1,074 Freezer (8.1 cu. Ft.) SunDazer DCF225 50 0.8 N/A $1,074

Phase I Totals: 733 4.5 8.0 $9,367

Autoclave Midmark Ritter M7 1,150 1.2 15.7 $1,829

Water Purifiers Solardyne UV-1 system 12 0.0 0.2 $459

UV Air Filter Air purifier-Model A-60 90 0.5 1.2 $350*

Lights (4) Spectrum Arco 6 104 0.6 1.4 $120*

Portable Fans (3) Revel BF12 90 0.9 1.2 $45*

Phase II Totals: 1,446 3.2 19.7 $2,803

Laptops (3) HP Compaq nx6325 195 1.2 2.7 $679 Laser Printer (stdby/printing)

HP Laserjet 1600 13/190 0.1 0.1 $224

Scanner HP Scanjet G4010 25 0.0 0.3 $150 FAX (stdby/Tx/Rx) Panasonic KXFL501C 5/25/200 0.2 0.1 $105*

Lights (4) Spectrum Arco 6 104 0.6 1.4 $120*

Portable Fans (3) Revel BF12 90 0.9 1.2 $45*

Phase III Totals: 804 3.1 5.8 $1,218

Small X-Ray (adapter) PX-110CL / United 1,200 1.9 16.4 $2,150*

Freezer/Fridge combo Barnstead 3750-1 160 2.9 2.2 $1,488

Phase IV Totals: 1,360 4.8 18.5 $3,638

Device Totals: 4,344 15.6 52.1 $17,026

Prices with an * are estimates.

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SUMMARY

Phase Equipment Load Phase Total

I $19,770 $9,367 $29,137

II $6,746 $2,803 $9,549

III $9,509 $1,218 $10,727

IV $9,022 $3,638 $12,660

System Grand Total $62,073

34

Appendix B: User Manual Although solar power systems are reliable and rugged, they do require periodic

maintenance. With that in mind, and realizing that the end users of this system will need a document to refer to, Fuji has prepared a brief user manual for the system it designed.

35

Project Fuji – PV System

Sample User Guide

Introduction

This document is written for the end user of the PV system designed by Team Fuji, and is intended to help the user better understand their system. For detailed information about the individual system components or installation information see the manufacture’s manuals.

System Description

Components AC System

All balance of system components, both inverters, and both of the charge controllers are located on a single mounting plate and located within the passive cooling shed within the solar farm enclosure. This mounted unit should look similar to the picture below.

The breaker panel on the left side of this mounting plate provides breakers for the AC lines. The breaker panel on the right side is for the DC lines. These breakers are labeled by which components they break the power to and at what current level. Also on the AC panel is a dual breaker labeled “Bypass”. When in “normal” mode this breaker allows current flow from the inverters to the load. When in “Bypass” mode this breaker disconnects the inverters from the hospital and allows current to flow directly from the generator (if installed) to the hospital. Be aware that in order to fully disconnect an inverter from the system, an additional breaker needs to be switched off which breaks the inverter AC input from the AC HOT IN bus bar. The DC panel has two large 175 Amp breakers for each of the inverters, and several smaller breakers for each side of both charge controllers.

36

The system MATE is also attached to this mount in the upper right corner. This device monitors and controls the system operation. When changes to the system operation need to be made, an administrator will re-program this device. The MATE is connected through the HUB (also located on the mount) to both of the inverters and both of the charge controllers. The MATE allows these devices to work in conjunction to prevent over-charge/over-discharge of the battery bank.

Both the solar array and the battery bank interface with the system through this mount. The battery bank positive line feeds to the battery positive bus bar (also located on the DC breaker panel) after which two lines feed power through the 175 amp breakers to the inverters. The array is split into two halves and each half is connected to the input of one charge controller. This charge controller will operate that half of the array at its maximum power voltage point. The charge controllers are then connected (through breakers) to the battery positive bus bar. The battery bank voltage level can be monitored on the status screen of the charge controller. The nominal voltage of the battery bank is 48 V. When the bank is adequately charged the bank voltage will be above this. When the screen shows a voltage at or below 48 V, consider disconnecting some devices until the voltage level rises again. If a generator is connected to the system, this will not be necessary since whenever the bank capacity drops to low levels the generator will be auto-started to help charge the batteries again. If this is the case, just make sure the generator always has fuel.

This setup is also described pictorially on the next page. DC System The DC system is much simpler in design. Since this system only supplies two DC refrigerators and a DC freezer, an inverter is not necessary and the system only requires two solar modules and four batteries. The modules are connected to the charge controller which is also connected across the terminals of the battery bank. Also connected across the battery bank terminals are the refrigerators and freezer. This system is also slightly oversized so that it may be able to support additional DC devices such as a fan and/or DC lighting. Be careful adding additional equipment, however. If the charge controller’s battery monitoring LED indicators ever turn yellow, disconnect all non-critical equipment immediately. If these LEDs glow red, this means the batteries are severely low and you should keep the refrigerator and freezer doors shut until they glow green again. The system is sized so that this should rarely happen, however, it is good to always keep an eye out. This system is also described pictorially on the next page.

37

Routine Maintenance

Weekly Tasks Clean the solar panels. This will help keep their output at the rated power level. Sweep off any debris, sand, dirt or dust and scrub any bird droppings clear. Anything that blocks the sunlight’s path to the surface of the panels must be cleared. Do this for both the DC and AC system panels. Check the generator fuel level. If the system includes a generator, check to make sure the generator’s fuel tank is full. If the tank needs to be filled more than once every other week complete the monthly tasks described below. Check system breakers. Check all DC and AC breakers on the AC system mount located in the shed within the solar farm enclosure. Since the AC system has multiple charge controllers and multiple inverters, the system can still operate (although at half capacity) even if some of these breakers have switched. If any breaker is “off”, reset it.

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Monthly Tasks Check system performance. If possible (and if desired) connect a laptop to the RS-232 port of the charge controller, download data (instructions available in the charge controller’s manual), plot, print, and FAX to a system administrator to be analyzed. Contact information for the administrator (including FAX number) should have been provided when the system was initially set-up. If an internet connection is available, simply send the data files via E-mail. This task is recommended if system performance is poor and/or erratic.

Troubleshooting

Symptom Diagnosis Solution AC system power outage

Hospital over-current Check AC breakers on the mounting plate in system shed. If “AC out” breakers are off, reset them.

Battery bank over-current

Check DC breakers on the mounting plate in system shed. If “DC in” breakers are off, reset them.

Battery bank low capacity

Check bank voltage level on charge controller status screen. If bank voltage is at or below 48 V, disconnect all electrical devices until bank is recharged. This could take up to several days if weather is cloudy.

Loose terminals Check wiring at all component terminals including charge controllers, inverters, battery bank, and breaker assemblies.

DC system power outage

Disconnect switched Check the panel and battery disconnects located on each side of the charge controller. If they are off, reset them.

Low batteries Check the charge controller LED indicators. If they are red than system has automatically shut off load due to low battery level. Keep doors of units closed until system charges.

Loose wiring Check wiring at all component terminals including charge controller, solar panels, and breakers.

39

Appendix C: Manuals and Specification Sheets Here’s where we put the manuals and spec sheets for the components of the system. These should be included in the final report, the installation manual, and the user manual. Concorde PVX-25080L http://www.concordebattery.com/xtenderpdf/PVX-2580L.pdf Outback MX60 http://www.outbackpower.com/pdfs_spec/MX60_a.pdf Xantrex C35 http://www.xantrex.com/web/id/63/docserve.asp Outback HUB4 http://www.outbackpower.com/pdfs_manuals/HUB%20rev%201.1.pdf Outback VFX3048E http://www.outbackpower.com/pdfs_manuals/Americas%20and%20Mobile%20manual%20rev%2072.pdf Outback PS2DC-175 and Outback PS2AC50D http://www.outbackpower.com/pdfs_manuals/PS2AC%20&%20DC%20Instructions%20REV%20G%20_900-0033-1_.pdf Sharp ND-167U1F http://solar.sharpusa.com/files/sol_dow_167U1F_ss.pdf Solar World SW-165 http://www.wholesalesolar.com/pdf.folder/module%20pdf%20folder/SW165175185.pdf Outback MATE http://www.outbackpower.com/pdfs_manuals/Mate%20rev%20230.pdf

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Appendix D: DC Load Analysis

This document contains the steps taken to determine the initial cost savings of a partial DC load. CALCULATIONS Instantaneous DC load (W) = ID DC load consumption (W*hrs/day) = DC Decreased System Load (W*hrs/day) = DL Savings in decreased panels ($) = SP Savings in decreased batteries ($) = SB Maximum DC line resistance (Ohms) = LR DC transmission wire diameter (in) = WD DC transmission wire gauge (AWG) = WG Added cost of DC transmission line ($) = CL Net Cost Savings ($) = NS CONSTANTS Cost per panel = CP DC load voltage (V) = V Panel peak output = PO max power loss (%) = PL Peak hrs per day = PH resistivity of copper (rho) = R Cost per battery ($) = CB Max ambient air temp (°C) = T Battery capacity (W*hrs) = BC Trans line dist (in) = LI Bank reserve (days) = BR Trans line dist (ft) = LF Delta of copper = D Inverter Losses = IL

( )[ ]( )

( )

CLSBSPNS

WG

LFWGCL

WDWG

DTLR

LIRWD

ID

PLV

LR

BC

CBBRDLSB

PHPO

CPDLSP

ILDCDL

−+=

×+×−=

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×−+××=

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72.1864.0

log2010

2014

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41

42

Appendix E: Wire Sizing Chart

43

44

Appendix F: Solicitation Packet The Fuji team has prepared a solicitation packet which can be used in the process of gathering donations from individuals, companies, and organizations. It contains three components: a business letter, a one-page brochure, and a website. The business letter and brochure can be found in this appendix. The website can be found at http://eecs.wsu.edu/~krobinso/sudan/.

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Project Fuji Senior Design Team <Address 1> <Address 2> Pullman, WA 99163 26 March 2007 <Company Contact> <Company Name> <Address 1> <Address 2> <City, State ZIP> Dear <Contact Name>: We are Project Fuji, an undergraduate senior design team at Washington State University. It is made up of five engineering students who are sponsored by a student group called Engineers Without Borders. The team has just completed the design of a solar power generation system for a hospital in Abri, Sudan. The hospital serves a population of 40,000 people but does not have access to electrical power so it cannot operate essential pieces of medical equipment. As a consequence, patients are often forced to travel over 200 miles for adequate treatment. This project will directly improve the quality of life for people living in Abri. We are excited about this project and very dedicated to its success, and we would like to invite <Company Name> to share a part in this important philanthropic work. If your <company/organization> is interested in sponsoring our group, we would like you to consider contributing <product> for use in our team’s prototype. We also need to continue collecting funding and supplies for the full implementation of the system in Sudan. Whatever you can do to help will be greatly appreciated, and all donations will be 501(c)(3) tax deductible. If you have any questions, please feel free to contact any of the following people: Kylan Robinson, Fuji Team Leader kylan@wsu.edu (253)426-8395 Dr. Patrick Pedrow, Supervising Professor <email> <phone> Dr. Mohamed Osman, Fuji Team Mentor <email>

46

<phone> For more information, please see the enclosed brochure, or visit the project web page, which is located at http://www.eecs.wsu.edu/~krobinso/sudan. Thank you for your time. Sincerely, The Project Fuji Team Enclosure

47

Washington State University Senior Design Project:

Designing a Solar Power System for a Hospital in Sudan

This project is focused on serving a community hospital in Abri, Sudan. The hospital is located in a rural area and supports a population of nearly 40,000 people. Due to a lack of electricity, though, the hospital is unable to adequately serve the public. This means that patients often must travel over 200 miles for sufficient treatment. Currently, an undergraduate senior design team from Washington State University is working to design a standalone solar power system that can provide for the hospital’s electricity needs. The Abri Hospital

Patients at the Hospital

The WSU team is made up of five undergraduate students who have a strong desire to apply their skills in a way that can assist Abri’s doctors in treating the ill and saving lives. The team is completing the project as part of an Engineers Without Borders initiative. Once the design is complete and funding is secured, the system will be implemented by Builders Without Borders. Throughout the project, the design team has also been working with Napata.org, a local NGO in Sudan.

In order for this project to be successfully implemented, the design team needs to secure funding and equipment from companies and organizations like yours. Any donations made are tax deductible and would be greatly appreciated. The design team is planning to prominently display the names and logos of sponsors at the team’s design showcase this coming April. For more information, please go to

http://www.eecs.wsu.edu/~krobinso/sudan Thank you for your time.

The WSU Senior Design Team