Associated Students: Solar Charging Station

Title Pa

Maytham Alhaddad

Salam Ali

Erik Marquis

Jairo Orozco

Chao Vang

MECH/MECA 440A

Final Design Report

May 17, 2016

Department of Mechanical and Mechatronic Engineering

and Sustainable Manufacturing

California State University, Chico

Chico, CA 95929-0789

ii

Executive Summary

The AS Solar Charging Station project was brought forth to the Sustainability Fund

Allocation Committee (SFAC) by Trenten N. Bilodeaux, Director of the Panel Law Project

Community Legal Information Center (CLIC) and Dr. Gregory Kallio, Professor of Mechanical

and Mechatronic Engineering, in an effort to provide a visible campus element that underscores a

commitment to sustainability.

The primary objective of this project is to design and implement an off-grid solar charging

station that will allow up to six students to charge and use their portable electronic devices.

Currently, there are no outdoor facilities for charging electronic devices on campus. The station

adds a visual element of campus sustainability, while teaching students of the technologies

associated with solar energy. The Solar Charging Station features thin-film photovoltaic solar

modules, a 14’ x 14’ pyramidal shade structure, security lighting, dual GFCI/USB outlets, auxiliary

charging cords, sustainably sourced wood, as well as access to an integrated monitoring system of

the charging stations performance. Furthermore, the station provides up to 1457 kWh/day to allow

up to 18 devices (phones, laptops, tablets) to be charged for the 12 hours of operation, all while

providing two days of autonomy on days of overcast and little sun via a 780 Amp hour (Ah) battery

bank.

iii

Acknowledgements

Sponsor

Sustainability Fund Allocation Committee, Associated Students

Ricardo Jacquez

Dean, College of Engineering, Computer Science and Construction Management

Ben Juliano

Interim Assoc. Dean, College of Engineering, Computer Science and Construction Management

Dr. Gregory Kallio

Professor of Mechanical and Mechatronic Engineering

Steven Eckhart

College of Engineering, Tech Shop Supervisor

Dave Gislon

College of Engineering, Tech Shop Technician

Scott Vanni

Lecturer of Mechanical and Mechatronic Engineering

David Sprague

Assistant Director of Design, Construction and Maintenance

Tom Ussery

Academic Facilities Administrator

Jenny Dempsey

Regional Manager, USA Shade & Fabric Structures

Dennis Partington

Network Manager, Network Operations

iv

Table of Contents

Executive Summary.................................................................................................................... ii

Acknowledgements.................................................................................................................... iii

List of Figures............................................................................................................................. vi

List of Tables.............................................................................................................................. vii

Nomenclature.............................................................................................................................. viii

1. Background and Introduction.................................................................................................. 1

2. Problem Definition................................................................................................................. 2

3. Concept Generation................................................................................................................ 3

4. Final Design............................................................................................................................ 5

5. Detailed Analysis and Design................................................................................................ 6

5.1 Solar Access.............................................................................................................. 6

5.2 Electrical Load Analysis........................................................................................... 7

5.3 PV module Selection................................................................................................ 10

5.4 Battery Sizing and Selection.................................................................................... 10

5.5 PV Array Sizing and Charge Controller Selection.................................................. 11

5.6 Inverter Sizing and Selection................................................................................... 12

5.7 Wire and Breaker Sizing.......................................................................................... 12

5.8 Educational Signage and Monitoring Equipment.................................................... 14

5.9 System Integration................................................................................................... 15

5.10 Shade Structure and PV Mounting........................................................................ 16

5.11 Seating: Table and Benches....................................................................................18

5.12 Testing Results and Interpretation..........................................................................24

6. Planning................................................................................................................................. 29

7. Budget.................................................................................................................................... 29

8. Justification............................................................................................................................ 32

9. Discussion.............................................................................................................................. 33

10. Recommendations................................................................................................................34

References..................................................................................................................................35

v

Appendix A: Load Analysis and Equations..................................................................................A1

Appendix B: PUGH Analysis...................................................................................................... B1

Appendix C: Component Spec Sheets..........................................................................................C1

Appendix D: Wiring Diagram.......................................................................................................D1

Appendix E: CAD Drawings.........................................................................................................E1

Appendix F: Full Test Plan and Data ...........................................................................................F1

Appendix G: Budget Analysis......................................................................................................G1

Appendix H: Login Information...................................................................................................H1

Appendix I: Gantt Chart.................................................................................................................I1

vi

List of Figures

Figure 1: Solar Charging Station Location......................................................................................4

Figure 2: Design Concept 1.............................................................................................................4

Figure 3: Design Concept 2.............................................................................................................4

Figure 4: Final Design Concept.......................................................................................................6

Figure 5: MiaSole FLEX-01, 220W Module.................................................................................10

Figure 6: Login Display Location..................................................................................................15

Figure 7: Single Post, Pyramidal Shade Structure.........................................................................17

Figure 8: PV Array Arrangement..................................................................................................18

Figure 9: Table and Bench Final Design Concept.........................................................................19

Figure 10: Battery Storage.............................................................................................................20

Figure 11: Tabletop Decal.............................................................................................................21

Figure 12: Center Console Component Storage............................................................................22

Figure 13: GFCI/USB Outlets and Auxiliary Cords......................................................................23

Figure 14: Evening Lighting at Location.......................................................................................24

Figure 15: State of Charge Test ....................................................................................................26

Figure 16: Budget Breakdown.......................................................................................................31

vii

List of Tables

Table 1: Must Do Engineering Specifications...............................................................................3

Table 2: Average Sun Hours..........................................................................................................7

Table 3: Average Laptop Charger Output......................................................................................8

Table 4: Average Cell Phone Charger Output................................................................................8

Table 5: Average Tablet Charger Output.......................................................................................9

Table 6: Load Calculation..............................................................................................................9

Table 7: Wire Sizing......................................................................................................................13

Table 8: Breaker Sizing.................................................................................................................14

Table 9: Battery State of Charge...................................................................................................28

Table 10: Section Budget Breakdown...........................................................................................32

viii

Nomenclature

𝑉𝑜𝑐,𝑀𝑎𝑥 Maximum Open Circuit Voltage

𝑉𝑜𝑐,𝑆𝑇𝐶 Standard Test Condition Open Circuit Voltage

𝛽𝑜𝑐 Open Circuit Temperature Coefficient

𝑇𝑎𝑚𝑏,𝑚𝑖𝑛 Minimum Ambient Temperature

𝐼𝑆𝐶 Short Circuit Current

𝐼𝑐𝑐,𝑚𝑎𝑥 Maximum Charge Controller Current

VDI Voltage Drop Index

𝑉𝑚𝑝𝑝 Voltage at Maximum Power

1

1. Background and Introduction

Starting in 2006, the Associated Students (AS) Sustainability Fund was created when

students voted to fund the creation of the AS Sustainability Program and a fund for student-driven

sustainability projects. Approximately $80,000 in funds are available annually for these projects.

The Sustainability Fund Allocation Committee (SFAC) is in charge of allocating funds to projects

each semester. The AS Solar Charging Station project was proposed to SFAC by Trenten N.

Bilodeaux, a student and Director of the Panel Law Project Community Legal Information Center

(CLIC) and Dr. Gregory Kallio, Professor of Mechanical and Mechatronic Engineering, in an

effort to provide a visible campus element that underscores a commitment to sustainability.

This project is intended to fulfill a technological need and an educational objective in the

area of sustainable energy. The technological need is a widespread demand for charging portable

electronics devices on campus, especially in an outdoor environment where students can gather

and enjoy the wonderful Chico climate. The educational objective is to provide a visible campus

element that underscores a commitment to sustainability while teaching students of the

technologies associated with solar energy. To date, no other physical entity exists on campus that

fulfills these goals in the area of solar energy. Currently, there are several solar charging stations

on the market for purchase; unfortunately, most are simply too expensive and do not provide

students the opportunity to implement the engineering design and fabrication process. Funding for

this project has been secured from SFAC in the amount of $12,000, with a contribution of an

additional $3,325 from the College of Engineering bringing the total amount of this project to

$15,325.

2

2. Problem Definition

The problem is to design, build, and implement a solar photovoltaic (PV) charging station for

charging portable electronic devices. The design will incorporate University-approved seating

(table and benches) that are aesthetically integrated with the surrounding area. All this must be

considered, in addition to the following requirements:

The project must:

Be an off-grid system

Have educational signage

Have 120 VAC/Ground Fault Circuit Interrupter (GFCI) receptacles and Standard,

5VDC/2A max, USB receptacles

Have an emergency shutdown

Provide security lighting

Have all electrical components enclosed

Be aesthetically pleasing

Have seating for at least six people with 25% Americans with Disabilities Act (ADA)

access

Pass inspection by a licensed electrician

Be structurally robust

Have sufficient power and storage for six people charging typical devices (laptop and

smartphone) throughout the day

The project should provide:

A WIFI Hotspot

Shade

It would be nice if the project:

Has a system of cooling

3

Collaborated with the Art Department for the aesthetics of the shade structure

The Solar Charging Station (SCS) will provide sufficient power and storage to charge all

electronic devices (smartphones, tablets and laptops) throughout the day. The “Must-Do”

quantitative engineering specifications are given in Table 1. The target values for power and

storage are determined as part of the design process (Section 5).

Table 1: Must-Do Quantitative Engineering Specifications

Requirements Engineering

Specifications Metric Method Conditions Target

Maximum

Footprint Area m2 Tape Measure BMU Location 8’ x 8’

Structurally

Robust Wind Speed mph

Manufactures

Specifications

Chico maximum

Wind Speed 85 mph

Sufficient

Power Power kW

Inverter

Specifications

6 People Using

Devices <0.685 kW

Sufficient

Storage Energy kWh

Battery

Specifications

Laptops, smart

devices and fans 1.45 kWh/day

3. Concept Generation

The site selected for the installation of the SCS is the Bell Memorial Union (BMU) outdoor

seating area. Of four other sites considered, the BMU location has the highest traffic of students

throughout the day, is most well-lit at night, and has comparable solar insolation. Figure 1 shows

the location of where the charging station will be installed. In order to provide accessibility and

provide adequate room for the station, one of the tables would have to be removed or placed in a

different location, pending the approval from the Associated Students.

4

Figure 1: Solar Charging Station Location

Currently, there are several solar charging stations on the market for purchase in various

designs; however in keeping with the requirement that the SCS must be aesthetically pleasing and

integrated sympathetically with its surroundings, the design was based on the current seating, as

shown above. As Figures 2 and 3 illustrate, one design idea was to incorporate the same rectangular

seating in the SCS. Furthermore, as per customer requirement, the SCS will seat six people total;

seating for two people on each bench and two vacant areas at the ends of the table, reserved for

those with disabilities.

Figure 2: Design Concept 1 Figure 3: Design Concept 2

5

Current solar charging stations on the market today utilize rigid, crystalline PV solar modules.

Unknown to many, there is an entirely different type of solar panel that can simply be rolled out

and attached using pressure sensitive adhesive (PSA). This type of module is known as thin-film

PV. In comparison, the crystalline solar module weighs, on average, about 10.4 kg (23 lbs),

whereas thin film modules can weigh as little as 2.3 kg (5 lbs). As opposed to crystalline modules,

which are installed on strong rooftops with a robost mounting system tilted at a fixed angle, thin

film modules can be rolled out and directly adhered to rooftops, polycarbonate fabric,

thermoplastic polyolefin and high density polyethylene (HDPE). This allows them to be installed

on various surfaces without racks or heavy support structures. The process of determining which

module to use for the SCS will be discussed more in detail in Section 5, as well as the battery bank,

charge controller, inverter and other solar components.

4. Final Design

With the customer requirements in mind and analysis complete, Figure 4 illustrates the final

design. Shown in the figure, the SCS will incorporate a pyramidal shade structure, thin-film solar

modules, multiple GFCI and USB receptacles, as well as auxiliary cords for various smart devices.

Among the features listed below, all electrical components will be enclosed within the benches

and center console, beneath the table top. These enclosures will each have locked, maintenance

doors to ensure easiest access to the components within. The detailed analysis and design of each

component will be discussed further in Section 5.

6

5. Detailed Analysis and Design

The process for sizing and selecting the necessary components for an off-grid system are

as follows: solar access, measurements and analysis, electrical demand estimate, battery sizing,

module sizing, charge controller sizing, inverter sizing, wire sizing and breaker/fuse sizing. A step-

by-step analysis with corresponding calculations of theload analysis can be found in Appendix A.

5.1 Solar Access

It was necessary to collect details about the site of the project, which include effective sun

hours and longitude and latitude. Full-sky solar irradiation for Chico was computed by PVWatts,

a web source, and the Solmetric instrument, SunEye, was used for the shading analysis. Estimating

that the station will be in high demand 10 months (highlighted below) of the year and multiplying

the irradiation data from PVWatts by the percent solar access from the SunEye, the annual, average

sun hours per day is 4.2 hours, as shown in Table 2.

Figure 4: Final Design Concept

7

Table 2: Average Sun Hours

Month Solar Radiation

( kWh / m2 / day )

SunEye Solar

Access

Fraction

Sun Hours with

Shading

(kWh/m^2/day)

January 3.52 0.19 0.6688

February 3.88 0.494 1.91672

March 5.17 0.811 4.19287

April 6.32 0.853 5.39096

May 7.25 0.864 6.264

June 7.48 0.888 6.64224

July 7.49 0.865 6.47885

August 7.21 0.860 6.2006

September 6.82 0.843 5.74926

October 5.54 0.747 4.13838

November 3.71 0.272 1.00912

December 3.12 0.170 0.5304

Average for

SCS 5.65 4.19

5.2 Electrical Load Analysis

Estimating the electric load is a key component of the process and requires careful

consideration. As previously mentioned, there will be seating for six people with 120V, GFCI and

USB receptacles. The first step was to determine the average charger output of all the devices that

will likely be plugged into the receptacles, i.e. laptops, smartphones (Android and iPhone), and

tablets. As Table 3 illustrates, the average output/power for many name brand laptops is

approximately 80 W. For various smart phones, the average output is approximated at 10 W, as

Table 4 demonstrates. Lastly, the average output for several tablets was tabulated at 15 W (see

Table 5 below).

8

Table 3: Average Laptop Charger Output

Laptop Brand Potential Difference

(V)

Current

(A) Power (W)

APPLE 16.5 3.65 60.225

ASUS 19 2.37 45.03

ACER 19 3.42 64.98

ALIENWARE 19.5 7.7 150.15

DELL 19.5 4.62 90.09

GATEWAT 19 4 76

HP 19 4.72 89.68

LENOVO 20 3.25 65

SONY 19 4.74 90.06

SAMSUNG 19 3.33 63.27

TOSHIBA 19 3.95 75.05

FUJITSU 19 4.22 80.18

Average 18.96 4.16 79.14

Table 4: Average Cell Phone Charger Output

Cell Phones Potential Difference

(V) Current (A) Power (W)

Apple Iphone Charger 5.1 1 5.1

Samsung Smart Phone 7 2 14

Samsung Smart Phone 9 2 18

Blackberry Classic 5 0.85 4.25

Blackberry Passport 5 1.3 6.5

Average 6.22 1.43 9.57

9

Table 5: Average Tablet Charger Output

The maximum load of the system was assumed when all eight 120V and 4 USB receptacles

are in operation, in conjunction with four enclosure cooling fans; however, the assumption that the

system will rarely, if ever, be fully seated and serving eight laptops and/or eight tablets and phones,

can be made. In addition, the assumption was made that each device would be used six days a

week; however the hours of operation for each differ, as Table 6 shows. The estimated average

daily use is 1457 Wh/Day.

Table 6: Load Calculation

Tablets Potential

Difference (V) Current (A) Power (W)

Apple iPad & iPad mini wall

charger 5.2 2.4 12.48

Apple USB cord 5.1 2.1 10.71

USB Power Adapter /

Charger for Samsung Galaxy 5 2 10

Sony Xperia Z4 Tablet 5 1 5

Toshiba - Excite tablet 12 3 36

Average 6.46 2.1 14.84

Appliance Quantity Watts Minutes

On/Hour

Hours

On/Day

Days

On/Week

Average

Watt

Hours/Day

Max Watt

Hours/Day

Laptops 4 80 60 2.5 6 960 1120

Cell Phones

(Andriod &

iPhone)

6 10 60 1.5 6 128 150

Tablets 4 15 60 1 6 102 120

Fans 3 8 60 12 6 267 312

Total Average Watt-Hours/Day: 1457

10

5.3 PV Module Selection

The selection of which PV module to use, thin-film or rigid, began with a PUGH analysis

(refer to Appendix B). Using the Panasonic Hit Power 240S rigid module as the datum, various

thin-film and rigid PV panels were analyzed based on weight, dimensions, efficiency, warranty,

ease of installation and cost per Watt. The MiaSole FLEX-01, 220W module is the best option as

it is significantly lighter and smaller in dimension, as well as easier to install, than the rigid panel

(refer to Appendix C). Not only does the MiaSole FLEX-01, 220W module excel in the areas

mentioned above, the power output of the thin-film modules is less affected by high temperatures

and shading, meaning that the efficiency is slightly higher than rigid panels. As Figure 5 shows,

because of the modules thin and sleek design, the chance of vandalism and theft are reduced as the

flexible modules will not shatter if struck by debris.

Figure 5: MiaSole FLEX-01, 220W Module

5.4 Battery Sizing and Selection

The battery bank must meet the load demands without risk of more than 50% discharge or

producing harmful gases of the batteries. Per the customer requirements, the SCS must be easy to

maintain; thus Absorbent Glass Mat (AGM) batteries will be used. AGM batteries are lead-acid

11

batteries, one of the safest lead acid batteries as there is little chance of a hydrogen gas explosion

or corrosion when in use and need minimal maintenance.

To size the battery bank, the daily load is divided by inverter efficiency, desired system

voltage, depth of discharge, and the battery temperature modifier. The days of autonomy are an

important factor in sizing the system. It is essentially a safety factor to account for days of overcast

and even modular malfunction. For this system, two days of autonomy was chosen as the stations

GFCI and USB outlets will completely shut down on Saturday, rendering it simply as a seating

area. This will allow the SCS to fully replenish its battery bank. The needed amp hours was

calculated to be approximately 630 AhDC/day. Assuming the system will be a 24V system, to

completely charge the battery bank, the maximum power point voltage (Vmpp) would need to be in

the range of 30 to 32V. Noting that the maximum power point voltage of the module is 22.6V and

that the wiring of the modules will be parallel (the voltage of each panel remains the same and the

amperage of each panel is added), a 24V system voltage would be incompatible with the modules;

therefore, the system will be 12V. Essentially, a battery bank of 648 Ah would have been sufficient,

however after further analysis in cost, the SCS will use four, 6V, 390 Ah Crown AGM batteries

(refer to Appendix C). The batteries will be arranged in two strings, each wired in series and

parallel so that the resulting voltage and amp-hour are 12V and 780 Ah. There are added benefits

to having a battery bank larger than what is calculated/needed, such as a large safety factor (~100

Ah) which, in turn, allows for more days of autonomy.

5.5 PV Array Sizing and Charge Controller Selection

The array sizing is determined by taking the daily load calculated above and dividing it by

battery and controller efficiency, sun hours, temperature loss factor, shading coefficient, and derate

12

factor. This ensures that the battery bank will recharge in one typical day. The result of this was

685 WDC. The daily load of 685 WDC was divided by the MiaSole power rating of 220W,

yielding a need of 3 modules, with a very negligible deficit in power. The modules will be wired

in parallel so that the voltage of each module remains the same and the amperage of each module

is added. A charge controller was selected that could deliver the needed current and handle the

incoming voltage from the modules. Two charge controllers were considered: the Outback Power

FlexMax 60 and 80. Based on the calculations, a 77 amp max output is needed for the system;

therefore, the Outback Power FlexMax 80 charge controller is chosen (refer to Appendix C for

specification sheet).

5.6 Inverter Sizing and Selection

Powering the outlets, cooling fans, auxiliary cords and other system components requires

converting the DC power output of the batteries to useable AC power. This is done through an

inverter. The inverter is determined primarily by the system voltage (12V) and the largest,

simultaneous power draw. Given the predefined power loads described in Sections 5.2-5.4 and

noting that the derate factor accounts for all the system power losses that isn't equipment related

(i.e. wire lengths, wire connections, panel mismatch, etc.), the largest concurrent power loads

equates to 492 W. The inverter chosen is the Outback FX2012T.

5.7 Wire and Breaker Sizing

Wire and breaker sizing is crucial for delivering proper power to, for and between solar

components. Since the modules will be arranged in parallel, a combiner box with a circuit breaker

for each module is needed to prevent module damage from possible reverse currents. The PV

13

arrays grounding conductor will be wired to a ground rod, which will be embedded 8 feet into the

concrete below the stations location. A direct current (DC) disconnect switch will be installed near

the place where the cables from the combiner box enter the housing. The main DC disconnect

switch is followed by a DC ground fault interrupter hat is designed to open the circuit when a

certain leakage current to ground from an ungrounded bus is detected. The current from the PV

array is responsible for charging and recharging the batteries. To protect them from overcharging

or from discharging by reverse currents, normally they are connected to the PV array via a battery

charger. To extract the maximum power out of the array, the PV panels should operate near

maximum power point (VMPP) of their I-V curve, as previously discussed. A DC voltage from the

battery bank is then converted to AC by a DC-AC inverter. Estimating the distances between each

component and box then calculating the ampacity and the voltage drop of the PV array to combiner

box, combiner box to the charge controller, charge controller to the DC disconnect, the DC

disconnect to the battery bank and battery bank to the inverter, the wire sizing for each was

determined, as Table 7 illustrates.

Table 7: Wire Sizing

PV array to combiner box: 10 AWG

Combiner box to charge controller: 6 AWG

Charge controller to Disconnect: 4 AWG

Disconnect box to inverter: 2/0 AWG

Inverter to Battery Bank: 2/0 AWG

The breakers needed for the SCS were determined by first calculating the maximum current of

each wire as it enters and exits each solar component. Once calculated, the breakers are sized and

the results are shown in Table 8.

14

Table 8: Breaker Sizing

PV array to combiner box: 30 A

Combiner box to charge controller: 65 A

Charge controller to battery bank: 85 A

Battery bank to inverter: 175 A

5.8 Educational Signage and Monitoring System

The goal of the SCS is to provide a visible campus element that underscores a commitment

to sustainability while teaching students of the technologies associated with solar energy. As such,

an educational signage/display must be implemented into the overall design. Many design options

were considered; however after further research into Outback Power products, it was found that

the MATE3 System Display and Controller (MATE3) provides that ability to monitor and program

each OutBack component (inverter and charge controller). Along with the Outback HUB4, the

MATE3 coordinates system operation, maximizes performance, and prevents multiple products

from conflicting with each other, which could result in power drainage. In addition, it monitors the

overall system, provides feedback and can store data via SD card for system monitoring (refer to

Appendix C). In regards to system monitoring, the MATE3 is compatible with OpticsRE, an

interactive monitoring software provided exclusively for OutBack Power systems. By connecting

the MATE3 to the University’s network, via Ubiquiti AirWire, the information the MATE3

collects is sent wirelessly to a static IP address specific to the station. Once there, the data can be

configured and displayed into various graphs and charts displaying such data as battery state of

charge, energy coming into the modules and how much is being consumed by devices. Users of

the station can then login into OpticsRE with the username and password provides, placed next to

the GFCI/USB outlets as Figure 6 shows, to see the energy use and production and monitor factors

15

such as kilowatt hours produced per day (kWh/day), depth of charge in the batteries and much

more. Furthermore, OpticsRE is accessible from any computer, tablet or phone, to allow those who

are curious accessibility at all times of the day, from the comfort of their homes.

Additionally, OpticRE allows the technician to monitor and configure parameters on the inverter,

MATE3 and charge controller, in addition to monitoring the system efficiency and performance.

Figure 6: Login Display Location

5.9 System Integration

With all the solar components chosen, as well as the wire and breaker sizes complete, the

wiring of the entire system and component layout was next to be planned out. As such, the four,

6V batteries will be located under one bench, whereas the remainder of the solar components such

as the inverter, charge controller and DC disconnect box will be located in the center console. The

16

exact placement of these components will be elaborated on in Section 5.11. The complete wiring

diagrams, including breaker and wires sizing, can be found in Appendix D.

5.10 Shade Structure and PV Layout

With the use of thin-film PV modules, the need for heavy, bulky mounting equipment used

for traditional, rigid panels is unnecessary. The current seating at the BMU features a red,

collapsible and adjustable umbrella. In keeping with the surrounding design, the shade structure

will be single posted; however it will be pyramidal in shape, as shown in Figure 7 below. The

single post, pyramidal shade structure is a 14’ x 14’, non-collapsible and manufactured by Shade

Structures USA. Shade Structures USA is the largest fabric structure designer and manufacturer

in North America and handle everything from conceptual design to installation. The shade

structure is rated to withstand 115 mph winds, which fulfills the 85 mph wind requirement. It also

has a snow load of about 20 pounds, which is important as the modules will be adhered to the top

of it. Since the shade structures fabric is made of HDPE, the MiaSole modules adhesive will

securely fasten to it; however, as the modules have yet to be installed due to the timing of

permitting, it is unclear at how securely the modules will adhere. If the adhesive does not adhere

as expected, thin pieces of aluminum will be placed on all corners and two-thirds down each side

of the module and the underside of the fabric and riveted together. This creates a frame around the

modules and secures them into place, all while allowing air to flow in between fabric and module

to reduce the oscillation of the shade structures fabric.

As shown in the figure below, grommets have been placed in the fabric to allow the MC4

connectors to be pulled through, secured to the rafters and run down the column through grommets

placed at the top and bottom. In regards to the placement of the modules, keeping in mind that

17

they will be wired in parallel, each module will be placed horizontally on the South, East and West

facing sides in order to receive optimal sunlight throughout the day. Below, Figure 8 illustrates the

concept.

Figure 7: Single Post, Pyramidal Shade Structure

18

Figure 8: PV Array Arrangement

5.11 Table and Benches

Initially, various solar charging station manufacturing companies were looked into to

manufacture the table and benches for the SCS, however due to various constraints such as design

implementation and manufacturing capabilities, the decision to simply manufacture the seating in

house was made. As such, the production of the seating was put under the direction of CSU,

Chico’s fabrication shop. The fabrication shop was provided with all necessary computer-aided

design (CAD) drawings, which can be found in Appendix E. As previously states, the benches and

19

tabletop will be rectangular in shape in an effort to integrate the SCS with the surrounding tables

and be 25 percent ADA compliant, as Figure 9 illustrates.

Figure 9: Table and Bench Final Design Concept

To construct the benches, which will house the 4 AGM batteries in one bench as illustrated

in Figure 10, A-36 mild steel c-channels was used to create the skeleton and welded together with

one truss in each bench to ensure structural rigidity. To cover the frame, 12 gauge steel sheet metal

was used. The outer side of the benches (long panel facing away from table) are secured with torx

pin-in security machine screws, to allow for accessibility and maintenance of the batteries. The

remaining panels are secured to the frame through rivets and can only be removed with a power

drill. To ensure the batteries have adequate ventilation to maintain proper and safe battery

temperatures, one 115V, AC fan has been mounted (data sheet in Appendix C), in addition to a

natural vent to allow for proper circulation. Both ventilation slots will have mesh in the interior to

deter pests and dust from entering.

20

To allow battery wiring to connect to other components and keep these wires safely enclosed and

out of the way a conduit has been placed underground, with the conduit openings located between

the bench and center console. A full dimensional drawing of the trench layout can be found in

Appendix E.

As shown in Figure 9, wood will be fastened to the bench and tabletop for aesthetics and

comfort. In an effort to uphold the sustainable practices shown throughout the campus, the wood

used came from a 400-year-old blue pine, that fell naturally up in Red Bluff. Brandon Grissom,

owner of Enjoy the Store reached out to this project and agreed to do the wood work.

Unfortunately, due to time constraints, the wood was unfinished by Grissom, but was completed

by the team. The work to ensure the completion and weatherproofing of the wood consisted of

sanding, staining, priming and applying resin and epoxy. In addition, a decal was added to the

tabletop, as Figure 11 illustrates. The decal was CNC’d by the Sustainable Manufacturing

department and inlaid within the table.

Figure 10: Battery Storage

21

Figure 11: Tabletop decal

The center median was constructed similar to the benches: using c-channels to form a

skeleton, placing 12-guage sheet metal panels over the frame and placing the blue pin wood on

top. Similar to the benches, the center median contains important solar components such as the

charge controller, DC disconnect box, inverter, etc. Once again, to maintain an optimal functioning

temperature for the components within, two 115V, AC fans are mounted to the sheet metal with

corresponding natural ventilation slots. All fans within the SCS are turned on and off via a

temperature controller. Once the temperature controller reads the interior temperature of the center

console at 90 degrees Fahrenheit, the three fans turn on and continue to run until the interior

temperature drops below 80 degrees Fahrenheit. In order to access the components within to

perform routine system maintenance and/or perform checks, the components are mounted to a

separate sheet of sheet metal and placed on a rail system to allow the technician to simply unlock

the side panels and easily monitor all components. The layout of all components is illustrated in

Figure 12.

22

Figure 12: Center Console Component Layout

As stated earlier, a customer requirement is that the SCS has 120V GFCI and USB

receptacles. As Figure 13 shows, the GFCI and USB receptacles are placed in the middle of the

table with a dual outlet containing both the GFCI and USB plug-ins; there is a total of 8 GFCI

outlets and 4 USB outlets. All electrical wiring is encased and out of the way with all the outlets

protected from the elements by adding a weatherproof flip lid cover to each. In addition to the

GFCI and USB outlets, the station provides its users with two, 4-in-1 charging auxiliary cords for

all smartphone devices. The auxiliary cords will be available for the following phones and there

will be a total of 8 cords (2 for each category):

iPhone 4/4S

iPhone 5/5S/5C/6/6S

23

Android

In an effort to deter the cords from being damaged or tampered with, the length of the cords will

be kept at 0.0381 meters (1.5 inches). In case of vandalism or damage to the cords, the vendor list

and price of all components can be found in Appendix G.

Figure 13: GFCI/USB Outlets and Auxiliary Cords

Another customer requirement dictates that the SCS have security features such as lighting,

emergency shut off switch and hours of operation. As Figure 14 shows, the location of the solar

charging station is adequately lit; however additional lighting is intended to deter vandals and

transients from approaching the SCS in the evening hours. This is achieved by the addition of

LED, motion detection lights that is set to turn on when someone approaches (within 15 feet) the

24

station and stays on for a burst of 45 seconds. Another security measure will be to turn off all

power to the GFCI/USB receptacles, as well as the auxiliary cords, during hours of non-use. As

such, the SCS will be in operation from the hours of 8am to 8pm, Monday through Friday and

Sunday. This is achieved through a timer which is preset to “power on/off” the outlets and auxiliary

cords based on the parameters and times set.

5.12 Testing Results and Interpretation

As described in Section 1 and illustrated in Table 1, the SCS has a set of Must Do

Quantitative requirements that need to be tested in order to ensure that all customer requirements

are met and that the station works as designed (refer to Appendix F for full test plan and data

sheets). The tests conducted were as follows:

Figure 14: Evening Lighting at Location

25

1. Maximum Footprint

a. Cannot exceed 8 x 8 feet

2. Storage Capacity/Days of Autonomy

a. Must sustain 2.78 kWh for 2 days without discharging the battery bank

more than 50%.

3. Maximum Power Specification

a. Inverter must sustain up to 0.685 kW/day to allow 6 people to charge

various devices.

4. Monitoring System and Mate3 Reconfiguration

a. Accurately monitor and collect data from the MATE3 and display said

data to OpticsRE, while allowing it to be user-friendly.

5. Safety Features

a. Ensure that the inverter shuts down once the battery state of charge

(SOC) reaches 50% to maximize the lifespan of the battery bank.

b. GFCI/USB receptacles will shut down after 8pm and turn back on at

8am.

The first quantitative test was the total footprint and straightforward to test. The maximum

footprint of the station cannot exceed 8 x 8 feet; the SCS total footprint is measured at 8 x 6 feet,

meeting and passing the requirement.

For the storage capacity and days of autonomy test, the station was designed to sustain a

2.78 kWh load for two days without depleting the batteries more than 50% in days of overcast and

little sun. The battery bank of the SCS is responsible for sufficiently storing solar energy collected

and allowing users to charge their electronic devices. Considering the battery bank is 780 Ah,

26

about 100 Ah more than what is required, it was highly likely that the station would pass this test.

After sustaining an 800W load for three and a half hours, the state of charge (SOC) was 63%,

meeting and passing the requirement, as Figure 15 illustrates.

Figure 15: State of Charge Test

Powering the outlets, cooling fans, auxiliary cords and other system components requires

converting the DC power output of the batteries to useable AC power and is achieved through the

inverter. For the maximum power specification test, the inverter must sustain up to 0.685 kW to

allow 6 people to charge various devices. After the battery bank reached 100% SOC, the inverter

was loaded with an 800W load and monitored for an hour and half to ensure the inverter did not

shut down due to an overload. As expected, the inverter was able to sustain an 800W load for an

hour and a half, meeting and passing the third requirement.

The objective of the Monitoring System and MATE3 Reconfiguration test is to verify that

the collected data from the MATE3 is monitoring and accessible on the OpticsRE website. The

test process did not involve any measurements as it is assumed that the purchased components will

27

function as specified in the vendor document. Once the initial log-in and configuration of the

MATE3 connectivity to a known network and OpticsRE was established, the display of features

such as battery SOC, inverter consumption, load consumption, etc. needed to be verified. By

powering the station and applying various loads via plugging in phones/laptops/tablets, real-time

data was monitored via OpticsRE. After setting up a guest account that users will be able to log

into, it was determined that the MATE3 and OpticsRE were communicating properly and

displaying real-time data, meeting and passing this requirement. Note that with the guest account,

users can only view data coming in and cannot change or view parameters set on the MATE3,

inverter and charge controller; only the administrator can do so (refer to Appendix H for login

information). In addition, it is necessary to check every 2 months with Outback Power Systems

via website for firmware updates for the MATE3 to ensure proper connectivity with OpticsRE.

Per customer requirement, the SCS will have security features such as lighting, emergency

shut off switches and hours of operation. One security feature is ensuring the inverter shuts down

once the battery state of charge (SOC) reaches 50% to maximize the lifespan of the battery bank.

If a battery is discharged more than 50% and not fully charged, the cycle life drops significantly

and permanent and irreversible damage could occur to the battery bank. As Table 9, on the

following page illustrates, the SOC of a 12V system should not fall under 12.1 Voc. Once the “cut

in/out voltage” parameters were set on the MATE3, an 800W load was once again placed on the

system.

28

Table 9: Battery State of Charge

As expected, the inverter shut down all power to the receptacles and auxiliary cords once 12.1V

was reached. The charge controller then went into the bulk stage, in which all energy coming from

the modules are used to recharge the batteries. Once an open circuit voltage of 12.62V was reached

(90%), the inverter turned back on and provided power to the receptacles and auxiliary cords once

again. It is important to note that the batteries should never be discharged more than 50%, as this

can permanently cause damage to the battery bank. Once one battery is damaged, the entire bank

will need to be replaced. The SOC can be monitored at all times via OpticsRE. Technicians should

check it frequently; at least once a day.

In addition to the inverter shutdown, the SCS will utilize a system timer that will turn the

receptacles and auxiliary cords on and off at 8am and 8pm. This is in an effort to deter late night

use by transients and allow sufficient power storage for the following day. The timer used in this

application was the Outdoor Digital 2-Outlet timer. This timer features to-the-minute digital

settings and a countdown function. Once the timer was set with specific dates and times of

29

operation and shut down, electronic devices were plugged into the receptacles and auxiliary cords

to determine if no power was coming to them. Upon seeing that the charging indicator not turn on

for the electronic devices, then come on at the defined time, the test was determined to be a success.

Note that the timer has a setting for daylight savings time and a technician can use the manual

override button to turn the timer off and outlet on. Even if the inverter does not supply the outlet

that the timer is plugged into with power, this timer retains its settings with a self-charging battery

backup. Once again, the full testing procedure documentation, as well as test data can be found in

Appendix F.

Planning

Project planning is an important aspect to the success of any project. The main milestones

for the SCS for the Fall semester included components of overall design: load calculations, concept

designs, working drawings and ordering all components before the semester concludes. The Spring

semester, on the other hand, focused on implementation. Among other things, the spring semester

included acquiring additional funds to complete the project, creating a test procedure for the

quantitative requirements, coordinating with Facilities Management Services regarding

installation of the shade structure, participating in the Sustainability Conference XI, as well as

acquiring proper permitting from the University. Testing procedures and the total Engineering

Hours for the Fall semester is estimated at 191 hours, whereas the Spring semester is estimated at

206 hours (subject to change). The start and finish dates reflect those on the detailed schedule in

Appendix I.

30

Budget

In 2006, students voted to increase their fees by $5 each semester to support the creation

of the AS Sustainability Program and Fund. The majority of this money goes into the AS

Sustainability Fund which makes available approximately $60,000 annually for student-driven

projects. The SCS has received funding from SFAC in the amount of $12,000, as well as an

additional contribution of $3,325 from the College of Engineering, Construction Management and

Computer Science. The budget for the SCS was broken down into six sections:

1. Solar Modules

MiaSole FLEX-01, 220W Modules

2. Power

OutBack Power solar components

Battery Bank

Disconnects/Breakers

3. Electrical Accessories

Duplex, GFCI/USB outlets and auxiliary cords

Security Lighting

Fans

Timer

4. Seating and Shade Structure

Steel: C-Channel and Sheet Metal

Blue Pine Wood

Shade Structure

Powder Coating

Rivets and Security Machine Screws

5. Wiring

31

6. Miscellaneous

Shipping and tax

Electrical Inspection

PE/EE Stamp of Approval

Figure 15 shows the budget breakdown of the project. As shown, the biggest contributor

of the budget goes to power, which includes items such as the charge controller, inverter, MATE3

and the battery bank. The second would be the seating and shade structure. The main reason for

this is that the shade structure itself cost $3763 and is the most expensive item on the budget. All

the remaining sections (solar panels, wiring, miscellaneous, etc.) play a small role in the overall

budget, none reaching 10 percent of the budget.

Figure 16: Budget Breakdown

8%

41%

4%

43%

2%

2% Current Budget Breakdown

PV Panel

Power

Electrical Components

Seating and ShadeStructureWiring

Miscellaneous

32

Table 10, below, shows the amount for each of the six sections. The solar power component

section amounts to $5,465.75; taking up over 40% of the budget. On the other hand, the seating

and shade structure amounts to $5,900.26, the largest portion of the budget at 44%. The remainder

of the sections amounts to $2,160.27, bringing the grand total of the solar charging station to

$13,556.28. This leaves the SCS with $1,799.72 remaining in the budget. What has not been

accounted for in the budget is the work done by Facilities, Management & Services which includes

management, design, labor and materials of the installation of the shade structure. This cost has

been offset by Lori Hoffman, the Vice President of Business and Finance. Furthermore, the cost

of a Professional Electrical Engineering stamp of approval on the solar calculations has yet to be

accounted for in the budget, but has been included in the budget. A full budget analysis can be

found in Appendix G.

Table 10: Section Budget Breakdown

Section Cost

PV Panels $1,142.98

Solar Power Components $5465.75

Electrical Components $555.27

Seating and Shade Structure $5,900,26

Wiring $242.34

Miscellaneous $219.68

Total $13,526.28

33

Justification

CSU, Chico is one of only 21 schools on the Princeton Review’s Green Honor Roll for

campus sustainability and has long been a sustainability trailblazer. President Paul J. Zingg was a

founding signatory of the American College and University Presidents’ Climate Commitment. The

Institute for Sustainable Development helps guide CSU, Chico's strong commitment to balancing

human, social, cultural, and economic needs with the natural environment. As such, in partnership

with SFAC, this solar charging station adds a visual element of campus sustainability, while

teaching students of the technologies associated with solar energy. In addition, it will be the first

of its kind to be implemented on the CSU, Chico campus and the first to allow students to monitor

factors such as kilowatt hours produced per day (kWh/day), depth of charge in the batteries and

much more. As the previous sections demonstrate, the SCS will successfully charge laptops, smart

devices and tablets throughout the day, all while capturing the SCS progress in real-time and

displaying it for all the students to monitor. With all of seating and installation of the shade

structure and fabric complete, as well as the component layout, the installation of the SCS on site

will occur by graduation weekend. However, it has been discussed that if the station cannot be

fully installed, pending the arrival of permitting from the University, the stations installation will

be completed before the beginning of the Fall 2016 semester.

Discussion

In summation, all calculations have been checked and approved and all of the customers

Must-Do, quantitative requirements have been tested and met. This station will be able to

accommodate any laptop, smart device and tablet plugged into it. The overall SCS system is the

first of its kind on the Chico State campus and first of its kind in the nation to utilize thin-film

34

photovoltaic modules and a allow not only technicians, but its users to monitor the stations

progress. With the added ability for all users to monitor the stations progress at any time, from the

comfort of their handheld devices or laptops, it is the hope that users learn more about the

technologies associated with solar energy and hopefully foster sustainable practices and living.

The SCS not only met all of the specifications set forth by the customer, but also took steps

in ensuring its longevity and safety by securing funding for any maintenance that is required in the

years to come. Safety precautions have been put in place to decrease the level of vandalism;

however, it is understood that vandalism and possible harm to the station is inevitable. The College

of Engineering, Construction Management and Computer Science, in partnership with Associated

Students and Engineers for Alternative Energy, will ensure that the station is maintained and

remains a lasting entity to this campus’ goal of sustainability.

Recommendations

It is the recommendation of this group that more solar charging stations be implemented

throughout this campus. With a detailed design report that includes calculations, vendors and all

steps necessary at implementing more, it is achievable. However, this group does advise that all

parties and departments involved in the installation and implementation of the station meet to

discuss what is expected and jobs performed by each. Furthermore, it is recommended that

contracts be drafted to ensure that what each department agrees upon doing, is actually completed

in a timely manner. First and foremost, all permits should be acquired before components are

purchased. Once all proper permits are acquired, the implementation can begin.

35

It is this teams hope to see more solar charging stations implemented on this campus, so

that generations upon generations of future Wildcats can enjoy the wonderful Chico weather, while

charging their personal electronic devices in a sustainable way.

References