AC 2012-3249: INDOOR SECURITY LIGHTING WITH SOLAR POW-ERED LED TECHNOLOGY

Dr. Faruk Yildiz, Sam Houston State UniversityMr. Keith L. Coogler, Sam Houston State University

Keith L. Coogler is an instructor of industrial technology at Sam Houston State University. He receiveda B.S. in design and development and holds a M.A. in industrial education and is pursuing an Ed.D. inhigher education from Texas A&M University, Commerce. His primary teaching area is constructionmanagement. Research interests include automation, electronics, alternative energy, and ”green” con-struction.

c©American Society for Engineering Education, 2012

Indoor Security Lighting with Solar Powered LED Technology

Abstract

People are becoming increasingly concerned about protecting their properties from theft and

vandalism. Insurance companies and police are very aware that satisfactory lighting is a plausible

deterrent to crime. Although nearly any type of lighting helps reduce the risk of becoming a

victim; correct lighting, when properly used, improves security. Most buildings are illuminated

by a night light and the building is unoccupied. A security or night light allows the security

personnel to check the building without turning other lights on. A drawback to leaving lights on

is that it results in an increased electric bill and reduces the nation’s energy conservation efforts.

Another drawback is that conventional security or night lights become non-functioning in

electric outages. A viable solution to these shortcomings would be to use a battery powered

energy source to power energy efficient DC/AC LED lights. Recently, students majoring in

electronics/design and development programs were given an opportunity to design and build an

indoor security light system for one of the lab facilities, a large metal building remotely located

to the main campus and surrounded by residential properties. Some portions of the lab have

interior night security lights, but the classroom sections did not. Along with the new design, the

existing security lights were replaced with LED lights, and classroom areas were illuminated

with new night LED security lights which are completely powered by a 170W solar module with

a solar tracker system.

Introduction

Like a normal diode, the light emitting diode (LED) consists of a chip of semiconducting

material soaked or doped with impurities to create a p-n junction. As in other diodes, current

flows easily from the p-side, or anode, to the n-side, or cathode, but not in the reverse direction.

Charge-carriers (electrons and holes) flow into the junction from electrodes with different

voltages. When an electron meets a hole, it falls into a lower energy level and releases energy in

the form of a photon. The wavelength of the light emitted, and therefore its color, depends on the

band gap energy of the materials forming the p-n junction. In silicon or germanium diodes, the

electrons and holes recombine by a non-radiative transition which produces no optical emission,

because these are indirect band gap materials. Figure 1 shows parts of LED [1].

Figure 1. Parts of an LED [1]

The materials used for the LED have a direct band gap with energies corresponding to near-

infrared, visible, or near-ultraviolet light. LED development began with infrared and red devices

made with gallium arsenide. Advances in materials science have made possible the production of

devices with ever-shorter wavelengths, producing light in a variety of colors. LED technology is

evolving at a rapid rate with the development and advancement of increased light output while

maintaining efficiency and reliability [2].

The rapid development of efficient high power LEDs has led to the production of a variety of

lighting applications, broadening our horizons and giving us different concepts and uses of

lighting design. The advantages of LEDs are that they can now compete with, even surpass,

traditional illumination. Furthermore, powerful new legislation demands consideration of the

environmental impact of a product over its life cycle, from production to disposal. All of this

makes LEDs the ideal candidate for an environmentally-friendly light source. According to Tsuei

[5], the worsening of the problems regarding global warming has made the development of

renewable energy sources the focus of world-wide attention, one of which is solar energy and its

applications [3-5].

There have been many energy conservation attempts recently to incorporate LED lighting to

decrease power consumption, increase life-span of lights, and to decrease maintenance of lights.

The Department of Energy has been supporting LED projects under the program called

“Gateway Demonstrations” [6-7]. One of the recent state-wide Gateway Demonstration projects

has been created for the Jordan Schnitzer Museum of Art, Eugene, OR in January 2011; the

“Demonstration Assessment of Light-Emitting Diode (LED) Retrofit Lamps” [8]. In this project,

90W PAR38 130V narrow flood lamps used for accent lighting were replaced with 12W LED

PAR38 replacement lamps for a special exhibition, and the museum also staged a side-by-side

comparison of three different LED PAR38 replacement lamps against their standard halogen

lamp. The LED system lighting the exhibition showed a lower present value life-cycle cost,

using 14% of the energy and having a life 10 times longer than the halogen system. Another

similar project has been done under the same program called “LED Freezer Case Lighting:

Albertsons Grocery” in Eugene, OR [9]. In this project, upright freezer cases were retrofitted

with LED striplights combined with occupancy sensors and compared against standard

fluorescent lighting on the opposite side of the aisle. Calculated payback periods approached five

years from estimated energy and maintenance savings for a typical 5-door case. Another example

of similar projects was completed at the Bonneville Power Administration headquarters in July

2011 [10]. In the building, 15W and 23W reflectorized compact fluorescent (CFL) track lights

used to illuminate artwork were replaced with 12W LED lamps. Although the study did not show

rapid payback on the LED installation compared to the CFL products, color quality and power

quality improved with the LED lamps, and the narrower light distribution of the LED product

more effectively concentrated the lumens on the artwork.

For educational projects, faculty members, students, and staff from the Southwestern University

(Georgetown, TX), developed a course that focuses on energy conservation strategies for the

theater, particularly the replacement of incandescent lighting fixtures with systems that use

LEDs. This project initiated an extension of projects on campus, including the physical plant

which considered using LED lights for street lights and pedestrian lights [11]. Another

educational project was awarded to support renovations of buildings at DuPage College [12].

The Illinois Clean Energy Community Foundation awarded a $100,000 grant to support

renovations to the Berg Instructional Center, Student Resource Center, and College Center. The

funding enables progress toward U.S. Green Building Council LEED Silver Certification that

will assure energy efficient features are incorporated into building design and engineering plans.

LEED certification is a nationally recognized benchmark for the design, construction, and

operation of high performance green buildings. Through a $110,000 grant from the Illinois Clean

Energy Community Foundation, light emitting diodes (LEDs) will be installed as primary

lighting in the buildings’ high-profile public areas such as student lounges, snack bars, toilet

rooms, building entries, corridors and reception areas. LED lighting fixtures will also be installed

as supplemental accent lighting in classrooms and conference rooms. Energy savings ranging

from $14,000 to $23,000 per year will be realized as the College replaces 1,428 light fixtures

with those containing LEDs. Recently, there have been many attempts to incorporate solar power

with LED indoor and outdoor lighting due to its low power consumption. Researchers

investigated feasibility of such projects especially focusing on economic feasibility and site

assessments [13-16].

Faculty, students, and staff in the Industrial Technology program at Sam Houston State

University took the initiative to replace current security night lights for one of the biggest

laboratory facilities, a large metal building remotely located to the main campus and surrounded

by residential properties. This laboratory houses a large classroom, tool cabinets, production

equipment, and training resources for wood fabrication, metal fabrication, metal casting, and

plastic labs. One bank of classroom lights is left on for night visibility. Campus security

requested installation of security lights so the officers could check rooms in the lab area without

having to enter the building. Students took the initiative to install energy friendly solar powered

LED lighting in the classroom location with the approval and help of the on campus physical

plant. The system is powered by a battery which is charged by a 175W solar panel installed on a

solar tracker outside of the building. This system is powered by both AC and DC power. If the

charge state of the battery is low, the system will revert to utility power to operate the LED

lighting. Normally the system is powered by DC battery power allowing operation when there is

a power outage in the area.

Lab Facility Layout

Students majoring and minoring in Design/Development and Construction measured the overall

building and created layouts both on Autodesk Revit and AutoCAD software. Drawings served

for both materials estimation and to determine the location of the proposed LEDs, battery storage

box, solar panel with a tracker system, and conduits for wiring. Since it is an on-campus project,

drawings and material estimations were also shared with physical plant electricians for approval

and the inspection process. In the layout drawing, blue lines show the shop floor wiring that goes

to ten LED flood lights. In the classroom area of the lab facility there were no security lights; in

the new design, two LED flood light fixtures were proposed and installed. The red lines show

classroom for the lab facility wiring that goes to two LED flood lights. Green lines in the layout

show the wiring coming from the solar module on the solar tracking system to the battery storage

box, shown as a green junction box. The locations for the LED flood lights were also determined

and are indicated on the layout drawing. Figure 1 shows a drawing of the proposed and approved

locations of the new LEDs, the power box with two batteries, a solar module on a tracker system,

and conduits. A group of students worked with the campus physical plant technicians who

inspected and approved the measurements. Students have also proposed new locations for the

project components. Since it was low voltage and DC (direct current) power, the physical plant

suggested that the conduits be painted with blue or to tag them to separate them from existing

AC (alternating current) power. This was necessary in the case of maintenance of the system and

possible power outages that might occur in the future.

Figure 1. AutoCAD facility layout of proposed LED project components

Materials Estimating and Cost

The cost of the project was estimated after determining the materials, according to the

measurements of the lab facility. Three students worked on the project estimate. Figure 2 shows

estimation of all components including wiring, conduits, light fixtures, LED lights, battery,

charge controller, light sensor/timer, solar module, and solar tracker.

Figure 2. Cost and material estimate of the project

The partial cost of the project (503.10 dollars for wiring and conduits) was covered by the

physical plant. The rest of the components were purchased by the faculty using departmental

funding. For the material estimation, students made extensive measurements of the building and

attempted to keep the cost of the project low by finding the shortest route for the wiring and to

identify the most effective LED light fixture locations on the walls.

LED Lighting

For the energy conservation attempt, ten PAR38 Ultra Bright LED flood lights were used to

replace 40W traditional fluorescent lights [17]. Each LED consumes 13W of power and has 600

lumen output. These LED lights are comparable to an incandescent equivalent of a 50 to 60 watts

flood light. LED lights replaced existing 4ft long six-fluorescent light fixtures in the lab area.

Each of the existing light fixtures housed two 40W fluorescent lights. The total power of 12

fluorescent lights was 480W and operated for 12 hours as security lighting. By placing LEDs, the

power consumption dropped to 117 Watts and the number of light fixtures was increased to 10

(10 LEDs X 13W = 130 Watts). This project covered the areas in the lab without security

lighting, which include classroom, concrete research area, and restroom areas. In the classroom

area of the lab facility, there were no security lights; so in the new design, two small wattage

LED light fixtures were installed [18]. Two 10W DC (direct current) LEDs were installed in the

classroom area of the lab facility. Figure 3 shows the picture of the lab facility with the existing

fluorescent lighting. Figure 4 shows the lab section and classroom area of the lab facility with the

LED lighting.

Figure 3. Pictures of existing lighting of the lab facility

Figure 4. Pictures of lab facility and classroom area with LED lighting

Power Generation and Storage System

For the energy source for the LEDs, a photovoltaic module on a solar tracker system was placed

on the south side of the lab facility that is closest to the LED light fixtures and control box. The

type of solar tracker was the “UTR-020 Universal Solar Tracker”, which was studied and

installed by three students [19]. Track Racks use only the sun's heat and gravity to follow the

sun; there is no motors, no gears, and no control units used for this equipment. Solar trackers

increase the electrical output of photovoltaic modules by 25% or more compared to modules on

fixed mounts. Features of the tracker include: a) track racks always produce more power than a

fixed rack, b) track racks produce 25-45% more power in the summer. Figure 5 shows the

installation process of UTR-20 solar tracker by the students. A solar module was used as a power

generation source for the LEDs.

Figure 5: Installation of UTR-20 Solar tracker unit with BP 175W photovoltaic module

Design/development and electronics student majors drew the diagram for overall system

connections and components depicted in Figure 6.

Breaker

P

O

S

N

E

G

6A

+ -

Lighting / Charge

Controller

Solar Panel

grounded w/

Grounding clip

Grounding

rod

Lightening

Arrestor

6A20

A

A

C

AC Light+ -

DC

Breaker

Box

DC Load

DC Light controlled

by light controller

DC LEDs

Power Monitoring

Battery Monitoring

Power Monitoring

Inverter

RS-232 Computer

Monitoring

+ -

Figure 6. The LED system wiring diagram for connections and measurements

The list below summarizes the basic specifications/configurations of the components used in the

project, including the items purchased [20-21].

Argus Battery Bug Deep Cycle Battery Monitor (www.powerwrex.com)

PWRcheck, DC power analyzer, watt meter (www.powerwrex.com)

Doc Wattson Meter - DC Inline (www.powerwrex.com)

Digitek DT-4000ZC PC RS232-Interfaced Digital Multimeter (www.powerwrex.com)

Kyocera KD135SX-UPU 135W 12V Solar Panel with J-Box (www.altestores.com)

Zomeworks Utr-020 Universal Solar Tracker (www.altestores.com)

Multi-Contact 15 FT MC3 Connector Extension #10 AWG (www.altestores.com)

LA302 DC Lightning Arrestor (www.altestores.com)

Xantrex XPower Micro Inverter 400 - 120 VAC/60 H (www.altestores.com)

Deka Solar 8G24 12V@73.6AH (20HR) Sealed Gel Cell (www.altestores.com)

20 Amp Din Rail Mount Breaker (www.altestores.com)

6 Amp Din Rail Mount Breaker (www.altestores.com)

Midnite Solar BabyBox 4 Slot AC or DC Breaker Panel (www.altestores.com)

Morningstar SunLight SL-10L-24V 10A, Lighting Controller with LVD

DC (12V or 24V) LED Bulbs & Fixtures (www.altestores.com)

Measurements

The installed system was tested to find out how long the batteries would last. The reason of this

test is to find out how long an autonomous system will run in the case the power generation

system (solar module) is out of the order. Initially, two deep cycle batteries (75Ah) were charged

fully. All twelve lights on the batteries operated for 12 hours with no appreciable drain. All lights

pulled about 3.25A @ 11.5V. The batteries got down to 11.1 V when the system turned off.

Overall testing showed the overall system operates for about 60 hours on fully charged batteries.

For the test purposes, students left the LEDs burning with fully charged batteries to determine

the number of days the LEDs would operate without an additional charge. The hours of operation

until the battery became neutral was 60 hours, which is estimated to be 5 nights of operation as

security lighting. The cut-out voltage is about 9.5V. LEDs are currently controlled with a light

switch because of night classes in the lab facility. Students monitored the solar module output,

battery life, the number of days LEDs can work on battery without any charging from solar

modules, and illumination of LEDs as security lights during the night. Findings are summarized

in Table 1. Due to budget issues, students only installed one type of LED light which prevented

them from doing a comparison study to determine most efficient LED light for the application.

Table 1. Summary of system testing

Component EHW1

(H)

VIN

(V)

VOUT

(V)

IIN

(A)

IOUT

(A)

PIN

(W)

POUT

(W) Variables

Solar Module ~8-10 17.7 8.37 148

Battery Charging ~10 12.7V 7.9 100

Battery Discharging ~12 12 3.4 40.8

LEDs (12) ~12 11.5 3.25 37.3

1 Estimated hours of working

Note: Hours of operation are based on specific time period tests that were conducted (November

–December 2011). The sunrise and sunset information is based on duration of daylight/darkness

table for one year [22-23]. Two discharged batteries left for a charge without any load were

connected to determine how long it takes to charge batteries under average sun irradiation

received by the solar module. It took 18 hours to charge two batteries fully under average 5.2

watts/m2.

Students Learned

According to the student comments about the project

LEDs are still expensive, but they have a long life

In order to determine LED type and illumination, a careful selection process should be

conducted

Look for lights that have a lighting facts label

Learn how to read the label and specifications

Look for lights that have an energy star label

An energy star label determines not only energy efficiency but also certain level of CRI

(Color Rendition Index) and noise levels

Read the customer and company reviews of a certain product because quality varies

considerably

When comparing LED lights to incandescent lights, the energy saving is considerably

high and the payback period is short even though the initial LED price is high

When comparing LED lights to CFLs, remember that

o the number of parts to run CFLs are more than LEDs

o b) CFL has a short life period because it gets cycled off and on frequently

o c) the maintenance of lights are difficult and costly, but LEDs have long operating

lives

o it is difficult to use a dimmer with CFL lights, but LEDs dimmed easily and well

o sometimes it takes time for a CFL come up to full brightness

o the mercury content of CFLs could be a problem in some cases

Conclusion

This project was mainly accomplished by students and is very supportive to the campus-wide

efforts to promote energy conservation and use of clean renewable energy resources. The

University Physical Plant decided to hire two of students who were involved in the renewable

energy projects to do campus wide energy assessment. This and similar projects have been done

on campus and demonstrate the viability of the renewable energy to reduce the amount of money

the university pays to the utility company as well as reduce harmful gases which speed-up global

warming. Student feedback has been very positive in terms of learning outcomes gained from

this project. Students asked to be involved in more campus-wide projects and asked to extend

this project to local community for energy assessments. Two of the students requested small

funding to prepare and mail brochures/flyers about LED lighting and energy conservations.

References

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