1 Introduction - Messiah College · OtherPower.com, explains step-by-step instructions for building wind-solar hybrid systems. Their designs show how to easily build a wind system

1

PREFACE

Wind and solar energies are clean forms of energy and have great potential for power that engineers have barely begun to harness. The combination of a lift-type windmill and a PV solar panel generates electricity both day and night for use on a farm. The electricity created by the wind-solar hybrid system can be stored in batteries and used when wind and sun are unavailable. The design of the entire system focuses on low-cost, reproducibility, environmental protection, and effectiveness for the farm application. The system has been implemented at Professor Erikson’s farm by the team of Michael Dell, Jonathan Siemen, and William Tanis.

TABLE OF CONTENTS

1 Introduction ................................................................................................................................................. 1

1.1 Description ........................................................................................................................................... 2

1.2 Literature Review ................................................................................................................................. 2

1.3 Solution ................................................................................................................................................ 3

2 Design Process ............................................................................................................................................ 4

2.1 Anemometer Tower Design Process .................................................................................................... 4

2.2 Wind Turbine Tower Design Process ................................................................................................... 4

2.3 Charging System Design ...................................................................................................................... 6

3 Implementation ............................................................................................................................................ 7

3.1 Construction ......................................................................................................................................... 7

3.1.1 Anemometer Tower Construction ................................................................................................. 7

3.1.2 Wind Turbine Tower Construction ................................................................................................ 7

3.1.3 Charging System Construction ...................................................................................................... 7

3.2 Operation .............................................................................................................................................. 8

4 Schedule ...................................................................................................................................................... 8

5 Budget ......................................................................................................................................................... 9

6 Conclusions ................................................................................................................................................10

7 Recommendations for Future Work ...........................................................................................................11

References .....................................................................................................................................................12

Appendices ....................................................................................................................................................13

ACKNOWLEDGEMENTS

1 Introduction

In the face of a global energy crisis, many are turning to the conversion of free energy from the sun and wind. A wind-solar hybrid energy system utilizes the availability of both resources in one versatile and convenient package. Small solar and wind systems are quickly gaining popularity and in combination present an affordable, clean, and effective solution to meeting household energy needs. By using battery storage, we designed a wind-solar hybrid system capable of offering consistent power despite less than ideal sunlight and wind conditions. With a comprehensive, detailed display and custom designs for the application, the system is not only practical but also user-friendly and easy to maintain.

2

1.1 Description

The purpose of this project was to design and implement a wind-solar hybrid energy system on Professor Erikson’s farm. Initially, we had to test the wind speed and tendencies at the farm to validate the implementation of such a system. By replacing an existing solar PV charging system and combining its output with that of a wind turbine, we charged a battery bank capable of simultaneously powering five 22 Watt light bulbs four hours a day for three consecutive days without charging.

1.2 Literature Review

Fifty years ago, one would not have been able to imagine the focus engineers have taken on alternative energy forms. Entire engineering disciplines are dedicated to alternative, clean, “green” energy sources. Oil, coal, and other fossil fuels create about 85% of the world’s human produced energy (Fossil Fuels). Renewable energy uses human produced methods to capture naturally occurring energy sources on Earth. Two of the most easily harnessed are solar and wind energy. They work well in combination and provide alternatives for one another if the sun is not shining or the wind is not blowing. In many cases, when the sun is not shining, the wind is blowing and vice versa. According to Home Power Magazine, 82% of “small wind turbines” are used in combination with PV panels (Gipe, 1999). Because of their effectiveness in combination, household and small-scale wind-solar hybrid systems are quickly gaining recognition and popularity. Investment capital into the renewable energy sector rose from $80 billion in 2005 to $100 billion in 2006. The advantages of owning one such system go beyond the obvious. Real Goods, a magazine and catalog for reasonably priced alternative energy solutions, reminds its readers and customers that residential renewable energy systems are not only environmentally sensible but also economically conscientious. A hybrid system raises a house’s value, is sustainable with little or no work by homeowners, and provides a relatively quick payback period (Solarize Now and Start Saving Money, 2007). The United States recognizes the advantages of solar and wind energy by offering a federal tax credit of $2,000 for household, residential systems (Tax Incentives Assistance Project, 2007). Many books estimate costs for home systems ranging anywhere between $1,000 and $20,000 depending on electricity production needs, location, amount of self-installation, and other factors. Options vary for each company’s design. For example, SunWind Concepts offers a range of products for large and small applications. They offer systems for use in cabins or garages that include two fluorescent lights powered by PV panels only for $450 and a four fluorescent light system powered by PV panels only for $750. They also offer household systems designed to fully and permanently power an energy-efficient home. System 3.6 from SunWind Concepts includes 600 Watts of PV power, 900 Watts of wind energy, and a 3.6 kW inverter/battery charger for approximately $12,000 (Rentz, 2005). Real Goods, like some other companies researched, focus mainly on solar energy and, therefore, do not offer solar and wind together in a hybrid package.

3

The cost of a system seems to vary mostly by the application for which it is used. Suppose a customer wants to power an RV’s DC powered lights and cigarette lighter outlets for a weekend. A similar system to power the same RV for a week might cost several times more because of the exponential increase in cost of larger PV panels, charge controller for increased battery charge, larger installation requirements, and increased need for safety features. There is another approach to the hybrid system: minimize every cost by only using junky, used parts to make components. Two men from Colorado started a website dedicated to informing others who wish to use Volvo disc brakes as windmill rotors, for example, the art of constructing homemade renewable energy systems. The website, OtherPower.com, explains step-by-step instructions for building wind-solar hybrid systems. Their designs show how to easily build a wind system for under $1,000. Since their applications are mostly for remote Colorado residents powering cabins and RV’s, the website is a valuable source for our project and may be referenced for low-cost alternators, generators, or battery-charging designs. They have extensive experience with surviving solely on these systems far away from any grid electricity sources (Bartmann & Fink). Research on hybrid systems has revealed a general design that our group may mimic. The two sources of energy, a wind turbine and PV panel(s) are placed in their optimal positions according to research, theory, and testing for wind and solar strength. These energy sources input DC power through a charge controller and into a load center, which directs current where it needs to go: either batteries or directly to DC appliances. Normal appliances that plug into home outlets use AC, meaning an inverter must take the DC stored in the batteries and convert it into AC. It is also important to note that wiring certain components of the system, such as batteries or multiple PV panels, in series (to increase voltage) or parallel (to increase amperage) yield different results and can be switched or combined depending on application needs. This basic outline of the system seems to be the general model for effective systems.

1.3 Solution

In order to efficiently implement a wind-solar energy system, our group elected to purchase a wind turbine and solar panel while attempting to reuse as many components from the preexisting solar PV system as possible. We decided to purchase the wind turbine instead of making one due to the complexity and the potential cost of the turbine construction. The support structure for the turbine was constructed on the barn roof. By utilizing the existing height of the barn, we simplified the turbine tower design, minimized power loss due to wiring, and facilitated future maintenance. Due to the degrading state of the existing solar PV system, the most efficient alternative for our group was to purchase a new panel. By integrating several components of the old system along with some additional ones in our new layout, we were able to combine the outputs from both the solar panel and the wind turbine to optimize charging potential. Our system design allows users to draw from the battery bank while simultaneously charging.

4

2 Design Process

Our project included three unique designs applicable to meeting our objectives. These designs were the anemometer tower, the wind turbine tower, and the charging system.

2.1 Anemometer Tower Design Process

The design of our anemometer tower aimed towards one of functionality and cost. Our primary aim was to support our anemometer thirty feet from the ground for an extended period of time. By reusing discarded PVC piping and utilizing an existing structure, we easily built a structure thirty feet high. Due to the anticipated flexibility of the PVC piping, guy wires were added to add more stability to the structure. A final design consideration for this tower was securing the anemometer to the top of the tower with the ability to later safely remove the device. To accomplish this, a screw was used for the anemometer to rest on and the remainder of the device could be secured using a combination of zip ties and duct tape. The design of the anemometer tower can be found in Appendix B.

2.2 Wind Turbine Tower Design Process

A basic understanding of the geometry of the barn was necessary before design or construction of the tower could begin. The barn roof is designed with trusses spaced approximately 23” apart, though some truss spacing was different than others. With a height of 40” and a length of 104.5”, the roof is angled at 20.9°. The 4 x 4 posts were designed and cut so that the posts would stand at 65° to the horizontal, meaning that the bottom of the posts were cut to 45° to account for the 20° slope in the roof. The base of the 4 x 4 posts were placed 9’6” apart so that the tops of the 4 x 4 posts were 3’ apart.

The pipe is supported mainly by a series of three square brackets that fit snuggly on the pipe and keep it in place. Once hammered on the pipe, they were slid in place. Then, the three brackets, as shown in Appendix C figures 2 and 3 were screwed to four supporting beams staggered on each side. These beams were screwed into the other supporting beams on the A-frames and into the beams crossing between the two A-frames. These brackets were cut precisely and left less than a 1/16” gap around the pipe.

Several specifications needed to be met by the wind turbine pipe. The inner diameter of the wind turbine was approximately 1.9”, meaning that it would fit onto a 1 ½” pipe. The nominal outside diameter of 1 ½” pipe is 1.900” with a nominal thickness of .138”. The top point of the barn is approximately 19 ½’ above ground level. This means that in order to reach our goal wind turbine height of 30’, a 10’ pipe resting on the top point of the barn could be used.

5

The pipe on which the wind turbine sits is 1 ½” x 10’ rigid metal conduit (RMC) pipe. RMC is one of the three major types of conduit, which is often used for the protection and housing of wires. The RMC used in this project is, in fact, galvanized steel, though RMC is also available in aluminum. Stainless steel would have been preferred but the RMC was available at the time of purchase, cheaper than stainless steel, the correct dimensions/specifications for the design, and had threaded ends. The threaded ends allowed flexibility in case the design called for a threaded base into which the threaded pipe could fit. Lowe’s, where a majority of the tower materials were bought, only had 1” galvanized pipe or 1 ½” black iron pipe as additional options to the RMC. The black iron pipe would be susceptible to rust in the outdoor elements, leaving the 1 ½” x 10’ RMC as the only real option.

The RMC is still a very appropriate material choice for the application despite it not being our number one choice. Galvanization of steel involves coating the surfaces of the steel with a layer of zinc, a relatively corrosion resistant metal. Being galvanized, the pipe has several important features beneficial to the function of the tower: 1) rust and corrosion resistance, 2) easy wire transfers through the pipe, and 3) low cost.

It is important to note that in order for the wind turbine to be most effective, the wind hitting the blades should be laminar, meaning that there is no interference nearby structures and that the airflow is, more or less, out of the boundary layer created by friction of the wind with the ground or surroundings. The fact is that ignoring expense, the ideal design for the wind turbine tower would have been a stand-alone tower away from the barn. However, prices and structural volatility grow exponentially with the increased size of a stand-alone tower, whether a guyed tower or a lattice type tower. Several stand-alone designs were considered but a smaller-scale lattice design was implemented simply because money and time constraints limited the potential size and complexity. We used the barn to gain height without cost and, thus, sacrificed the quality of the wind flow into the wind turbine. It was a necessary sacrifice, however, because budget constraints were such that even building a structure on the barn roof nearly overstrained the allotted amount.

With the 26.3 lb pipe and 13 lb wind turbine, the actual tower itself needed to properly support the pipe to keep it from deflecting and to keep it upright. Untreated wood is susceptible to defects and deterioration due to insects, fungi, other organisms, and moisture. A combination of these factors would be very likely in central Pennsylvania as verified by the team’s run-ins with weather and insects (especially bees) during the spring months when most of the construction took place. That in mind, every piece of wood on the tower is pressure treated. Pressure treated wood is wood treated with a preservative applied under pressure in order to evenly penetrate all of the wood. Also, the screws on the tower are galvanized, further protecting the structure from weather factors.

Additional pictures demonstrating the design of the wind turbine tower can be found in Appendix C figures 4-9.

6

2.3 Charging System Design

In order for our two different sources to be combined correctly, a charging system was designed to properly merge the two different power systems. Both the wind turbine and the solar panel we chose work properly with a twelve volt power system, therefore allowing us to join the two sources safely. Since the two sources are compatible to be combined, we needed to design a system that would properly and safely complete that task. Initially the existing system was studied for an early idea for the system. Soon after examining the system, we realized that the design would only allow for charging or discharging of the battery. We then began designing the system to allow for simultaneous charging and discharging. With designing a new system, the existing system was disassembled and as many components as possible were salvaged in order to save on cost. The design process for our system started with the inverter that is used for AC loads. From that point the wiring led to the batteries, which the capacity and quantity of the batteries was determined by calculations that can be seen in Appendix A figure 1. The wiring then continues to the combination point. Two bus bars were used to join the two sources, one for the combination of the positive wiring and one for the negative wires. The bus bars hold the wires that run from the wind turbine and the solar panel. Safety of the overall system was the next step in the designing of the charging system. Each of the components needs to be isolated from the rest of the system at any time, mostly for maintenance purposes. The system contains five main different components, the wind turbine, solar panel, solar panel charge controller, batteries, and inverter. This could have been accomplished in two different ways. DC circuit breakers could be used or a switch/fuse combination. Since there was no advantage to using either method for component isolation, we looked to another safety step for our decision. Correct wire size is needed for proper use of each of the components. We used a general standard in choosing what wire size was needed for the wiring of that component. The standard is that the wire needs to be able to carry 125% of the maximum current that the component can produce. The standard for solar panels is slightly different in the fact that the wire needs to be able to carry 25% over 125% current. These calculations can also be seen in Appendix A figure 2. There also needed to be protection of the wire which can also be accomplished with a circuit breaker or a fuse. We decided to use circuit breakers for our system protection, with each breaker to trip at a current slightly below the limit of the wire as to protect it. Details on each of the charing system components can be found in Appendix A figure 3. In order to check on the efficiency and the productivity of the components different gages were wired into the system. There are two amp gages in the system, one to measure the charging amps of the solar panel and one to measure the charging amps of the wind turbine. The last gage is a volt meter that is used to monitor the battery voltage. By being able to monitor the battery voltage, we can check the performance of the solar and built in wind charge controllers as well as protecting from over charging the batteries. Additional pictures of the charging system can be found in Appendix C figures 10 and 11.

7

3 Implementation

3.1 Construction

Summarize the process of constructing your prototype. Include a discussion of what was learned during construction, and how the design changed as challenges were encountered and overcome.

3.1.1 Anemometer Tower Construction

The construction of the anemometer tower was fairly simple. The initial task was to glue together the sections of PVC piping. One eight-foot section of 2 inch PVC was glued together with a twelve-foot section of 1 ½ inch PVC using an adapter. A threaded connection was glued to the bottom of the 2-inch PVC pipe so that the PVC could be connected to the existing structure. To secure the anemometer to the top of the tower, we placed a screw just below the anemometer. This gave the anemometer something to rest on. We then drilled a series of holes halfway through the PVC at the top 4 inches of the pipe. By wrapping zip ties around the anemometer and through the PVC, we secured the anemometer to the PVC. As a final securing measure, we wrapped duct tape around the anemometer and the zip ties. To support the structure, we drilled two holes completely through the PVC around 20 feet off the ground. By feeding rope through the holes and securing the ends into the ground, we effectively secured the tower. A photograph of the finished anemometer tower can be found in Appendix C figure 1.

3.1.2 Wind Turbine Tower Construction

In the construction of the wind turbine tower, the two A-frames were first constructed on the ground. This was the only portion of the tower completely constructed on the ground. The A-frames consisted of two 4 x 4 posts whose bases were cut at 20° to the horizontal to account for the roof slope. 2 x 4 beams were cut at an arbitrary length and screwed into the base of the 4 x 4’s. These were then screwed through the roof and into the truss below. This ensured that they were not just connected to the thin metal roof but also to the supporting trusses under the metal roof.

3.1.3 Charging System Construction

In order to save money during the construction of the box for the charging system, we used to box that housed the charging system from the existing system. Using this box for the mounting of the different components made the system easy to manage as well as space efficient. The five circuit breakers were mounted on one side of the box, all of them labeled as to what stage of the component isolation they pertain. The gages were all mounted in the front door of the box, where they would be easily accessible. The only component that remained in the same location was the charge controller which was mounted on the back wall inside the box. All decisions for component locations, circuit

8

breakers, bus bars, gages, and the charge controller, were made to reduce the amount of wire necessary to complete the entire system. The greatest manipulation we had to do to the existing box was drilling some holes in the walls of the box. The holes that we drilled were for the mounting of the circuit breakers, bus bars, and gages. As for the many locations where wires needed to be connected, screw terminals are mostly used therefore having solder-less connectors on the end of the wires. These type of connectors make assembly and maintenance easy.

3.2 Operation

Our project saw immediate results. As soon as the system wiring was completed, the system responded by showing readings on all gages. To test the accuracy of the gages, we used a multimeter and physically probed the wires in question. Through some minor adjustments, we were able to accurately calibrate the gages to accurately represent the actual values. To test the success of the charging ability of the system, we monitored the battery voltage over time. By first checking the gage every so often, we saw a steady increase in the batter voltage. By applying loads to the system, we were able to drop the total system voltage. When the loads were removed, the battery voltage began to climb again. The rate at which the system charged depended solely on the weather conditions and the power output from the solar panel and the wind turbine. Details from the results of our anemometer wind speed testing can be found in Appendix D.

4 Schedule A detailed Gantt Chart showing projected and acutal scheduled time frames can be found in Appendix E.

9

5 Budget

TOTAL BUDGET: $1,500

PURCHASED ITEMS COST

BUDGETED

AMOUNT DIFFERENCE

ANEMOMETER DATA LOGGING

EQUIPMENT $111.89 $175.00 $63.11

ANEMOMETER TOWER SUPPLIES $15.82 $50.00 $34.18

WIND TURBINE $555.34 $750.00 $194.66

SOLAR PANEL $255.11 $300.00 $44.89

BATTERIES $231.08 $0.00 -$231.08

TURBINE TOWER $33.80 $200.00 $166.20

TOTAL COST $1,203.04

TOTAL

DIFFERENCE $271.96

10

6 Conclusions Overall, the project was a success and the team was able to meet each objective. The major power objective is what classified the system as a success or not: being able to power the series of lights in the barn for four hours for three days without recharging. Though time did not allow for ample testing of the system to see exactly how long it took for the system to “need” a recharge, the 12 hours were easily passed in preliminary testing and our system proved to be sufficiently over-designed. Many parts of the project took awhile to get off the ground because we assumed that some of the components from the previous project were in working order. The solar panel, originally thought to have some value, ended up being completely discarded. Nearly all of the components in the box were unusable as well. Through numerous searches, we were unable to find any notebooks or reports from the previous team, leaving us with only an observational knowledge and forcing us to take a learn-as-you-go approach to the project. In fact, originally, we thought the project would simply be a wind turbine; there was no initial mention of a hybrid system and we were unable to fully understand the difficulties that were ahead. Therefore, we learned that documentation and thorough instructions are just as important as the actual end product. Because we did not have any schematics of the previous solar project, we were not able to use it to the best of our abilities. For this project, however, we took many pictures, made many clear notes for future projects, and made detailed instructions for how to use the system. This, along with the successful physical system, makes our work on the project feel complete and comprehensive.

11

7 Recommendations for Future Work Our wind-solar hybrid energy system was a pioneering endeavor for Messiah College. Through the success of our project, we showed the effectiveness of hybrid systems. The project serves as a gateway and building block for future projects. The next logical step for a hybrid energy charging system is a grid tied system. The capabilities and effectiveness of our project were limited by the size of our battery bank. During hours when no loads are placed on the batteries, any power generated is wasted. By instituting a grid tied system, the power generated during no load hours could be sold for a profit and there would no longer be “wasted energy.” The institution of a grid tied system would take a significant capital investment but the long term pay off would be well worth it. Another expansion of our project would be to increase the number of wind turbines and solar panels in the system. With the wiring in place, the addition of more turbines and panels would be an excellent way to easily increase output. In addition to make the system grid tied, adding additional components would greatly increase the margin of profit from selling energy produced. A final connation of our project would be to facilitate access to the inverter. Due to the length and location of the wire for the barn lights, the possible locations of the inverter are limited. This places the inverter, and all access to the power generated from our system in a less than ideal location. In order to turn on the lights, it is now necessary to walk a short distance through the dark to find the inverter. Making a switch accessible from the barn doorway would greatly increase the function and the effectiveness of our system.

12

References

Air-X Wind Module. (2007). Retrieved December 2, 2007, from Southwest Wind Company: http://www.windenergy.com/air_x.htm

Bartmann, D., & Fink, D. (n.d.). Wind Power Basics. Retrieved September 30, 2007, from OtherPower.com: http://www.otherpower.com/windbasics3.html

Fossil Fuels. (n.d.). Retrieved September 29, 2007, from Wikipedia: http://en.wikipedia.org/wiki/Fossil_fuel

Gipe, P. (1999). Wind Energy Basics: A Guide to Small and Micro Wind Systems. White River Junction, Vermont: Chelsea Green Publishing Company.

KC40T High Efficiency Multicrystal Photovoltaic Module. (2007). Retrieved December 6, 2007, from Kyocera Solar, Inc.: http://www.kyocerasolar.com/pdf/specsheets/KC40T.pdf

McNiff, B. (2002, May). Wind Turbine Lightning Protection Project. Retrieved December 12, 2007, from National Renewable Energy Laboratory: http://www.nrel.gov/docs/fy02osti/31115.pdf

Photovoltaics: Design and Installation Manual. (2004). Gabriola Island, Canada: New Society Publishers.

Rentz, T. W. (2005, March 8). Solar and wind energy system design/sales. Retrieved September 29, 2007, from SunWind Concepts: http://sunwindconcepts.bizland.com/id6.html

Solarize Now and Start Saving Money. (2007, Fall). Basic Goods , p. 5. Tax Incentives Assistance Project. (2007). Retrieved September 29, 2007, from http://www.energytaxincentives.org/

13

Appendices

Appendix A: Charging System

DayHoursAverageAmpageSystemVolt

DailyLoad/= dayAmpHours

V

dayWhr/667.36

12

/440=

tteriesNumberOfBaapacityBatteryAHCeLimitDisch

nomyDaysOfAutoDayHoursAverageAmp=

))(arg(

))(/(

BatteriesAmpHours

DaysDayAmpHours2

)115(5.

)3(/667.36≈

Figure 1: Battery number calculations

Wire current capacity ( ) %125×= Maxcurrent

Wire current capacity for PV panel ( ) %156×= Maxcurrent

Figure 2: Wire size calculations

Stage Max Current (amps) Wire Size Breaker Size

Panel to Bus bar 3.5 14 awg 5 amp

Wind turbine to bus bar 38 12 awg 40 amp

Bus bar to Batteries 41.5 8 awg 50 amp

Batteries to Inverter 72 8 awg 70 amp

Figure 3: Charging system components

14

APPENDIX B: Anemometer Tower

Anemometer

Zip ties; duct tape

PVC

Piping

Guy wires

Irrigation Tower

15

Appendix C: Photographs

Figure 1: Anemometer Tower

16

Figure 2: Pipe support connection to tower

17

Figure 3: Pipe support bracket

18

Figure 4: Panel mounting structure

19

Figure 5: Angle cut for flush roof mounting

20

Figure 6: Corner rook mount with side brace

21

Figure 7: Assembly of wind turbine

22

Figure 8: Complete structure on barn roof

23

Figure 9: Complete roof top structure

24

Figure 10: Charging system wiring

25

Figure 11: Complete charging system with batteries

26

Appendix D: Wind speed Data

Wind Speed

0

5

10

15

20

25

30

11/14/2007 0:00 11/19/2007 0:00 11/24/2007 0:00 11/29/2007 0:00 12/4/2007 0:00 12/9/2007 0:00

Time

mph MIN

MAX

Figure 1: November 17, 2007 to December 6, 2007

0

5

10

15

20

25

30

35

40

1/28/2008 0:00 2/2/2008 0:00 2/7/2008 0:00 2/12/2008 0:00 2/17/2008 0:00 2/22/2008 0:00 2/27/2008 0:00 3/3/2008 0:00

mph

Time

Wind Speed

Min

Max

Figure 2: February 1, 2008 to February 27, 2008

27

Appendix E: Gantt Chart