Project Specifications
SOLAR POWER CO-GENERATION SENIOR DESIGN PROJECT
GROUP MEMBERS:
TRECIA ASHMAN
PAOLA BARRY
MUKTI PATEL
ZARINA ZAYASORTIZ
ADVISOR:
R.B. COLE
DECEMBER 7th, 2004
I pledge my honor that I have abided by the Stevens Honor System
Table of Contents
Table of Contents 1
Objective 6
Reasons for Duke Farms’ Utilization of the Project 6
Approach to the Problem 6
Advantages of a Photovoltaic System 7
Solar (Photovoltaic) Power 8
Solar Radiation in New jersey 10
What is Co-generation? 11
Financial Incentives for a Photovoltaic System 12
PSE&G Specifications 13
System Information 14
Case Studies 15
Montville Home Case Study 15
Typical New Jersey Home 17
Duke Farms Data 18
Data for Employee Housing 18
Data for Powerhouse 20
Solar Calculations 23
Powerhouse System Size 23
Employee Housing System Size 24
System Layout 25
Supplying the Farm and the Grid 25
Feeding Directly to Grid 25
Benchmarking Data 25
PV Panel Data 25
Meter data 26
Tracker Data 27
Inverter Data 28
Mounting System Designs 28
Design #1- Pole Support 29
Design #2- Pyramid Tripod Design 29
Design #3- Cone Design 30
Design #4- Lounge Chair Design 30
Conceptual Designs 31
Calculation of Wind Loading 31
Importance of Finite Element Analysis for Conceptual Designs 32
Design 1 Description-Lounge Chair Design 32
Results of ANSYS Analysis 33
Design 2 Description- Pole Support: 34
Results of CosmosWorks Analysis 35
Design 3 Description- Cone Design 35
Results of CosmosWorks Analysis 36
Exploded Views of Conceptual Designs 36
Price Quotes for Materials 36
Aluminum Pipe – Heavy Gauge (used for all designs analyzed) 36
System Placement 37
Deliverables 39
Conclusions and Future Work 39
Appendix A 40
Figure 1 – “Lounge Chair” Assembly created in Solidworks 40
Figure 2 – “Lounge Chair” ANSYS Representation of Deformation 40
Figure 3 – Pole Design in Solidworks 41
Figure 4 – CosmosWorks Graph of Von Mises Stress for Pole Design (weight as force) 42
Figure 5 – Close-up of Von Mises Stress in Hole for Pole Design (weight as force) 42
Figure 6 - CosmosWorks Graph of Strain for Pole Design (weight as force) 43
Figure 7 - CosmosWorks Graph of Static Displacement for Pole Design (weight as force) 43
Figure 8 - CosmosWorks Graph of Deformation for Pole Design (weight as force) 44
Figure 9 - CosmosWorks Graph of Von Mises Stress for Pole Design (weight + snow as force) 44
Figure 10 - Close-up of Von Mises Stress in Hole for Pole Design (weight + snow as force) 44
Figure 11 - CosmosWorks Graph of Strain for Pole Design (weight + snow as force) 45
Figure 12 - CosmosWorks Graph of Static Displacement for Pole Design (weight + snow as force) 45
Figure 13 - CosmosWorks Graph of Deformation for Pole Design (weight + snow as force) 46
Figure 14 - CosmosWorks Graph of Von Mises Stress for Cone Design (weight as force) 46
Figure 15 - CosmosWorks Graph of Strain for Cone Design (weight as force) 47
Figure 16 - CosmosWorks Graph of Static Displacement for Cone Design (weight as force) 47
Figure 17 - CosmosWorks Graph of Deformation for Cone Design (weight as force) 48
Figure 18 – CosmosWorks Graph of Factor of Safety for Cone Design (weight as force) 48
Figure 20 - CosmosWorks Graph of Strain for Cone Design (weight and snow as force) 49
Figure 21 - CosmosWorks Graph of Static Displacement for Cone Design (weight and snow as force) 50
Figure 22 - CosmosWorks Graph of Deformation for Cone Design (weight and snow as force) 50
Figure 23 - CosmosWorks Graph of Factor of Safety for Cone Design (weight and snow as force) 51
Appendix B 52
Figure 1 – Pole Structural Support (exploded view) 52
Figure 1 – Cone Structural Support (exploded view) 52
Appendix C 53
Gantt Chart 53
Technical Drawings……………………………………………………………………………………..………54
Financial Analysis……………………………………………………………………………………..……….. 58
ABSTRACT
The objective of the Solar Power Co-Generation project is to generate electric power using a photovoltaic co-generation system for Duke Farms in Hillsborough, New Jersey. The group must also explore another method for the generation of electricity using a renewable resource. The group performed several case studies in order to determine the feasibility of the project. After receiving energy data from Duke Farms, several different wattage photovoltaic systems were created in order to determine the amount of energy each system could create. A comparison was drawn between the usages of a fixed as opposed to a 1-axis or 2-axis tracking system. Different conceptual designs for solar cell support structures were created in CAD software and analyzed using Finite Element Analysis. From there, a materials list was created for the finalized structural design and a financial analysis was created. All this data will be included in our final presentation to Duke Farms where they will decide which photovoltaic system they would like to use.
Objective
The objective of this project is to generate electric power using a photovoltaic co-generation system for Duke Farms in Hillsborough, New Jersey. The group must also explore another method for the generation of electricity using a renewable resource.
Reasons for Duke Farms’ Utilization of the Project
Duke Farms was found to posses certain potentials for energy development onsite. These potentials made the photovoltaic system practical and appropriate due to the farm’s large land area. This project is one of the first steps towards an ongoing partnership between Stevens and Duke Farms involving energy-related and research projects. Duke Farms has always had an interest in this kind of technology and their work with Stevens is their response to this interest.
A photovoltaic system would also satisfy Duke Farms’ concern for the environment. One of the most favorable characteristics of solar power is the ability to conserve energy. Duke Farms also has a great willingness to utilize innovative technology. Cogeneration is not only innovative, but also provides support for the Doris Duke Charitable Foundation’s mission to “preserve the cultural and environmental legacy of Doris Duke’s properties.”
Approach to the Problem
The team first started this project by reading the project description to get a feel for the task at hand and discuss what we already knew about the topic. After making preliminary notes, the team felt that more in depth research had to be done. The work was divided into two groups that focused on the photovoltaic potion and one on the co-generation aspect of the project.
The solar group investigated the following:
▪ The advantages of a photovoltaic system
▪ How a photovoltaic cell works
▪ The average amount of sunlight that during day
▪ The worse case scenario, meaning how much sun shines on NJ, when its cloudy
▪ The efficiency of cells vs. the amount of land space needed for certain Kilowatt hr system
The co-generation group investigated the following:
▪ How co-generation works
▪ The benefits of co-generation
▪ The economics of this process
The team then reported its findings the next week; after the literature review the team decided that a case study should be performed using an average home in New Jersey for sample calculations. The simplified example of supplying power to one home by the use of the photovoltaic system can be scaled up for the Duke Farm project.
The approach that will be used for Duke Farm is the PV Co-generation system. The team feels that this will be a viable solution for client because they are interested in solar power and the battery storage system will be too much maintenance for the client to handle. The PV system is also a good way to utilize the large land area that is available. This PV system will be used to show other groups and farms in the area that solar power can be used to power an entire facility and gain a profit as well.
Different types of arrangements and cell efficiencies will be tested to see which suits the client best. For example if they want to use as little land space as possible the highest efficiency cells will be used; although if cost is an issue, the cheapest cells will be used because a large amount of land can be used for project.
After cell efficiency and layout was determined, three different design scenarios were created in order to illustrate the energy collection differences between a stationary, one-axis, and two-axis tracking systems. The PVWATTS software was utilized in order to perform these calculations since this software is a standard used in the determination of photovoltaic system sizes. These same calculations were applied once data from Duke Farms regarding energy consumption was received.
Being as how photovoltaic systems are already existing designs, the group decided to engineer a new support structure for the solar cells. Research was conducted on the internet to view existing support structures. From there, the group constructed four designs and analyzed them in Finite Element Analysis software such as CosmosWorks and ANSYS. Based on the results (stress/strain analysis), the group decided on final structural support design.
After determining final structural support and size of the system, the materials list was tabulated. From there, a financial analysis of the entire project was performed including rebates considerations and breakeven analysis.
Advantages of a Photovoltaic System
One of the reasons why so many people have expressed interest in photovoltaic systems is because of how environmentally-friendly it is. The fuel, sunlight, is free and no noise or pollution is created as a result of the process.
Photovoltaic systems are also extremely safe and reliable. Minimal maintenance is needed and failure rates are very low. Generally, projected service lifetime of a solar cell is between twenty and thirty years. Most manufacturers offer warranties of twenty or more years for maintaining a high percentage of initial rated power output. Therefore, in the rare case that a solar cell does malfunction, it would most likely be covered by warranty, saving the consumer money.
Duke Farms will be utilizing a photovoltaic system that is still connected to the power grid. The AC power produced by the photovoltaic system can supply onsite electrical loads or back-feed the grid when the photovoltaic output is greater than the onsite load demand. At night and during other periods when the electrical loads are greater than the photovoltaic system output, the balance of power required by the loads is received from the electric utility. This feature is required in all grid-connected systems and ensures that the system will not continue to operate and feed back onto the grid when it is down for service or repair. If the power grid ever does go down, battery storage can be used for energy instead. Safety guards such as the ones mentioned above help ensure that during different emergency scenarios, Duke Farms would still be able to receive power.
A photovoltaic system is also very versatile. It can be designed for a variety of applications and operational requirements. If Duke Farms ever needs to increase its power consumption, the photovoltaic system could compensate for the change. It has no moving parts, is modular, easily expandable, and also easily transportable. This system can also be used for either centralized or distributed power generation.
Solar (Photovoltaic) Power
The concept of using the sun’s rays to generate power is not a new one; this idea has been around for a number of years. The first solar cells were built in the 1950’s and had an efficiency of around four percent. Solar energy is harnessed by using photovoltaic cells. By using photovoltaic cells, sunlight can be directly converted to electricity. The way these cells work is that when light hits the cell, the energy knocks electrons loose from atoms allowing them to move freely throughout the material and therefore produce electricity. An example of this is shown below:
[pic]
Reference:
One solar cell is not capable of producing much electricity, so many cells, usually around 40 are grouped together to form modules. These modules are then grouped to form arrays. An example of this is shown below:
[pic]
Reference:
Using these arrays or panels, a significant amount of energy can be harnessed. The amount of energy that can be obtained by the cells depends on the efficiency of the cells. The lower the efficiency of the cells the more of panels that are required which in turn leads to a higher initial cost of installation. If the cells are very efficient less space will be needed. The highest efficiency solar cell on the market is around 16 percent efficient.
Even though the efficiencies do not seem quite high, there are reasons to go solar powered. By using a renewable energy source such as the sun instead of coal or petroleum many environmental impacts can be reduced. Another reason why consumers choose to go solar is that after you install the photovoltaic system (PV system); one will not have to pay for your energy again, if a battery storage system is used. However, some consumers choose to be connected to the utility grid. The latter option will reduce the cost of having a battery operated system, also the consumer will not have to maintain and service the battery operated system. If the consumer decides to be connected to the utility grid, co-generation is an option. Co-generation allows the customer to buy energy when they need to, for example when the weather is bad. Co-generation also allows the consumer to feed energy back to the grid when a surplus is produced. The utility company has to pay for this energy that it receives, so extra income can be made by the consumer by selling power. Another advantage is that the PV panel is that they last from 20 to 30 years with little to no maintenance, because the cells have no moving parts.
Solar Radiation in New jersey
After researching the topic, the group found the following maps depicting the average and worst case scenarios of sunlight distributed on the United States.
[pic]
The above graph shows that New Jersey receives the least amount of sunlight per year. This data was used while designing the photovoltaic system.
[pic]
The above illustration shows the worst case scenario regarding the amount of sunlight per region.
|PV Module Efficiency |PV Capacity Rating |
|(%) |(Watts) |
| |
The above graph shows the amount of area needed for a certain wattage and efficiency.
Reference: (graphs and illustration)
It was also found that:
• The state of New Jersey get 4.6 hours of sunlight on average per day, per year
• PV systems in the Northern Hemisphere should point toward true south (this is the orientation)
• The PV system should be inclined at an angle equal to the area's latitude to absorb the maximum amount of energy year-round
• 1Kw system generates 1,250 Kwhr/yr
• typical home uses 8,500 Kwhr/yr
These findings were used to produce a design scenario that would be used as a model for the actual Duke Farms scenario.
Reference:
What is Co-generation?
There are many different kinds of co-generations systems. The one the group is focusing on is on the type of co-generation that could very easily be interchanged with a “parallel” system.
In “parallel” system the customer supplies energy back to the power grid while at the same time consuming energy from the power utility company. This system is used for facilities which produce some of their own electricity but may not have the capacity to produce enough energy during their peak times.
As system like this is advantageous because one overall reduces their electricity cost significantly. Not only is producing your own energy cheaper most of the time, but the utilities companies pay the customer for the energy they supply.
Financial Incentives for a Photovoltaic System
The system being designed is not only economically beneficial because the customer is creating a “business” with the utility company, but because the fact that method of producing energy is through a renewable resource. The New Jersey government supplies the community with a lot financial incentives.
The Mainstay Energy Rewards Program and Solar Renewable Energy Certificates are two production incentives that would benefit users of photovoltaics. In the Mainstay Program, people who install photovoltaic systems are eligible to sell green tags (or renewable energy credits, REC’s). Participating customers can either receive an up-front payment or quarterly production-based payments. The amount received depends on the amount of energy produced by the system and the length of the contract period. The longer the contract period is, the greater the incentive payment is. Incentives can range from 5.3 cents/kWh to 9.5 cents/kWh depending on the type of payment plan and contract chosen.
Solar Renewable Energy Certificates represent the renewable attributes of solar generation, bundled in minimum denominations of one megawatt hour of production. Any solar system owners interested in the program sign an Attestation and can then upload monthly meter readings and/or production onto a website online with their account information. Once these S-REC’s are uploaded, individuals can buy and sell their certificates and use the website as a means to transfer them. The maximum price for an S-REC is estimated to be about $250/MWH. S-REC’s are anticipated to compensate New Jersey solar system owners an average rate of $0.20/kWh generated.
The Solar and Wind Energy Systems Exemption provides a sales tax exemption for users of solar energy. New Jersey offers a full exemption from the 6% sales tax for all solar equipment. Reference to New Jersey’s technical sufficiency standards is necessary in order to certify eligible solar energy equipment for tax exemptions.
The Renewable Energy Advanced Power Program was established to encourage the development of distributive renewable electricity generation projects in the state. Projects are expected to supply electricity to large power users by installing a minimum of 1 Megawatt power generation at the facility. This project was designed to make renewable energy competitive with conventional power plants. Facilities that are eligible for this program are granted an award of up to 20% of the total construction costs as well as guaranteed long-term financing for the cost of the project.
The Renewable Energy Economic Development Program provides funding for the development of renewable energy businesses and technologies. The program is open to people seeking funding in research, business development, commercialization, and technology demonstrations of renewable energy. The company will be required to repay this grant as the company generates revenue. The grant can range from $50,000 to $500,000.
The New Jersey Clean Energy Rebate Program is a rebate program administered by the state’s utilities. There is no maximum installation size for the photovoltaic system; however, every system must include at least a 5-year all-inclusive warranty. Systems of up to 10kW are eligible to receive up to 70% of installed cost. Any system greater than 10kW may receive up to 60% of installed cost.
PSE&G Specifications
In order for the co-generation project to be approved by PSE&G, the following specifications have to be met:
• The installation must comply with the provisions of the NEC
• Modules must be UL listed
• The maximum amount of sunlight available per year should not be obstructed
• All the solar array orientations are require that the estimated system output must be 75% of the default output estimated by PVWATTS
• The inverter must be certified as compliant with the requirements of IEEE 929 and with UL 1741
The system also needs to have the following visual indicators:
• On/off switch
• Operating mode setting indicator
• AC/DC overcurrent protection
• Operating status indicator
• Warning labels must be posted on the control panels and junction boxes indicating that the circuits are energized by an alternate power source
Reference:
System Information
The team used the PVWATTS calculator as PSE&G indicated. To find the projected amount of solar energy that would be gained from the solar modules, the team first had to find out some geographical information. After some research it was found that Duke Farms is located at latitude of 40.38. The closest station that the PVWATTS user had was Newark, NJ which is at latitude 40.70, which is only a difference of 0.32. The team felt that this small difference was negligible and should not affect the calculations of the PVWATTS program. The PVWATTS program can be modified to fit the design configuration of your solar system. The program can accommodate solar modules that are fixed tilt, one way, or two way axis tracking. The following diagrams illustrate the configurations that can be used:
[pic] [pic] [pic]
Reference:
Case Studies
Montville Home Case Study
This study was done for a new 4,000 square foot home in Montville, NJ. The system included 36,167 watt solar energy modules installed on the south roof and the west roof of the garage. A total of 6,012 watts of peak power is capable of being generated by these modules according to manufacturer output ratings.
|[pic] |Costs of the system: |
| |$45,000 |
| |$31,215 rebate was received from NJ Clean Energy |
| |Program. |
| |Total Cost to the homeowner was $13,785, not including |
| |the $2,000 Federal Tax Credit that is still pending |
Based on the following current residential electric rates, a 7% discount rate, 30 year solar energy system lifetime, 5% annual rate increase, 6% borrowing rates and 42% combined State and Federal tax rates, this system will save the homeowner $755 per year.
The following charts show the homeowner’s energy cost before and after the PV system was installed.
[pic]
The above graph shows the amount of money the family paid in a year under previous electrical provider (gas/electric).
[pic]
The above graph shows the amount of money the family paid after installation of photovoltaic system.
The following is a summary of the environmental and financial savings:
[pic]
Reference: (illustration and graph) residential_systems/nj_residential_case_study.html
This information proves that even though the PV system is not strong enough to power this house independently it still saves the homeowners a large amount of money on their utility bill, thus a photovoltaic system is a viable energy alternative in New Jersey.
Typical New Jersey Home
Our sample model is of a typical home in NJ, this model took into account the group’s research findings. The group used the following information to calculate the amount of space that would be needed to provide this home with enough energy to meet its requirements for the whole year.
Assumptions:
• House is in NJ
• 8,500 Kwhr/yr is used
• 1Kw system generates 1,250 Kwhr/yr
• Solar Panels are at the right orientation and inclination
Therefore:
[pic]
This means it would take a 6.8 Kw system to run this house for the year without any other power source. According to the chart above, this would take approximately 2040ft2.
Reference: and
Duke Farms Data
Data for Employee Housing
The team received five years of power usage data from Duke Farms and analyzed the data, to see what size system is right for this electrical load. Since the Farms data did not change much from year to year, the group decided to use 2003’s data and run the calculations of that data set. The team decided to examine three systems. The systems were 10%, 50% and 75% of Duke Farms’ peak annual load.
|Duke Farms’ 2003-2004 PSE&G Data |
|Month |Energy (kW*hr) |
|January |14986 |
|February |13862 |
|March |9430 |
|April |9197 |
|May |8424 |
|June |9630 |
|July |11312 |
|August |9741 |
|September |11574 |
|October |9318 |
|November |9463 |
|December |14211 |
Using the PVWATTS calculator, the group then calculated the amount of power that would be given off by a fixed tilt, one axis and two axis tracking system. The group then generated graphs to illustrate how much energy would be generated by the PV system.
[pic][pic]
[pic]Data for Powerhouse
The team also had to consider the Power House that is located on the Duke Estate. The Power house uses a vast amount of energy; the monthly data is shown below:
|Month |Duke Farms |
| |Power House Usage (kW-hr) |
|Aug-03 |146424 |
|Sep-03 |247055 |
|Oct-03 |137557 |
|Nov-03 |97546 |
|Dec-03 |156921 |
|Jan-04 |169716 |
|Feb-04 |162028 |
|Mar-04 |140565 |
|Apr-04 |137610 |
|May-04 |112532 |
|Jun-04 |130047 |
|Jul-04 |137338 |
|Aug-04 |128162 |
Reference: Duke Farms energy spreadsheet
Using the PVWATTS calculator, the group then calculated the amount of power that would be given off by a fixed tilt, one axis and two axis tracking system. The group then generated graphs to illustrate how much energy would be generated by the PV system. The group designed the system for the average monthly load. The average monthly load for the Power House is 146,423.08 kW-hr. The graphs that follow illustrate how much power would be generated if a 1000 kW system, 702 kW system or a 350 kW system was installed.
[pic]
[pic][pic]
Solar Calculations
Powerhouse System Size
The team had to calculate how many solar panels would be needed in order to run Duke Farms’ Power House. To calculate the amount of panels, the team took the following things into consideration:
• Rated output wattage of the panel
o Using 80 Watt panels
• How long the panel is in the sun
o NJ gets 4.6 hours of sunlight
• Shell SQ80 panel
o Area of one panel = 6.81 ft2
• Average monthly Power House usage
o 146,424 kW-hr/month
• 1kW system produces 1,250 kW-hr/yr
[pic]
The area needed to place 13,264 panels is:
[pic]
According to the calculations, in order to generate enough power to meet the Power House’s average monthly consumption, 13,264, 80 watt panels would be needed, which is equivalent to a 1400 kW system. The group decided to do a breakdown of how many panels would be needed if only 50% and 25% of the average monthly usage.
• 50% of Power House monthly average (equivalent to a 702 kW system)
[pic]
• Area needed
[pic]
• 25% of Power House monthly average (equivalent to a 350 kW system)
[pic]
• Area needed
[pic]
Employee Housing System Size
The team decided to create another system which would supply power to the housing facilities at Duke Farms. The group had to consider the same criteria as above and also the following:
• Average monthly Employee Housing Usage
o 10,929 kW-hr/month
In order to provide100 percent of the Employee housing needs the following amount of panels is needed:
[pic]
The area that would be needed to accommodate 990 panels is 0.154 acre; this is equivalent to a 100 kW system.
• In order to supply 50% of the power needs the following amount of panels is needed:
[pic]
The area that would be needed to accommodate 495 panels is 0.77 acre, which is equivalent to a 50 kW system.
• In order to supply 25% of the power needs the following amount of panels is needed:
[pic]
The area that would be needed to accommodate 248 panels is 0.38 acre, which is equivalent to a 26kW system.
Reference: (equations) sourcebook/Photovoltaic.html
System Layout
Supplying the Farm and the Grid
If the group decides to not only supply the grid but the customers on the facility as well the system will look like the one below.
[pic]
Reference:
Feeding Directly to Grid
The system is going to be laid out as shown below. The photovoltaic panels create DC electricity. The DC current is the converted to AC 3-phase electricity in the inverter. Then it will pass through a meter which logs the amount of electricity that is being sent back to PSE&G.
The group will be feeding directly to the grid in order to simplify the system design.
Benchmarking Data
The team gathered research to find which inverters, solar panels, meter and tracker best fit the team’s specifications and power requirements.
PV Panel Data
|Company |Model # |Peak Power |Peak Voltage |Dimensions (L”xW”xD”)|
| | |(Watts) | | |
|BP Solar |BP 4170 |6 |81.8 |$1,995.00 |
|Shell Solar |85-P |12 |82.8 |$1,195.00 |
|Sharp |NE-80E1U |10 |69 |$1,975.00 |
The trackers that the group investigated were all one axis tracking. The group chose one axis trackers because from the graphs of the power output, the difference between one axis tracking and two axis tracking is negligible. The team chose the Shell Solar 85-P solar tracker. The team chose this model because it was compatible to the Shell Solar Panels. The Shell tracker also is the cheapest of the three models, and can accommodate a larger area of solar modules.
Reference:
Inverter Data
|Model |Meets Criteria |Extra features |Price |
|PV225 |Yes |LCD Display |$2,195 |
| | |Digital Signal Processor (DSP) | |
|GT500E |Yes |LCD |$3,595 |
| | |Digital Signal Processor (DSP) | |
| | |Remote monitoring via telephone modem or web server | |
| | |Faults notification via modem | |
| | |Data acquisition and logging | |
| | |Analog inputs for external measurements | |
|GT100E |Yes |Optional Features: |$2,895 |
| | |Remote monitoring via telephone modem | |
| | |Faults notification via modem | |
| | |Data acquisition and logging | |
| | |Analog inputs for external measurements | |
Reference:
The inverters were all studied. They all fulfill the necessary safety requirements set forth by PSE&G. The inverter chosen is the GT500E. The reason this was chosen is because it has the built in logging of the system. Since this system is going to be for the most part unattended, logging the faults will allow for simpler trouble shooting, and in the future reduce possible maintenance costs.
Mounting System Designs
The team had to design a mount to hold the solar panels. The team researched different mounts and took into consideration Duke Farms’ needs. The Farms need a mounting system that is unique and aesthetically pleasing, since the client will want to show the finished product to park visitors. The group had to make sure that the designs were structurally sound and could handle the wind and snow conditions of New Jersey.
The team came up with a few preliminary designs that can be seen below. The team feels that these designs meet the needs of Duke Farms.
Design #1- Pole Support
[pic]
The first design is based on research that was conducted by the group. The design is simple; it consists of a rod for support, a pivot for tracking purposes and a flat backing with braces to hold the solar panel.
Design #2- Pyramid Tripod Design
[pic]
The second design is very unique and creative and requires the use of flexible solar panels. The team thought that this design would get the attention that Duke Farms was looking for. This design is based on a pyramid, the solar panels sit firmly in place using brackets and a pivot would also be used in order to accommodate tracking.
Design #3- Cone Design
[pic]
The third design is conical shape. The design consists of a plate to rest the solar panel, and two conical shapes with a shaft. The pipe structure will sit in the ground to support the system. This design is for a non-tracking system.
Design #4- Lounge Chair Design
[pic]
The fourth and last design was taken from an already existing mounting system and modified to fit this projects needs. The original design was meant for a stationary, fixed tilt system.
The team decided to analyze designs # 1, 3 and 4. The team wanted to test the mounting structures to make sure that it would be able to withstand snow and wind conditions in New Jersey. The first thing that had to be done was to create these models using SolidWorks. After creating the assembly of the models, the group used ComosWorks in order to model the wind and snow loads that might be applied to the mounting system throughout the course of a year.
Conceptual Designs
During analysis, it was found that there was a great difference between the amounts of money saved via the use of a tracking system as opposed to a stationary system. This was one of the major factors considered when the group was designing different structures for the support of the solar module. Some of the designs considered were a “lounge chair” structure, a standing pole, and a cup-like shape. These designs were chosen to be analyzed after careful research online of existing support structures and were expanded/improved upon by group members. Static analysis was performed on each of the designs after they were created in various CAD programs such as Solidworks in order to help determine which design was to be used as our final structure. There were three different types of design scenarios implemented during analysis: the weight of a solar cell (16.7 lbs), weight and snow loading, and weight and wind loading. The difference between the numerical value of snow and wind was minimal so therefore, there was not much of a difference between the reactions of the structures under snow loading as opposed to wind loading. As referenced from the IBC (§§ 1608.1 and 1608.9) and IRC (§§ R301.23), it was found that for New Jersey, the typical load used for snow in worst-case design scenarios is 25 lbs/ft2. Through calculations provided below, it was found that wind loading was about 22.56 lbs/ft2.
Calculation of Wind Loading
Velocity Pressure: [pic]
- Kz velocity pressure exposure coefficient (accounts for wind speed profiles in given terrain)
- Kzt = topographic factor (accounts for wind speed over hills and escarpments)
- Kd = wind directionality factor (accounts for reduced probability of either maximum winds occurring from any direction or maximum pressure coefficient occurring in any direction)
- V = basic wind speed (mph)
- I = importance factor
From Table 6-5: Exposure B Buildings (60-80% of all locations); evaluated at height “h” (33 feet or less) ( Kz = 0.72
From Table 6-2: Kzt = 1.0
Wind Directionality Factor Kd = 0.85
Importance Factor = 1.0
Maximum Wind Speed (mph) = 120
[pic]
Reference: (tables and equations) ASCE 7-98, 2000 IBC,
Importance of Finite Element Analysis for Conceptual Designs
Finite Element Analysis is a computer-based numerical technique for calculating the strength and behavior of engineering structures. It was used to calculate deflection, stress, deformation, and strain in the various structures. The computer software was required because of the astronomical number of calculations needed to analyze a large structure.
In the finite element method, a structure is broken down into many small simple blocks or (elements). The behavior of an individual element can be described with a relatively small amount of equations. Just like the set of elements can be joined together to create the entire structure, the equations describing the behaviors of the individual elements are joined into a larger set of equations to describe the behavior of the whole structure. Software like Solidworks or ANSYS solves this large set of simultaneous equations. The behavior of the individual elements are extracted and then used to find the stress and deflection of all the parts in the structure. The stresses were then compared to allowable values of stress for the materials to be used in order to determine if the structure was strong enough.
Finite Element Analysis makes it possible to evaluate a detailed and complex structure in a relatively short period of time. Via the software’s analysis of the structure strength, one can determine if the structure is too weak or overly designed.
Design 1 Description-Lounge Chair Design
This design resembled almost a 3-D truss-like structure. It was chosen due to its ability to have solar cells rest very easily on the two horizontal poles. The support appeared sturdy and easy to build. However, its own drawback was that it lacked the ability to contain a tracking system as well. Therefore, only stationary solar cells could be used, drastically cutting down on the amount of energy that could possibly be collected.
First, the design was created in Solidworks (See Appendix A, Figure 1). Usually, the assembly is then analyzed in CosmosWorks, however, due to the complexity of the assembly, the analysis was not able to be completed. Sometimes, if a part/assembly has too many small/intricate parts, meshing cannot be completed and no static analysis can be performed. Instead, the structure was redesigned in software called ANSYS.
ANSYS Graphical Representation of Design
[pic]
ANSYS uses a three-dimensional coordinate system in order to create structures. After key points are created, they are connected by lines in order to complete the structure. The material was then selected to be Aluminum 1060 and the numerical values for Young’s Modulus 2.75e7 and Poisson’s Ratio of 0.33 was inputted. Although most existing structures for solar cells consisted of Stainless Steel, due to financial issues, the group decided to go with the cheaper Aluminum. Then, the connecting beams in the structure had to be defined. Element Type was selected to be a Structural Mass – Link which is a three-dimensional element. Each beam’s area was defined to be 12 units. In the software, ANSYS, units do not have to be inputted just as long as the user makes sure that all data is in the same units. The mesh was created with a number of element divisions of one and all lines were meshed. Restraints were created in the bottom four legs of the structure (displacement = 0 in the X,Y,Z directions) in order to simulate an anchored structure. Then, a force equal to the weight of a solar cell (16.7 lbs distributed uniformly) was added to the top of the structure and the simulation was run.
Results of ANSYS Analysis
A figure of the resulting structure after inputted force can be found in Appendix A – Figure 2. From the figure, we can see that there was very little deformation once the weight of a solar cell was added. The results in tabular form can be found below.
Deformation Data
|Node |Ux (in) |Uy (in) |Uz (in) |Usum (in) |
|1 |-0.800 x 10-4 |-0.120 x 10-3 |-0.120 x 10-3 |0.187 x 10-3 |
|2 |0.00 |0.00 |0.00 |0.00 |
|3 |0.00 |0.00 |0.00 |0.00 |
|4 |0.00 |0.00 |0.00 |0.00 |
|5 |0.00 |0.00 |0.00 |0.00 |
|6 |0.00 |0.00 |0.00 |0.00 |
|7 |0.00 |0.00 |0.00 |0.00 |
|8 |-0.800 x 10-4 |-0.120 x 10-3 |-0.120 x 10-3 |0.187 x 10-3 |
Based on the data above, we can see that the most deformation would occur on the nodes on the top of the structure. However, this deformation is negligible due to its smallness in value (fractions of an inch).
Stress Components
| |Sx (psi) |Sy (psi) |Sz (psi) |Sxy (psi) |Syz (psi) |Sxz (psi) |
|Min. Node Value |0.10 x 1032 |0.10 x 1032 |0.10 x 1032 |0.10 x 1032 |0.10 x 1032 |0.10 x 1032 |
|Max. Node Value |-0.10 x 1032 |-0.10 x 1032 |-0.10 x 1032 |-0.10 x 1032 |-0.10 x 1032 |-0.10 x 1032 |
Principal Stress
| |S1 (psi) |S2 (psi) |S3 (psi) |Sint (psi) |Seqv (psi) |
|Min. Node Value |0.10 x 1032 |0.10 x 1032 |0.10 x 1032 |0.10 x 1032 |0.10 x 1032 |
|Max. Node Value |-0.10 x 1032 |-0.10 x 1032 |-0.10 x 1032 |-0.10 x 1032 |-0.10 x 1032 |
It was interesting to see how similar stresses were that acted on the structure. Despite the size of the stresses, the structure did not fail.
Design 2 Description- Pole Support:
The next design examined was a simple pole/support structure. A tall pole with a 2-inch diameter would be erected and anchored with cement. The solar cell support would be fastened on top. One positive point about this structure is its ability to contain a tracking system. Therefore, more solar energy could be collected due to the 1-axis or 2-axis tracking system.
After the model was created in Solidworks (see Appendix A – Figure 3), it was analyzed with CosmosWorks. Due to the relative simplicity of the model, it was easily meshed. A fine mesh was used due to some small parts (pipe with 2-inch diameter). Restraints were placed on the bottom face of the pipe in order to simulate that the pole would be anchored into the ground. Two simulations were run with this model (force of weight, force of weight and snow). Due to the closeness in numerical values of wind and snow, the group decided just to run one simulation. Since snow had a higher numerical value (25 lbs/in2 as opposed to wind’s value of 22.56 lbs/in2), it was decided that if the structure could support the higher value, then it would certainly support the lower force of wind.
Results of CosmosWorks Analysis
The weight of the solar cell was first inputted and analyzed in CosmosWorks. Graphical results can be found in Appendix A – Figures 4-8. For the Von Mises Stress (Appendix A - Figure 4), it was found that most of the structure experienced minimal stress. The support had an average stress of 19.89 N/m2 whereas the pole had a substantially higher stress of 143,300 N/m2. Upon closer examination, it was found that most of the higher stress occurred around the hole in the solar cell support (Appendix A – Figure 5). This hole experienced a stress of about 573,100 N/m2. Strain (Appendix A – Figure 6) was about 8.779 x 10-9 (about a value of 0) which makes sense since this structure is not being pulled at all and the majority of structure is more affected by stress. Static displacement (Appendix A – Figure 7) ranged from 1 x 10-33 (about a value of 0) in the pole to 2.157 x 10-5 in the solar cell support. The structure can be seen with the final amount of deformation in Appendix A – Figure 8.
The weight of the solar cell plus snow was then inputted and analyzed in CosmosWorks. Graphical results can be found in Appendix A – Figures 9-13. For the Von Mises Stress (Appendix A - Figure 9), it was found that most of the structure experienced a much higher stress under weight and snow loading as opposed to simple weight loading. The support had an average stress of 1.36 x 106 N/m2 whereas the pole had a substantially higher stress of 1.38 x 1010 N/m2. Upon closer examination, it was found that most of the higher stress occurred around the hole in the solar cell support (Appendix A – Figure 10). This hole experienced a stress of about 3.449 x 1010 N/m2. Strain (Appendix A – Figure 11) was about 6.345 x 10-4 (about a value of 0) which makes sense since this structure is not being pulled at all and the majority of structure is more affected by stress. Static displacement (Appendix A – Figure 12) ranged from 1 x 10-33 (about a value of 0) in the pole to 1.558 in the solar cell support. The structure can be seen with the final amount of deformation in Appendix A – Figure 13.
Design 3 Description- Cone Design
The following design is called the Cone Design. The entire structure is 3 feet tall and 1.5 feet wide. It is designed so minimum assembly is necessary. The top part slides through the bottom base and into the ground. This design could be used with a tracking device as well as a stationery design, by just making a few minor adjustments. In the design seen in Appendix A – Figure 1, it is intended for stationery designs in which there is no tracking device.
The model created in Solidworks was then analyzed using CosmosWorks. Due to the simplicity and uniformity of the design only the bottom portion was analyzed. Restraints were placed on the bottom, which is where the ground would be. Force was placed normal to the top which will account for snow, wind and weight. Two simulations were done: force of the weight and force of the weight and snow/wind (Appendix A- Figures14- 23). The forces of the weight and wind/snow are the same as above, 16.7 lbs and 22 lbs, respectively.
Results of CosmosWorks Analysis
The weight of the solar cell was first inputted and analyzed in CosmosWorks. Graphical results can be found in (Appendix A – Figures 14- 23). For the Von Mises Stress (Appendix A - Figure 14), it was found that most of the structure experienced minimal stress. Upon closer examination, it was found that most of the higher stress occurred around the hole in the solar cell support (Appendix A – Figure 14). This hole experienced a stress of about 2830 N/m2. Strain (Appendix A – Figure 15) was about 3.439 x 10-8 (about a value of 0) which makes sense since this structure is not being pulled at all and the majority of structure is more affected by stress. Static displacement (Appendix A – Figure 16) ranged from 1 x 10-33 (about a value of 0) in the base to 1.039 x 10-8 in the solar cell support. The structure can be seen with the final amount of deformation in Appendix A – Figure 17.
The weight of the solar cell plus snow was then inputted and analyzed in CosmosWorks. Graphical results can be found in Appendix A – Figures 19-23. For the Von Mises Stress (Appendix A - Figure 19), it was found that most of the structure experienced a much higher stress under weight and snow loading as opposed to simple weight loading. Upon closer examination, it was found that most of the higher stress occurred around the hole in the solar cell support (Appendix A – Figure 19). This hole experienced a stress of about 2.830x 103 N/m2. Strain (Appendix A – Figure 20) was about 3.439 x 10-8 (about a value of 0) which makes sense since this structure is not being pulled at all and the majority of structure is more affected by stress. Static displacement (Appendix A – Figure 21) ranged from 1 x 10-33 (about a value of 0) in the base to 1.039 x 10-8 in the solar cell support. The structure can be seen with the final amount of deformation in Appendix A – Figure 22.
Exploded Views of Conceptual Designs
For exploded views of some of the conceptual designs analyzed in this report, please refer to Appendix B. These views show how these structural supports are put together.
Price Quotes for Materials
The group decided on researching the different materials needed per structural design in order to see how expensive each structure would be to create. The following quotes were found:
Aluminum Pipe – Heavy Gauge (used for all designs analyzed)
|[pic] |No. P3 Aluminum Pipe – 3” Diameter x 24” Length (Item 265340) |$2.19/each |
|[pic] | | |
|[pic] |No. P4 Aluminum Pipe – 4” Diameter x 24” Length (Item 265359) |$2.19/each |
Reference:
Axle U-bolt (used for Lounge Chair design)
|Part# |Style |
Reference:
Flange Nut (used for Lounge Chair design)
|No. 7392 Flange Nut – 3/8” (box of 100) |$12.93/each |
Reference:
Screws (used for all designs)
|No. 7597 Screw – 3/8” (box of 100) |$2.28/each |
Reference:
System Placement
[pic]
Reference: Duke Farms map from Joe Wyatt
Duke Farms would like the PV Co-generation system to be placed within the park (the enclosed red area on the map). The group believes that this space allotted by the Farms is not a good spot, because of the trees. The group feels that one of the open fields would be a better spot to locate the system because there is more open space. The PV system should not be obstructed or shaded by trees.
PATENT RESEARCH
The group is not creating any new services. However, due to the fact that the group is creating a new structural support, research was still needed. The group’s new design for a support structure is not only unique, but relatively inexpensive. This saves the consumer money and would be appealing for a patent.
|Product/Process/Copyright |Owner |
|Mounting Apparatus for Solar Panel |Donald Bradley, Jr. |
|Method and Apparatus for Testing Solar Panel |Fumitaka Toyomura |
|Detachable Solar Panel |Sass M. Peress |
Reference: paft/index.html
FINANCIAL ANALYSIS
After researching and analyzing our designs, the team decided to go with design #1 with aluminum parts because it is the most cost effective and also does not require complicated assembly.
New Jersey offers a solar energy system incentive program where customers receive direct rebates of $5.50 per AC watt up to 70% of the total cost for systems less than 10kw. For systems over 10kW, the rebate is $5.50 for the first 10kW and then $4.00 per AC watt for each watt over 10kw, up to 60% of the total cost. In addition, PV systems are not subject to 6% State sales tax.
Direct financial incentives are paid through the public utility company to reduce the initial cost of the clean generation system. Incentives are paid incrementally based on the size of the solar energy system installed.
After evaluating Duke Farms’ need for power, for their Powerhouse, the team as decided to go with the 702 kW system because it is the most economical. It will not only fulfill their need for power, but they will also be able to sell back some of the power. The 1000 kW system would be too expensive and would leave them with an excess of power and the 350 kW system would not be sufficient.
We did a similar analysis for their Employee Housing and came to the conclusion that the 100 kW System best fit the needs of Duke Farms. Although it is the more expensive system, it is the only system that can efficiently power Duke Farms. The other two systems could not efficiently power Duke Farms’ employee housing facilities.
Deliverables
A final written report will be submitted at the end of the spring 2005 semester to the Mechanical Engineering Department as well as Duke Farms. More time to work on this project could provide the team with a more detailed and specific designs. A detailed electrical layout will de designed for the farm as well as a continuation of analysis on the support and power cells.
Conclusions and Future Work
The spring 2005 semester is mostly dedicated to focusing on the electrical layout and design of the project. The team will focus on the different components that can be used as well as specific tie-in and layout on the farm. The team will take this opportunity to explore with more details the facilities in order to engineer a system that will adequately fulfill our customer needs.
Appendix A
[pic]
Figure 1 – “Lounge Chair” Assembly created in Solidworks
(Later found unable to be analyzed due to complexity of small parts)
[pic]
Figure 2 – “Lounge Chair” ANSYS Representation of Deformation
(Comparison of final and original figure after force was added)
[pic]
Figure 3 – Pole Design in Solidworks
[pic]
Figure 4 – CosmosWorks Graph of Von Mises Stress for Pole Design (weight as force)
[pic]
Figure 5 – Close-up of Von Mises Stress in Hole for Pole Design (weight as force)
[pic]
Figure 6 - CosmosWorks Graph of Strain for Pole Design (weight as force)
[pic]
Figure 7 - CosmosWorks Graph of Static Displacement for Pole Design (weight as force)
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Figure 8 - CosmosWorks Graph of Deformation for Pole Design (weight as force)
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Figure 9 - CosmosWorks Graph of Von Mises Stress for Pole Design (weight + snow as force)
[pic]
Figure 10 - Close-up of Von Mises Stress in Hole for Pole Design (weight + snow as force)
[pic]
Figure 11 - CosmosWorks Graph of Strain for Pole Design (weight + snow as force)
[pic]
Figure 12 - CosmosWorks Graph of Static Displacement for Pole Design (weight + snow as force)
[pic]
Figure 13 - CosmosWorks Graph of Deformation for Pole Design (weight + snow as force)
[pic]
Figure 14 - CosmosWorks Graph of Von Mises Stress for Cone Design (weight as force)
[pic]
Figure 15 - CosmosWorks Graph of Strain for Cone Design (weight as force)
[pic]
Figure 16 - CosmosWorks Graph of Static Displacement for Cone Design (weight as force)
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Figure 17 - CosmosWorks Graph of Deformation for Cone Design (weight as force)
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Figure 18 – CosmosWorks Graph of Factor of Safety for Cone Design (weight as force)
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Figure 19 - CosmosWorks Graph of Von Mises Stress for Cone Design (snow and weight as force)
[pic]
Figure 20 - CosmosWorks Graph of Strain for Cone Design (weight and snow as force)
[pic]
Figure 21 - CosmosWorks Graph of Static Displacement for Cone Design (weight and snow as force)
[pic]
Figure 22 - CosmosWorks Graph of Deformation for Cone Design (weight and snow as force)
[pic]
Figure 23 - CosmosWorks Graph of Factor of Safety for Cone Design (weight and snow as force)
Appendix B
[pic]
Figure 1 – Pole Structural Support (exploded view)
[pic]
Figure 1 – Cone Structural Support (exploded view)
Appendix C
Gantt Chart
[pic]
-----------------------
Single pole mount/array
1-Axis tracking
Pyramid Tripod design
Fixed plate
Estimated Solar Energy For The Contiguous U.S.
Kilowatt Hours Per Region per YEAR
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