Nate White
Applied Solar Power Research
An Analysis of the Photovoltaic Potential of WWU
Prepared by Nate White
Senior, Environmental Policy
Huxley College of the Environment
Western Washington University
Bellingham, WA
Introduction:
This paper began as a project in Huxley College’s Environmental Policy Analysis class winter quarter 2008. We were assigned to find a problem that needed to be solved using alternative solutions. The problem focused on was reducing Western’s carbon footprint by using renewable energy. My alternatives were an energy conservation policy, a renewable energy credit policy and a solar energy policy. The policy that interested me the most was the solar energy policy, and I continued research after the class was over in the form of an independent study. This report is the culmination of that work.
Background:
Currently, the U.S. meets 70% of its electricity needs through the use of fossil fuels, including petroleum, coal, and natural gas.[1] Depending on the scale of implementation, the use of renewable energy can slow, halt, or even reverse the growing trend of fossil fuel greenhouse gas emissions. Solar electric technology in particular holds much promise for replacing dirty, fossil fuel electricity with clean, renewable electricity.
Photovoltaic (PV) panels convert radiation from the sun into electricity. With proper siting, solar radiation, orientation and scale, a PV system can provide anywhere from a portion to the total electrical needs of a building. However, drawbacks do exist. Current PV technology is limited in the conversion of solar radiation to electricity, and relatively high costs discourage wide-scale implementation. Additionally, the local climate plays a large role in the productivity of a PV system. Especially in Bellingham, where the solar resource is highly seasonal, PV systems produce more electricity in the summer and less during the winter.
Despite these drawbacks, the popularity of PV technologies has spiked in recent years due to fears of climate change, increases in financial incentives and technological improvements. This paper is a result of these issues and considers whether Western can capitalize on this new wave of renewable energy opportunity.
Paper Layout:
This paper analyzes the basic considerations of installing a PV system and recommends five buildings on Western’s campus that would qualify as productive sites for a rooftop PV installation. This paper is divided into three sections:
1. A research section that briefly explains the research relevant to this project
2. A results section that analyzes the research results in terms of PV potential
3. A conclusion section that compares the best PV study site on campus to other renewable energy options that Western might pursue
At the end of the paper, I hope that anyone curious about the photovoltaic potential of Western can understand the opportunities and obstacles facing such a system. Ultimately, I envision this study as a tool for students, faculty and administrators to use to decide whether photovoltaics should be a component of Western’s commitment to effective, innovative and sustainable solutions to environmental problems.
Acknowledgements:
I would like to thank the generous support of Ron Bailey and Tim Williams at Western’s Facilities Management, Robert Foster of the Institute for Energy and the Environment at New Mexico State University, Dana Brandt at EcoTech Energy Systems LLC, and the members of the Students for Renewable Energy Solar Committee. Without the help and support of these people, this project would have been overwhelming and not nearly as much fun as it was. Because of them, I have learned an incredible amount of renewable energy knowledge that I hope to turn into a career.
Thank you for reading, and please do not hesitate to contact me for further information or questions.
Sincerely,
[pic]
Nathan White
Table of Contents
Section 1: Research Areas 5
Area #1: Appropriate buildings for a PV array 5
Area #2: Availability of insolation 5
Area #3: Site area 6
Area #4: System size 6
Area #5: Conversion efficiencies 7
Area #6: Estimated power output 7
Area #7: Estimated system cost 8
Section 2: Results 9
1. Appropriate buildings for a PV array 9
2. Availability of insolation 10
3. Site area 11
4. System size 13
5. Conversion efficiencies 15
6. Estimated power output 16
7. Estimated system cost 17
Section 3: Conclusions 21
Evaluative Criteria 21
1. Promote energy self-sufficiency 21
2. Reduce the cost of electricity 24
3. Reduce greenhouse gas (GHG) emissions 27
4. Educate people about renewable energy 29
Decision Matrix 31
Other Alternatives: 32
Improved REC Policy 32
Energy Conservation Measures 34
Final comments 36
Appendix 37
Figure 1: Solar Pathfinder 37
Figure 2: Excel spreadsheet 38
Figure 3: Estimated annual insolation of other studied buildings 38
Figure 4: Average insolation values for Seattle and Bellingham 38
Figure 5: Sample floor plans 39
Figure 6: Derate calculator 45
Figure 7: Average insolation values for San Diego 46
Figure 8: Map of Western Washington University 47
References: 48
Section 1: Research Areas
The following research areas are relevant to the siting and installation of a PV system. The information and data gathered for each area is specific to the installation of a PV system at Western, and was gathered from a combination of methods. Primary measurements, industry standards and procedures, and the experience of professionals within the renewable energy and campus administration fields are all used within the report, and offer a unique perspective on the opportunities and challenges for PV systems at Western.
The following are the areas researched for this project:
1. Appropriate buildings for a PV array
2. The availability of insolation at a site
3. The geometric area of a site
4. The estimated size of a PV system at each study site
5. The conversion efficiencies of a PV system at each study site
6. The estimated power output of a PV system at each study site
7. The estimated system cost of a PV system at each study site
Each research area is an important part of determining the PV potential of a site. They relate to the availability of energy that powers a PV system, the physical footprint of such a system, and the estimated performance and cost of a system. Each area is explained in further detail below.
Area #1: Appropriate buildings for a PV array
The buildings that were used in this report were chosen by a combined method of first-hand observations of sun exposure and more sophisticated collection of insolation (solar radiation) data using a Solar Pathfinder (explained below). Buildings with exposure to the south were ideal candidates because they receive the greatest exposure to the sun as it travels east to west in the Northern Hemisphere.
Area #2: Availability of insolation
Insolation is measured in kilowatt hours per meter squared per day (kWh/m2/day). The higher the insolation, the more effectively solar panels can convert solar radiation into electricity. The average insolation received by certain cities during a thirty year period can be found using charts generated by the National Renewable Energy Laboratory (NREL). The closest chart applicable to Bellingham is Seattle’s, and because the weather patterns between the two cities are similar, the trends are used for Bellingham.[2]
To measure the insolation received by specific roofs around campus, I worked with Facilities Management employee Tim Williams to get access to the roofs of the preferred buildings. To take these measurements, I used a Solar Pathfinder. A Solar Pathfinder is a small device with a clear dome that reflects the shadows influencing a site onto a chart of the sun arcs and total sun hours of each month. By tracing the shadows and adding up the total sun hours unaffected by the shading, you can determine the percentage of the site that is shaded and how much it will interfere with the array’s exposure to the sun. This analysis will provide site-specific insolation data and ultimately indicate whether a specific site is appropriate for installation or not. See Figure 1 in the Appendix for a Solar Pathfinder diagram, picture and a sample chart.
Area #3: Site area
Measurements of the area of preferred roofs were taken using the original floor plans found in Facilities Management’s vault. Use of the original plans, combined with first-hand observations and the professional expertise of Tim Williams, allowed accurate measurements of the geometric area of specific roofs that take into account aspects of roof shape, surfaces and obstacles.
Area #4: System size
Estimates of the physical area of a PV system are made using the dimensions and power rating of an example panel, an example tilt and the measured geometric area of the preferred roofs.
The estimated panel dimensions are based on the PV panels being installed on the Viking Union roof. These panels are assumed for familiarity purposes, and because it represents an average composition, power rating and size for PV modules today.
The example tilt is 34˚ in order to maximize the collection of insolation during the summer when the sun is higher in the sky. If panels were mounted in multiple rows of single panels oriented horizontally, they would have to be spaced far enough from each other to avoid shading the row behind.
Finally, the geometric area of the roof can only fit a finite number of panels. Dividing the roof area by the area of one panel and its shadow will give the total number of panels that can fit on a given roof. Multiplying the number of panels that will fit on a given roof by their 165 Watt power rating will give the estimated system size in watts, and if you divide by 1000, kilowatts.
Area #5: Conversion efficiencies
The efficiency of a solar array is determined by multiple factors:[3]
1. The average amount of insolation a locality receives over time
2. The amount of shade blocking incoming insolation
3. The orientation of the array
4. The power rating of the PV panels
5. The individual efficiencies of the balance of system components (i.e. “parts”: invertors and transformers, wiring, and diodes and other connectors)
6. Maintenance
7. Age
Values for the categories were found using a combination of first-hand measurements, correspondence with PV professionals and industry averages. Collectively, they provide an overall value called the “Derate Factor” that is used to represent the estimated efficiency of the entire PV system. The industry average is a 77% Derate Factor, meaning that the average AC power rating of a photovoltaic system is 77% of the nameplate DC power rating after conversion.[4]
Area #6: Estimated power output
Estimates of potential power are used to forecast the productivity of a PV system into the future. They can be used to determine the percentage of a building’s energy a system can produce, how much money will be saved by avoiding paying for electricity in the short and long term, and ultimately whether a system is worth the investment. Monthly and yearly estimates of electricity production can be calculated to see the bell-shaped trend of photovoltaic electricity production in our climate, which peaks during the sunny summer months and ebbs during the rainy winter months.
Area #7: Estimated system cost
Estimates for photovoltaic systems are difficult to make because of the variable costs of modules, parts and installation, which in turn are influenced by the location and specific characteristics of a site. That being said, system costs can be based on the linear nature of some components (modules, racking and grounding) and the experience of photovoltaic professionals for variable cost components like inverters, grid interconnect, design and installation time.[5] Generally, a contemporary grid-tied PV systems cost between $8.00-10.00 per Watt, with larger systems costing less and smaller systems costing more.[6] Additionally, the cost-per kilowatt-hour can be estimated by dividing the total cost of a PV system (in cents) by its lifetime production of kilowatt-hours (a PV system lasts anywhere between thirty to fifty years).[7] Depending on the economies of scale and available incentives, electricity from modern PV systems costs anywhere from twenty one to thirty-seven cents per kilowatt-hour.[8]
Section 2: Results
The information and data gathered during the research was analyzed and tabulated in an Excel spreadsheet to graphically portray the crucial information needed to make an assessment of the photovoltaic potential of Western. See Figure 2 in the Appendix to review the tabulated results of the study. Sheet 1 contains information on physical site characteristics and output estimates for each PV site, and Sheet 2 contains estimates of the costs for each PV system.
Explanations of the analysis are listed under the individual research areas to show the specific methodology, calculations and techniques that were used to obtain the results. The example results in the paper differ slightly from the results in the spreadsheet because of differences in rounding: consult the spreadsheet for the most accurate results
1. Appropriate buildings for a PV array
➢ The buildings studied to host a PV system are listed at the top left of each data block in Sheet 1 of the spreadsheet
The five buildings chosen for study in this report are Parks Hall, Bond Hall, Wilson Library, the Performing Arts Center (PAC) and Buchanan Towers (BT). These five buildings were chosen because they range in size from large to small and have low shading interference. The lower the percentage of the site that is shaded, the more insolation it receives to convert to electricity. These buildings also have flat roofs that would allow them to easily hold a PV system. Six other buildings were measured for the affect of shading on their annual insolation estimates. They can be found in Figure 3 in the Appendix.
Additionally, the roofs of these five buildings are partially or fully hidden from view at the street level. This limited visibility satisfies an important criterion of Facilities Management relating to the aesthetics of campus architecture. Concerns were raised that any PV system on campus should be out of sight to the general public, so as to not disrupt the historic aesthetics of Western’s campus. Each of the buildings recommended in this report fully or partially satisfies that criterion, with those only partially hidden still being relatively inconspicuous.
2. Availability of insolation
➢ The raw insolation for Bellingham is listed in Sheet 1 the spreadsheet under “Raw Insolation”
➢ The percent shading of each site is listed in Sheet 1 of the spreadsheet under “Shading”
➢ The actual insolation of each site is listed in Sheet 1 of the spreadsheet under “Actual Insolation”
Results:
In order, the highest insolation measurements of the study sites are:
1. Buchanan Towers 2. Parks Hall
3. PAC 4. Wilson Library
5. Bond Hall
Raw Insolation:
The raw insolation for Bellingham is found using the NREL chart showing the thirty-year average insolation for Seattle. [9] Because the climates of the two cities are similar, the data can be extrapolated north. The data is read from the “Latitude” tilt row. Although the recommended angle for a PV system at Western will be thirty-four degrees (as discussed in the “System Size” results), the chart’s measurements will work fine.
The chart lists monthly averages as well as a yearly average. See Figure 4 in the Appendix for the NREL chart showing the average insolation values for each month.
Shading:
To figure out the actual insolation measurements of the five preferred sites on campus, the shading must be measured first.
1. Position a Solar Pathfinder due south, correcting for the 18° magnetic declination of Bellingham.
2. Trace the edge of any shadows that are reflected through the clear dome of the Solar Pathfinder on the sheet below. The sheet has the different sun arcs for each month of the year along with values representing the intensity of the sun at different hours of the day. All of the intensity values for each month add up to 100.
3. Figure out the percentage of a site that is shaded by adding up the intensity values that are partially or fully covered by a shadow. Since all the intensity values add up to 100, the sum of the shaded values can be expressed as a percentage.
Actual insolation:
To find the actual insolation for each month, subtract the percentage of the site that is shaded from 1, and multiply that value by the raw insolation received each month by Seattle (and by proxy, Bellingham). Round to the nearest hundredth.
Example:
(1 – Percent shading of the PAC site for January) x average insolation for January
(1 - 0.03 = .97) x 1.6 kWh/m2/day = 1.552 kWh/m2/day
= 1.552 ~ 1.55 kWh/m2/day
To find the actual insolation for each year, find the sum of the actual insolation received each month and divide by twelve. Round to the nearest hundredth.
Example:
Sum of the PAC site’s actual insolation received each month / 12 =
44.27 kWh/m2/day / 12 = 3.689 kWh/m2/day
= 3.689 ~ 3.69 kWh/m2/day
3. Site area
➢ The geometric area of each site is listed in Sheet 1 of the spreadsheet under “Roof Area”
Results:
In order, the sites with the largest studied roof area are:
1. Parks Hall (full roof) 2. Bond Hall
3. PAC 4. Parks Hall (partial roof)
5. Wilson Library 6. Buchanan Towers
The geometric area of each preferred site was measured using the original floor plans of the buildings. Additional features were measured based on dimensions provided by Tim Williams and first-hand measurements. Floor plan measurements were taken using an architectural ruler at 1/16 scale, with the exception of the 1/32 scale of the PAC floor plan. See Figure 5 in the Appendix for sample floor plans from Facility Management’s Planning, Design and Construction Administration’s website.[10] A sample floor plan is pictured below.
Source: Planning, Design and Construction Administration, Facilities Management, “Campus Floor Plans,” 12 February 2008 .
Explanation of drawing:
1. The red “X” shows where the insolation reading was taken
2. The numbers along features and boundaries show the measurements used to calculate the geographic area
3. The large and bolded font shows the geographic area calculated
4. The yellow shade shows the general area that is available to install PV panels, leaving out local obstacles such as storm drains, vents and pipes.
4. System size
➢ The area of an individual PV panel is listed in Sheet 1 of the spreadsheet under “Panel Area”
➢ The number of PV panels that will fit on the roof at each site is listed in the spreadsheet under “Number of Panels”
➢ The estimated system size for each site is listed in the spreadsheet under “System Size”
Results:
In order, the roofs of the study sites that could hold the largest PV system are:
1. Parks Hall (full roof) 2. Bond Hall
3. PAC 4. Parks Hall (partial roof)
5. Wilson Library 6. Buchanan Towers
Estimates of the physical area a PV system are based on the dimensions and power rating of the PV panels installed on the Viking Union. They measure 1.58 meters long by .808 meters wide and are rated to a maximum power of 165 Watts.[11] The panels are recommended to be tilted at thirty-four degrees in order to take advantage of the more intense summer insolation of the more vertical sun arcs. Tilting the panels at that angle will require a distance of 2.06 meters between each row of panels to avoid shading the row behind. Additionally, the panels are recommended to be installed horizontally in rows of single panels so as to reduce visibility from street-level. A graphic depicting these measurements and orientation of the panels is pictured below.
Source: Jack Hardy, Western Washington Solar, personal communication, 28 April 2008
Panel Area:
The area that one panel will take up is calculated by multiplying the length of an individual panel by the distance between each row to avoid shading. Round to the nearest hundredth.
Example:
Length of individual panel x width of shadow cast by an individual panel =
1.58 meters x 2.06 meters = 3.2548
= 3.25 square meters
Number of Panels:
The number of panels that will fit on each preferred roof is estimated by dividing the individual area of a panel by the area of the preferred roofs. Because a fraction of a panel cannot exist, the number of panels is rounded down the nearest whole panel.
Example:
Area Wilson Library’s studied site / area an individual panel =
165 square meters / 3.25 square meters = 50.76
= 50 panels
System Size:
In this context, the system size refers to the estimated amount of electricity (in Watts) produced from a PV system. It is estimated by multiplying the number of panels that will fit on the roof by their 165 Watt power rating. To find the system size in kilowatts, divide the system size in Watts by 1000 and round to the nearest tenth.
Example:
Number of PV panels that will fit on Wilson Library’s site x 165 Watts =
50 panels x 165 W= 8,250 W
8,250 W/ 1000 = 8.25 kW
= 8.25 kW ~ 8.3 kW
5. Conversion efficiencies
➢ The estimated conversion efficiencies of each PV system is listed in Sheet 1 of the spreadsheet under “Derate Factor”
Results:
In order, the roofs of the study sites with the highest conversion efficiencies are:
1. Buchanan Towers 2. PAC
3. Parks Hall 4. Bond Hall
5. Wilson Library
The factors affecting the conversion efficiency from DC to AC can be estimated by using a calculator provided by NREL. The PVWatts Derate Factor Calculator lists ten factors that influence the conversion efficiency. Default values based on industry averages are included for each factor in the calculator. These values can be changed based on available information. Detailed explanations of each efficiency factor can be found online at the PVWatts calculator website.[12] The default Derate Factor is .77, or 77%. The higher the Derate Factor, the more efficient a PV system is. See Figure 6 in the Appendix for the calculator with default values included.
Of the ten factors, the only one that is able to be estimated at this stage in the project is the shading. For this factor, the monthly shading values measured at each preferred site with the Solar Pathfinder are the ones used to estimate their effect on conversion efficiency. The shading values range from 0.00 – 1.00, which relates to the percent shading of a site: 0.00 shading means that a site is completely shaded; 1.00 means a site is completely un-shaded.
Derate Factor:
The Derate Factor is essentially the percent efficiency of an entire PV system with all components considered. To figure out the monthly Derate Factor for a PV system at each of the preferred sites, convert the percent of a site that is shaded each month into a decimal. Then subtract this number from one. Enter this value into the Derate Factor calculator. Leave all other values in the calculator alone. Press “Calculate Derate Factor” to calculate the conversion efficiency for each month.
Example:
Percent of Bond Hall site shaded in January = 15% → 0.15
1 – 0.15 = 0.85
0.85 goes into the Derate Factor calculator under “Shading”
= .654 = 65.4% Derate Factor for January
To figure out the yearly Derate Factor for a PV system at each of the preferred sites, add up the monthly Derate Factors at each site and divide by twelve. Round to the nearest thousandth.
Example:
Sum of the monthly Derate Factors for the Bond Hall site / 12
8.41 / 12 = .7008 ~ .701
= 70.1% yearly Derate Factor
6. Estimated power output
➢ The estimated power output of each PV system is listed in Sheet 1 of the spreadsheet under “Potential Power”
Results:
In order, the roofs of the study sites with the highest potential power output are:
1. Parks Hall (full roof) 2. PAC
3. Bond Hall 4. Parks Hall (partial roof)
5. Buchanan Towers 6. Wilson Library
The potential power is measured in units of kilowatt-hours per day (kWh/day) for each month. It represents the average amount of power expected to be produced each day for a month. It is affected by the amount of raw insolation available, the collective efficiencies of a PV system and the electrical size of a system (in kilowatts).
Potential Power:
To estimate the monthly potential power of a PV system in kilowatt-hours, multiply the available monthly insolation of a site by the monthly Derate Factor by the system’s size (in kilowatts)[13]. Round to the nearest tenth.
Example:
January insolation for the PAC x January Derate Factor of the PAC x PAC system size =
1.55 kWh/m2/day x .745 x 32.8 kW = 37.8758
= 37.9 kWh/day
Yearly estimates of potential power can be calculated by averaging the monthly potential power estimates for one year and multiplying that number by the number of days in a year. Round to the nearest whole number.
Example:
PAC’s yearly average monthly potential power x 365 days
92.3 kWh/day x 365 days
= 33,690 kWh/year
7. Estimated system cost
➢ The estimated cost of PV modules for each site is listed in Sheet 2 of the spreadsheet under “Estimated Module Cost”
➢ The estimated cost of PV balance of system components at each site is listed in Sheet 2 of the spreadsheet under “Estimated Parts Cost”
➢ The estimated cost of labor for installing each PV system is listed in Sheet 2 of the spreadsheet under “Estimated Labor Cost”
➢ The estimated total cost of each PV system is listed in Sheet 2 of the spreadsheet under “Estimated System Cost”
➢ The estimated electricity cost for each PV system is listed in Sheet 2 of the spreadsheet under “Estimated Electricity Rate”
Results:
In order, the roofs of the study sites with the highest total system cost are:
1. Parks Hall (full roof) 2. Bond Hall
3. PAC 4. Parks Hall (partial roof)
5. Wilson Library 6. Buchanan Towers
Estimates of system costs are based on personal correspondence with Robert Foster, Program Manager of the Institute for Energy and the Environment, New Mexico State University and Dana Brandt, President of Ecotech Energy Systems LLC. Each are professionals within the PV field, and are capable of estimating general costs for PV systems based on their experience.
Foster estimated that a contemporary on-grid system would cost between $8.00-10.00 per Watt. He broke down the costs between module costs (40%), balance-of-system, or “parts” costs (45%) and labor costs (15%).[14] Brandt estimated that given the range of estimated system sizes studied (7.6 kW to 48 kW) costs would be $7.50-$8.00 per Watt.[15] The overlapping cost of $8.00 per Watt was chosen for this study, as well as Foster’s cost breakdown for the variables of a PV system.
These cost estimates do not factor in available subsidies and other financial incentives. Many incentives exist that Western could qualify for if a PV system was installed. However, due to project-specific requirements of many incentives, it is difficult to estimate applicable incentives without more detailed project information. Further study of applicable incentives for future PV projects at Western would be a logical follow-up to this study, and is recommended to make a PV system more economically feasible.
Estimated Module Cost:
Because the module cost represents 40 percent of the total system cost of $8.00 per Watt, then the module cost is $3.20 per Watt. To estimate the costs of modules for each site, covert the site’s estimated system size from kilowatts to Watts, and multiply by $3.20 per Watt.
Example:
System size of Parks Hall full roof (in kW) x 1000W x estimated module cost =
48 kW x 1000W x (40% x $8.00/W)
48,000 W x $3.20/W
= $153,600 estimated PV module cost
Estimated Parts Cost:
Because the balance of system (parts) represents 45 percent of the total system cost of $8.00 per Watt, then the parts cost is $3.60 per Watt. To estimate the cost of parts for each site, convert the site’s estimated system size from kilowatts to Watts, and multiply by $3.60 per Watt.
Example:
System size of Parks Hall full roof (in kW) x 1000W x estimated parts cost =
48 kW x 1000W x (45% x $8.00/W)
48,000 W x $3.60/W
= $172,800 estimated parts cost
Estimated Labor Cost:
Because the labor cost represents 15 percent of the total system cost of $8.00 per Watt, then the labor cost is $1.20 per Watt. To estimate the cost of labor for each site, convert the site’s estimated system size from kilowatts to Watts, and multiply by $1.20 per Watt.
Example:
System size of Parks Hall full roof (in kW) x 1000W x estimated labor cost =
48 kW x 1000W x (15% x $8.00/W)
48,000 W x $1.20/W
= $57,600 estimated labor cost
Estimated System Cost:
Because the estimate of the total cost of a contemporary PV system is $8.00 per Watt, it is found by converting the system size from kilowatts into Watts and multiplying by $8.00 per Watt.
Example:
System size of Parks Hall full roof (in kW) x 1000W x total system cost =
48 kW x 1000W x $8.00/W
48,000 W x $8.00/W
= $384,000 estimated total system cost
Estimated Electricity Cost:
Estimates of the cost per kilowatt-hour of a PV system are made by dividing the total unsubsidized cost of the PV system (in cents) by the estimated average kilowatt-hours produced per year over the lifetime of the PV system.
Example:
(Cost of the PAC site x 100 cents) / (kWh/year of the PAC site x PV system lifetime)
($262,680 x 100 cents) / (33,741 kWh/year x 30 years)
26,268,000 cents / 1,012,230 kWh
= 26.0 ¢/kWh
Section 3: Conclusions
The conclusions made from this project are based on a set of evaluative criteria that reflect the specific goals for installing another PV system on campus. They are meant as guidelines to categorize the performance of each study site towards reaching the goals of the project. The data used for these conclusions comes from the research spreadsheet in Figure 2 in the Appendix. A decision matrix has been constructed to clearly illustrate the performance of each site under the evaluative criteria. The matrix is meant as a tool for decision-makers to select the building that performs the highest under the criteria important to them. In the end, other alternatives are briefly discussed that could achieve the same or better results under each evaluative criteria than a PV system could.
Evaluative Criteria
Not all possible evaluative criteria are considered here; only a representative sample of various interests around campus. For this project, the goals are four-fold:
1. Promote energy self-sufficiency
2. Reduce the cost of electricity
3. Reduce greenhouse gas (GHG) emissions
4. Educate people about renewable energy
These goals will be used to judge the performance of each studied site toward meeting the goals.
1. Promote energy self-sufficiency
Promoting energy self-sufficiency refers to generation of local energy to be used for local purposes. In the context of this project, it is measured by the percentage of Western’s average yearly electricity consumption each study site is estimated to produce. Western’s average yearly electricity consumption is 39,000,000 kilowatt-hours per year, an amount of electricity so large that even the largest PV system studied in this project (Parks Hall full roof) would be less than one percent of Western’s annual electricity needs.[16] The table below shows each site’s percentages of Western’s average annual electricity use.
Table 1:
Percentage of Western’s average annual electricity use
|Study Site |Potential Power of PV system |% of WWU’s average yearly |
| | |electricity use |
| |(kWh/year) | |
|Parks Hall | | |
|(full roof) |47,089 |0.12 % |
| | | |
|PAC |33,741 |0.09 % |
| | | |
|Bond Hall |29,953 |0.08 % |
|Parks Hall (partial roof) | | |
| |21,198 |0.05 % |
|Buchanan Towers | | |
| |7,914 |0.02 % |
| | | |
|Wilson Library |7,598 |0.02 % |
However, when taking the average yearly electricity usage of the studied buildings into account, a PV system may provide a larger fraction of the electrical needs of that building. For example, a PV system covering the full roof of Parks Hall would rate the highest of the six study sites, offering 9.1% of the building’s average yearly electricity consumption. A table showing the percentage each PV site would produce of the study building’s average annual electricity consumption is shown below.
Table: 2
Percentage of building’s average yearly electricity consumption
|Study Site |Potential Power of PV system |Average yearly electricity use |% of |
| | |(2006-07)[17] |average yearly electricity use |
| |(kWh/year) |(kWh/year) | |
|Parks Hall | | | |
|(full roof) |47,089 |518,200 |9.1 % |
| | | | |
|PAC |33,741 |731,541 |4.6 % |
| | | | |
|Bond Hall |29,953 |1,277,464 |2.3 % |
|Parks Hall (partial roof) | | | |
| |21,198 |518,200 |4.1 % |
|Buchanan Towers | | | |
| |7,914 |694,509 |1.1 % |
| | | | |
|Wilson Library |7,598 | |0.6 % |
| | |1,237,248 | |
Conclusion:
The most productive PV study site (the full roof of Parks Hall) would be a “drop in the bucket” compared to the total campus electricity consumption. Because of this, the performance of all of the PV study sites toward campus self-sufficiency would be low. The largest limiting factor of a highly productive system on Western’s campus is the local climate. Bellingham’s yearly insolation averages are quite low compared to sunnier places like San Diego. In fact, Bellingham’s yearly average insolation of 3.7 kWh/m2/day is 35% less abundant than San Diego’s 5.7 kWh/m2/day.[18] See Figure 7 in the Appendix for the thirty-year average insolation chart for San Diego. Like anything else, PV panels, components and the materials used to make them are finite resources. Using them in one place makes them unavailable in another. Because of Bellingham’s marginal climate, the application of PV systems here may be an inefficient use of resources that could be more efficiently used in more appropriate climates like San Diego. This fact must be considered and decided if it is important or not to the objectives of the decision makers.
While not substantial when compared to the total university, the PV sites would make more of an impact in promoting the self-sufficiency of each study building. In this sense, self-sufficiency per building may be more obtainable than on a campus-wide level. In the case of Parks Hall, a PV system occupying the whole roof would produce nearly ten percent of the building’s 2006-2007 annual electricity consumption. Regardless of what PV site is considered, careful thought must be given to make sure they satisfy self-sufficiency concerns.
2. Reduce the cost of electricity
Reducing the cost of electricity is possible through the production of “free” energy once the PV system is installed. While the PV system itself is certainly not free, the energy source (the sun) is a resource that is limited only by the local climate and nighttime. However, the cost of a PV system is so high without (and sometimes with) incentives that it often acts as a barrier to installation. The key to making a PV system economical is to get the cost of electricity produced by a PV system to compete with prices of conventional energy. Western currently pays seven cents per kilowatt-hour for energy: 6.4 cents per kilowatt-hour for electricity and 0.6 cents per kilowatt-hour for green tags.[19] In order to be economical, a PV system on campus would have to be close to this price. (Review the Estimated System Cost estimates in the Results section for a reminder on calculating the cost per kilowatt-hour). The cost per kilowatt-hour of each PV study site is listed below.
Table 3:
Cost per kilowatt-hour
| |Estimated System Cost |Potential Power of PV |Lifetime of PV system |PV system’s Cost of |
|Study Site |(no subsidies) |system | |electricity |
| |($) |(kWh/year) |(years) |(¢ / kWh) |
|Parks Hall |$384,120 |47,089 |30 |27.2¢ |
|(full roof) | | | | |
| |$262,680 |33,741 |30 |26.0¢ |
|PAC | | | | |
| |$264,000 |29,953 |30 |29.4¢ |
|Bond Hall | | | | |
|Parks Hall (partial |$172,920 |21,198 |30 |27.2¢ |
|roof) | | | | |
|Buchanan Towers |$60,720 |7,914 |30 |25.6¢ |
| |$66,000 |7,598 |30 |29.0¢ |
|Wilson Library | | | | |
However, because Western is a state university committed to sustainability, with high support for renewable energy among the administration, faculty, staff and students, it is possible that the economics of a PV system may matter less than it would in the private sector. Furthermore, the notion that universities are meant for innovation for the benefit of present and future generations may also diminish the importance of economics.
Additionally, when rising electricity costs are taken into account over the thirty to fifty year lifespan of the PV system, the economics start to make sense (a conservative PV lifespan estimate of thirty years is used for this project). Current forecasts show electricity costs increasing by four percent above the inflation rate per year.[20] Right now, the inflation rate is around four percent, meaning the total increase in electricity prices will be eight percent per year.[21] It this trend continues, it will take seventeen to nineteen years for the PV study sites to become nearly even with the price of electricity Western will be paying. The table below illustrates the payback period for each PV study site.
Table 4:
Payback period
|Years |Western |PV Study Sites electricity prices |
| |electricity prices (¢/kWh) | |
| | |(¢/kWh) |
| |8% increase per year | |
|0 |7 |
|1 |7.6 |
|2 |8.2 |
|3 |8.8 |
|4 |9.5 |
|5 |10.3 |
|6 |11.1 |
|7 |12.0 |
|8 |13.0 |
|9 |14.0 |
|10 |15.1 |
|11 |16.3 |
|12 |17.6 |
|13 |19.0 |
|14 |20.6 |
|15 |22.2 |
|16 |24.0 |25.6 |
| | |Buchanan Towers |
|17 |25.9 |26.0 |
| | |PAC |
| | | |
| | |27.2 |
| | |Parks Hall |
|18 |28.0 |29.0 |
| | |Wilson Library |
| | | |
| | |29.4 |
| | |Bond Hall |
|19 |30.2 |
Conclusion:
The cheapest electricity cost of the sites studied is 25.6 cents per kilowatt-hour (Buchanan Towers), which is much more than the 7 cents per kilowatt-hour Western currently purchases. Because of this, the immediate ability of the PV study sites to reduce electricity costs would be low. However, when rising electricity costs are taken into account, the PV systems will eventually help lower the cost of electricity Western pays for in the future. If current trends continue, then in 2025-2027 (seventeen to nineteen years from now) Western will be saving money on electricity generated from any of the five PV study sites. As one solar energy professional stated, “With PV (systems), you are essentially buying twenty-five plus years of power all at once”.[22]
The attractiveness of buying energy upfront for use later may become increasingly popular due to increasing energy prices in the near future, which may ultimately swing favor in support of another PV system on campus. However, if immediate reductions in energy costs are desired, than a PV system may not provide the same results as would an increase in energy efficiency projects, for example. These are the sort of questions that must be addressed when evaluating different renewable energy alternatives.
3. Reduce greenhouse gas (GHG) emissions
Installing a PV system is one way to reduce the GHG emissions produced by Western. A draft report of Western’s 2006 GHG emissions finds that 37,229 metric tons (82,075,896 pounds) of carbon dioxide equivalent gases were produced that year.[23] Reducing GHG emissions is an important goal of the university, and will take special significance once the President’s Climate Action Plan to achieve carbon neutrality is implemented.
Online emission reduction calculators can help quantify the amount of GHG (CO2) emissions avoided by reducing the use of fossil fuel energy. The Cleaner and Greener Emission Reduction Calculator is such a calculator that allows you to input reductions of electricity (in kilowatt-hours), what customer type you are (residential, commercial or industrial) and what state you live in. It outputs the amount of pounds of GHG emissions and other pollutants avoided per year, among other things.[24] To estimate the yearly reduction of GHG emissions:
1. Enter the amount of kilowatt-hours per year generated by each PV system into the Enter Your Estimated Annual Electricity Reduction input
2. Enter “Commercial” into the Select Your Customer Type input (Western buys electricity at 6.4 cents per kilowatt-hour: close to the Commercial rate of 6.33 cents per kilowatt-hour assumed in the calculator.[25])
3. Enter “Washington” into the Select Your State value
These inputs show that the five PV study sites on campus will reduce the following amount of GHG emissions:
Table 5:
Amount of GHG emissions reduced
| | |% reduction of Western’s 2006 GHG |
|Study Site |Pounds of CO2 reduced per year |emissions |
|Parks Hall (full roof) |77,367 |0.09 |
|PAC |55,436 |0.07 |
|Bond Hall |49,213 |0.06 |
|Parks Hall (partial roof) |34,828 |0.04 |
|Buchanan Towers |13,003 |0.02 |
|Wilson Library |12,484 |0.02 |
Conclusion:
Because the highest amount of GHG emission reduction of the six study sites (Parks Hall full roof) is less than one percent of Western’s total GHG emissions, the performance of the PV study sites to reduce GHG emissions would be low. The reduction is so small because Western is a large institution and produces many GHG emissions across all sectors under its jurisdiction. The sectors studied were:
1. Purchased electricity 2. Purchased steam and chilled water
3. Stationary sources 4. Transportation
5. Agriculture 6. Solid Waste
7. Refrigeration 8. Offsets
The limited productivity of the climate, restraints on roof sizes and the collective efficiencies of a PV system’s components all affect the reduction of GHG emissions. However, a reduction of GHG emissions is still a tangible and beneficial result, and a few of the study sites can provide a locally productive reduction of GHG emissions. Specifically, the full roof of Parks Hall would reduce 77,367 pounds of carbon dioxide per year, the highest reduction among the six study sites. While not much, it represents one of the best sites on campus for reducing GHG emissions.
4. Educate people about renewable energy
Educating people about renewable energy is an important goal of this project because only through the support of the public and consumers can renewable energy be implemented on a meaningful scale. Currently, many people support renewable energy, but have limited knowledge of the full benefits these technologies offer. Installing another PV system on campus would further the education of the administration, faculty, staff, students and general public. Especially if another PV system was integrated with the educational kiosk in the Viking Union, the educational aspects of PV technology would be strengthened.
However, because of concerns over aesthetics, another PV system would have to be generally out of sight from street level of campus. This would limit the connection between system size, physical area, orientation and location, all of which are very important elements of a PV system that affect the end result most people care about: productivity. The severance of this connection could be amended through pictures, schematics or live video of the PV system on the Viking Union’s kiosk to restore that connection, but it would not have the full, visual impact.
Conclusion:
Each site’s educational ability will be measured by its visibility. Because the desired limited visibility of another PV system can be somewhat accommodated through various visual aids on the Viking Union kiosk, the ability of the PV study sites to educate about renewable energy would be moderate. Few of the six study sites would be entirely visible from the streetscape; most would be partially or fully hidden. The most visible sites would be Buchanan Towers and Bond Hall, and only from a distance (it would be too tall to see a rooftop PV system from directly below the buildings)
Decision Matrix
The study sites are rated against each other along a scale of one to six to reflect their performance under each criterion: one being the lowest and six being the highest. The ratings are mutually exclusive and meant to show a clear preference for the best site for each evaluative criterion.
(Low) 1 → 6 (High)
| | |
| |Evaluative Criteria |
|Study Site | | | | |
| |Self-sufficiency |Reduce electricity costs|Reduce |Educate about Renewable |
| | | |GHG emissions |Energy |
| |(% kWh of WWU’s / |(¢ / kWh) | | |
| |building’s electricity | |(Pounds of CO2 reduced) |(Level of visibility) |
| |use) | | | |
| |6 |4 |6 |3 |
|Parks Hall | | | | |
|(full roof) | | | | |
| |5 |5 |5 |2 |
| | | | | |
|PAC | | | | |
| |4 |2 |4 |5 |
| | | | | |
|Bond Hall | | | | |
| |3 |4 |3 |4 |
|Parks Hall (partial | | | | |
|roof) | | | | |
| |2 |6 |2 |6 |
|Buchanan Towers | | | | |
| |1 |3 |1 |1 |
| | | | | |
|Wilson Library | | | | |
Other Alternatives:
Other options for achieving the goals of the evaluative criteria are improving the effectiveness of Western’s Renewable Energy Credit (RECs) policy and continued investment into on-campus energy efficiency projects. Each of these alternatives enjoys support from the higher offices on campus, as well as student support. This acceptability makes these alternatives viable options for achieving the objectives of the evaluative criteria, with possibly equal or better results.
Improved REC Policy:
Purchasing “green power” is another way to achieve some of the goals of the evaluative criteria. A reduction in GHG emissions, especially carbon dioxide, can be enjoyed locally without installing renewable technologies in the locality. These reductions, known as Renewable Energy Certificates (RECs), can be purchased from somewhere else as a way to offset the carbon dioxide produced locally. Since carbon dioxide is a global pollutant, a reduction in one place is equivalent to reducing it somewhere else.
Since spring quarter 2005, Western has purchased RECs from wind farms in Washington and Oregon to power the entire campus with 100 percent renewable energy through Puget Sound Energy’s (PSE) Green Power Program.[26] However, recent concerns have focused on the effectiveness of these benefits at reducing GHG emissions to the fullest extent possible. Specifically, a closer look at the energy mix where the RECs are generated must occur if they are to be effective at reducing GHG emissions.
Clean vs. dirty energy mix:
Renewable energy generation in a region with a relatively clean energy mix will reduce GHG emissions less than an area with a dirtier and more polluting energy mix. Case in point, 69 percent of Washington State’s energy mix comes from relatively clean hydroelectricity, so a wind farm built in Washington will reduce less dirty electricity than other regions of the U.S. with far dirtier mixes of energy sources.[27]
Because of this desire to maximize GHG emission reductions, comparisons between the cleaner Northwest energy mix and other regions of the country with dirtier energy mixes has been conducted by a Green Power RFP committee. Based on this research, Western has switched its purchase of RECs from Pacific Northwest wind farms to two wind farms in North Dakota to increase the reduction of GHG emissions.
The quality of CO2 reductions:
The Midwest is powered almost exclusively with coal, creating an opportunity for renewable energy projects in this region to have a significant impact on reducing GHG emissions. Since Western has raised concern over this issue, PSE has begun using our REC money to purchase wind power from North Dakota, a state with a 94% percent use of coal.[28] This disparity between the “cleanliness” of energy mixes is reflected in the carbon dioxide offset factors of each state:
Table 6:
CO2 offset factors[29]
| | |
|State |lbs of CO2 reduced/MWh |
| | |
|North Dakota |1,813 |
| | |
| | |
|Washington |1,295 |
The chart clearly reflects the significance of location when siting renewable energy projects, showing that any discussion of the quality of CO2 reductions must include location.
Conclusion:
Reworking the green fee is beginning to materialize into a more effective REC policy. Decisions whether Western should continue with this approach instead of (or in addition to) installing another PV system will have to be made. The performance of each alternative under the evaluative criteria should be done before making such a decision. For example, purchasing RECs from dirtier energy regions may reduce GHG emissions more than a PV system will, but will not increase the self-sufficiency of Western due to its detachment from the electricity grid feeding Western. The ultimate determination will incorporate the values of the decision-makers when deciding whether investing money into distant renewable energy projects is as successful in achieving the project goals as a local PV system may be.
Energy Conservation Measures
This option considers investments into energy efficiency projects on campus that save energy and money.
Energy savings:
Since 2005, Western has saved 889,214 kilowatt-hours per year through Energy Conservation Measures (ECMs) implemented by Western’s Facilities Management. The majority of these projects are upgrades to more efficient lighting, but some power management and equipment upgrades have been made as well.[30] The nine lighting upgrades since 2005 have saved an average 78,596 kilowatt-hours per year for an average cost (including rebates) of $22,216. For comparison, the 24,582 average yearly kilowatt-hours that will be saved by the six PV study sites on campus will cost an average of $201,740 (without subsidies). The table below compares the average costs and energy savings of lighting upgrades since 2005 and the six PV study sites.
Table 7:
Average costs and energy savings
| |Nine lighting upgrades since 2005 |Six PV study sites |
|Average costs |$22,216* |$201,740 |
|(*with rebates) | | |
|Average annual |78,596 kWh |24,582 kWh |
|kWh savings | | |
Cost Savings:
Energy conservation is an attractive alternative because the costs to upgrade equipment and improve energy management are willingly shared by PSE and Western. PSE has an incentive to pay for energy efficiency projects, because the more efficient their energy is used, the lower the demand and expense of generating additional power. This option is attractive to Western as well, because the cost sharing provision allows them to save significant money and energy use while only paying a portion for the benefits. From 2002-2007, Western has saved $96,872.36 per year in energy costs and $332,218 from PSE project rebates. For a specific example, the Physical Plant’s lighting upgrade will save 55,011 kilowatt-hours per year and will cost only $2,713 after PSE rebates.[31] For comparison, the largest PV system studied (the full roof of Parks Hall) with save 47,089 kilowatt-hours per year and will cost $384,120 (without subsidies). The table below compares the costs and energy savings of the Physical Plant’s lighting upgrade and the Parks Hall (full roof) PV study site.
Table 8:
Average costs and energy savings
| |Physical Plant |Parks Hall (full roof) |
| |lighting upgrade |PV site |
|Average costs |$2,713* |$384,120 |
|(*with rebates) | | |
|Average annual |55,011 kWh |47,089 kWh |
|kWh savings | | |
Conclusion:
The significant differences between energy conservation savings and PV system savings must be kept in mind when making decisions about which criteria and goals are important to energy projects on campus. If reducing GHG emissions and reducing electricity costs are important values, then perhaps further ECMs will be favored. However, if self-sufficiency and education about renewable energy are important goals, than perhaps installing another PV system on campus will be preferred. It is also possible that a mix of the two strategies could be used to achieve all the objectives. Whatever the decision, the significant savings of ECMs provide an impetus for continued exploration of energy efficiency around campus.
Final comments
Future renewable energy proposals on campus should be evaluated with this solar study and its discussion of other renewable energy alternatives in mind. While PV technologies are currently a popular alternative energy source, the research in this study suggests that careful thought must be made when considering further installation of PV systems at Western. Further studies of solar energy subsidies and incentives as well as the solar potential of other campus buildings can build off of this preliminary research, and can provide auxiliary sources of information for decision-makers at Western to base alternative energy policies off of.
As time goes on, additional evaluative criteria and values may arise to influence energy policy at Western and the University’s relationship to the environment. Whatever the case, an exciting era of energy opportunities await in the near future as the world prepares to transform into a post-carbon economy.
Appendix
Figure 1: Solar Pathfinder[32],[33]
Figure 2: Excel spreadsheet
Figure 3: Estimated annual insolation of other studied buildings
Table 9:
Estimated annual insolation measurements
|Building |Insolation |
|Viking Union Level 7: |3.52 kWh/m2/day |
|Viking Union Level 8: |3.62 kWh/m2/day |
|Environmental studies: |3.58 kWh/m2/day |
|Chemistry: |3.59 kWh/m2/day |
|Biology: |3.49 kWh/m2/day |
|Campus Services: |3.50 kWh/m2/day |
|Commissary: |3.66 kWh/m2/day |
Figure 4: Average insolation values for Seattle and Bellingham
[pic]Source: National Renewable Energy Laboratory, “Solar Radiation Data Manual for Flat-Plate and Concentrating Collectors: Washington,” 14 February 2008 .
Figure 5: Sample floor plans
Source: Facilities Management, “Campus Floor Plans,” 12 February 2008 .
[pic]
Source: Facilities Management, “Campus Floor Plans,” 12 February 2008
.
Source: Facilities Management, “Campus Floor Plans,” 12 February 2008 .
[pic]
Source: Facilities Management, “Campus Floor Plans,” 12 February 2008 ................
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