A Case Study: Solar Panels at Boston College

A Case Study: Solar Panels at Boston College

Annie Meyer April 1, 2014 Farhin Zaman Elizabeth Norton

GE 580 Environmental Studies Senior Seminar

Boston College

Chestnut Hill, MA

Introduction

Solar Photovoltaic: Background

Solar cells and photovoltaics were first invented in 1954 after a lot of

research around photoelectric technologies and beginning to use the sun’s energy

for other purposes (“Timeline…”). Now, solar has been around for many decades,

and has been proved to consistently work well. Like most other technology, solar

has improved immensely over time, gaining more efficiency and becoming a more

viable option for homes and businesses. When it was first invented, each cell had a

6% efficiency rate (“Timeline…”). Currently most cells have an efficiency rate of

approximately 25% though there are cells being developed with over 40% efficiency

(“Stacking the Deck” 2014). That is truly an amazing transformation, and a

testament to technology.

Solar PV can be difficult to understand, especially when you are thinking

about using it for your home or business. There is a long list of things to consider,

but the first step is to understand the basic technology behind the panels. Solar

panels contain solar cells (mentioned above) that collect heat energy from the sun.

Once this energy is trapped, an inverter is used to convert the energy so that it is

usable within your home to power things with electricity (EnergySage). Though you

may not be able to produce enough energy to meet 100% of the needs for your

home, solar PV can still help you save a lot of money.

Solar PV is considered ‘clean’ energy because it harnesses energy from a

renewable resource: the sun. Our planet is constantly receiving energy from the sun,

so why not utilize it? Overall solar is a very environmentally friendly solution in a

society that uses colossal amounts of energy.

Solar at other Colleges/Universities: Brandeis, Harvard, and Stonehill

By looking at the solar installations at other colleges and universities, we were

able to get solid and successful examples of solar working in different ways at places

similar to BC.

Harvard has solar panel systems on eight of its buildings, the largest of which

produces 590,000 kWh/year. The university also purchases renewable energy from offsite

sources and has a wind turbine mounted on one of its buildings. Combined, 17% of their

electricity comes from renewable sources, while saving them money on the use of fuel

and utilities (“Sustainability…” 2013). Harvard is clearly making a statement about being

green and moving towards cleaner technologies. While we understand that BC hopes to

do the same, the university is also working on a ten year plan to add housing and new

facilities. Taking on one solar project is much more reasonable at the moment.

Stonehill College is currently building one of the nation’s largest college campus

solar fields. It is a 2.7 megawatt field that will contain 9,000 solar panels. The solar field

is expected to save about $185,000 a year on energy costs and account for 20% of the

campus’ electrical usage (“One of Nation’s…” 2014). This array produces such a large

portion of the college’s energy mostly because Stonehill is only a quarter of the size of

BC, making it’s energy use much smaller (“Stonehill College” 2014). In addition, field

arrays have to be built away from the campus, making the use of solar less noticeable.

While we do not propose making solar extremely visible at BC, we think that it is

important that students can physically identify the connection between the panels and

energy use.

Brandeis installed solar on the roofs of two buildings in 2010. At the time, the

project was one of the largest in the state, and these panels currently produce 10% of the

annual energy needed at their sports center (“Campus Sustainability Initiative”).This plan

is what we think should be the closest to our proposed project at Boston College. This

type of system offers energy savings and becomes iconic to the university. This is a good

place to start, and hopefully, if BC falls in love with solar, the administration would then

add more.

Solar at Boston College

Implementing solar panels on Boston College’s campus is an effective and easy

way to introduce clean energy with proven technology. Solar panels offer both an

environmental and economic benefit, especially at universities where energy

consumption is high. With an undergraduate population of over 9,000 students, 2 major

stadiums, 3 major dining locations, and over 20 dormitories, Boston College is always

using large amounts of energy. Our report will outline the thorough investigation of four

different buildings on campus, and what a Solar PV system offers in each situation. The

findings will compare third party ownership with private ownership, giving a

comprehensive plan for Boston College moving forward. Solar PV will help reduce BC’s

electricity bills, protect against rising energy costs, and increase sustainability initiatives.

Our primary objective is to create a realistic plan for the first implementation of solar

panels on campus with the hope that the B.C. administration will accept the idea.

Methods

Picking the location

Over the course of this project our team used process of elimination to

determine the best location for a solar PV system on Boston College properties.

Through meetings with two of our mentors -‐ John MacDonald the BC Energy

Manager, and Bob Pion the BC Sustainability Director -‐ we were given advice on how

to decide which locations would be feasible and most beneficial to the school. We

examined the multitude of buildings that Boston College maintains on several

properties -‐ Main campus, Newton campus, Brighton campus, and the Weston

Observatory. From these options, building choices were narrowed down based on a

series of criteria, an overview of which can be seen in Figure 1. The basic variables

involved were aesthetics, BC’s ten year plan, and annual energy use.

Figure 1: Flow chart outlining the process of elimination for solar system locations.

The initial proposal of this project was to implement solar panels on the roof

of the Commonwealth Ave Parking garage. We ruled this option out due to

aesthetics. Its proximity to St. Mary’s means that the Jesuit residents would directly

overlook the panels on top of the garage. We ruled out all of middle campus because

it consists of buildings with gothic architecture, which is the aesthetic that the BC

administration is most dedicated to in regards to the campus’ appearance. This

group includes buildings such as Devlin, Lyons, Gasson, Fulton, and Stokes Hall. It

also includes buildings in close proximity to gothic architecture, like McGuinn, as

well as buildings in view of middle campus, such as Conte Forum (the roof of which

is also taken up mostly by skylights, leaving little area left for solar panels).

Next, our team was shown the 10-‐year construction plan for Boston College’s

campus which revealed several buildings and structures that will be knocked down

in the near future, including Edmond’s Hall and Carney. Our team decided not to

propose installing solar panels on any buildings that will be built in the near future,

such as the new Plex athletic building, because the construction plans for them are

not yet fully concrete and we want this proposal to be applicable in real time. A

couple of buildings, like the Brighton Campus Dance Studio building, were removed

from our list because they are simply too small to hold a valuable number of solar

panels.

The remaining buildings were reviewed based on their year-‐round energy

use. Buildings that are not used throughout the entire year (i.e. not used very much

during the summer) were also eliminated since solar panels are most efficient and

useful in places where energy is used all the time. This group included all

dormitories, including all those on Newton Campus, upper Main campus, and lower

Main campus.

All of main campus runs on one energy meter, which makes it more difficult

to involve another type of energy generating system on one of the main campus

buildings. The energy offset from the panels would come out of the campus’ total

energy use rather than out of just the energy use of the building it is installed on.

Though it would be possible to have the system in place on a single building while

having it hooked up to the school’s net metering system, our team agreed that since

we are proposing installing solar panels at Boston College for the first time, it would

be best to make this a contained system on a single building. This way the

administration can look at the project and decide how to move forward.

This process of elimination narrowed down our choices to four locations -‐

Cadigan Alumni Center (Figure 2a), 129 Lake Street (Figure 2b), the Beacon Street

Garage (Figure 2c), and St. Clement’s Hall, the campus data center (Figure 2d). All

four of these buildings we have flat roof tops, which means that solar panels could

be set at the proper angle and direction for best possible production. The Beacon St

Garage is large, which would allow it to accommodate a very large solar panel

system. Unfortunately, it has parking spots on its roof, so a canopy structure would

have to be built to accommodate the panels. This is a fairly standard procedure but

it can be costly. Though we did not calculate the expense of building these solar

canopies on top of the garage, it would be an added expense on top of the cost of

buying and installing a system at this location. Unlike the Beacon Street Garage (and

all buildings on main campus for that matter), the three other buildings, all on

Brighton Campus, run on their own individual meters. This would make it easy for

the solar panel system to directly offset the energy use of the building on which it is

installed.

Figure 2: Aerial views of the four buildings that were considered as the location for a solar panel

system, with roof areas mapped out in blue (a. Cadigan Alumni center, b. 129 Lake Street, c. Beacon

Street Garage, and d. St. Clement’s Hall).

Financial Analysis

a. Building and System Estimates

At this point in the process we began a financial analysis of a potential

system on each of the four buildings. This was made possible by the information

provided to us by John MacDonald. The estimate involved finding the system size (in

kilowatts per hour -‐kWh) that would be able to fit on the roof of the building in

question, as well as the cost of purchasing that sized system. In order to get the most

well-‐rounded estimate possible our team employed three different sources for these

calculations. After finding three different values, we took an average to obtain the

most accurate numbers.

The first source was our team’s own calculations. We used the tools on

Google Earth to measure out the roof area of the four buildings. We then deduced

how many panels would be able to fit on that sized roof by dividing the area by the

size of a standard sized solar panel, which is 19.5 square ft (“Timeline…”). Since a

standard sized panel produces 250 watts per hour, we multiplied the number of

panels by 0.25 kilowatts per hour to calculate the system size in kWh (Aggarwal,

2014). These types of systems generally cost $2.50 per watt, so in order to calculate

the cost of purchasing the panels, we multiplied the system size by the price for kWh

($2,500). The error involved in this calculation is the fact that solar panels are often

tilted meaning that the roof may fit more or less than the exact number that fit

inside the initial roof area.

The second source was the solar energy calculator on the PV Watts website.

Using their program, we again mapped out the roof area of each building, and were

provided with the system size in kWh. We then calculated the cost using the given

system size, using the method mentioned previously. When using this method,

tracing the building area was difficult. We could not be sure that the area we traced

was the viable area on each building.

The last source was a website called Energysage. On their program we

selected each building on a map by pinning the roof and were provided with an

estimate of cost and savings. Personnel at the company were kind enough to give us

the system size they calculated using their own tools. Because you pin the building

on EnergySage, it is hard to tell whether it will calculate the right parts of the roof.

For example, Cadigan Alumni Center has skylights that we did not want included as

part of the panel area.

Since the three sources we used had some measure of error involved, we

took the average of all three in order to provide the BC administration with the best

estimate possible. Additionally, while the two websites take into consideration

several factors that we were not able to -‐ such as factoring in the amount of shading

on each roof as well as accounting for the tilt of the panels when placed on the roof -‐

they have their faults. These programs spat out numbers without us being able to

see their calculations, and as mentioned above, we had different concerns with each.

We took an average system size from our three estimates to see how much energy a

system on each of these roofs would produce and how much of that building’s

energy use would be able to be offset by that particular system size.

b. Pro forma Calculations

Our mentors at the green energy company First Wind gave us a pro forma

model for excel. This model provided us with a basic outline of how much energy a

solar system could possibly produce on main campus and the potential savings for

BC. We wanted to compare the costs and savings between private (BC) ownership

and 3rd party ownership of the system in order to deduce the most financially

sound conclusion. In order to come to this conclusion we had to tailor the pro forma

by creating four different proformas -‐ one for each of the four final buildings. We

input data we received from the Boston College energy manager, John MacDonald,

in order to calculate the financial aspects of installing solar panel systems on each of

the four buildings. This analysis was based on the buildings’ annual energy uses,

annual energy costs, and the campus energy rates from NSTAR.

Results

Building and System Estimates Table 1: The annual electrical use and bill for each building chosen.

Annual electrical

use (kWh) Annual Bill

Cadigan Alumni Center 528,538 $71,881.17

129 Lake St. 261,544 $35,569.98

Beacon St. Garage 1,576,800 $214,444.80

St. Clements Hall 4,091,784 $556,482.62

Table 2: The number of panels, the size of those panels in kWh, and the net cost of that system as

calculated from the area by using aerial shots of each building on Google Earth.

Our

Calculations

Our Area

(sq. ft)

Sq. Ft

per Panel

# of

Panels

System size

(kWh)

Net Cost of

Panels

($2.50 per

panel)

Cadigan Alumni

Center 12,432 19.25 646 161.5 $403,750.00

129 Lake St. 20,785 19.25 1080 270 $675,000.00

Beacon St.

Garage 39,406 19.25 2047 511.75 $1,279,375.00

St. Clements

Hall 17,965 19.25 933 233.25 $583,125.00


calculated by the PV Watts website energy system calculator.

PV Watts

Calculations

# of

Panels

System size

(kWh) Net Cost of Panels

Cadigan Alumni

Center 713 178.2 $445,500.00

129 Lake St. 1016 254.4 $636,000.00

Beacon St. Garage 2680 670 $1,675,000.00

St. Clements Hall 800 200 $500,000.00


calculated by the Energy Sage website instant solar estimator.

Energy Sage

Calculations

# of

Panels

System

size

(kWh)

Net cost of system

($2.50 per panel)

Cadigan Alumni

Center 473.6 118.4 $296,000

129 Lake St. 642.94 160.74 $401,850

Beacon St. Garage 3876.2 969.05 $2,422,625

St. Clements Hall 666.164 166.54 $416,350

Table 5: List of the system sizes of each of the four buildings in kWh, averaged from the results listed

in Tables 2, 3, and 4, along with the cost of that averaged system size.

Average System size (kWh)

Cost

(private ownership)

Cadigan Alumni

Center 152.7 $381,750.00

129 Lake St. 228.4 $571,000.00

Beacon St. Garage 625.9 $1,564,750.00

St. Clements Hall 200 $500,000.00

Pro forma Calculations

The financial costs and benefits are a major part of whether an institution,

like BC, would consider implementing solar panels and the type of system that

would be used. An important tool in our analysis was the use of pro forma financial

statements, which present the anticipated results of a certain project/ transaction.

In our case, Matt Marino from First Wind, provided a pro forma model that outlined

the 3rd party ownership of the solar system through a Power Purchase Agreement

(PPA). In a PPA, BC would have to pay a discounted rate per kWh for the energy

produced by the solar panels. In our case, a solar company, like First Wind, would

charge BC $0.12 per kWh for the energy produced by the solar system, which is a

lower rate than $0.136 per kWh that is currently charged by NSTAR. First Wind

would charge BC for the energy produced by the solar panels at a reduced rate and

then BC would pay for the rest of their electrical needs through NSTAR. As a result,

BC’s annual energy bill would be lower from their average annual bill with NSTAR.

The pro forma outlines the costs and savings in Tables 6-‐9 for the respective

buildings in our study. For example, in Table 6, the pro forma model for Cadigan

Alumni Center uses the building’s annual electrical usage and utility bill that were

calculated in Table 1. From there, we used the average system size, calculated in

Table 5, to estimate the energy production of the panels and the amount BC would

save. We did not calculate the costs of the solar PV system under 3rd party leasing

because BC would not be responsible for the installation and maintenance costs

under this system. In Table 6, the estimated solar project size (1 MW) and

percentage of energy production provided for BC (15%) was given to us by First

Wind. To calculate the amount of energy produced by the solar system for Cadigan,

we took 15% of the amount of energy produced annually, which would be 79280.7

kWh annual solar energy produced and BC would pay a discounted rate for that

energy. The energy bill for Cadigan would save $10,782.18 on it’s usual bill.

Cadigan’s current bill, calculated in Table 1, is $71,881.17 per year, but with the

solar system, the new bill would be $61,098.99. If this value is carried throughout

the life of the solar system, which is around 20 years, then BC would save

$25,369.82 in that amount of time for just one building.

If BC decided to purchase the solar panels and own the system and reap

benefits like Solar Renewable Energy Credits (SRECS), then the financial projections

are a bit different. Unlike the 3rd party leasing system, BC would have to pay

significant upfront costs for the installation of the panels. In the same example from

Table 6 of Cadigan Center, we used our estimate of the solar system size (152.7

kWh) that BC could install on the roof of the building. From there, we calculated the

potential annual production that a 152.7 kWh solar system could produce

throughout the year, which is 1,231,372.8 kWH of energy. However, based

estimates from EnergySage, a solar system on top of Cadigan could only produce

10% of the potential energy. Using that information, we predicted that Cadigan

Center would only be able to use 123137.82 kWh of energy from the panels, but

would still save $16,746. 67 on their current utility bill. Over the course of 20 years,

this would amount to $334,933.40 in savings. However, this number is not entirely

accurate since BC would first have to break even on the investment of the solar

system, which we calculated would cost around $381,750.00, as shown in Table 5.

The time for BC to break even on the investment could take several years and is

based on calculations that we did not have time to explore in the scope of this

project.

Despite the initial costs of installing a solar system, there are a few benefits

that BC should consider such as the use of SRECS. In Table 6, we had predicted that

the solar system would only be able to produce about 10% of what the system can

potentially produce. However, if the system was able to produce excess energy,

outside of Cadigan’s utility needs, then BC could lower the bill even more by using

net metering. In addition, all energy produced by solar is eligible for SRECs (solar

renewable energy credits), We estimated that if the solar system worked to it’s full

potential, and SRECS were bought for $0.30 per kWh produced, then BC could

possibly earn $332,470.66 in one year.

This process of estimations and calculations were repeated for 129 Lake St.,

Beacon St. Garage, and St. Clements Hall. In Table 7, we analyzed the financial

projections of 129 Lake St and see that the 3rd party system could save BC around

$627.71 a year from the current utility bills. Over the 20 year life of the solar

system, BC could possibly save $12,554.71 in total. For private ownership, BC

would be able to save $35,569.98 annually and $711,399.68 over the life of the

system. However, the initial cost of the system would be around $571,000.00 that

would see a return on investment of around five to seven years. There is also the

possibility of earning around $474,082.08 in SRECs.

In Table 8, we observe the costs and savings of Beacon Street Garage.

Under the 3rd party lease, the garage has the potential to save BC around $3,784.32

a year and $75,686.40 over the life of the system. With private ownership, both the

Beacon Street Garage and 129 Lake St. are unique because EnergySage had

predicted that both solar systems would be capable of producing 100% of the

energy needed by both buildings. Therefore, the annual savings would be the value

of the current energy bill itself, which, for the Beacon St. Garage, is $214,444.80 a

year and around $4,288,896.00 over the life of the system. The initial cost of the

system is predicted to be around $1,564,750.00 with the possibility of earning

$1,041,137.28 in SRECs.

Our final analysis was on St. Clements Hall, also known as the data center on

Brighton Campus. In Table 9, we predicted that 3rd party ownership would save BC

around $9,820.28 annually and around $196,405.63 for the life of the system. For

private ownership, EnergySage had predicted that the solar system would be able to

produce around 5% of the energy used by St. Clements Hall. Even with this small

percentage of energy production, the system would be able to save BC around

$10,967.04 a year and $219,340.80 over the life of the system. The initial cost to

the system is around $500,000 with the possibility of earning $1,203,343.20 in

SRECs if the system was able to produce energy at full capacity.

Table 6: The estimated pro forma model for Cadigan Alumni Center.

Table 7: The estimated pro forma model for 129 Lake St.

Table 8. The estimated pro forma model for Beacon St. Garage

Table 9. The estimate pro forma model for St. Clements Hall

Discussion/Analysis

Mention some errors in analysis to be rectified in the future

There are some imperfections in the pro forma financial estimates that need

to be addressed for future analysis on such a case study. Many of the values used

on the pro forma were based on generalizations of data that we had been given or

research done online and may not be specific to the buildings we studied. For

example, we used two different system sizes to compare 3rd party ownership and

private ownership. The system size used in the pro forma for 3rd party ownership

(1 MWh) was provided to us by First Wind and based on the net metering cap for

non municipal and public customers. We also assumed that the solar energy

company would only provide 15% of the energy produced by each building, but this

value could change between solar companies and the different sizes of the system.

We also estimated that the solar energy company would provide BC energy at a

discounted rate of $0.12 per kWh, but this could also vary amongst different energy

companies. These factors could alter the value of the savings calculated for 3rd

party ownership per year and over the life of the system.

The pro forma also analyzes private ownership but only provides basic costs

and savings associated with owning a system. We stated the cost of the overall

system for BC and the annual savings on utility bills and over the 20 year life span of

the system. These basic statistics, however, are oversimplified. The annual savings

under private ownership would only be experienced by BC once the entire system

had been paid off, which usually varies between five to seven years depending on

the size and capacity of the system. Therefore, the gross savings presented in the

current pro formas could vary for each building. Further analysis of private

ownership could be done through an economic cost benefit analysis to produce

more accurate values on the net present value of each project. Such an analysis

would provide a clearer picture on the investment in private ownership.

Conclusions

Based on our findings, the most optimal location for solar panels at Boston

College is St. Clement’s Hall. Even though these panels will only produce 5% of the

building’s annual energy, this significantly lowers the energy bill, and means more

savings over time. In addition, the carbon offset is ~521,702lbs per year. This is the

equivalent to the amount of carbon 10,869 trees can absorb in a year or is the same

as taking 46 cars off the road for the year (Tree Facts, 2014; Greenhouse Gas, 2011).

Third party ownership makes the most sense for Boston College because it

means immediate savings rather than an initial deficit. The annual savings for

private ownership are much higher but because a system is expensive to own, it

would take years to pay off the initial deficit. By putting a solar PV system on St.

Clement’s, BC will save almost 10,000 dollars on energy each year. Because BC

would not own the panels, it would not be responsible for maintenance or other

costs the panels might require.

Solar is the perfect way for BC to improve sustainability while saving quite a

bit of money!

Acknowledgements

We would like to thank our many mentors who have supported us

throughout our project’s duration: Vikram Aggarwal for aiding us with solar

statistics and mathematical configurations, Peter Sullivan and Matt Marino for a pro

forma that assisted us in calculating the cost of solar at different locations, and John

MacDonald and Bob Pion for their advice on BC’s energy use and policy. We must

also thank Professor David who gave valuable feedback and guided us through the

process.

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A Case Study: Solar Panels at Boston College

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