The need for energy from renewable sources has become a pressing issue in recent years. Many

1. Introduction
The need for energy from renewable sources has become a pressing issue in recent years. Many individuals and organizations have become concerned about the future energy needs of our society and have begun searching for ways to meet these needs. With the finite and rapidly depleting reserves of oil, coal, and natural gas, it has become a chief issue to discover sources of renewable energy and implement systems that harness them. An energy infrastructure based on renewable sources would be better able to sustain the needs of a society with continually increasing energy demands due to its growth in size and its increased standard of living. The adoption of such systems would also have a positive impact on our environment. Renewable forms of energy, such as solar, wind, or geothermal power produce virtually no pollution. The implementation of renewable energy systems may even be a wise investment; energy produced by such systems would no longer have to be purchased, and over a period of time, these savings in energy costs may exceed the price of the system. The Wesley United Methodist Church, located in Worcester, Massachusetts, is interested in the feasibility of implementing such a system. The church incurs a costly electric bill, which, coupled with a gas heating bill, imposes a significant financial burden. Concerned that the costs of electricity would only rise in the future, the church’s business administrator began looking into alternative energy options. The church has a prominent, south-facing roof space, and its leadership is particularly interested in determining if a solar power system could be installed to utilize this space.
The goal of this project was to determine the economic feasibility of installing a solar power system on the roof of the Wesley United Methodist Church. New incentives and agencies, such as Commonwealth Solar, are making it more affordable to install renewable energy systems. Also, as the demand grows for renewable energy, more cost effective technologies and production processes are being developed to meet the growing demand. It is the infancy and volatility of this market that warrants an up to date investigation of the current options and their costs.
The feasibility of installing a solar array on the Wesley United Methodist Church was determined by gathering pertinent weather data, conducting a site analysis, investigating possible solar panels and mounting solutions, and finally, creating an economic model. These attributes combined to form a final solution through which we determined the investment potential as well as the social and environmental impacts of implementing such a system. Our results indicated that both a system of small size and a larger size would both have a payback period of roughly 19 years.
2. Background
Humans have always been fascinated with the power of the sun. Egyptian pharaohs claimed to be direct descendents of Re, the sun god, and creator of light and all other things. Greek mythology tells the story of Icarus, who flew too close to the sun while using wax wings and plunged to his death. For years, cultures worshipped the sun for the power it gave to life. Many cultures still respect the sun for its central role in sustaining life on earth. Since the 1800s, scientists have made progress towards harnessing the sun’s power in the form of electrical energy. Throughout the last two centuries, significant progress has been made in developing the solar technologies we have today. Many photovoltaic installations are connected to the power grid, and thus each installation is accompanied by many regulations. This chapter provides a broad overview of how photovoltaic panels work, the economics involved in determining the feasibility of a photovoltaic system, and a summary of similar case studies.
2.1 History of the Church
The vision of building Wesley United Methodist Church began in two smaller congregations in 1923. After months of planning, the members of Grace Church (formerly on Walnut Street) and Trinity Church (on Main and Chandler Streets) came together with their pastors (Dr. James Wagner and Dr. Berton Jennings) to join their two churches and establish one Methodist Church in the city of Worcester. The present location was chosen as the future site of this joint effort. It was decided that a new name would be chosen for this new church. Wesley United Methodist Church is named after the founder of Methodism, John Wesley. In addition to a new name, both pastors felt a new minister should be appointed to pastor this newly joined congregation.
According to the official histories of Wesley United Methodist Church, the first construction loan of $350,000 was made possible by the trustees who put themselves and their families on the line,
signing the bank notes personally. The women of the church had taken on the responsibility of paying for the marble altar in the sanctuary. This was done by donations of gold and silver jewelry as well as other items which were sold to make this gift possible. A construction firm from Boston was hired and on May 8, 1927 the first Sunday worship was held in the present building. The first Easter services included 2552 people in two services! The church’s foundational statement is etched in stone over the entrance on 114 Main Street. It reads, “To the glory of God and the service of man.” Wesley Church continues to exist as a place where all may come to worship God and be nourished by God’s love.
2.2 Solar Technology
Solar technology has evolved drastically since humans first became interested in the sun. In the 1800s the photoelectric effect was discovered, and since then, scientific progress has been made towards harnessing the sun’s power. Today, there are many types of solar technology, including crystalline silicon (the traditional method) and newer alternatives such as string ribbon and thin film technologies.
2.2.1 The History of Solar Power
The word “photovoltaic” comes from the Greek word “photo” meaning light and after Count Volta, the Italian physicist (1745-1827) whom the electrical unit Volt is named after. Photovoltaic technology began in 1839 with the French physicist Alexandre Becqueral’s discovery of the photo effect. In 1877 the first photovoltaic cell was constructed from Selenium. The photovoltaic effect was further explained by Albert Einstein and Robert Millikan in the early 1900’s. Finally, in the 1950’s, Shockley
provided a model for the p-n junction, which enabled the beginning of modern photovoltaic technology development.1
1 Quaschning, Volkerr. Understanding Renewable Energy Sources. London : Earthscan, 2005.
2 Lund, H., Nilson, R., Solamatova, D. & Skare, E. The History Highlight of Solar Cells. Retrieved October, 2008, from http://org.ntnu.no/solarcells/pages/history.php
3 Aldous, S. How Solar Cells Work. Retrieved October, 2008, from http://www.howstuffworks.com/solar-cell.htm
4 Radiochemistry Society. Periodic Table of Elements: Silicon. Retrieved October, 2008, from http://www.radiochemistry.org/periodictable/elements/14.html
In 1954 Bell Labs produced the first modern photovoltaic cell with an efficiency of only four percent.2 Early solar panels carried high price tags, usually costing a couple of thousand dollars per Watt. Energy generated at this cost was only feasible for space projects. Research in this arena progressively drove the costs lower and the efficiencies higher. In the last half century, photovoltaic technology has continued to improve, as has the economics of photovoltaic power generation.
2.2.2 How Solar Power Works
Solar cells, also called photovoltaic cells, are used to convert the electromagnetic radiation from the sun into electricity that can be used to power today’s electronic gadgets, as well as residential and commercial dwellings. The simplest photovoltaic cells are comprised primarily of three materials, silicon, and two doping agents.3 Silicon, which comprises a majority of the photovoltaic cell, has several chemical properties that make it well suited for the use in solar cells. It is the second most abundant element on Earth and has four valence electrons.4 Valence electrons, in layman’s terms, can be thought of as "free" electrons. These "free" electrons are capable of bonding atoms together, as well as doing electro-magnetic work. In pure silicon, atoms bond together via their valence electrons to form a crystalline structure. However, because these valence electrons are tied up bonding atoms together, they cannot be used to produce electricity. This is the primary reason two doping agents are applied to the silicon material. Silicon, on its own, cannot produce electricity. Instead, atoms with greater than or
less than four valence electrons are added to the silicon structure to produce an impurity. Adding this impurity to the silicon structure is what allows the flow of electricity.5 If a Phosphorous doping agent, which has five valence electrons, is added to a group of silicon atoms, it produces a crystalline structure with a "free" valence electron. This "free" valence electron can be used to generate electricity. This type of material is given the name "n-type material". The only thing needed is a place for this "free" electron to flow. No electrical work can be done if there is no potential between two points. The solution to this problem lies within our second doping agent. The second doping agent, unlike the first, has fewer than four valence electrons. As a result, when a structure of Silicon and Boron, an element with only three valence electrons, is formed, "holes" begin to develop within the material structure. These "holes" are the absence of an electron and are capable of being filled by other electrons within the structure. This material is given the name "p-type" material. Now we have two parts to this puzzle. One puzzle piece is Silicon doped with a material that produces "free" electrons. The second is Silicon doped with an element that produces "holes" within the structure that is capable of being filled by "free" electrons. A solar panel is comprised of both n-type material and p-type material. Both materials are sandwiched together to produce what is referred to as a "p-n junction".
5 Cooler Planet. (2008). How Photovoltaic Cells Work. Retrieved October, 2008, from http://solar.coolerplanet.com/Content/Photovoltaic.aspx