Solar Energy, Photovoltaics, and Domestic Hot Water

A Technical and Economic Guide for Project Planners, Builders, and Property Owners

Russell H. Plante

• Publisher: Academic Press
• Year: 2014
• Print ISBN: 9780124201552
• eBook ISBN: 9780124202139
• Topic: Business
• Subtopic: Energy Industry
• Index: Business

Solar Energy, Photovoltaics, and Domestic Hot Water provides a fundamental understanding of heat and energy conversions and of both solar domestic hot water system types with associated components and photovoltaic/inverter system combinations. It provides the information needed to determine and understand the proper siting requirements, the amount of energy needed (based upon usage), the amount of solar energy available, the methods of comparing collectors for both hot water and photovoltaic situations, and the number of collectors necessary for either hot water or electricity. Solar Energy, Photovoltaics, and Domestic Hot Water also details the investment and cost savings advantages of using solar energy through a unique compilation of information and explanations not available in other publications or on the internet. This includes comprehensive financial explanations with examples using basic engineering management analysis methods. These examples include present and future worth relative to break-even costs and cash flow analysis and actual quoted systems and worksheets for typical electrical solar PV and DHW demand scenarios allowing you to calculate your own cost estimates and to evaluate your own projects relative to investment payback. Solar Energy, Photovoltaics, and Domestic Hot Water will enable readers make informed decisions about the economic practicality of solar generation sources for residential or commercial use based upon location, energy demands, associated conventional fuel costs, solar energy system costs, and tax incentives. - Provides a fundamental understanding of solar DHW and photovoltaic systems - Uses clear guidelines to evaluate solar DHW and photovoltaic systems' value as a long-term investment vs traditional power and heat generation methods - Discusses cost and operating expenses relative to investment and return on capital which will be beneficial to project planners, installers, energy managers, builders and property owners

Chapter one

Considering the Solar Alternative

Abstract

This chapter introduces the considerations important in understanding the prerequisites prior to purchasing and installing a solar domestic hot water or photovoltaic system. Alternative energy concepts are defined, and the chapter elaborates upon the sequential information contained throughout the book relative to the practical economic applications of solar domestic hot water and photovoltaic systems. Topics such as energy cost comparisons, proper siting and sizing of systems, availability of solar insolation, component configurations, operating fundamentals, and the feasibility to use alternative energy systems versus conventional systems are addressed. Specific arguments against the use of such systems are dispelled with explanations to the contrary.

Keywords

Economic analysis; Economic criteria; Economy; Energy alternatives; Energy output; Financial decisions; Green energy; Investment; Payback; Photovoltaic; Savings; Siting; Sizing; Solar domestic hot water; Worksheets

The direct use of solar energy has never been adopted on a worldwide scale because cheaper alternative energy sources always have been available. It really was not that these sources were cheaper than the sun’s energy, which is free, but rather that the costs of constructing devices or systems to use the sun’s energy were greater than the costs needed to use the other sources that were available. The cost of conventional energy sources will continue to increase, and the reliability of foreign energy imports will continue to be questionable at best. We are overdue in making a serious effort to apply the sun’s energy to complement a larger portion of our ever-increasing energy needs. The most appropriate and cost-effective large-scale application of solar energy involves the heating of water for domestic use and the generation of electricity for grid-tied residential use.

Discussions regarding solar domestic hot water (DHW) and photovoltaic (PV) systems have been separated into individual chapters and topic sections in this book so that you can pick and choose the subjects that hold your particular interest. For instance, if you already have the basic knowledge to site and orient a solar DHW or PV system, then simply progress to the next chapter. The information presented in this book is considered to be a prerequisite to purchasing a system and to either having it installed or deciding that additional knowledge is required to install it yourself. The following chapters and their specific sections will sequentially and logically provide you with information so that you can

1. determine whether or not you have the proper site for collecting sufficient solar radiant energy (Chapter 2, Section 2.4, Siting a Solar Energy System),

2. determine what your energy requirements are for hot water (Chapter 3, Section 3.5.1, Hot Water Requirements) and electricity (Chapter 3, Section 3.5.2, Electricity Requirements),

3. determine the amount of solar energy available (Chapter 4, Section 4.5, Determining Solar Energy Availability),

4. determine how to size a solar DHW system (Chapter 4, Section 4.6, Sizing a Solar DHW System) or how to size a solar PV system (Chapter 5, Section 5.4, Sizing a Solar Photovoltaic System),

5. understand the economic criteria involved with making a financial decision (Chapter 6; Economic Criteria for Financial Decisions),

6. evaluate and determine economic payback for hot water (Chapters 7 and 9) and electricity (Chapters 8 and 9), and

7. consider the importance of using renewable energies while understanding implications relative to energy policies and regulations and their effects on the economy (Chapter 10, The Energy Conundrum and Economic Consequences).

Many sections throughout this book provide additional details regarding these two distinct energy alternatives. Worksheets are included to provide a manual (non-Internet) approach to calculating and estimating sizing, energy output, and economic analysis, as well as information relative to Internet online calculators and estimator programs. If you decide that you meet the site conditions necessary to support these solar applications, then other sections of this book should be of further interest by assisting you in making an informed decision regarding purchase and installation.

The cost of energy changes from day to day because of price variations in demand, fuel costs, and availability of generation sources. Whether you heat water by oil, electricity, or other means, or are concerned with the continued price volatility of your electricity demands, a properly installed solar DHW or PV system can save you money. These cost savings are discussed in more detail in Chapters 7, 8, and 9. Simply stated, the first most practical application of “green energy” is the use of solar DHW systems because of the smaller investment expense. Being initially more expensive than solar DHW systems and normally having a slightly longer payback period, PV systems are the second most practical application of solar energy.

The average residential price of electricity in the United States in 2012–2013 was approximately $0.12 per kilowatt-hour (kWh), and in the Northeast, as high as $0.17 per kWh, including line delivery fees. (At times the delivery fees are a large percentage of the total price per kilowatt-hour.) The average price of oil during that same period was $3.69 per gallon. These prices vary over time and by locality because of the availability of power plants, fuel costs, and regulations.

This book’s intent is not to elaborate on conservation measures or the assessment of the variety of alternative energy applications, but rather to develop an understanding of the practical and economic applications of solar DHW and solar PV systems. In the past, homeowners have not had adequate assurance or knowledge about either solar DHW systems or PV systems, or their operation and proper installation. Today, such information is available in abundance, almost to the point at which it can be confusing.

Many people are quite capable of installing their own systems, thereby defraying installation costs. Such installations, however, require the do-it-yourselfer to be multidisciplined in carpentry, plumbing, electrical, and solar, meeting all pertinent local and state codes. In particular, PV installations require an in depth understanding of Article 609 of the National Electrical Code to ensure electrical safety requirements are met. In addition, some states that offer tax incentives require that a solar energy system be installed by a certified installer to receive a state tax rebate. Even if a person intends to have the system installed professionally, they still should have an understanding of the various types of systems available to make an intelligent decision. The following chapters, therefore, provide a logical approach to evaluating and understanding energy cost comparisons per British thermal units, to determining proper siting, sizing, and availability of solar insolation, and to understanding some of the basic component configurations and operating fundamentals.

Time after time the same arguments against the use of solar energy systems have appeared, and these beliefs have slowed their adoption, resulting in the delay of our independence from oil. These arguments include the following:

1. Solar cannot work in many of the northern sections of the United States.

2. Solar energy systems are not a good investment and will never pay for themselves.

3. Equipment will be cheaper in the future.

4. Solar technology is untried and not perfected.

5. Solar energy systems are difficult to install.

All of these statements are false. One should carefully consider the following:

1. Solar energy utilization is feasible in every part of the country. The amount of radiant energy (insolation) received in the Northeast is only slightly less than the national average, still providing sufficient solar energy to supply hot water and electricity.

2. Solar DHW is the most cost-effective use of solar energy and can be justified economically. With current energy sources growing increasingly expensive, a solar DHW system will increase the value of the home as it reduces the utility bills. In most cases, payback is within 5–10 years depending on system type and whether or not the system is self-installed, thereby saving labor costs. Solar PV systems normally require a slightly longer payback period, but the percentage savings can be calculated more readily than other solar applications because there are fewer parameters to consider and because the demand for energy consumption is defined more strictly.

3. Solar equipment is becoming more costly because of increasing material and labor prices. Furthermore, recurrent federal and some state tax credits make this an opportune time to purchase equipment now, not later.

4. Solar DHW technology is a safe, proven, and reliable low-energy technology that has been used since the early 1900s in this country and earlier in others. The technology for solar DHW is well developed. Standard flat-plate collectors, storage tanks, and control systems are commercially available. In the past, issues such as faulty and careless installation, poor workmanship, and the improper use of components and materials have produced consumer skepticism. Engineering detail and design integrity also have been ignored previously in many instances, resulting in either system inoperability or in poor system performance. These unfortunate situations have become more isolated because of the increased field expertise of the solar installer or dealer. You simply have to engage a reputable company to ensure that an installation is completed properly, not unlike any other contractor you would hire. The technology is proven.

In addition to solar DHW, solar PV technology has made gigantic strides in the past several years in the conversion of light to energy and the variety of solar cells available. Twenty-first-century PV modules have a 25 plus years of life with little degradation and have been proven to be a reliable alternative energy application. Research in this area continues, including such advancements in studies involving “quantum dots” as well as “thermophotovoltaics” and their impact regarding improvements in PV efficiency. Technology will always continue to evolve.

5. Solar energy systems are not difficult to install. It is, however, necessary that these systems be properly sized, sited, mounted, equipped, and maintained to ensure their economic viability. It is recommended that the homeowner have such systems installed by a reputable certified dealer. For those people who are construction savvy, however, very good installation guide books are available. Although this book contains information on siting and sizing a system to address the economic feasibility of using solar as a “green energy” solution, it does not address detailed installation procedures. Its main premise is to provide a technical and economic set of guidelines.

The use of solar energy to heat water for domestic use as well as to provide electricity is questioned because it is unfamiliar and not considered to be conventional. There appears to be a mental block against using new methods to replace the conventio...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Dedication
• Preface
• Acknowledgments
• Chapter one. Considering the Solar Alternative
• Chapter two. Simple Solar Basics
• Chapter three. Determining Energy Usage
• Chapter four. Solar Domestic Hot Water Systems
• Chapter five. Solar Photovoltaic Systems
• Chapter six. Economic Criteria for Financial Decisions
• Chapter seven. The Economics of Solar Domestic Hot Water Systems
• Chapter eight. The Economics of Solar Photovoltaic Systems
• Chapter nine. The Solar Investment
• Chapter ten. The Energy Conundrum and Economic Consequences
• Appendix A. Mathematical Tables, Relationships, and Conversions
• Appendix B. Worksheets
• Appendix C
• Glossary
• References
• Index