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 conventional ones because of the lack of education. Everyone is familiar with the older methods using gas, electric hot water tanks, and furnaces, and feels “comfortable” with them. It is now time, however, to understand the newer methods of employing these alternative energies. Increasing the use of solar DHW and solar PV is a viable first step in energy independence, which also reduces fossil fuel consumption, leaving more fossil fuels in the ground, and thereby lessening our carbon emissions.
Cost considerations can be made by contacting a state certified installer or dealer to provide a design plan and purchase estimate, normally free of charge. Before you request an estimate, however, it is advisable that you understand a few basic solar and investment fundamentals. You can then make a comprehensive decision as to whether or not you can benefit from the use of solar energy. In other words, it is always a good idea to have some knowledge about a subject when you are going to discuss it with someone, simply because ultimately you will have a more in-depth conversation and better understanding before making a financial commitment. If it is not a practical application in both function and cost, then solar is not a solution. If it is concluded that solar might be a viable alternative after reading this book, then at least an informed decision can then be made on whether or not to invest in a system.
The sun has provided us with stored chemical energy in the form of fossil fuels, which constantly is being depleted, and this depletion is responsible for escalated social and economic issues. To curtail these adversities, the direct application of the sun’s radiant energy to alternative conversion processes such as PV, photochemical, thermoelectric, and heat must be developed and utilized continuously. An economic first application involves the use of solar collectors to convert the sun’s radiant energy into heat energy for domestic water heating and electricity. We should now take the opportunity to use the most vast, continuing energy resource available to us on a worldwide basis: our sun.