Great lakes renewable energy conference (20 questions)

Michigan Energy Fair20 Questions About Residential Renewables

Thomas ReinkeOwner of a small Renewable Energy Company in Fowlerville, Michigan. Background Mostly MechanicalServed a Tool & Die maker Apprenticeship After 10 years in my chosen field, shops were closing to outsourcing.Back to school for Mechanical DesignFew years later those jobs started being outsourced.Back to school for Mechanical Engineer.WOW who knew this would happen?Any Employed Engineers among us?

Michigan Energy Fair20 Questions About Residential Renewables

• Can We Create Jobs in Michigan That Can not be outsourced?

• Can Residents significantly reduce their utility costs?

• Do you want to play an active role in reducing your carbon footprint?

• Will we soon see a “Home Depot “ of Renewable Energy Equipment?

Michigan Energy Fair

• As a responsible citizen and as a responsible home owner, you should definitely consider your options for renewable energy. With the advancing technology of today, there are even more options for renewable energy systems that you can have for residential use. Although these systems have been in use since the beginning of the 20th century, the efficiency of these systems have been on the rise for the past decade. Nowadays, residential renewable energy systems are very efficient and their prices are getting lower everyday with technological advancements. Hence, it is not too expensive nowadays to install a residential energy system at your home.


• How does average homeowner who knows little about renewable energy get information?

Libraries (wind, solar, biomass, hydro)

Magazines (Mother Earth, Home Power, Renewable Energy World etc.) Internet Search (Renewable,Sustainable,Alternative,Back Yard Energy.) Web: US Department of Energy www.eere.energy.gov Sustainable Energy Coalition www.sustainableenergycolaition.org Great Lakes Renewable Energy Association www.glrea.org Renewable Energy and Health renewableenergy&health.com Wind Power Engineering www.windpowerengineering.com Solar Today www.solartoday.com

http://www.sustainableenergycolaition.org/

http://www.glrea.org/

http://www.windpowerengineering.com/


• What cost effective home projects can homeowner get involved with to reduce utility costs?

Insulate (pipes, ductwork, attics, walls, crawl spaces, everything) Weatherstrip (doors, windows etc.) Caulking & Reglazing (windows exterior areas where air can enter.) Conserving Water (leaking faucets, cold water wash, low-flow aerators) Using Energy Efficient Lighting ( CF or LED) Using Energy Efficient Appliances ( when replacing those appliances) Energy Conservation Awareness (turn stuff off when not in use) Eliminating Vampire Power (where ever possible)


• What is renewable energy?

Energy produced from Wind (mechanical and electrical), Sun (heat air, water electricity cooking) Hydro (falling water, niagra falls) Biomass (corn, switchgrass, rye, cherry pits, walnut shells, soy beans)

• What is fossil fuel?

Energy produced from Coal, Oil & Natural Gas, Coal Shale


• What are the benefits of renewable energy?

Energy sources are clean and inexhaustible. Money spent on renewable energy tends to remain in the community

creating jobs and fueling local economies. The use of this equipment will lessen our dependence on oil Promote healthier air and water quality. Reduce our home and business, utility / operating costs Protect wildlife on land and sea. Create a future for children & grandchildren Encourage a lifestyle of conservation Knowing it’s the right thing to do.


• How do we know it there is enough sun to power our home or business?

According to the National Renewable Energy Laboratory Michigan gets 2-3 kWh/m2/day.Most places have enough solar energy to meet some or all of their

needs. Return on Investment and percentage of energy created can be further discussed with solar designer, installer, solar architect

• Will I need a building permit to install renewable energy equipment?

Yes, contact your city or county, building and safety department, home owners association zoning commissioner and homeowners insurance company

Michigan Energy Fair• How many types of solar systems are there

available?

There are 3 types of residential solar applications 1. Passive: the sun heats panels or multiple panels to a 90+ temp internal fan turns on to bring heat into living space.

2. Active or Thermal Solar: Flat plate or evacuated tube collectors heat fluid (non toxic antifreeze) to then be transferred to domestic hot water, boiler, geothermal, forced air, under-floor radiant or heat pump heating systems

3. Photovoltaic Solar: Modules create electricity in DC then inverted to AC and can be used to support our needs.


• How do wind turbines / generators work

Wind turbines work opposite of a fan. Instead of using electricity to move the blades.Wind is used to turn a blade which in turn rotates a shaft to a generator to create electricity.

• Is there enough wind potential to be a realistic source of energy?

According to the National Renewable Energy Laboratory, Michigan has a 13.4 mph average wind speed. Residential wind generators can produce electricity at 5 – 8 mph wind speeds.


• Why is conventional electrical generation harmful?

According to the EPA electricity generation is the largest industrial polluter in our nation. Emissions from coal and Natural Gas are responsible for:

1. 1/3 of our nations nitrogen oxide emissions (smog) 2. 1/3 of our nations carbon dioxide emissions (global warming) 3. 1/3 of our nations sulfur dioxide emissions (acid rain)

These fossil fuels emit harmful toxins into the air we breathe and are related to asthma, broncitus, upper respiratory ailments.


• Do wind Turbines kill birds and bats?

Not often. The Audubon Society estimates that 25,000 birds were killed by wind turbines compared to 800 million killed by man made items such as windows, windshields, buildings and power lines.

• How long does it take for equipment installs?

Many factors determine installs, concrete trenching, building and safety, equipment delivery, weather. Normally 2-7 days


• If Equipment fails who do I call? Can utility services be used until equipment is serviced or repaired.

All equipment and installation have warranties. During product and installation warranty, contractor will be responsible for all service within the guidelines of the warranty.

If service is required after warranty expires you may chose to contact installation contractor or one of your choosing.

Utility supplied services can always be available as a stand-buy in the event of equipment failure


• How does my home continue to heat, create electricity in grey / unlit conditions?

c. Passive solar systems can only heat air on sunny or slightly sunny days (energy stored in rock, stone or brick) [least investment cost]

d. Active solar will heat fluid on sunny or partly cloudy days and store heated fluid, stored in tanks and used to support

( domestic, boiler, geothermal, forced air, under floor radiant)c. Photovoltaic solar will create electricity even with no direct sunlight.

Productivity and current will increase proportional to direct sunlight. Energy can be stores on the interactive grid for normal use or stored in batteries to be inverted to AC during power outages.


• Do I need Utility Companies service for some things or will new energy source cover electric and fuel needs?

Systems will be designed based on your needs, budget, energy consumption location of equipment and design. Unless a stand-Alone system is developed, your regular utility services will remain. This will provide service on days of no wind or sun.

The objective is to reduce purchased energy services and replace them with new renewable energy sources

• How fast is the need for energy growing?

The World Bank projects the world generating capacity will increase to 5 million megawatts by the year 2020 that is up from 3.8 million in 1999.


• I live in a sub-division is the equipment compact?

Newer technology has created the most compact, durable ease of installation and increased warranties in the industry.

Solar equipment can be roof mounted, ground mounted, southern facing in limited spacing. Co-operatives and Associations may create installation issues.

Wind Turbine Tower heights can cause zoning issues without variance.

Equipment manufacturers have met with these challenges to create products with these obstacles reduced.


• How do (PV) Photovoltaic solar modules work?

The solar, modules, panels, collectors you see on rooftops use a process called photovoltaic. Silicon element found in sand is used to Convert sunlight into DC electricity.

Why don’t we use renewable energy all the time?

Unlike Natural Gas and Coal we can not store wind energy and sunshine to use whenever we want to create more electricity.

At this time coal is still the least costly way to produce electricity

1 lb coal can light a 100 watt light bulb for an hour.


• Three types of solar collectors are used for residential applications:

• Flat-plate collector• Glazed flat-plate collectors

are insulated, weatherproofed boxes that contain a dark absorber plate under one or more glass or plastic (polymer) covers. Unglazed flat-plate collectors—typically used for solar pool heating—have a dark absorber plate, made of metal or polymer, without a cover or enclosure.



• Evacuated-tube solar collectors• They feature parallel rows of transparent glass tubes. Each

tube contains a glass outer tube and metal absorber tube attached to a fin. The fin's coating absorbs solar energy but inhibits radiating heat loss. These collectors are used more frequently for U.S. commercial applications.

• There are two types of active solar water heating systems:• Direct circulation systems• Pumps circulate household water through the collectors and

into the home. They work well in climates where it rarely freezes.

• Indirect circulation systems• Pumps circulate a non-freezing, heat-transfer fluid through the

collectors and a heat exchanger. This heats the water that then flows into the home. They are popular in climates prone to freezing temperatures


• Passive solar water heating systems are typically less expensive than active systems, but they're usually not as efficient. However, passive systems can be more reliable and may last longer. There are two basic types of passive systems:

• Integral collector-storage passive systems

• These work best in areas where temperatures rarely fall below freezing. They also work well in households with significant daytime and evening hot-water needs.



• Solar water heating systems almost always require a backup system for cloudy days and times of increased demand. Conventional storage water heaters usually provide backup and may already be part of the solar system package. A backup system may also be part of the solar collector, such as rooftop tanks with thermo-syphon systems. Since an integral-collector storage system already stores hot water in addition to collecting solar heat, it may be packaged with a demand (tank-less or instantaneous) water heater for backup.


• Heat Exchangers for Solar Water Heating Systems

• Solar water heating systems use heat exchangers to transfer solar energy absorbed in solar collectors to the liquid or air used to heat water or a space.

• Heat exchangers can be made of steel, copper, bronze, stainless steel, aluminum, or cast iron. Solar heating systems usually use copper, because it is a good thermal conductor and has greater resistance to corrosion.



• Types of Heat Exchangers• Solar water heating systems use three types of heat

exchangers:• Liquid-to-liquid• This heat exchanger uses a heat-transfer fluid that

circulates through the solar collector, absorbs heat, and then flows through a heat exchanger to transfer its heat to water in a storage tank. Heat-transfer fluids, such as antifreeze, protect the solar collector from freezing in cold weather. Liquid-to-liquid heat exchangers have either one or two barriers (single wall or double wall) between the heat-transfer fluid and the domestic water supply.


• Air-to-liquid• Solar heating systems with air heater

collectors usually do not need a heat exchanger between the solar collector and the air distribution system. Those systems with air heater collectors that heat water use air-to-liquid heat exchangers, which are similar to liquid-to-air heat exchangers.


• Heat Exchanger Designs• There are many heat exchanger designs. Here are some common ones:• Coil-in-tank• The heat exchanger is a coil of tubing in the storage tank. It can be a

single tube (single-wall heat exchanger) or the thickness of two tubes (double-wall heat exchanger). A less efficient alternative is to place the coil on the outside of the collector tank with a cover of insulation.

• Shell-and-tube• The heat exchanger is separate from (external to) the storage tank. It

has two separate fluid loops inside a case or shell. The fluids flow in opposite directions to each other through the heat exchanger, maximizing heat transfer. In one loop, the fluid to be heated (such as potable water) circulates through the inner tubes. In the second loop, the heat-transfer fluid flows between the shell and the tubes of water. The tubes and shell should be made of the same material. When the collector or heat-transfer fluid is toxic, double-wall tubes are used, and a non-toxic intermediary transfer fluid is placed between the outer and inner walls of the tubes..


• Tube-in-tube• In this very efficient design, the tubes of water and the heat-transfer

fluid are in direct thermal contact with each other. The water and the heat-transfer fluid flow in opposite directions to each other. This type of heat exchanger has two loops similar to those described in the shell-and-tube heat exchanger.

• Sizing• A heat exchanger must be sized correctly to be effective. There are many

factors to consider for proper sizing, including the following:• Type of heat exchanger • Characteristics of the heat-transfer fluid (specific heat, viscosity, and

density) • Flow rate • Inlet and outlet temperatures for each fluid. • Usually, manufacturers will supply heat transfer ratings for their heat

exchangers (in Btu/hour) for various fluid temperatures and flow rates. Also, the size of a heat exchanger's surface area affects its speed and efficiency: a large surface area transfers heat faster and more efficiently.


• Solar (Thermal) Water Heaters• Solar water heaters—also called solar domestic hot

water systems—can be a cost-effective way to generate hot water for your home. They can be used in any climate, and the fuel they use—sunshine—is free.

• How They Work• Solar water heating systems include storage tanks and

solar collectors. There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don't.

• Most solar water heaters require a well-insulated storage tank. Solar storage tanks have an additional outlet and inlet connected to and from the collector. In two-tank systems, the solar water heater preheats water before it enters the conventional water heater. In one-tank systems, the back-up heater is combined with the solar storage in one tank.


• Heat-Transfer Fluids for Solar Water Heating Systems

• Heat-transfer fluids carry heat through solar collectors and a heat exchanger to the heat storage tanks in solar water heating systems. When selecting a heat-transfer fluid, you and your solar heating contractor should consider the following criteria:

• Coefficient of expansion – the fractional change in length (or sometimes in volume, when specified) of a material for a unit change in temperature

• Viscosity – resistance of a liquid to sheer forces (and hence to flow)

• Thermal capacity – the ability of matter to store heat


• Freezing point – the temperature below which a liquid turns into a solid

• Boiling point – the temperature at which a liquid boils • Flash point – the lowest temperature at which the vapor above

a liquid can be ignited in air. • For example, in a cold climate, solar water heating systems require

fluids with low freezing points. Fluids exposed to high temperatures, as in a desert climate, should have a high boiling point. Viscosity and thermal capacity determine the amount of pumping energy required. A fluid with low viscosity and high specific heat is easier to pump, because it is less resistant to flow and transfers more heat. Other properties that help determine the effectiveness of a fluid are its corrosiveness and stability.


• Types of Heat-Transfer Fluids• The following are some of the most commonly used heat-transfer

fluids and their properties:

• Air• Air will not freeze or boil, and is non-corrosive. However, it has

a very low heat capacity, and tends to leak out of collectors, ducts, and dampers.

• Water• Water is nontoxic and inexpensive. With a high specific heat,

and a very low viscosity, it's easy to pump. Unfortunately, water has a relatively low boiling point and a high freezing point. It can also be corrosive if the pH (acidity/alkalinity level) is not maintained at a neutral level. Water with a high mineral content (i.e., "hard" water) can cause mineral deposits to form in collector tubing and system plumbing.


• Glycol/water mixtures

• Glycol/water mixtures have a 50/50 or 60/40 glycol-to-water ratio. Ethylene and propylene glycol are "antifreezes." Ethylene glycol is extremely toxic and should only be used in a double-walled, closed-loop system. You can use food-grade propylene glycol/water mixtures in a single-walled heat exchanger, as long as the mixture has been certified as nontoxic. Make sure that no toxic dyes or inhibitors have been added to it. Most glycols deteriorate at very high temperatures. You must check the pH value, freezing point, and concentration of inhibitors annually to determine whether the mixture needs any adjustments or replacements to maintain its stability and effectiveness.


• Hydrocarbon oils

• Hydrocarbon oils have a higher viscosity and lower specific heat than water. They require more energy to pump. These oils are relatively inexpensive and have a low freezing point. The basic categories of hydrocarbon oils are synthetic hydrocarbons, paraffin hydrocarbons, and aromatic refined mineral oils. Synthetic hydrocarbons are relatively nontoxic and require little maintenance. Paraffin hydrocarbons have a wider temperature range between freezing and boiling points than water, but they are toxic and require a double-walled, closed-loop heat exchanger. Aromatic oils are the least viscous of the hydrocarbon oils.


• Refrigerants/phase change fluids• These are commonly used as the heat transfer fluid

in refrigerators, air conditioners, and heat pumps. They generally have a low boiling point and a high heat capacity. This enables a small amount of the refrigerant to transfer a large amount of heat very efficiently. Refrigerants respond quickly to solar heat, making them more effective on cloudy days than other transfer fluids. Heat absorption occurs when the refrigerant boils (changes phase from liquid to gas) in the solar collector. Release of the collected heat takes place when the now-gaseous refrigerant condenses to a liquid again in a heat exchanger or condenser.


• For years chlorofluorocarbon (CFC) refrigerants, such as Freon, were the primary fluids used by refrigerator, air-conditioner, and heat pump manufacturers because they are nonflammable, low in toxicity, stable, noncorrosive, and do not freeze. However, due the negative effect that CFCs have on the earth's ozone layer, CFC production is being phased out, as is the production of hydro-chloro-fluorocarbons (HCFC). The few companies that produced refrigerant-charged solar systems have either stopped manufacturing the systems entirely, or are currently seeking alternative refrigerants. Some companies have investigated methyl alcohol as a replacement for refrigerants.


• If you currently own a refrigerant-charged solar system and it needs servicing, you should contact your local solar or refrigeration service professional. Since July 1, 1992, intentional venting of CFCs and HCFCs during service and maintenance or disposal of the equipment containing these compounds is illegal and punishable by stiff fines. Although production of CFCs ceased in the U.S. 1996, a licensed refrigeration technician can still service your system. You may wish to contact your service professional to discuss the possible replacement of the CFC refrigerant with methyl alcohol or some other heat transfer fluid.


• Ammonia can also be used as a refrigerant. It's commonly used in industrial applications. Due to safety considerations it's not used in residential systems. The refrigerants can be aqueous ammonia or a calcium chloride ammonia mixture.

• Silicones• Silicones have a very low freezing point, and a very

high boiling point. They are noncorrosive and long-lasting. Because silicones have a high viscosity and low heat capacities, they require more energy to pump. Silicones also leak easily, even through microscopic holes in a solar loop.


• Selecting a Solar Water Heater• Before you purchase and install a solar water

heating system, you want to do the following:• Consider the economics of a solar water

heating system • Evaluate your site's solar resource • Determine the correct system size • Determine the system's energy efficiency • Estimate and compare system costs • Investigate local codes, covenants, and

regulations.


• Installing and Maintaining the System• The proper installation of solar water heaters depends on many

factors. These factors include solar resource, climate, local building code requirements, and safety issues; therefore, it's best to have a qualified, solar thermal systems contractor install your system.

• After installation, properly maintaining your system will keep it running smoothly. Passive systems don't require much maintenance. For active systems, discuss the maintenance requirements with your system provider, and consult the system's owner's manual. Plumbing and other conventional water heating components require the same maintenance as conventional systems. Glazing may need to be cleaned in dry climates where rainwater doesn't provide a natural rinse.

• Regular maintenance on simple systems can be as infrequent as every 3–5 years, preferably by a solar contractor. Systems with electrical components usually require a replacement part after or two after 10 years.


• When screening potential contractors for installation and/or maintenance, ask the following questions:

• Does your company have experience installing and maintaining solar water heating systems?Choose a company that has experience installing the type of system you want and servicing the applications you select.

• How many years of experience does your company have with solar heating installation and maintenance?The more experience the better. Request a list of past customers who can provide references.


• Is your Solar/ Wind company licensed or certified?Having a valid plumber's and/or solar contractor's license is required in some states. Contact your city and county for more information. Confirm licensing with your state's contractor licensing board. The licensing board can also tell you about any complaints against state-licensed contractors.

• Improving Energy Efficiency• After your water heater is properly installed and

maintained, try some additional energy-saving strategies to help lower your water heating bills, especially if you require a back-up system. Some energy-saving devices and systems are more cost-effective to install with the water heater.


• Solar Swimming Pool Heaters

• You can significantly reduce swimming pool heating costs by installing a solar pool heater. They're cost competitive with both gas and heat pump pool heaters, and they have very low annual operating costs. Actually, solar pool heating is the most cost-effective use of solar energy in many climates.


• How They Work• Most solar pool heating

systems include the following:• A solar collector — the

device through which pool water is circulated to be heated by the sun

• A filter — removes debris before water is pumped through the collector

• A pump — circulates water through the filter and collector and back to the pool

• A flow control valve — automatic or manual device that diverts pool water through the solar collector.


• Pool water is pumped through the filter and then through the solar collector or collectors where it is heated before it is returned to the pool. In hot climates, the collector can also be used to cool the pool during peak summer months by circulating the water through the collector at night.

• Some systems include sensors and an automatic or manual valve to divert water through the collector when the collector temperature is sufficiently greater than the pool temperature. When the collector temperature is similar to the pool temperature, filtered water simply bypasses the collector and is returned to the pool.


• Solar pool collectors are made out of different materials. The type you'll need depends on your climate and how you intend to use the collector. If you'll only be using your pool when temperatures are above freezing, then you'll probably only need an unglazed collector system. Unglazed collectors don't include a glass covering (glazing). They are generally made of heavy-duty rubber or plastic treated with an ultraviolet (UV) light inhibitor to extend the life of the panels. Because of their inexpensive parts and simple design, unglazed collectors are usually less expensive than glazed collectors. These unglazed systems can even work for indoor pools in cold climates if the system is designed to drain back to the pool when not in use. Even if you have to shut the system down during cold weather, unglazed collectors may be more cost effective than installing a more expensive glazed collector system.


• Glazed collector systems are generally made of copper tubing on an aluminum plate with an iron-tempered glass covering, which increases their cost. In colder weather, glazed collector systems—with heat exchangers and transfer fluids—capture solar heat more efficiently than unglazed systems. Therefore, they can be used year-round in many climates. Glazed collectors also can be used to heat domestic hot water year-round.

• Both glazed and unglazed collector systems should include freeze protection if they'll be used in colder conditions.


• Selecting a Solar Pool Heater• A solar pool heating system usually costs between $3,000 and

$4,000 to buy and install. This provides a payback of between 1.5 and 7 years, depending on your local fuel costs. They also typically last longer than gas and heat pump pool heaters. Your actual cost and payback depend on many factors. Therefore, before you purchase and install a solar pool heating system, you should do the following:

• Evaluate your site's solar resource • Determine the correct system size • Determine the system's efficiency • Compare system costs • Investigate local codes, covenants, and regulations.

Michigan Energy Fair• Installation and Maintenance• The proper installation of a solar pool heating system depends on many factors. These factors

include solar resource, climate, local building code requirements, and safety issues. Therefore, it's best to have a qualified solar thermal systems contractor install your system.

• After installation, properly maintaining your system will keep it running smoothly for 10–20 years. Consult your contractor and read your owner's manual for maintenance requirements. Your collector should require little maintenance if the pool's chemical balance and filtering system are checked regularly. Glazed collectors may need to be cleaned in dry climates where rainwater doesn't provide a natural rinse.

• When screening potential contractors for installation and/or maintenance, ask the following questions:

• Does your company have experience installing and maintaining solar pool heating systems?

• Choose a company that has experience installing the type of system you want and servicing the applications you select.

• How many years of experience does your company have with solar heating installation and maintenance?

• The more experience the better. Request a list of past customers who can provide references.

• Is your company licensed or certified?• Having a valid plumber's and/or solar contractor's license is required in some states.

Contact your city and county for more information. Confirm licensing with your state's contractor licensing board. The licensing board can also tell you about any complaints against state-licensed contractors.

Michigan Energy Fair• The Economics of a Solar Water Heater• Solar water heating systems usually cost more to purchase and install than conventional water

heating systems. However, a solar water heater can usually save you money in the long run.• How much money you save depends on the following:• The amount of hot water you use • Your system's performance • Your geographic location and solar resource • Available financing and incentives • The cost of conventional fuels (natural gas, oil, and electricity) • The cost of the fuel you use for your backup water heating system, if you have one. • On average, if you install a solar water heater, your water heating bills should drop 50%–80%.

Also, because the sun is free, you're protected from future fuel shortages and price hikes.• If you're building a new home or refinancing, the economics are even more attractive. Including

the price of a solar water heater in a new 30-year mortgage usually amounts to between $13 and $20 per month. The federal income tax deduction for mortgage interest attributable to the solar system reduces that by about $3–$5 per month. So if your fuel savings are more than $15 per month, the solar investment is profitable immediately. On a monthly basis, you're saving more than you're paying.


• Evaluating Your Site's Solar Resource for Solar Water Heating• Before you buy and install a solar water heating system, you need

to first consider your site's solar resource. The efficiency and design of a solar water heating system depends on how much of the sun's energy reaches your building site.

• Solar water heating systems use both direct and diffuse solar radiation. Even if you don't live in a climate that's warm and sunny most of the time—like the southwestern United States—your site still might have an adequate solar resource. If your building site has un-shaded areas and generally faces south, it's a good candidate for a solar water heating system.

• Your local solar system supplier or installer can perform a solar site analysis.

Michigan Energy Fair• Sizing a Solar Water Heating System• Sizing your solar water heating system basically involves determining the total collector area and

the storage volume you'll need to meet 90%–100% of your household's hot water needs during the summer. Solar system contractors use worksheets and computer programs to help determine system requirements and collector sizing.

• Collector Area• Contractors usually follow a guideline of around 20 square feet (2 square meters) of collector

area for each of the first two family members. For every additional person, add 8 square feet (0.7 square meters) if you live in the U.S. Sun Belt area or 12–14 square feet if you live in the northern United States.

• Storage Volume• A small (50- to 60-gallon) storage tank is usually sufficient for one to two three people. A medium

(80-gallon) storage tank works well for three to four people. A large tank is appropriate for four to six people.

• For active systems, the size of the solar storage tank increases with the size of the collector—typically 1.5 gallons per square foot of collector. This helps prevent the system from overheating when the demand for hot water is low. In very warm, sunny climates, some experts suggest that the ratio should be increased to as much as 2 gallons of storage to 1 square foot of collector area.

• Other Calculations• Additional calculations involved in sizing your solar water heating system will include the

following:• Evaluation of your building site's solar resource • Orientation and tilt of the solar collector.


• Solar Water Heater Energy Efficiency• For a solar water heating system, use the solar energy factor (SEF)

and solar fraction (SF) to determine its energy efficiency.• The solar energy factor is defined as the energy delivered by the

system divided by the electrical or gas energy put into the system. The higher the number, the more energy efficient. Solar energy factors range from 1.0 to 11. Systems with solar energy factors of 2 or 3 are the most common.

• Another solar water heater performance metric is the solar fraction. The solar fraction is the portion of the total conventional hot water heating load (delivered energy and tank standby losses). The higher the solar fraction, the greater the solar contribution to water heating, which reduces the energy required by the backup water heater. The solar fraction varies from 0 to 1.0. Typical solar factors are 0.5–0.75.


• Estimating a Solar Water Heater System's Cost• Before purchasing a solar water heating system, you can estimate

its annual operating cost and compare it with other more and/or less efficient systems. This will help you determine the energy savings and payback period of investing in a more energy-efficient system, which will probably have a higher purchase price.

• Before you can choose and compare the costs of various systems, you need to know the system size required for your home.

• Calculating Annual Operating Cost• To estimate the annual operating cost of a solar water heating

system, you need the following: • The system's solar energy factor (SEF) • The auxiliary tank fuel type (gas or electric) and costs (your

local utility can provide current rates). • Then, use the following calculations.



• Other Costs• When comparing solar water heating systems,

you should also consider installation and maintenance costs. Some systems might cost more to install and maintain.

• Consult the manufacturer and a qualified contractor to help estimate these costs. These costs will vary among system types and sometimes even from model to model.


• Building Codes, Covenants, and Regulations for Solar Water Heating Systems

• Before installing a solar water heating system, you should investigate local building codes, zoning ordinances, and subdivision covenants, as well as any special regulations pertaining to the site. You will probably need a building permit to install a solar energy system onto an existing building.

• Not every community or municipality initially welcomes residential renewable energy installations. Although this is often due to ignorance or the comparative novelty of renewable energy systems, you must comply with existing building and permit procedures to install your system.

• The matter of building code and zoning compliance for a solar system installation is typically a local issue. Even if a statewide building code is in effect, it's usually enforced locally by your city, county, or parish. Common problems homeowners have encountered with building codes include the following:


• Exceeding roof load • Unacceptable heat exchangers • Improper wiring • Unlawful tampering with potable water

supplies. • Potential zoning issues include the following:• Obstructing side-yards • Erecting unlawful protrusions on roofs • Location of the system too close to streets or

lot boundaries.


• Special area regulations—such as local community, subdivision, or homeowner's association covenants—also demand compliance. These covenants, historic district regulations, and flood-plain provisions can easily be overlooked.

• To find out what's needed for local compliance, contact the following:• Your local jurisdiction's zoning and building enforcement divisions

– Briefly describe your intended construction, asking for other relevant ordinances/codes that might be in effect.

– Find out if there are any additional local amendments or modifications to the regulations in effect.

– Ask how to determine whether you are located in a historic district, flood-plain area, or any other special category regulated by a government body.

– Ask where you may find pertinent ordinances/codes (local library, government office, etc.).

– Read pertinent sections of the regulations, making photocopies of information you wish to file for future review and design/installation analysis.

• Homeowner's, subdivision, neighborhood, and/or community associations– Ask if they have any ordinances, provisions, or covenants that may affect the design

and installation of the system.– Copy and file pertinent sections for reference.


• Making Your Own Clean Electricity• Generating electricity using your own small renewable energy

system fits the circumstances and values of some home and small-business owners. Although it takes time and money to research, buy, and maintain a system, many people enjoy the independence they gain and the knowledge that their actions are helping the environment.

• A renewable energy system can be used to supply some or all of your electricity needs. Some people, especially those in remote areas, use the electricity from their systems in place of electricity supplied to them by power providers (i.e., electric utilities). These are called stand-alone (off-grid) systems.

• Others connect their systems to the grid and use them to reduce the amount of conventional power supplied to them through the grid. A grid-connected system allows you to sell any excess power you produce back to your power provider.


• These are some renewable energy technologies available for use today:

• Small solar electric systems • Small wind electric systems • Small hybrid electric systems (solar and wind). • Before you purchase and install a small renewable energy system,

you should analyze your electricity loads to see if one of the small renewable energy systems can meet all or enough of your electricity needs—is it economically feasible? You will also want to research your local codes and requirements for installing a system.

• If you're designing a new home, you should work with the builder and your contractor to incorporate your small renewable energy system into your whole-house design—an approach for building an energy-efficient home.


• Small Solar Electric Systems• A small solar electric or photovoltaic (PV) system can be a reliable

and pollution-free producer of electricity for your home or office. And they're becoming more affordable all the time. Small PV systems also provide a cost-effective power supply in locations where it is expensive or impossible to send electricity through conventional power lines.

• Because PV technologies use both direct and scattered sunlight to create electricity, the solar resource across the United States is ample for small solar electric systems. However, the amount of power generated by a solar system at a particular site depends on how much of the sun's energy reaches it. Thus, PV systems, like all solar technologies, function most efficiently in the southwestern United States, which receives the greatest amount of solar energy.

• You can also use PV technology to provide outdoor lighting.


• Small Wind Electric Systems• Small wind electric systems are one of the most cost-effective

home-based renewable energy systems. These systems are also nonpolluting.

• If a small wind electric system is right for you, it can do the following:• Lower your electricity bills by 50%–90% • Help you avoid the high costs of having utility power lines

extended to a remote location • Help uninterruptible power supplies ride through extended

utility outages.• Small wind electric systems can also be used for a variety of other

applications, including water pumping on farms and ranches.


• Small "Hybrid" Solar and Wind Electric Systems

• According to many renewable energy experts, a small "hybrid" electric system that combines wind and solar (photovoltaic) technologies offers several advantages over either single system.

• In much of the United States, wind speeds are low in the summer when the sun shines brightest and longest. The wind is strong in the winter when less sunlight is available. Because the peak operating times for wind and solar systems occur at different times of the day and year, hybrid systems are more likely to produce power when you need it.

•This building is powered by a hybrid wind and photovoltaic system. Photo credit: K. Bullard, National Park Services.



• Operating Your System Off-Grid

• For many people, powering their homes or small businesses using a small renewable energy system that is not connected to the electricity grid—called a stand-alone system—makes economic sense and appeals to their environmental values.

• In remote locations, stand-alone systems can be more cost-effective than extending a power line to the electricity grid (the cost of which can range from $15,000 to $50,000 per mile). But these systems are also used by people who live near the grid and wish to obtain independence from the power provider or demonstrate a commitment to non-polluting energy sources.

Stand-alone systems can be more cost-effective than connecting to the grid in remote locations.Photo credit: Dave Parsons.


• Successful stand-alone systems generally take advantage of a combination of techniques and technologies to generate reliable power, reduce costs, and minimize inconvenience. Some of these strategies include using fossil fuel or renewable hybrid systems and reducing the amount of electricity required to meet your needs.

• The topics below provide more information on issues involved in setting up a stand-alone system. Your local system supplier or installer, a local renewable energy organization, or your state energy office should be able to help you navigate the specific requirements in your community.

Self Improvement

Great lakes renewable energy conference (20 questions)