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Solar Energy FAQs

Q: What is photovoltaics (solar electricity) or "PV"?
A: What do we mean by photovoltaics? The word itself helps to explain how photovoltaic (PV) or solar electric technologies work. First used in about 1890, the word has two parts: photo, a stem derived from the Greek phos, which means light, and volt, a measurement unit named for Alessandro Volta (1745-1827), a pioneer in the study of electricity. So, photovoltaics could literally be translated as light-electricity. And that's just what photovoltaic materials and devices do; they convert light energy to electricity, as Edmond Becquerel and others discovered in the 18th Century.
Q: How can we get electricity from the sun?

A: When certain semiconducting materials, such as certain kinds of silicon, are exposed to sunlight, they release small amounts of electricity. This process is known as the photoelectric effect. The photoelectric effect refers to the emission, or ejection, of electrons from the surface of a metal in response to light. It is the basic physical process in which a solar electric or photovoltaic (PV) cell converts sunlight to electricity.

Sunlight is made up of photons, or particles of solar energy. Photons contain various amounts of energy, corresponding to the different wavelengths of the solar spectrum. When photons strike a PV cell, they may be reflected or absorbed, or they may pass right through. Only the absorbed photons generate electricity. When this happens, the energy of the photon is transferred to an electron in an atom of the PV cell (which is actually a semiconductor).

With its newfound energy, the electron escapes from its normal position in an atom of the semiconductor material and becomes part of the current in an electrical circuit. By leaving its position, the electron causes a hole to form. Special electrical properties of the PV cell—a built-in electric field—provide the voltage needed to drive the current through an external load (such as a light bulb)..

Q: What are the components of a photovoltaic (PV) system?
A: A PV system is made up of different components. These include PV modules (groups of PV cells), which are commonly called PV panels; one or more batteries; a charge regulator or controller for a stand-alone system; an inverter for a utility-grid-connected system and when alternating current (ac) rather than direct current (dc) is required; wiring; and mounting hardware or a framework.
Q: How long do photovoltaic (PV) systems last?
A: A PV system that is designed, installed, and maintained well will operate for more than 20 years. The basic PV module (interconnected, enclosed panel of PV cells) has no moving parts and can last more than 30 years. The best way to ensure and extend the life and effectiveness of your PV system is by having it installed and maintained properly. Experience has shown that most problems occur because of poor or sloppy system installation.
Q: What's the difference between PV and other solar energy technologies?
A: There are four main types of solar energy technologies: 1.Photovoltaic (PV) systems, which convert sunlight directly to electricity by means of PV cells made of semiconductor materials. 2.Concentrating solar power (CSP) systems, which concentrate the sun's energy using reflective devices such as troughs or mirror panels to produce heat that is then used to generate electricity. 3.Solar water heating systems, which contain a solar collector that faces the sun and either heats water directly or heats a "working fluid" that, in turn, is used to heat water. 4.Transpired solar collectors, or "solar walls," which use solar energy to preheat ventilation air for a building.
Q: Can I use photovoltaics (PV) to power my home?
A: PV can be used to power your entire home's electrical systems, including lights, cooling systems, and appliances. PV systems today can be blended easily into both traditional and nontraditional homes. The most common practice is to mount modules onto a south-facing roof or wall. For an additional aesthetic appeal, some modules resemble traditional roof shingles
Q: Can I use photovoltaics (PV) to power my business?
A: PV systems can be blended into virtually every conceivable structure for commercial buildings. You will find PV being used outdoors for security lighting as well as in structures that serve as covers for parking lots and bus shelters, generating power at the same time.
Q: How do I know if I have enough sunlight for PV?
A: A photovoltaic (PV) system needs unobstructed access to the sun's rays for most or all of the day. Shading on the system can significantly reduce energy output. Climate is not really a concern, because PV systems are relatively unaffected by severe weather. In fact, some PV modules actually work better in colder weather. Most PV modules are angled to catch the sun's rays, so any snow that collects on them usually melts quickly. There is enough sunlight to make solar energy systems useful and effective nearly everywhere in California.
Q: How big a solar energy system do I need?
A: The size of solar system you need depends on several factors such as how much electricity or hot water or space heat you use, how, the size of your roof, and how much you're willing to invest. Also, do you want the system to supply your complete energy usage or to supplant a portion of your higher cost energy usage? You can contact a system designer/installer to determine what type of system would suit your needs.
Q: Why should I purchase a PV system?

A: People decide to buy solar energy systems for a variety of reasons. For example, some individuals buy solar products to preserve the Earth's finite fossil-fuel resources and to reduce air pollution. Others would rather spend their money on an energy-producing improvement to their property than send their money to a utility. Some people like the security of reducing the amount of electricity they buy from their utility, because it makes them less vulnerable to future increases in the price of electricity.

If it's designed correctly, a solar system might be able to provide power during a utility power outage, thereby adding power reliability to your home. Finally, some individuals live in areas where the cost of extending power lines to their home is more expensive than buying a solar energy system. .

Q: How is a solar electric system designed, installed, and maintained?
A: You could install a photovoltaic (PV) or solar electric system yourself. But to avoid complications or injury, you will probably want to hire a reputable professional contractor with experience in installing solar systems. PV systems have few moving parts, so they require little maintenance. The components are designed to meet strict dependability and durability standards so they can stand up to the elements. However, they are fairly sophisticated electric systems, so installation usually requires the knowledge and experience of a licensed electrical equipment contractor.
Q: Where can I find someone who designs, installs, and maintains photovoltaic (PV) systems?
A: We suggest you look for a PV installer or equipment provider in the telephone directory under "Solar Energy Equipment and Systems Dealers." It is a good idea select a designer or installer of solar energy systems from the list in your local yellow pages by first asking for information from several of them about their experience with PV systems as well as how much their services and products cost. With a system designer, you can discuss power requirements or hot water needs for your building, sunlight availability, and other important factors, and determine the type of system that's needed to meet your needs. System designers and installers should be able to provide you with cost estimates and other pertinent information. If your house is not yet designed or built, it is important to make the building as energy efficient as possible to reduce your PV system's energy requirements.
Q: How much does a solar energy system cost, and how much will I save on utility bills?
A: Some of the following documents are available as Adobe Acrobat PDFs [Click here]. Unfortunately, there is no single or simple answer. But a solar rebate and other incentives can reduce the cost of a PV system. This cost depends on a number of factors, such as whether it is a stand-alone system or is integrated into the building design, the size of the system, and the particular system manufacturer, retailer, and installer. For solar water heaters and space heaters, you also have to consider the price of the fuel used to back up the system. In most cases, you would have to add the cost of natural gas or electricity to get a more accurate estimate of how much you can expect to pay for a solar energy system. It is also difficult to say how much you will save with a solar energy system, because savings depend on how much you pay your utility for electricity or natural gas, and how much your utility will pay you for any excess power that you generate with your solar system. You can ask your solar system provider how much your new system will produce on an annual basis and compare that number to your annual electricity or hot water demand to get an idea of how much you will save.
Q: What is net metering? Is net metering available where I live and work?
A: Net metering is a policy that allows homeowners to receive the full retail value for the electricity that their solar energy system produces. The term net metering refers to the method of accounting for the photovoltaic (PV) system's electricity production. Net metering allows homeowners with PV systems to use any excess electricity they produce to offset their electric bill. As the homeowner's PV system produces electricity, the kilowatts are first used for any electric appliances in the home. If the PV system produces more electricity than the homeowner needs, the extra kilowatts are fed into the utility grid.
Q: How big a solar energy system do I need?
A: The size of solar system you need depends on several factors such as how much electricity or hot water or space heat you use, how, the size of your roof, and how much you're willing to invest. Also, do you want the system to supply your complete energy usage or to supplant a portion of your higher cost energy usage? You can contact a system designer/installer to determine what type of system would suit your needs.
Q: How/Where do I start?
A: Before you install a PV system on your existing home, you will need to have an energy efficiency audit. This audit will tell you the things you can do to cut your energy use. Some suggestions might include: •Replacing old appliances with new energy-efficient models. •Replacing older water heaters with new ones. •Insulating the home if it has no insulation. Or increasing the insulation in attics or below the floors. •Caulking around doors and windows. •Replacing incandescent lights with compact fluorescent or LED bulbs.
Q: What is a residential solar electric system?
A: We offer comprehensive, code-compliant systems that allow you to generate your own electricity at home. Designed to interconnect with your existing utility service, they feature solar modules, plug-and-play wiring, power electronics and our patented mounting kits. Our installer network provides system installation and service..
Q: How does a residential solar electric system work?
A: Solar cells in the modules mounted on your roof convert sunlight directly into DC power. A component called an inverter converts this DC power into AC power that can be used in your home. The system is interconnected with your utility. During the day, if your solar system produces more electricity than your home is using, your utility may allow net metering or the crediting of your utility account for the excess power generated being returned to the grid. Your utility would provide power as usual at night and during the day when your electricity demand exceeds that produced by your solar system. Systems are also available with a battery backup. Part of the power produced by your solar system during the day is used to charge the batteries, which provide power for your critical loads in the event of a power outage.
Q: Will my system work at night?
A: No. Sunlight must be present for your solar modules to produce power. At night, you draw power from your utility.
Q: Will my system work on cloudy days?
A: Yes, though they produce less electricity. Under a light overcast sky, panels might produce about half as much as under full sun.
Q: What happens during a power outage?
A: We offer two types of solar residential systems. One type of system powers your home during daylight hours but does not provide power in an outage, even on a sunny day. Another type of system powers your home during daylight hours but also has a battery backup designed to provide power to your home's critical loads during an outage, day or night.
Q: Does your solar system make hot water?
A: No. People often confuse our products with solar thermal panels that involve water circulating through tubes to be heated by the sun for swimming pool water heating. Our solar modules convert sunlight into electric current to operate appliances, motors, pumps and other devices.
Q: How can I tell a water-heating panel from a solar electric module?
A: Solar electric modules are typically one to two inches (2.5 to 5 cm) thick with 32 or more three to four inch (7.5 to 10 cm) blue or black solar cells on the back of the cover glass. Solar water heating panels are generally much thicker and may have tubes connected to a flat black plate under the glass, or a black tank inside the collector panel.
Q: Can I generate heat for my home with a residential solar electric system?
A: No. Our solar power systems are designed to provide electricity to run your lights, appliances and other electric devices in your home. Other solar technologies are designed to turn the sun's light into heat instead of electricity.
Q: What do the terms on-grid, grid-connected, grid-tied and off-grid mean?
A: On-grid, grid-connected or grid-tied means connected to the utility electrical grid. Our solar electric systems are designed as on-grid systems, meaning that they interconnect with your existing utility service. Off-grid refers to systems that are not connected to the utility electrical grid. Our solar electric packaged systems are not designed for off-grid applications. An off-grid system must be custom designed by a solar power expert.
Q: How do I know if a residential solar electric system would work on my home?
A: Solar electric power works for most homes. Our systems are engineered to work with most roofing materials, in most locations where direct sunlight is available, in almost every region of the United States. You need a sunny place on your roof about 120 square feet or 11 square meters (10 by 12 feet or 3 by 3.67 meters) for our smaller systems, and up to 1,000 square feet (93 square meters) for our largest systems. Shading from trees or other obstructions can reduce the practicality of a specific installation. A south-facing roof area is optimal, but solar electric panels can be mounted on west- or east- facing roofs and still produce better than 90 percent of the power of a true south roof mounting.
Q: Why does it require at least 120 square feet (11 square meters) of roof space?
A: Each solar module is approximately 5 feet (1.5 meters) long and 2-1/2 feet (0.75 meters) wide. The modules are always grouped in a set of four, and the minimum number of modules for our smallest system is twelve modules. This requires an area of at least 120 square feet (11 square meters).
Q: Why is shade a problem?
A: Because of the wiring design of a solar module, all of the individual solar cells on a module must receive full sunlight for the module to work properly. If any portion of the module is shaded, the entire module power output-even those sections still exposed to sunlight-is lowered.
Q: What if I need a new roof or am building a new house?
A: This is the ideal situation for installing solar. Before laying the roof, you can install flashable mounting brackets that provide the highest level of protection from leakage.
Q: Can I add reflectors or mirrors around the solar panels to increase the power they generate?
A: No. Our solar panels designed for use in direct sunlight only.
Q: How many solar panels do I need to produce enough electricity to run my house?
A: The array size you need depends on your average electrical usage, climate, roof angle, shading problems and many other factors. To approximate the array size you need, multiply your average daily electrical demand in kilowatt-hours by 0.25. The result is the approximate size of solar array, in kilowatts, needed to meet your electrical demand.
Q: Will a system produce enough energy to cover all my electricity needs?
A: It is important to understand that a solar electric system does not need to provide all of the electricity you need to be of great value. A small system that displaces an average of one-quarter to one-half of your average demand reduces your electric bill. With battery backup, it can deliver uninterrupted power to critical loads during utility outages for days or weeks. We are happy to provide you with a system that supplies 100 percent of your energy needs, but cutting your electricity by 40 to 50 percent is typically the most cost-efficient approach for home solar power.
Q: What other options do I have if the system cannot be mounted on my roof?
A: If a roof-mounted system proves impractical, a ground-mount, trellis or pergola application may be an option.
Q: If I rent a home or apartment, can I still get a system?
A: No. Solar electric systems are available only to property owners. The installation of a solar electric system involves the property owner entering a contractual agreement that includes a potential property lien (called a mechanic's lien).