Solar Photovoltaic Energy Basics
Solar panels or photovoltaic (PV) panels convert sunlight to electricity. Solar energy is a non-polluting form of energy production and can provide "free" power after the equipment and installation are paid, lasting as long as the equipment holds up. Thanks to rebates and new state and federal policies, the payback on solar power is getting better all the time. New leasing programs and utility purchase plans allow all of us to support solar power. And there are different ways to pay for it.
Photovoltaics use sheets of special materials to create electricity from the sun. Photo- means "light," and voltaic means "producing electricity."
Photovoltaics are typically panels and usually are mounted on a home's roof or on a stand that moves the panels to follow the sun. PV is also available in the form of roof shingles and even a thin film.
Very simply, this is how it works: Sunlight hits the panel, which contains two layers of different materials. When light hits these two layers, one of the layers becomes positively charged, and the other becomes negatively charged. This works similarly to a regular flashlight battery, which has a positive end and a negative end. When a wire connects the two ends, they produce an electric current. When the two layers of material in a solar photovoltaic cell are exposed to light, they create an electric current.
The amount of electricity generated by a solar power cell depends on several factors, mainly:
• The surface area of the panel and how much of it is exposed to the sun
• The strength of the sun (depending on time of day, weather, latitude, etc.)
• The length of the solar exposure
• Whether there are impediments to sunlight (trees, buildings, clouds, mist, dust, dirt, etc.)
The electricity produced by PV panels is in DC form. An inverter converts that to AC electricity, the energy current used in the U.S. That electricity can be fed into the power grid, your electric utility's system of power lines and storage, for everyone to use. (If a home is off the grid, large high-voltage batteries are used to store the power.)
Voila! You are a electrical power plant! Your utility company gives you credits for this power production. Electricity you use in your house is offset by the amount of electricity your panels provide to your utility company.
A "grid-tied" photovoltaic system creates electricity with the sun and feeds it into the electrical grid. (Graphic: U.S. Department of Energy)
Is PV for you?
You are a good candidate for solar PV if:
• Your electricity bills are high
• Your roof is oriented more or less to due south or slightly southwest
• Your roof is not shaded
3 Ways to Go Solar
Think capturing the sun’s energy is too expensive? There are at least three ways to use photovoltaic power.
1. Buy the PV system.
Think of solar energy as an investment. Instead of investing in the uncertain stock market that might or might not produce a return on your money, invest in a predictable value proposition: Your own energy use.
For example, a family in California installed a solar photovoltaic system that powers a 2,000-square-foot home occupied by four people. The system consisted of 36 100-watt solar panels—a 3.6-kilowatt system—for a total of $14,000 to $17,500. (Note: These figures vary widely; consult a solar installer for prices in your area). State rebates in California (many states provide rebates) reduce the cost by $4,000 and a federal tax credit brings it down a further 30 percent. The panels reduce the homeowners' electricity use by half, saving them $600 annually. If net metering is required in California, these homeowners will be paid for the power they do not use and instead contribute to the grid, resulting in a better return on investment.
The photovoltaic (PV) system converts sunlight into energy, powering the freezer and refrigerator; washer and dryer; window air conditioner; wall heaters; and shop tools. Maintenance is easy, usually entailing washing the panels with a long-handled broom and a garden hose. ??Solar panel installation can be pricey—even with credits and rebates. At current energy rates, it can take 15 to 20 years or more to break even. If electricity rates rise, the payback will be even sooner.
After the payback period, this homeowner will have free electricity for the life of his PV equipment, the average life of which is 30 years. In this way, the homeowner will make $600 annually (and more, adjusting for inflation and electrical rate increases) in avoided electricity costs. What's more, this homeowner's power costs will be predictable.
The payback could be dramatically shorter and the return much higher in cold climates.
2. Rent the PV system.
For homeowners who do not have the upfront money for a photovoltaic system, even with rebates and tax incentives—there is a relatively new option: Leasing. Several companies are entering the market with programs that allow you to lease a solar energy system.
The leasing company installs the PV panels that produce power. Any excess power unused by the house is sold to the power company, and if their electrical loads exceed the system's capacity, they can pull power from the grid. Ideally, the excess power produced by the system offsets much of what is purchased from the grid. The company maintains the system.
Costs are any local permitting fees and a monthly leasing fee of anywhere from $50 to $200 depending on the size of the system with a small annual percentage to keep up with inflation, etc. A homeowner could expect to save 10 to 15 percent annual after all costs are factored in.
The homeowner can use all the energy their panels produce. That's particularly good for all-electric homes and high power users.
Similar to a car lease, at the end of 15 years, the customer can renew, upgrade, or have the panels removed free of charge. Some programs also allow them to buy the panels at that point. If they sell their house before the lease term is up, the lease can be taken over by the home's buyer.
It's a way to help supply solar energy and reduce one's reliance on dirty fuel and reduce your carbon footprint. At the same time, you are providing clean energy to your neighborhood. ?
3. Support solar energy through your utility.
Many utility companies now offer customers an option to pay a small premium on their utility bills to support solar and wind energy projects in their region.??For an extra $10 to $12 a month on their utility bills, customers help offset the costs of local solar installations, such as those installed by businesses as well as municipal and private renewable energy generation systems.
Whatever they don’t use is sold to the power utility for use by its customers. While this adds to the customer's cost of power, it is an effective way to support clean power and give it a boost when profits alone would not support the introduction of these systems. This is also a great arrangement for renters who can't convince their landlords to install solar systems. ??Utility-based green power programs let you support renewable energy producers, but the electricity that’s fed into your home isn’t necessarily solar or other renewable energy sources. Programs vary. Some utilities directly fund local renewable energy system installations while others simply purchase renewable energy credits from producers that are already up and running.
However, on balance, the effect is perhaps the same: More renewable energy is produced, displacing power sources that use polluting fuel sources. It's an investment in a future in which all of our power is produced with clean and sustainable sources.
