Solar Photovoltaic (PV)
Photovoltaics (PV) are arrays of solar cells that convert light into electricity. Producing electricity with PV emits no pollution, produces no greenhouse gases and uses no finite fossil-fuel resources. Electricity production capacity by a PV system is measured in kilowatts, while the amount of electricity produced over time by a PV system is measured in kilowatt hours. PV technologies have declined in price since they were first introduced onto the market, driven by improved research and development, and most of all by steady increases in sales volume. Most home owners start small, since PV can be added in modular increments as your energy needs and investment capabilities grow. It is important to focus on reducing your overall energy use through energy efficiency and solar water heating prior to sizing a solar PV system. PV arrays can be mounted at a fixed angle facing south in an un-shaded region of the roof or on a tracking device that follows the sun, allowing them to capture the most sunlight over the course of a day. Integrated PV cells are now available in a variety of shapes and sizes including triangular shaped panels as well as small roofing tiles.
In Your Home…
A one-kilowatt PV system will produce about 1,350 kilowatt hours (kWh) per year and has an expected lifetime of 30 years, for a total production of 40,500 kWh. To calculate a simple payback on your PV system, divide the total installed cost of your system by the monetary value of the energy produced from your system each year. Maintenance should also be considered and generally averages about one percent of the total system cost. For a typical Florida home that consumes about 2,000 kWh a month, a 4.0 kilowatt PV system should offset about 22 percent of the energy.
In Your Business…
Businesses should base solar decisions on lifecycle costs analyses, which include the cost of operating and maintaining a system throughout the anticipated service life. This is important since solar technologies can be expensive to purchase. However, they require minimal maintenance, no fuel and produce no emissions, which make them a good long-term investment. A 4,000 square foot office building might require around 10,000 watts of PV to meet its daily energy needs.
Today’s solar heaters, or solar thermal systems, provide environmentally friendly heat for water and swimming pools in residential applications. The solar systems collect the sun’s energy to heat air or a fluid. Two commonly used systems include active and passive systems. Active solar water heaters use pumps to circulate water or another fluid from the storage tanks through the collectors. Passive solar water heaters require no pumps or controls and combine the storage tank and collector in one unit. The use of a solar water heater will benefit you by lowering your electric bills and insulating you from rising energy costs, even though solar thermal doesn’t explicitly generate electricity. When installed properly, solar water heaters are more economical over the life of the system than heating water with electricity, dedicated heat pumps, heat recovery units, natural gas or propane. Many systems include sleek, attractive, low-relief collectors that people often mistake for skylights. Properly designed and installed systems with glass covered collectors should perform well for more than 20 years.
In Your Home…
Solar water heaters, sometimes called solar domestic hot-water systems, can be a good investment for your home. The average system takes up just 40 square feet of roof space and should save between 50 percent and 85 percent of the hot water portion of the monthly bill. Most residential solar thermal systems cost between $4,000 and $5,000. An average 40-square-foot collector should be able to offset 10 percent to 15 percent of the energy for homes that consume about 2,000 kilowatt hours a month.
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