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May 27, 2018
Rooftop solar systems vs. solar farm dynamics

Photo: FPL

FPL's DeSoto Next Generation Solar Energy Center in Arcadia, Florida

Green Development

Rooftop solar systems vs. solar farm dynamics

Amy Martinez | 10/28/2015

Price of a 5-kilowatt system: $15,000, or $10,500 after a 30% federal tax credit, according to Solar Energy Industries Association/GTM Research. The typical system includes up to 25 panels and an inverter and comes with a 25-year power warranty. The price has fallen 45% since 2011. Under state law, households and businesses can lease rather than own a solar system, but the leasing company can't take advantage of the 30% federal tax credit, says Scott McIntyre, CEO of Solar Energy Management, a solar project contractor in Tampa.

Output: 7,100 kilowatt-hours a year, enough to power a small home

Price per watt: $3.00

Factor: Insurance. A $4,000 rider for a homeowner's policy to protect solar panels costs about $200 a year, McIntyre says.

Factor: Installation and Maintenance. Every rooftop is its own engineering project, requiring permitting and labor, which accounts for a third of the overall cost. Post-installation, the panels don't require much maintenance, says McIntyre. A checkup and cleaning once every two years costs about $190, he says.

Factor: Efficiency. Panels may not be situated in the best direction or at the best angle to maximize exposure to the sun. Homes may be shaded. Tree branches may fall.

Factor: Subsidies. Homeowners who buy a solar system and have it installed on their property can claim a 30% credit on their federal income taxes. Florida provides a property tax exemption for homesolar systems, and they're not subject to sales taxes.

Factor: Savings. McIntyre estimates that households can reduce their monthly electric bills by as much as 90%, assuming they also take steps to improve energy efficiency.

Factor: Net metering. Under Florida's net metering policy, customers can send their solar-generated excess energy to the utility grid and receive credits worth the local retail price for electricity. Utilities say credits should be set at wholesale prices, which are much lower than retail, because homeowners with solar systems don't incur costs that utilities face in building and maintaining the distribution system. Advocates for net-metered solar energy say it reduces the need for new power plants and lowers transmission costs.

Factor: The grid. Homes with rooftop solar still have some power if the grid is disrupted. Tea Party activist Debbie Dooley says she prefers small-scale solar to large centralized generation for national security and other reasons. "There's nothing more vulnerable to a terrorist attack than our power grid," she says.

Factor: Capacity. Environmental groups note that rooftop solar makes use of otherwise empty space and doesn't require large chunks of land.

Factor: Zero fuel cost. And the sun is, of course, not a fossil fuel.

Factor: Growth. Florida more than tripled its rooftop solar installations from about 2,800 in 2010 to 8,500 in 2014, according to the Florida Public Service Commission.

Solar Farm/Utility

Example: Utility-scale solar projects in Florida run the gamut from Duke's 6-megawatt photovoltaic array in Orange County to FPL's 75-megawatt Martin County plant that runs on solar thermal. In 2009, FPL built a 25-megawatt solar farm in DeSoto County. The facility includes 90,000 solar panels and cost $152 million.

Output: 52,000 megawatt-hours a year, enough to power about 3,125 Florida homes

Price per watt: $5.50 (represents the DeSoto plant's capital cost in 2009. At three solar plants currently under construction in Florida, FPL expects the per-watt cost to be $1.20.)

Factor: Economies of scale. Utilities say they can design solar plants to maximize production and minimize costs. A large solar array typically is on a flat expanse of land near transmission lines and substations, away from trees that would shade the panels and drop debris. Because of the economies of scale inherent in large investments, utility-scale solar can generate 2½ times more electricity for the same amount of money as home-solar systems, according to industry estimates.

Factor: Growth. Florida has eight utility-scale solar plants, according to the Solar Energy Industries Association. Last year, Florida Power & Light announced plans to build three new solar plants by the end of 2016. All told, the plants will triple FPL's solar capacity to 335 megawatts. Meanwhile, Duke Energy says it will add 500 megawatts of utilityscale solar by 2024. Gulf Power plans to install three new solar plants at military bases in northwest Florida. And Tampa Electric will build a 25-megawatt solar facility to power more than 3,500 homes.

Factor: Savings. FPL expects to spend about $410 million to build three solar plants with a combined capacity of 223.5 megawatts. FPL says the plants will generate power 26% of the time, which amounts to 500,000 megawatt-hours of electricity in the first full year of operation. FPL says it will recoup the construction costs over a 25-year lifespan, resulting in "no net cost to customers." Fenton, of UCF's Florida Solar Energy Center, says the plants probably will "lower your electric bill over time." FPL also is spending about $1.1 billion to build a 1,237-megawatt natural gas plant at Port Everglades. It's projected to operate 90% of the time and generate about 10 million megawatt-hours of electricity in its first year. FPL says the plant will reduce the utility's overall consumption of fuel and save customers more than $400 million over a 30-year lifespan.

Factor: Operational efficiency. Solar panels tilt toward the sun to capture more energy. Tracking technology enables them to follow the sun as it moves across the sky. Space is left between the panels and the ground to keep them cool and boost production. Utilities can build in ideal locations - large, flat expanses of land in rural or semi-rural areas that tend to get a lot of sunlight. Preferred sites also have grid infrastructure nearby, such as substations and transmission lines. Employees are on hand to clean panels and replace them when they fail.

Factor: Dispersion of benefits. The utilities say large-scale solar makes renewable energy available to a broader swath of the population than rooftop solar, which only upper income customers can afford to install. Solar advocacy groups say more jobs can be created from the construction of rooftop systems.

Factor: Subsidies. Utility-scale solar plants are eligible for the 30% federal tax credit, plus an accelerated depreciation tax deduction.

Tags: Energy & Utilities, Environment, Green Trends

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