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Solar Power

Frying eggs from 93 million miles away—now that’s power

The sun is an incredibly powerful source of energy. That’s why TVA is using photovoltaic panels to transform solar energy into usable electricity.

When rays of sunshine strike a solar panel, they give some of the electrons inside it more energy, a process that creates an electrical current.

What is the role of solar energy in Green Power Switch?

Solar energy constitutes a small but important part of Green Power Switch’s energy resources. The combined generating capacity of TVA’s solar installations is over 300 kilowatts (kW)—an amount that demonstrates TVA’s leadership among Southeastern utilities in its commitment to solar energy.

How is solar energy generated?

It’s generated by photovoltaic (PV) systems. PV systems use semiconductor cells, or modules, that convert sunlight directly into electricity. The systems also contain additional equipment like inverters, which change direct current to alternating current (the type that we use in our homes). The PV cells are connected in the form of flat panels that can be mounted on rooftops or canopies, or integrated into roofing shingles and other building materials.

How much electricity does a PV system produce?

The production ranges from four to 50 kilowatts. On average, a 10-kW PV system located in the Tennessee Valley will generate between 12,000 to 14,000 kilowatt-hours (kWh) a year, or a little more than the total amount of electricity used in a typical home.

Does a PV system produce electricity all the time?

No. Depending on the season, it ordinarily generates power from 8 a.m. to 6 p.m., reaching its maximum output between noon and 1 p.m. Since solar energy isn't a primary element of the power mix for Green Power Switch, batteries or collection-and-storage systems aren't used. When the PV systems aren’t producing power, TVA’s other resources continue to supply reliable electricity.

Can PV systems produce power on cloudy days?

Yes. PV modules generate electricity when the weather is cloudy, although their output is diminished. On a dark, overcast day, a PV system might receive only 5 percent to 10 percent of the usual amount of sunlight, so the power output would decrease proportionately.

Do PV systems work well in the cold?

PV modules actually generate more power at lower temperatures. Like most other electronic devices, they operate more efficiently when it’s cooler. PV systems generate less energy in the winter than in the summer, but that’s due to the combination of fewer daylight hours and lower sun angles, not to cooler temperatures.

What about breakage? Don’t most modules contain glass?

PV modules are designed to withstand all the potential rigors of the environment, including arctic cold, desert heat, tropical humidity, winds of more than 125 miles per hour, and one-inch hail at terminal velocity. In spite of this very durable construction, though, the glass may break under an extremely strong impact.


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