Solar Backup Myth

November 24th, 2011 by Nicholas Brown

MYTH: Solar Power Isn’t Green When It Requires Backup Gas Power Plants:

Solar opponents often argue that solar power plants create the need for additional power plants. The first problem I noticed with this argument is that the installation of additional electricity generation capacity does not create the need for more electricity.

That is illogical. If you were to cancel the construction of a solar power plant, then this means that electricity would have to come from another power plant, and that is likely a natural gas one. The natural gas power plant would have to operate and burn gas 24 hours per day.

If the solar power plant was installed, then that same natural gas plant would back it up at night, and would operate only a fraction of the time, and, hence, burn a fraction of the gas that it normally would.

During the day, when solar irradiance fluctuates, a relatively small (compared to an entire day of backup) amount of energy storage (batteries are an example) could back up the solar power plant with the excess energy stored from sunny periods.

Second: Such people argue that the natural gas generators required are unable to scale electricity generation up or down when solar power production decreases or increases, respectively. Therefore, they have to stay on all the time.

Note that while some power plants can take hours to start (especially coal and nuclear plants), modern gas peaking plants can start in 10-20 and hydro generators can start almost instantaneously.

The solution to the problem above, nonetheless, is pretty simple — set up an hour (or even less) of energy storage that the solar panels would keep charged, and if it becomes cloudy, the battery will back up the solar power plant by providing electricity for up to an hour, which is plenty of time for the natural gas or hydro power plant to start.

One hour of energy storage is inexpensive and the energy storage would act as a buffer for solar power. Another characteristic about solar panels that complements that is they already generate DC, so no AC to DC conversion is required to charge the batteries.

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Photo Credit: SolarShop









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