Unreliable output

To learn more, hover over the illuminated words in these paragraphs.

Saving for a rainy day might be a good strategy for holding onto loose change, but it’s useless when it comes to solar power. Even passing clouds lead to intermittent output that can compromise electric reliability. And nighttime? Maybe someday we’ll invent lunar energy, but for now that’s a dead zone.

Even on perfect, sunny summer days, solar power systems don’t fully cooperate with Tucson’s needs, especially at home. Summer energy usage peaks between 4-6 p.m., but the sun does its best energy-producing work in the middle of the day.

Solar power has been a big help in reducing our use of other energy resources, but Tucson residents are still reliant on the TEP grid throughout the day.

Today’s real-time grid requires the generation of exactly as much power as customers are using at all times. That’s why it’s so important to have backup systems. In coming years, TEP will deploy a growing fleet of local, natural gas-fired turbine generators that can quickly compensate for solar power fluctuations. Even customers with rooftop solar arrays are charging their cell phones and powering their prime-time TV shows with energy from coal-fired power plants that run 24 hours a day. TEP plans to develop an energy storage system this year to see if it can help stabilize the frequency of our local grid, which can be compromised by the intermittent output of solar power systems. That's when everyone is getting home from work, cranking the A/C and powering on their gadgets. We’re looking for ways to reduce our reliance on backup generation. Utilities are testing different storage technologies, like batteries, compressed air and molten salt.