How a solar home is powered when sun is not shining

Choosing to install solar can be a challenging process. This article is the first in a three-part series aimed at educating Gunnison County Electric Association (GCEA) members about how solar energy ties into the electrical grid, as well as the financial considerations to keep in mind when penciling out a solar investment.

Solar electric energy has been available for decades, but residential and small commercial installations only became common after federal tax credits were introduced in 2005. The federal government is currently offering a 30% tax credit for new solar installations (inclusive of materials and labor), and many homeowners and small businesses may now be seriously considering the possibility of generating their own electricity via rooftop or ground mounted solar arrays.

Accordingly, solar development companies and solar advertising has become widespread and is growing. Ad campaigns to “reduce your electric bill to zero” and “provide your home with 100% clean energy” are very enticing, and solar may be a great choice for many homeowners. However, solar’s true potential and actual limitations should be clearly understood before homeowners and businesses make significant financial investments in individual “net-metered” solar electric systems.

Net-metering is a billing mechanism created by the Colorado legislature to provide a financial incentive to consumers who may wish to install grid attached solar systems. Net-metering is also the industry term commonly used for individual solar-electric systems that both generate electricity for consumption in individual homes and businesses and, when conditions are right, inject unconsumed electricity back into the electric grid.

Where your energy comes from

When the sun is shining, photovoltaic panels provide energy for immediate consumption. Whenever a solar system is producing more energy than is being consumed, the local grid provides the means to move excess generation to other local electricity users.

After dark, when it is cloudy, when solar panels are covered by snow or when a home or business is consuming more electricity than their solar system is able to produce in real time, the electric utility provider’s electric grid becomes the energy provider. If a home or business has a battery storage system, reliance on the grid can be reduced, but likely not eliminated.

Like traditional consumers, net-metered solar consumers rely on electricity from a mix of sources for their power supply when the sun is not shining — even if the net-metered solar consumers have a net-zero home. GCEA and other electric utilities provide the necessary “backup” supply of electricity when solar arrays are not producing.

Being tied to GCEA’s service means when residents want power, the system is equipped to instantaneously handle the demand on the electric grid. GCEA, in turn, relies on Tri-State Generation and Transmission Association to generate and transmit power to the local area through GCEA distribution lines.

When the sun comes up, the snow has melted or the clouds have passed, net-metered solar systems will begin producing power again. Using electricity during this time means GCEA members are consuming the electrons produced by their solar arrays and using 100% clean energy produced by the sun. If a GCEA member uses more electricity than their array is producing in real time, they are using electricity from the grid to supplement their needs.

But what happens when net-metered homes or businesses do not consume as much as their solar arrays produce? What happens to the excess power generated? In the next article, GCEA will share how net-metered consumers are compensated for any unused energy.

For more information about solar, visit gcea.coop and go to GCEA’s “Solar Opportunities” page.

(GCEA is a member-owned, not-for-profit electric cooperative, that delivers electricity to homes and businesses throughout Gunnison County, Hinsdale County and parts of Saguache County.)