Celebrate Clean Energy This Sunday at Sun Day

Trees have Arbor Day. The environment has Earth Day. Even ice cream gets National Ice Cream Day on the third Sunday of every July.

Now clean energy is getting its own day in the spotlight. Sun Day, this coming Sunday, September 21, is a day for celebrating all things clean energy. Events around the country will highlight the many benefits of clean energy and clean energy technologies: from solar panels to electric vehicles to heat pumps.

What is Sun Day?

Sun Day is a global day of action and celebration focused on the power of clean energy and its ability to power the world without climate warming emissions. It’s brand new for 2025, and the first ever iteration is being marked by groups around the world hosting special events in their communities.

From solar tours to all-electric vehicle rallies to agrivoltaic tours to homeowners inviting their neighbors over to view their solar panel-heat pump-battery setup and ask questions, there's an event for most corners of the clean energy world. Find an event near you or use the event's toolkit to host your own.

What’s the Big Deal About Solar Power?

In 2024, the United States installed 50 gigawatts of new solar panels. That’s more new generating capacity added in one year than any other technology in more than two decades, according to the Solar Energy Industries Association. Solar and storage made up 84% of all new electricity generation added that year. At the start of 2025, solar and storage were projected to have an equally strong year.

Residential solar panels can reduce electricity bills and, paired with a backup battery, provide emergency power in a blackout. While solar panels are helping people control their costs at home and build a bit more resiliency into neighborhoods, not everyone favors them.

“We now live on a planet where the cheapest way to produce energy is to point a sheet of glass at the sun. This isn't 'alternative energy' anymore--it's the common sense obvious path,” said Bill McKibben, one of the event’s organizers.

Sun Day is an opportunity to highlight and celebrate their benefits.