Sun Day is a grassroots day of action celebrating solar & wind power and advocating for the transition to clean energy. It was first designated by President Jimmy Carter on May 3, 1978. The International Solar Energy Society helped transition the event into an international observance in 1994. And since 2019, the United Nations has been marking June 21 as the International Day of the Solstice Celebration, or what is known as International Sun Day.
While National Sun Day is observed on May 3 and the International Day of the Solstice Celebration occurs on June 21, in 2025 a climate movement initiative spearheaded by activist Bill McKibben made September 21 a National Day of Action for clean energy, coinciding with the autumn equinox. Communities hosted Sun Day concerts, neighborhood solar tours, e-bike parades, and educational workshops to highlight renewable energy as an affordable source of power.
The Purpose of Sun Day
Sun Day’s core purposes have been to: (1) promote clean energy, highlighting the potential of solar technology, photovoltaic systems, & renewable energy to replace fossil fuels; (2) acknowledge life on Earth, reminding the public that sunlight drives weather, ocean currents, & photosynthesis; and (3) educate & take action, encouraging schools, research institutions, & businesses to host exhibits, open houses, and panel discussions on sustainability.
US Air Force & Master Sgt Beth Holliker
Sun Day 2026
This year, Sun Day seems to have been a bit neglected. There were some website postings about it in May and there are a few local celebrations this week & next around the country. But nothing very big or exciting.
Maybe May 3rd is not the best time of year for it. It certainly doesn’t have the symbolic value of the Summer Solstice or the Autumn Equinox. Maybe we spent all our energy on last year’s September event. Maybe spreading the celebrations out to different days and seasons has created confusion about when it should be celebrated.
The Growth of Solar Power
According to Electrek, solar added more new capacity to the US grid in 2024 than any energy source in 20 years, installing 50 gigawatts of new solar capacity. That’s enough to power 8.5 million households. Domestic solar module production tripled that year, and at full capacity, US factories can produce enough to meet nearly all demand for solar panels in the US. Total US solar capacity is expected to reach 739 gigawatts by 2035.
US Dept of Energy & Dennis Schroeder.
Solar energy is now the cheapest source of power on the planet and gives us a chance to actually do something about the climate crisis. We are already where we need to be technologically, solar & wind energy are already less expensive to produce than fossil fuel energy. And the rest of the world, most notably China, is already transitioning rapidly to renewable energy sources. We are at the point where we can move fairly quickly to a carbon neutral world. All we need is the proper motivation, and we can build a more equitable and sane civilization.
Impediments to Further Growth
But policy changes are impacting the solar energy market. Changes to federal tax credits, supply chain availability, and permitting policy are increasing costs for developers & manufacturers and causing a slowdown in solar deployment. A slowdown could leave the US without the electricity needed to meet rising demand, threatening growth in the manufacturing & technology sectors that rely on abundant power.
The utility-scale segment saw historic gains in 2024, and the community & commercial solar markets also set annual records. But the residential solar market experienced its lowest year of installations since 2021, due to policy changes and elevated interest rates. Forecasts show that the market is expected to rebound over the next decade, but clearly, there are forces working against it.
Let’s Make Sun Day 2027 Better
The mission of Sun Day is to push for local, state, & federal clean energy reforms, ease solar permitting, and counter political and industrial barriers to renewable technology. Sun Day is a day of action to celebrate the power of clean energy. Solar & wind are the cheapest form of power, lowering energy costs, creating new jobs, strengthening communities, and improving the planet.
We can’t allow complacency to slow the progress. We need a bigger & better Sun Day celebration in 2027. We need another day of action like last year, to collectively celebrate the progress that’s been made and fight for the solutions that can light up the world.
