A Luminalt employee installing a rooftop solar panel. Photo: Justin Sullivan via Getty Images

Solar energy has experienced rapid growth in the U.S. — from essentially no share of the nation's generation only 7 years ago to 1.5% of the total by 2016's end.

What to watch: In the medium term, solar energy will face significant headwinds in the form of tariffs, tax code changes and diminishing incentives, which threaten to reduce its cost-competitiveness. Despite these challenges, investors and developers remain bullish on solar’s long-term potential, with installed capacity projected to more than double in less than 5 years.

The challenges:

  1. Import tariffs on solar panels have increased the cost of solar projects, especially large-scale solar farms.
  2. Only weeks before the tariff announcement, changes to the U.S. tax code increased the economic attractiveness of other generation technologies like natural gas power, mainly because of newly available depreciation methods.
  3. Perhaps most importantly, the federal investment tax credit for solar projects is scheduled to sunset in 2022.

Yes, but: If past cost trajectories are maintained, none of these elements will have a material effect on solar’s long-term competitiveness. Here’s why:

  • Tariffs notwithstanding, solar panel costs have decreased tenfold in the past decade and continue to fall.
  • Entire system costs are also on the decline because of advances in other components and overall facility design.
  • Upgrades to the electricity grid and management systems are paving the way for greater solar diffusion by accommodating solar’s inherent intermittency.
  • Stationary storage facilities are increasing solar’s value by enabling its use after sunset, when electricity demand is high.

The bottom line: In some parts of the country, solar farms have already become the lowest-cost electricity source. Given cost-competitiveness, state-level renewable-energy mandates and complementary technology advances, solar power is likely to become even more commonplace.

Stephen Comello is director of the Sustainable Energy Initiative at Stanford Graduate School of Business and a fellow at the Steyer-Taylor Center for Energy Policy and Finance at Stanford University.

Go deeper

Updated 11 mins ago - World

Hong Kong media tycoon Jimmy Lai arrested under national security law

Media tycoon Jimmy Lai at the Next Digital offices in Hong Kong in June. Photo: Anthony Wallace/AFP via Getty Images

Hong Kong pro-democracy activist Jimmy Lai has been arrested for "collusion with foreign powers," said Mark Simon, an executive at the tycoon's media firm Next Digital Monday morning local time.

Why it matters: He was arrested under the national security law imposed by China in late June that gives Beijing more powers over the former British colony. Lai is the most prominent person arrested under the law, which prompted the U.S. to sanction Chinese officials, including Hong Kong leader Carrie Lam, over Beijing's efforts to strip the territory of its autonomy.

Updated 2 hours ago - Politics & Policy

Coronavirus dashboard

Illustration: Sarah Grillo/Axios

  1. Global: Total confirmed cases as of 8:30 p.m. ET: 19,769,560— Total deaths: 729,351 — Total recoveries — 12,030,061Map.
  2. U.S.: Total confirmed cases as of 8:30 p.m. ET: 5,041,573 — Total deaths: 162,913 — Total recoveries: 1,656,864 — Total tests: 61,792,571Map.
  3. Politics: Pelosi says states don't have the funds to comply with Trump's executive order on unemployment — Mnuchin says Trump executive orders were cleared by Justice Department.
  4. States: New York reports lowest rate of positive coronavirus test results since pandemic began
  5. Public health: Ex-FDA head: U.S. will "definitely" see 200,000 to 300,000 virus deaths by end of 2020. 
  6. Schools: Nine test positive at Georgia school where photo showing packed hallway went viral — How back-to-school is playing out in the South as coronavirus rages on.

New York reports new low positive coronavirus test rate

People physically distancing at tables in New York City's Times Square in June. Photo: Johannes Eisele/AFP via Getty Images

New York Gov. Andrew Cuomo (D) announced Sunday 515 people, or 0.78% of those tested, returned a positive reading for COVID-19 the previous day.

Why it matters: It's the lowest single-day positive rate since the start of the pandemic. It's another sign that the state that was once a global coronavirus epicenter is curbing the spread of the virus. "Our daily numbers remain low and steady, despite increasing infection rates across the country, and even in our region," Cuomo said in a statement. "But we must not become complacent: Everyone should continue to wear their masks and socially distance."

Go deeper: Cuomo says all New York schools can reopen for in-person learning