Solar energy stocks mostly dropped on Monday as a rare total eclipse blotted out solar power in many parts of the United States, but analysts say this is likely a case of correlation, not causation.
Trading in some solar stocks was slightly above average on Monday, with many of them trading sharply lower. This came as volume in the broader market was relatively low.
Jinkosolar — a maker of solar cells, panels and mounting systems — fell 10 percent. Canadian Solar was also down nearly 10 percent, though the solar module and solutions company was also downgraded by Barclays. The Guggenheim Solar exchange-traded fund was down 2.3 percent.
One theory is that headlines about the loss of solar power during the eclipse may have drummed up interest in the space — and maybe stirred long-held concerns about the reliability of solar power. However, analysts were skeptical about that theory.
"I think it maybe slightly brought people's attention to it. I don't think it's a big event," Ivan Feinseth, chief investment officer at Tigress Financial Partners, told CNBC's "Closing Bell."
If any news item was moving the market, it is more likely the start of a trade case last week that threatens to slap imported solar panels with new tariffs, analysts said. The United States International Trade Commission last week began holding hearings on a petition brought by two U.S. solar panel makers, who are seeking protection from low-cost panels made overseas.
New tariffs would benefit U.S.-based solar panel makers but could hurt the companies that install them and the utilities that draw power from them, as higher prices for the panels crimp demand.
The petitioners, Suniva and World Solar, began laying out their case last week. Investors may be taking positions in solar stocks based on what they learned in the hearings and how the issue will be resolved, said Bruce Jenkyn-Jones, co-head of listed equities at Impax Asset Management.
"That may be affecting investors' thinking a bit more" than the solar eclipse, he said.
First Solar, a maker of solar panels and the systems that operate them, could be one of the winners if tariffs are imposed, said Joseph Osha, an analyst covering industrial and energy technology for JMP Securities. Shares of First Solar were down more than 4 percent on Monday.
"I do think that's part of what's been moving that company's stock price," he told CNBC's "Closing Bell."
If anything, Monday's solar power outages showed that utilities have become adept at managing the power fluctuations that renewable energy sources such as wind and solar introduce into energy markets, analysts said.
"I think this has been a really good example of how the grid deals with solar intermittency," Osha said. "To be honest, I think the grid's come through with flying colors."
The event was very manageable for transmission and distribution companies because they were able to model out when solar power would go offline and about how much power they would need to produce from other sources, Jenkyn-Jones said.
"The great thing about the eclipse is that it's totally predictable," he explained. "It's actually more reliable to know there won't be any sun in that period."