Tesla founder Elon Musk is having a bad year so far. But that may not last for very long.

Due to recent stock market declines, he's lost a reported $3.5 billion on his holdings in electric car maker Tesla Motors and SolarCity, the solar panel company founded by Musk's cousin Lyndon Rive.

Musk is far from alone. In fact numerous clean energy technology startups are feeling the pain. For one thing, federal and state subsidies that helped support alternative energy are drying up, The New York Times reports. But perhaps more significantly, as the price of oil dives, world economies wobble and investor appetite for companies that challenge oil's dominance begins to waver.

"Overall, when oil goes down it drives down the market," says Charles Kane, an economist and senior lecturer at Massachusetts Institute of Technology's Sloan School of Business. "And when oil is [below] $30 a barrel, energy alternatives like solar and natural gas are priced out and they are not as economically viable."

The once high-flying stocks of Tesla and SolarCity have fallen precipitously in recent months, essentially tracking the steep fall in the price of oil, which has been cut in half since the summer and stands at around $29 a barrel today. Tesla's share price is down nearly 50 percent from its June 2015 high, while SolarCity's has dropped nearly 80 percent from its peak of $85 in February 2014.

Funding is one major area where startups across the clean technology industry are experiencing the effects of low oil prices. In 2015, venture capitalists invested $1.2 billion in 144 deals, a decrease of nearly 75 percent by dollar volume and 50 percent by number of deals compared with 2011. That's according to the most recent data from the National Venture Capital Association and PricewaterhouseCoopers. 

"[The] industry as a whole, I think, will definitely suffer from lower oil prices," Musk told CNN in late January. "No doubt...that is going to dampen interest in electric vehicles in general."

Yet venture capital investors such as Ross Fubini, a partner at Canaan Partners in Menlo Park, California, say the dip is likely to be temporary. That's because there are important structural shifts under way in the green tech industry, including cheaper production costs for things like solar panels and electric cars. That should bring consumers back to companies like Musk's in the years to come.

"Probably a third of [electric car or solar energy] purchasing is purely for economic reasons, and if the costs keep going down, the economic reasons come back," Fubini says.

Representatives from Tesla and SolarCity were unavailable to comment for this article.