With surges and slumps common among renewable energy investments, it’s no wonder many investors avoid them. But it is time to pay more attention to the highly volatile sector, particularly wind and solar.

The recent collapse in global oil prices has put pressure on green energy stocks, and meanwhile federal investment tax credits for solar projects are set to expire at the end of 2016. Even so, the industry’s long-term momentum is accelerating.

Concerns about energy security (the availability, reliability and affordability of energy supplies), climate change and the health toll of air pollution are boosting interest, as are steep declines in the cost of providing solar and wind energy.

Global investments in renewable energy, led by wind and solar, rose 17% last year to $270 billion—just 3% below the record high set in 2011—according to the 2015 annual trends report from the United Nations Environmental Programme (UNEP) and Bloomberg New Energy Finance.

China, which has ramped up its renewable energy policies, saw the biggest 2014 renewable energy investments, followed by the U.S. and Japan. Investment in developing nations jumped 36% in 2014 to $131 billion, nearly half the global total.

Europe also remains a strong force. Over the past decade, four-fifths of its investment in power generation went to renewables, with 60% to wind and solar photovoltaics, according to the International Energy Agency (IEA).

Impax Asset Management Group PLC—a $4.6 billion investment manager dedicated to investing in opportunities created by the scarcity of natural resources and growing demand for cleaner, more efficient products and services—has used the recent pullback in stock prices as an opportunity to boost its renewable energy holdings.

“There is a misperception in the market that lower oil prices are dampening prospects for renewables,” says David Richardson, a managing director and head of U.S. business development and client service for Impax, which has offices in London, New York, Portland, Ore., and Hong Kong. In reality, oil is more of a transportation fuel, he says, and most new electricity generation capacity is coming from renewable sources.

Impax anticipates numerous long-term drivers for renewable energy, including an extension of some tax credits and some new policy initiatives coming out of the U.N. climate talks in Paris later this year. Dramatic declines in the cost of solar and wind equipment and the energy they produce, which are expected to continue, will also help, he says.

“There is soon going to be this tipping point where renewables without legislation and government support are going to be less expensive than conventional sources,” says Richardson. “Then growth in renewables will really accelerate.”

There are several opportunity sets, he notes, to invest in the equipment-supply side of renewables. This includes original equipment manufacturers (OEMs) that make wind turbines and solar panels; firms that supply OEMs with components, such as gearboxes and generators for wind turbines and silicon wafers for solar panels; and producers of the sophisticated factory machinery used by OEMs.

“It’s easier to see earnings visibility through some of the second and third derivative companies involved in renewable energy,” he says. “We’re focused not so much on the miners, which would be the manufacturers, but on the pick suppliers.”

“All types of renewable energy will be important over decades to come,” he says, “but we see fewer investment opportunities for us in some areas such as geothermal, hydro and biofuels.” Fewer pure-play companies make components for geothermal and hydro, he says, and energy input costs for biofuels can be quite volatile. Longer term, this may become less important to the investment thesis for biofuels, he says.