• Ameresco (AMRC): The clean technology integrator now offers utility-scale battery storage solutions and boasts a large backlog.
• ON Semiconductor (ON): Growing demand for electric vehicles and business automation have boosted top line growth.
• Plug Power (PLUG): Hydrogen fuel cell manufacturer anticipates a 80% increase in revenue this year.

As the demand for solar, wind and hydroelectric energy sources continue to increase, cleantech stocks are poised to gain more investor attention. For instance, the S&P Kensho Clean Energy index has returned 7% since the start of the year.

Meanwhile, global efforts to move to renewable energy has been a key factor fueling growth in the cleantech sector. According to BloombergNEF (BNEF), “global investment in the energy transition totaled $755 billion in 2021, setting a new record,” with renewable energy taking the lion’s share with $366 billion.

In addition, the recent spike in oil and natural gas prices has highlighted the urgent need to accelerate renewable energy development on a global scale. According to the International Energy Agency’s (IEA) forecast, by 2026, the global renewable electricity capacity should increase more than 60% from 2020 levels to reach 4,800 GW. IEA also projects that renewables could account for almost 95% of the increase in global power capacity through 2026.

With that in mind, here are three cleantech stocks that could generate generous returns for long-term investors:

Ameresco (AMRC)

Our first cleantech stock is Ameresco (NYSE:AMRC). It is a leading clean technology integrator offering energy efficiency and renewable energy solutions in the U.S., Canada and the U.K. The company works with government and private enterprises, serving customers ranging from airports and industrial installations to hospitals and schools.

Ameresco released fourth-quarter results on Feb. 28. Revenue increased 32% year-over-year (YOY) to almost $416 million. Adjusted net income came in at $26.7 million, or 50 cents per diluted share, up from $23 million in the prior-year quarter. Cash and equivalents ended the period at $87 million.

The group’s energy assets generated more than half of the profits in 2021. Analysts suggest the entry into utility-scale battery storage solutions represents a significant long-term growth opportunity. In addition, the integrator boasts a solid backlog worth more than $5 billion.

AMRC stock is down 32% year-to-date (YTD). Shares are trading at 30 times forward earnings and 2.5 times trailing sales. Meanwhile, the 12-month median price forecast for Ameresco stock stands at $85.

ON Semiconductor (ON)

Next on our list of cleantech stocks is ON Semiconductor (NASDAQ:ON). It provides power and analog semiconductors as well as intelligent sensors for cleantech industries. The chipmaker generates two-thirds of its revenue from automotive and industrial end markets, primarily from electric vehicles (EVs).

ON Semiconductor announced Q4 results on Feb. 7. The company posted record quarterly revenue of $1.85 billion, up 27% YOY. Adjusted net income stood at $478 million, or $1.09 per diluted share, up from $147 million a year ago. Cash and equivalents ended the period at $1.38 billion.

Overall, gross margin improved from 33% in 2020 to 40% in 2021. Free cash flow soared 167% YOY to $1.38 billion. Meanwhile, management has signed agreements that will see committed revenue growth of more than $2.6 billion through 2024.

Like many other tech names, ON stock is down more than 22% YTD. As a result, shares are trading at 12.9 times forward earnings and 3.5 times trailing sales — an appealing valuation level. At present, the 12-month median price forecast for ON stock is at $75.

Plug Power (PLUG)

Our final cleantech stock for today is Plug Power (NASDAQ:PLUG). The group is regarded as an innovator in modern hydrogen and fuel cell technology. It develops hydrogen fuel cell systems that replace conventional batteries in vehicles as well as equipment powered by electricity.

Plug Power issued robust Q4 results on March 1, generating a record quarterly revenue of $162 million. Net loss narrowed to $193 million, or a loss of 33 cents per diluted share, up from a loss of $484 million a year ago. Cash and equivalents ended the period at $3.13 billion.

Hydrogen fuel cell technology is gaining traction worldwide. As a result, Plug Power has forged various partnerships to bolster growth. Those names include SK Group in South Korea, Renault (OTCMKTS:RNLSY) and Lhyfe. The agreements range from the promotion of hydrogen fuel cell EVs to building green hydrogen plants in Europe. Meanwhile, in 2022, management projects full-year revenue to increase 80% YOY to exceed $900 million.

Despite stable growth in operations, PLUG stock has lost nearly 12% YTD. Shares are trading at 28.6 times trailing sales. Finally, the 12-month median price forecast for PLUG stock stands at $38.

On the date of publication, Tezcan Gecgil did not have (either directly or indirectly) any positions in the securities mentioned in this article. The opinions expressed in this article are those of the writer, subject to the InvestorPlace.com Publishing Guidelines.