First Solar (NASDAQ:FSLR) and Enphase Energy (ENPH) rank among Monday's top gainers on the S&P 500, +5.2% and +4.4% respectively, as investors appear to bet increasingly that Vice President Kamala Harris will defeat former President Donald Trump in the presidential election on Tuesday after a weekend poll showed Harris with a surprising lead in Iowa, a state Trump won in 2016 and 2020.

A Harris presidency likely would offer more support for the solar industry, as well as other forms of alternative energy such as wind and hydroelectric power.

The Invesco Solar ETF (TAN) and iShares Global Clean Energy ETF (ICLN), which each have First Solar (FSLR) and Enphase Energy (ENPH) as their top two holdings, trade +3.4% and +2.3%, respectively.

Analysts at Citi said recently that if Harris wins, "we would expect a sharp recovery" for First Solar (FSLR) shares, which have slumped nearly 30% from their 52-week high reached in June.

Citi also said Array Technologies (ARRY) and Sunrun (RUN) would perform well if Harris wins the election; the stocks are +12.2% and +9.2%, respectively.

Among other solar and alternative energy stocks: Plug Power (PLUG) +20.3%, Green Plains (GPRE) +11.2%, Sunnova Energy (NOVA) +11.1%, Bloom Energy (BE) +8.6%, Shoals Technologies (SHLS) +7.3%, Canadian Solar (CSIQ) +5.7%, FuelCell Energy (FCEL) +5.4%, Brookfield Renewables Partners (BEP) +4.4%, AES Corp. (AES) +3.7%, JinkoSolar (JKS) +2.1%, NextEra Energy (NEE) +1%.