The Waukesha, Wis., company reported first-quarter adjusted earnings of $2.38 a share on a 70% increase in sales to $807 million.
Analysts surveyed by FactSet were expecting the company to report earnings of $1.86 a share on revenue of $730.6 million.
“Growth was broad-based," Chief Executive Aaron Jagdfeld said in a statement.
Home standby generators more than doubled from the year earlier "given the powerful megatrends that are driving incredible demand for these products."
The company said major power outages during the harsh winter storm in Texas sped up demand and backlog for those generators. Demand for them had been elevated even prior to the storm.
Overall, residential sales more than doubled (up 110%) and commercial and industrial sales rose 18%.
As a result, the company increased its guidance for full-year sales growth to between 40% and 45%, from its previous estimate of 25% to 30%.
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Last month, Generac joined the S&P 500 Dow Jones Indices along with three other companies after four were removed. The stock is up about 10% since then.
At last check the shares were trading 6% around $335. It touched a 52-week high $364 on Feb. 22.
Generac makes machines that store power.
Its legacy business began in 1959, when it built gas-powered generators. The company shifted gears in 2019 when it acquired Pika Energy and Neurio Technology. The deals enabled Generac to become a provider of power-storage appliances.