Shares of the San Francisco company rose nearly 4% to $43.47 in after hours trading.
Sunrun reported a net loss of $23.8 million, or 12 cents a share, an improvement over the year-ago loss of $28 million, or 23 cents a share.
Analysts surveyed by FactSet were expected the company to report a loss of 9 cents a share.
Revenue totaled $334.8 million in the quarter, up 59% from a year ago and beating the FactSet consensus of $322.3 million.
Sunrun said in a statement that it delivered "an all-time record Q1 volume in our direct-to-home sales channel, in our channel partner business, and in our home builder business."
Customer agreements and incentives revenue was $174.6 million, up 76% from the first quarter of 2020. Solar energy systems and product sales revenue was $160.2 million, up 44% from a year ago.
"This year is on track to be the best in the company’s history," Lynn Jurich, Sunrun’s CEO and co-founder, said in the statement. "With an accelerating growth rate and expanding market reach, Sunrun is leading the country to a clean energy future."
Looking ahead, Sunrun said it now expects growth to range from 25% to 30% for the full-year 2021, up from earlier guidance of 20% to 25% growth.
The company said it continues to expect about $120 million in run-rate synergies derived from the acquisition by the end of 2021.
Piper Sandler upgraded Sunrun to overweight from neutral last month with a $77 price target. The firm said it sees a "strong growth story associated with residential solar" and the company's management team as tailwinds.
RBC Capital initiated coverage of the solar-energy company in April with an outperform rating and $81 price target.