(Solar winners Power One story updated for Friday morning trading, analyst commentary)NEW YORK ( TheStreet) -- There were bigger solar sector companies reporting on Thursday after the market close, but the only one to receive a boost from its second quarter earnings was Power-One ( PWER). The solar inverter company kept the streak alive of solar inverter outperformance in the second quarter, beating the Street on earnings and revenue expectations. Power-One shares rose in the double-digit percentage level in after-hours trading on Thursday, and were among the market's top gainers early on Friday morning. Power-One shares were rising by as much as 25% on Friday morning, on double the average daily volume of shares traded, or close to 6 million shares traded in the first hour after the market open. Power-One's gains of close to $2.50 on Friday morning were most striking for doubling the stock's 52-week low of $1.19. The earnings reports from First Solar ( FSLR)and MEMC Electronic Materials ( WFR) were the highly anticipated solar sector reports kicking off the earnings season for solar stocks on Thursday afternoon. Advanced Energy Industries ( AEIS) reported a big earnings beat last week. Power-One, similarly, has seen its solar inverter business grow amid the high solar sector demand, even though it was not historically a core business for the company.