** Shares of solar firm Sunnova Energy NOVA.N rise 16.9% to 58 cents in afternoon trading
** Company names insider Paul Mathews as president and chief executive officer, effective immediately
** Paul will succeed William J. Berger who has been the company's CEO for 12 years
** "The circumstances of Mr. Berger's departure are yet to be clarified, but we remain cautious"- Jefferies
** Including session's moves, shares were down ~83% YTD
(Reporting by Katha Kalia in Bengaluru)
((Katha.Kalia@thomsonreuters.com))