The Hawaii-based Energy Excelerator, a small-business incubator created to help grow green-energy startups, on Friday opened its headquarters in Downtown Honolulu, which was funded by Hawaiian Electric Industries with $250,000. The 2,100-square-foot space on the fifth floor of the Cades Schutte Building at 1000 Bishop St. is designed to be a co-working, collaborative space for the Energy Excelerator team, its startups and industry stakeholders. “We were at the Manoa Innovation Center, but entrepreneurs…