After a decade of wrangling, developer John Rosenthal will break ground today with his ambitious plan to build a solar-powered neighborhood near Fenway Park, filling several acres of parking lots with apartments, offices, stores, and a revamped transit station. The five-building complex, known as Fenway Center, will be unlike anything now standing in Boston, with solar panels to generate much of its electricity. The development will fill a large void between Brookline Avenue and Beacon Street, along and over the Massachusetts Turnpike, and result in the construction of new roads that will improve travel around the neighborhood. “This is going to turn ugly, underutilized parking lots into a world-class neighborhood,’’ Rosenthal said. He won city approval for the project in 2009 and has since been working to get state permits and secure financing in the down economy. While private funding for the $450 million project is not locked down, the groundbreaking kicks off the public transportation improvements that will help clear the way for the development.