The future looks bright for roof-top solar systems in Manteca — at least through the end of 2016.Residential solar installations are pushing a record setting 900 units this year in Manteca. Eight years ago not a single solar photovoltaic permit for residential use was issued in Manteca.The 600 residential installations so far this year are producing 3.37 megawatts or enough to supply all the electricity needs of 593 homes. The installations represent almost $12 million worth of investment based on the average price for a single family home installation of $18,148.The biggest incentives are PG&E power bills for newer homes that often surpass $200 a month as well as a federal tax credit that expires at the end of 2016.