Grid-connected photovoltaic systems, also referred to as utility-connected or line-connected, have been operated at 30 residences and 8 commercial or institutional sites since 1986. All residential arrays are rated at 2.2 kW of dc power under standard test conditions (STC) and produce ac power at 240 volts. The commercial and institutional (C&I) systems range from 1.8 to 7.3 kW of dc power at STC; three-phase power is produced at 120/208 volts. The photovoltaic (PV) modules in all systems are crystalline silicon with an efficiency of 11%. Residential inverters are forced-commutated; C&I inverters are line commutated. A previous paper [1] discussed the design and installation of these systems, with initial analysis of energy production. The focus of this paper is a detailed examination of energy production, including a discussion of the capacity value of PV systems in New England. Reverse energy flow, from the customer to the utility, has been monitored and analyzed. The phenomenon is more frequent and more extensive than expected.
