Development of a new utility-connected photovoltaic inverter LINE BACK

A new utility-connected photovoltaic inverter called “LINE BACK”, which is suited to small-scale photovoltaic generation systems for use in private households, has been developed. The inverter converts DC power generated by rooftop photovoltaic cells into AC power, and provides it to house loads connected to the utility line. When photovoltaic power is greater than the loads, the excess power is fed to the utility line through a reverse power flow. The inverter has several special functions such as a utility protection relay, maximum power point tracking (MPPT) control, automatic operation with photovoltaic power, detection of islanding operation, and utility voltage compensation for reverse power flow. These functions and characteristics conform to the “Utility-Connected System Technical Guidelines” revised by Japan´s Ministry of International Trade and Industry in March 1993