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Micro-inverters are an electronic unit rated to handling the output of a single panel. Modern grid-tie panels are normally rated between 240 and 260 W, but they rarely produce this in practice, so micro-inverters are typically rated between 220 and 240 W.
ü More importantly, a micro-inverter attached to a single panel allows it to isolate and tune the output of that panel. Hence, with micro-inverters any panel that is under performing has no effect on panels around it. In that case, the array as a whole produces as much as 5 per cent more power than it would produce with a string inverter.
ü This has the major advantage that a single failing panel or inverter cannot take the entire string offline. Combined with the lower power and heat loads and improved MTBF, some suggest that overall array reliability of a micro-inverter-based system is significantly greater than a string inverter-based one.
Primary functions of micro-inverters are as follows:-
ü To extract maximum power from its companion solar panel using advanced MPPT algorithms.
ü To convert the panel output voltage to AC. This AC power is online and can be either grid tied or directly connected to load.
In this system 102 panels of 260 W each are mounted with a 240 W Darfon Inverters. This eliminates the DC cabling in addition to all the benefits of the micro-inverters. It is observed that currently this system is generating over 27 per cent extra power over the daily average calculated by modelling the same system for the location with string inverters. Its performance over the time frame is being monitored.