The standards that inverters for PV and grid applications must fulfill, are focused referring to: power quality, injection of dc currents into the grid, detection of islanding operation, and system grounding. Finally, the basic demands defined by the operator have also been addressed, such as low cost, high efficiency, and long lifetime. A historical summary of the solutions used in the past, where large areas of PV modules were connected to the grid by means of centralized inverters, is compared to the emerging multi-string inverter technology, which is believed to be one of the solutions for the future. A detailed analysis of these technologies implemented by using several inverter topologies yield to the following conclusions. 1) Large centralized single-stage inverters should be avoided. 2) High-Frequency Conversion reduces converter size and avoid resonance between the PV modules and inductances in the current main paths. 3) High-frequency Voltage Source Inverters are suitable for both low- and high-power systems, like the ac module, the string, and the multistring inverters.
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