Abstract: The present invention relates to a DC-AC inverter comprising a plurality of H-bridge converters, each being arranged to be integrated with a respective photovoltaic element and to be supplied with a DC voltage from the photovoltaic element, the H-bridge converters further being cascaded to produce a multilevel voltage output (Vout). The DC-AC inverter further comprises switch control circuitry connected to each one of the plurality of H-bridge converters to control switching thereof for producing the multilevel voltage output, and a central adaptation unit connected to the cascaded H-bridge converter for adapting the multilevel voltage output such that an AC grid voltage is output from the DC-AC inverter.

Abstract: A method of controlling a plurality of DC/AC converters in cascade configuration, each being arranged to receive an input direct current and voltage from a respective photovoltaic panel and to deliver an electric output. The method includes receiving information representing at least one of frequency, phase, amplitude and harmonics of a required AC, and receiving information on the input direct current and voltage to each one of the plurality of DC/AC converters. Based on the received information, each one of the plurality of DC/AC converters is individually controlled in such manner that the combined output from the plurality of DC/AC converters produces an AC matching the required AC.

Abstract: A storage apparatus with which billing amounts in the case of write count-dependent billing can be predicted, comprises a physical storage device which provides logical volumes of different types, and a controller which executes I/O control by classifying each of the logical volumes of different types into tiers of different response performances. In a case where a write request is issued to any virtual page which configures the virtual volume, the controller assigns any real page which configures a logical volume to the virtual page, writes data to the real page, and performs a write count. The controller calculates a billing amount per fixed time interval on the basis of the performed write count, calculates tier ranges so that the billing amount per fixed time interval does not exceed the billing upper limit value, and relocates the real page on the basis of the calculated tier range.