A power conversion system for converting power from a plurality of solar panels, the system comprising: a plurality of panel modules in connection with solar panels each having an input, an output and a storage device and being connected in series, the storage device being in connection with the solar panel such that the solar panel charges the storage device; and voltage control circuitry is provided within each of the panel modules in connection with the solar panel to vary the voltage supplied between the input and the output by the solar panel between a maximum module voltage and a minimum module voltage, characterised in that the system further comprises: a control unit in communication with the voltage control circuitry of each of the panel modules; wherein: A) the control unit is configured to control a switching regulator in each of the panel modules to control the voltage provided by the storage device across the input and output such that the voltage applied by each panel module is ramped up or down, such that the total voltage across the series connected modules (14, 40) forms an AC signal or a rectified version of an AC signal which approximates a sinusoidal mains signal; or B) the system comprises at least one further module which is connected in series with the panel modules, each further module having an input, an output, a storage device and voltage control circuitry, the voltage control circuitry being configured to vary the voltage supplied between the input and the output by the storage device, the control unit being configured to control the voltage control circuitry of each further module to charge the storage device of each further module such that a voltage below the maximum module voltage is provided to the series connection to provide a voltage smoothing function, such that the total voltage across the series connected modules (14, 40) forms an AC signal or a rectified version of an AC signal which approximates a sinusoidal mains signal. a plurality of panel modules in connection with solar panels each having an input, an output and a storage device and being connected in series, the storage device being in connection with the solar panel such that the solar panel charges the storage device; and voltage control circuitry is provided within each of the panel modules in connection with the solar panel to vary the voltage supplied between the input and the output by the solar panel between a maximum module voltage and a minimum module voltage, characterised in that the system further comprises: a control unit in communication with the voltage control circuitry of each of the panel modules; wherein: A) the control unit is configured to control a switching regulator in each of the panel modules to control the voltage provided by the storage device across the input and output such that the voltage applied by each panel module is ramped up or down, such that the total voltage across the series connected modules (14, 40) forms an AC signal or a rectified version of an AC signal which approximates a sinusoidal mains signal; or B) the system comprises at least one further module which is connected in series with the panel modules, each further module having an input, an output, a storage device and voltage control circuitry, the voltage control circuitry being configured to vary the voltage supplied between the input and the output by the storage device, the control unit being configured to control the voltage control circuitry of each further module to charge the storage device of each further module such that a voltage below the maximum module voltage is provided to the series connection to provide a voltage smoothing function, such that the total voltage across the series connected modules (14, 40) forms an AC signal or a rectified version of an AC signal which approximates a sinusoidal mains signal. A) the control unit is configured to control a switching regulator in each of the panel modules to control the voltage provided by the storage device across the input and output such that the voltage applied by each panel module is ramped up or down, such that the total voltage across the series connected modules (14, 40) forms an AC signal or a rectified version of an AC signal which approximates a sinusoidal mains signal; or B) the system comprises at least one further module which is connected in series with the panel modules, each further module having an input, an output, a storage device and voltage control circuitry, the voltage control circuitry being configured to vary the voltage supplied between the input and the output by the storage device, the control unit being configured to control the voltage control circuitry of each further module to charge the storage device of each further module such that a voltage below the maximum module voltage is provided to the series connection to provide a voltage smoothing function, such that the total voltage across the series connected modules (14, 40) forms an AC signal or a rectified version of an AC signal which approximates a sinusoidal mains signal.