A heating device, in particular for heating at least one fluid, includes at least one first heating resistor and at least one supply electronics unit, which is provided for supplying at least the first heating resistor with current provided by at least one first photovoltaic plant. The technology is called \u201ccherry picking\u201d because it allows each user to select what they judge to be the best terms among many available terms in the text, and use those terms to their own advantage. The actions include making a price comparison inquiry to a central server for the product, service, or price information.