NOVELTY - The method involves performing maximum power point tracking of a set of power sources connected respectively to inputs of a set of direct current power converters (305a-305d) e.g. cascaded buck-boost converters, by adjusting input voltage or input current at the inputs of the converters. Voltage is regulated across a pair of terminals to a fixed constant value, where the pair of terminals includes outputs of the converters connected in a series string (303). Direct-current power received from the power sources is converted to direct-current output power at the outputs of the converter.    USE - Method for combining power from direct-current power source i.e. photovoltaic solar panel, to a load i.e. alternating-current/direct-current inverter. Can also be used for combining a solar cell, electrical fuel cell and an electrical battery for hybrid car to a power grid and a storage bank.    ADVANTAGE - The method enables monitoring individual direct current power sources in a distributed power harvesting installation, and adjusting current and voltage from each direct current power source to maximize power output from the direct power source. The method enables providing a greater degree of fault tolerance, maintenance and serviceability by monitoring, logging and communicating performance of a solar panel. The method enables performing monitoring, logging and communication functions by a microcontroller for maximum power point tracking such that quick and easy troubleshooting can be allowed during installation, so that installation time can be significantly reduced, thus detecting problems during maintenance work in a quick manner. The method enables allowing easy location, repair or replacement of failed solar panel, thus increasing reliability when repair or replacement is not feasible.    DETAILED DESCRIPTION - The power source is a solar panel (301a). An INDEPENDENT CLAIM is also included for a system for combining power from direct-current power source to load.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of a distributed power harvesting system using direct-current power sources.    Distributed power harvesting configuration (30)    Solar panel (301a-301d)    String (303)    Inverter (304)    Direct-current power converters (305a-305d)