The present invention discloses power extractor circuit used to capture the power of a solar cell array during its less-than-optimum conditions. Under reduced incident solar radiation, the low power level supplied by the solar cell array normally would not be adequate to operating a load, but with the presence of the power extractor circuit, the low power generated by the solar panel would be accumulated to a high enough level to overcome the energy barrier of the battery or the load. The power extractor circuit preferably comprises a voltage and current booster circuit, and is designed to operated at all power levels of the solar cell array: low power level to provide the booster function during the low power period of the solar cell array, and high power level to prevent component failure during the normal operation of the solar cell array. Many power extractor circuits can also be installed in series to cover a wide range of power level of the solar cell array. The present invention power extractor circuit can also be used in other power sources to utilize the portion of power which normally would have been lost.