High efficiency back contact type solar cell, solar cell module, and photovoltaic power generation system

A solar cell module, comprising:

• a plurality of back contact type solar cells electrically connected to each other,
• each of the plurality of back contact type solar cells comprising:
• a first conductive type semiconductor substrate;
• an impurity diffusion layer where second conductive type impurities are diffused, the impurity diffusion layer being on a back surface, as a non-light receiving surface, of the first conductive type semiconductor substrate;
• and
• an electrode in contact with the impurity diffusion layer, wherein
• a surface concentration of the impurities in the impurity diffusion layer is not smaller than 5×1017 atms/cm3 and not larger than 5×1019 atms/cm3,
• a diffusion depth of the impurities in the impurity diffusion layer is not smaller than 1 μm and not larger than 2.9 μm from a top of the back surface,
• a maximum value of an impurity concentration of the impurity diffusion layer is not lower than 7×1017 atms/cm3 and not higher than 7×1019 atms/cm3,
• the impurity concentration of the impurity diffusion layer becomes the maximum value at a position not less than 0.1 μm and not more than 1 μm deep from the top of the back surface,
• the electrode partially penetrates into the impurity diffusion layer by sintering, and a depth of the penetration is not smaller than 0.1 μm and not larger than 1.9 μm from the top of the back surface, and a cross-sectional area of the electrode is not smaller than 350 μm2 and not larger than 1000 μm2.

A photovoltaic power generation system, comprising:

• a plurality of solar cell modules electrically connected to each other,
• each of the plurality of solar cell modules comprising a plurality of back contact type solar cells electrically connected to each other,
• each of the plurality of back contact type solar cells comprising:
• a first conductive type semiconductor substrate;
• an impurity diffusion layer where second conductive type impurities are diffused, the impurity diffusion layer being on a back surface, as a non-light receiving surface, of the first conductive type semiconductor substrate;
• and
• an electrode in contact with the impurity diffusion layer, wherein
• a surface concentration of the impurities in the impurity diffusion layer is not smaller than 5×1017 atms/cm3 and not larger than 5×1019 atms/cm3,
• a diffusion depth of the impurities in the impurity diffusion layer is not smaller than 1 μm and not larger than 2.9 μm from a top of the back surface,
• a maximum value of an impurity concentration of the impurity diffusion layer is not lower than 7×1017 atms/cm3 and not higher than 7×1019 atms/cm3,
• the impurity concentration of the impurity diffusion layer becomes the maximum value at a position not less than 0.1 μm and not more than 1 μm deep from the top of the back surface,
• the electrode partially penetrates into the impurity diffusion layer by sintering, and a depth of the penetration is not smaller than 0.1 μm and not larger than 1.9 μm from the top of the back surface, and a cross-sectional area of the electrode is not smaller than 350 μm2 and not larger than 1000 μm2.