Solar cell and solar cell module

A method for manufacturing a solar cell, the method comprising:

• preparing a P-type silicon substrate in which one main surface is a light-receiving surface and the other main surface is a backside, wherein:
• the P-type silicon substrate is a silicon single crystal substrate doped with gallium and is produced from an ingot grown by a Czochralski method, and
• the P-type silicon substrate has a resistivity of 0.2 to 2.5 Ω·cm;
• forming an N-type layer on at least a part of the light-receiving surface of the P-type silicon substrate;
• forming a first electrode on the light-receiving surface;
• forming a surface passivation layer on the backside of the P-type silicon substrate;
• determining a pitch Prm [mm] of contact areas to be formed between a plurality of back surface electrodes and the P-type silicon substrate such that:
• the pitch Prm [mm] and the resistivity Rsub [Ω·cm] of the P-type silicon substrate satisfy the relation represented by the following formula (1)
• log(Rsub)≤−log(Prm)+1.0 (1), and
• with the proviso that the pitch Prm, [mm] is in the horizontal axis and the resistivity Rsub [Ω·cm] of the P-type silicon substrate is in the vertical axis, the short-circuit current density shows smaller variations as compared to the resistivity Rsub [Ω·cm] and is more than 37 mA/cm2 and less than about 40 mA/cm2, but within a value defined by the lines of 0.2 Ω·cm and 2.5 Ω·cm of the resistivity of the P-type silicon substrate and the line of log (Rsub)=−log(Prm)+1.0;
• and
• forming a second electrode comprising the plurality of back surface electrodes on the backside of the P-type silicon substrate so that the plurality of back surface electrodes penetrate through the surface passivation layer to contact the P-type silicon substrate at the contact areas that satisfy the determined pitch Prm [mm],
• wherein:
• the pitch of the contact areas is 0.1 mm or more and 10 mm or less,
• the total area of the contact areas is about 5% or more and 20% or less on the basis of the whole of the backside,
• the solar cell shows a similar current throughout the range of 0.2 to 2.5 Ω·cm of the resistivity of the P-type silicon substrate, and
• a conversion efficiency of the solar cell is about 20%.

A method for manufacturing a solar cell comprising:

• (i) a P-type silicon substrate in which one main surface is a light-receiving surface and the other main surface is a backside, (ii) a backside electrode comprising a plurality of back surface electrodes in contact with the P-type silicon substrate in a plurality of contact areas, wherein the plurality of contact areas has a pitch Prm [mm] of 0.1 to 10 mm, (iii) an N-type layer formed on at least a part of the light-receiving surface of the P-type silicon substrate, (iv) a back surface passivation layer provided on the whole of backside of the P-type silicon substrate, (v) a light-receiving surface passivation layer, and (vi) a light-receiving surface electrode that is in electrical contact with the N-type layer,
• the method comprising:
• preparing, as the P-type silicon substrate, a silicon single crystal substrate doped with gallium, the silicon substrate being produced from an ingot grown by a Czochralski method and having the resistivity of 0.2 to 2.5 Ω·cm,
• determining a value of the pitch Prm [mm] of the plurality of contact areas such that, with the proviso that the pitch Prm [mm] is in the horizontal axis and the resistivity Rsub [Ω·cm] of the P-type silicon substrate is in the vertical axis, the short-circuit current density shows smaller variations as compared to the resistivity Rsub [Ω·cm] and is more than 37 mA/cm2 and less than about 40 mA/cm2, but within a value defined by the lines of 0.2 Ω·cm and 2.5 Ω·cm of the resistivity of the P-type silicon substrate and the line of log (Rsub)=−log(Prm)+1.0, and
• determining whether the pitch Prm [mm] of the plurality of contact areas and the resistivity Rsub [Ω·cm] of the P-type silicon substrate satisfy the relationship represented by the following formula (1)
• log(Rsub)≤−log(Prm)+1.0 (1),
• wherein:
• the plurality of back surface electrodes penetrate through the back surface passivation layer so as to be in contact with the P-type silicon substrate in the plurality of contact areas and the total area of the plurality of contact areas is about 5% or more and 20% or less on the basis of the whole of the backside,
• the solar cell shows a similar current throughout the range of 0.2 to 2.5 Ω·cm of the resistivity of the P-type silicon substrate, and
• a conversion efficiency of the solar cell is about 20%.

A method for manufacturing a solar cell, the method comprising:

• preparing a P-type silicon substrate in which one main surface is a light-receiving surface and the other main surface is a backside, wherein:
• the P-type silicon substrate is a silicon single crystal substrate doped with gallium and is produced from an ingot grown by a Czochralski method, and the P-type silicon substrate has a resistivity in a range of 0.2 to 2.5 Ω·cm;
• forming an N-type layer on at least a part of the light-receiving surface of the P-type silicon substrate;
• forming a surface passivation layer on the backside of the P-type silicon substrate;
• forming a first electrode on the light-receiving surface;
• forming a second electrode comprising a plurality of back surface electrodes onto the backside of the P-type silicon substrate such that:
• the plurality of back surface electrodes penetrate through the surface passivation layer to contact the P-type silicon substrate in a plurality of contact areas which are provided in a plurality of regular patterns with a regular pitch;
• and
• determining the regular pitch such that, with the proviso that the pitch Prm [mm] is in the horizontal axis and the resistivity Rsub [Ω·cm] of the P-type silicon substrate is in the vertical axis, the short-circuit current density of the solar cell shows a smaller variation as compared to the resistivity of the P-type silicon substrate and is more than 37 mA/cm2 and less than about 40 mA/cm2, but within a value defined by the lines of 0.2 Ω·cm and 2.5 Ω·cm of the resistivity of the P-type silicon substrate and the line of log (R sub)=−log(Prm)+1.0,
• wherein:
• the solar cell has a similar current throughout the range of the resistivity of 0.2 to 2.5 Ω·cm of the P-type silicon substrate,
• the total area of the plurality of contact areas of the back surface electrodes is 5% or more and 20% or lesson the basis of the whole of the backside, and
• a conversion efficiency of the solar cell is about 20%.