Solar cell having rear buffer layer and method of manufacturing the same

A solar cell module including solar unit cells connected in series, comprising:

• a substrate;
• and
• a plurality of unit cells,
• wherein each unit cell includes:
• a first electrode that is formed in a specific area on the substrate;
• a second electrode that is disposed separately at a predetermined gap from the first electrode, wherein the second electrode and the first electrode are in the same plane;
• a transparent electrode that is formed on the second electrode and on a side face of the second electrode opposed to the first electrode, and is disposed separately from the first electrode;
• a buffer layer that is formed on the transparent electrode and on a side face of the transparent electrode opposed to the first electrode, and is disposed separately from the first electrode;
• a light absorption layer that is directly formed on the first electrode, the substrate, and the buffer layer;
• and
• a reflection preventing layer that is formed on the light absorption layer,
• wherein the first electrode, the buffer layer, and the second electrode are disposed on the same side of the light absorption layer, wherein the first electrode is electrically separated from the buffer layer and the second electrode by a material of the light absorption layer
• wherein the solar cell module further comprises a serial connection portion that electrically connects the first electrode and the second electrode of each unit cell to have a serial connection structure,
• wherein the buffer layer is disposed under the light absorption layer to increase the amount of incident light,
• wherein one face of the first electrode opposed to the buffer layer has a saw-toothed pattern including a first electrode protrusion portion, a first electrode depression portion, and a connection portion electrically connecting the first electrode protrusion portion and the first electrode depression portion,
• wherein the first electrode protrusion portion is inserted into a depression portion of the buffer layer and is disposed separately at a predetermined space, and
• wherein a protrusion portion of the buffer layer is inserted into the first electrode depression portion and is disposed separately at a predetermined space to shorten movement distance to the electrode or the buffer layer even when the electron-hole pairs are formed at any position of the light absorption layer.