A method of manufacturing a solar cell, the method comprising: forming a conductive region on a semiconductor substrate; forming an electrode connected to the conductive region; and post-processing the semiconductor substrate to passivate the semiconductor substrate, wherein the post-processing of the semiconductor substrate comprises: performing a hydrogen diffusion process for diffusing hydrogen into an inside of the semiconductor substrate; performing a preliminary heat treatment process for preliminarily heat-treating the semiconductor substrate without providing light to the semiconductor substrate, after the hydrogen diffusion process; and performing a main processing process for heat-treating the semiconductor substrate while providing light to the semiconductor substrate, after the preliminary heat treatment process, wherein a temperature of the main processing process is 100°C to 800°C, and the temperature and a light intensity of the main processing process satisfy Equation 1, 1750 − 31.8 ⋅ T + 0.16 ⋅ T 2 ≤ I, where T is the temperature (°C) of the main processing process, and I is the light intensity (mW/cm 2) of the main processing process, wherein the light intensity of the light provided to the semiconductor substrate is equal to or more than a minimum light intensity at which hydrogen in an H + state may be converted into an H 0 state or H - state, and wherein the main processing process is performed after the forming of the electrode. forming a conductive region on a semiconductor substrate; forming an electrode connected to the conductive region; and post-processing the semiconductor substrate to passivate the semiconductor substrate, wherein the post-processing of the semiconductor substrate comprises: performing a hydrogen diffusion process for diffusing hydrogen into an inside of the semiconductor substrate; performing a preliminary heat treatment process for preliminarily heat-treating the semiconductor substrate without providing light to the semiconductor substrate, after the hydrogen diffusion process; and performing a main processing process for heat-treating the semiconductor substrate while providing light to the semiconductor substrate, after the preliminary heat treatment process, wherein a temperature of the main processing process is 100°C to 800°C, and the temperature and a light intensity of the main processing process satisfy Equation 1, 1750 − 31.8 ⋅ T + 0.16 ⋅ T 2 ≤ I, where T is the temperature (°C) of the main processing process, and I is the light intensity (mW/cm 2) of the main processing process, wherein the light intensity of the light provided to the semiconductor substrate is equal to or more than a minimum light intensity at which hydrogen in an H + state may be converted into an H 0 state or H - state, and wherein the main processing process is performed after the forming of the electrode. performing a hydrogen diffusion process for diffusing hydrogen into an inside of the semiconductor substrate; performing a preliminary heat treatment process for preliminarily heat-treating the semiconductor substrate without providing light to the semiconductor substrate, after the hydrogen diffusion process; and performing a main processing process for heat-treating the semiconductor substrate while providing light to the semiconductor substrate, after the preliminary heat treatment process, wherein a temperature of the main processing process is 100°C to 800°C, and the temperature and a light intensity of the main processing process satisfy Equation 1, 1750 − 31.8 ⋅ T + 0.16 ⋅ T 2 ≤ I, where T is the temperature (°C) of the main processing process, and I is the light intensity (mW/cm 2) of the main processing process, wherein the light intensity of the light provided to the semiconductor substrate is equal to or more than a minimum light intensity at which hydrogen in an H + state may be converted into an H 0 state or H - state, and wherein the main processing process is performed after the forming of the electrode.