Abstract: Through the alternating light injection for silicon heterojunction (SHJ) solar cells at front and rear surfaces, it is found that the single-side light injection under 1-Sun cannot saturate the efficiency gain, it can be saturated after two-step light injections from both front and rear sides, the efficiency gain was about 0.4%. The efficiency gain was degraded to the initial level after dark annealing at 100 ℃, which proves that the efficiency gain contributed by light injection was not stable. The efficiency gain can be recovered by repeated light injection. In order to find a more efficient and convenient light injection method for production line, light injection with high-intensity white light source and near infrared light source was performed for comparison. The results showed that the efficiency gain can be saturated by high-intensity single-sided light injection in a very short time of 30 s, where the efficiency gain is the same as that of alternating double sides light injection. An infrared light source has the same effect for light injection compared with white light source.