Due to the particularity of amorphous silicon thin film technology, all the processing temperatures of heterojunction batteries need to be completed at 200 degrees to ensure that the battery efficiency does not decrease.

Therefore, unlike crystalline silicon batteries, silver particles in high-temperature silver paste melt at high temperature, penetrate the antireflection film and form ohmic contact with the emitter of the battery. The low temperature process of 200 degrees makes the silver particles in silver paste can only be combined through polymers.

In order to ensure the low connection resistance of particles in silver paste, it is necessary to make the diameter of silver particles smaller, the specific surface area larger and the amount of silver used more, which leads to that the cost of low-temperature silver paste is more expensive than that of high-temperature silver paste at present, and the cost of low-temperature silver paste will not be reduced to a cheaper level than that of high-temperature silver paste in the foreseeable future. In addition, due to the natural symmetry of the heterojunction battery structure, it is necessary to complete the electrode processing on both sides of the upper and lower batteries, and the amount of silver paste used to manufacture the electrodes is naturally higher than that of the crystalline silicon battery.

If the cost of N-type silicon wafer may decrease with mass production, then low-temperature silver paste has become the biggest obstacle to reduce the cost of heterojunction, and it is also an embarrassing situation in the promotion of heterojunction battery technology at present.