JinkoSolar unveils new solar cell technology

Chinese photovoltaic module manufacturer JinkoSolar has introduced its first rear-contact solar cell technology, called TAC, during its Global Tech Day event in Shanghai on October 17. This innovation combines TOPCon technology with heterojunction passivation, aiming to improve efficiency and reduce losses in solar panels.

TAC architecture design

The TAC architecture merges selective electron contacts from TOPCon technology with selective hole contacts based on heterojunction (HJT) technology. It uses an n-type crystalline silicon wafer with two alternating contact regions on its rear side, placing both positive and negative electrodes on the back to eliminate front-side metal layers and reduce optical losses.

Electron contact structure

The n-type region designed to collect electrons retains the contact structure used in TOPCon cells. It includes a thin tunnel silicon oxide layer and highly doped polycrystalline silicon, enabling efficient electron transport with low resistance and minimizing carrier recombination.

Hole contact and passivation

The p-type region for collecting holes uses intrinsic and doped hydrogenated amorphous silicon, based on HJT technology. This setup enhances surface passivation and open-circuit voltage. A transparent conductive oxide layer helps move charges laterally, while the passivation process occurs at low temperatures, below 200 °C.

Laser structuring and insulation

High-precision laser structuring and dielectric insulation allow the separation of the two contact regions. JinkoSolar describes this as a "2+1" design, integrating TOPCon electron contacts, HJT hole contacts, and a rear-electrode structure into a single cell.

Rear-contact cell category

TAC belongs to the rear-contact (BC) cell category, which includes various designs using different passivation and contact technologies. Unlike traditional front-contact TOPCon cells, TAC removes metal contacts from the front to reduce shading, and it uniquely integrates both TOPCon and amorphous silicon heterojunction contacts on a single wafer.

Passivation processes

JinkoSolar has developed two passivation processes: the Global Passivation Process (GPP) to reduce recombination losses and Multi-Dimensional Charge Passivation (MCP 2.0) to minimize recombination at the edges of cut cells. These involve cutting before passivation, followed by chemical treatments and hydrogen passivation.

Cell efficiency and features

The TAC cell achieves production efficiencies exceeding 27 percent, with a claimed maximum of 28 percent. However, the white paper does not provide third-party certification, test area, or average line efficiency for this result. The company also mentions high-purity n-type silicon wafers and light-trapping structures to enhance performance.

Research and future paths

JinkoSolar previously reported a certified conversion efficiency of 27.2 percent for an n-type rear-contact research cell in its 2026 financial report, though this is not linked to the TAC technology. The company is also exploring development paths such as low-temperature metallization, copper-based contacts, and using TAC as a base for tandem solar cells combining perovskite and silicon.