The Ministry of New and Renewable Energy (MNRE) has mandated that only solar cells manufactured using undiffused wafers will qualify under the Domestic Content Requirement (DCR) policy, effectively prohibiting the use of “blue” or diffused wafers. This is to ensure that the most critical stages of solar cell manufacturing—such as diffusion, printing, and metallization—are carried out entirely in India to strengthen the domestic solar industry.

The manufacturing process of solar cells begins with silicon ingots, which are formed by melting and crystallizing high-purity silicon. These ingots are then sliced into thin wafers using precision cutting techniques. These “black” or undiffused wafers are the base material for solar cell production. At this stage, the wafers are shiny, metallic-looking, or slightly gray and do not yet possess the electrical properties required for photovoltaic activity.

They must undergo multiple processes to turn undiffused wafers into functional solar cells. The first critical step is diffusion, where wafers are exposed to high temperatures in a controlled environment, allowing dopant elements like phosphorus or boron to diffuse into the silicon surface. This process creates the essential p-n junction, which is fundamental for converting sunlight into electricity.

Avinash Hiranandani, Vice Chairman and Managing Director, RenewSys India, explained, “The process of making blue wafers begins with surface texturing using acid or alkaline solutions to create microscopic pyramid structures, along with thorough wafer cleaning to remove contaminants. Next, the wafers undergo doping or diffusion, where dopant elements like phosphorus or boron are introduced through thermal diffusion to modify their electrical properties. After diffusion, the wafers are annealed at high temperatures to activate and evenly distribute the dopants.”

A thin anti-reflective coating, typically silicon nitride, is deposited on the wafers’ surface to enhance light absorption. This coating reduces reflection, acts as a protection layer, and gives the wafers a distinctive blue color while enhancing solar energy conversion efficiency. Wafers then undergo metallization, inspection, and flash testing before being used in solar cell applications.

“However, some companies bypass these major manufacturing steps by importing pre-coated blue wafers instead. These companies may face challenges with new industry regulations that impact their operations. The industry norm is to use black wafers, which are then subjected to the complete solar cell manufacturing process steps, yielding high-efficiency solar cells,” said Hiranandani.

Without this regulation, companies could have imported pre-diffused wafers, limiting India’s role to the final, less significant processing steps and weakening the country’s position in the global solar manufacturing landscape.

This policy also aims to prevent the circumvention of DCR norms by importing partially processed wafers to strengthen India’s solar manufacturing ecosystem and reduce reliance on foreign supply chains.

According to major cell manufacturer, India does not have any wafer manufacturing capacity. “However, all the major cell manufacturers have the facility to turn undiffused wafers into diffused wafers as this is how almost all of the cell manufacturing currently takes place in India. “ They also noted that the new mandate necessary doesn’t affect cell supply capacity as none of the major players import blue wafers any more.

While India currently imports all its silicon wafers, the government’s policy mandates that only undiffused wafers can be used for manufacturing DCR-compliant solar cells. Diffused wafers, having undergone significant processing abroad, do not meet these criteria, as they bypass several key steps in the domestic cell manufacturing process. By enforcing this regulation, the MNRE aims to ensure that India’s solar industry grows beyond assembly and engages in comprehensive, value-added production.

Module manufacturers do not have specialized verification tools to distinguish between diffused and non-diffused cells. The primary verification is done through the DCR certificate, which is issued by the cell manufacturers themselves. A module manufacturer explained that the verification process involves tracking invoices and serial numbers to ensure compliance with the DCR policy. While concerns have been raised about distinguishing between diffused and undiffused cells, the current system relies on the certification process managed by cell manufacturers.