DAS Solar has submitted an environmental impact assessment (EIA) for a 5 GW return contact (BC) Solar Celf factory in Guizhou, China, which extends its existing production activities to deliver large-scale and buildings-integrated PV (BIPV) installations.
Das Solar has taken a formal step in the direction of the industrialization of BC solar cells after local authorities in Guizhou have published an EIA notification of public participation for a high-quality cell project of 5 GW BC.
The Weining County indoor, dated 8 September, identifies the developer as DAS Solar New Energy Technology (Weining) Co. And gives a site of 177,000 square meters planned for cell workshops, chemical stores, waste water treatment, a 110 kV substation and associated support infrastructure.
The project remains in the EIA public prosecutor’s phase. The company and the local government have not published a detailed timetable or definitive capital budget.
Das Solar signed a CNY 2 billion (280.7 million) agreement with the Weining authorities in April 2024 for a related N-type cell project. The existing Weining production base of the company also completed a 2.4 GW N-type tunneloxide-passivated contact (Topcon) moduleline in January 2024 with a reported investment of CNY 310 million and an annual output value of approximately CNY 2.5 billion. If the earlier CNY 2 billion framework corresponds to the new 5 GW factory, that would imply a development costs of approximately CNY 400 million per GW – a notional figure that requires official confirmation.
Technically, the movement reflects a deliberate shift from the established topcon expertise from Das Solar to a dual-track strategy. The company describes its BC approach as “DBC”-a hybrid that transfers the SioX/Poly-Si-passivated contact architecture from Topcon to the back of the cell and combines with a complete design with return contact. The intended result is a front surface free of metal bus, higher power density and preservation of the cost characteristics of Topcon.
Das Solar claimed external verification for recent performance extensions: a DBC cell registered on 27.77% efficiency with an open circuit voltage of 745.7 mv, certified by the China Photovoltaic Testing Center (CPVT). It said that it has submitted more than 60 patents with regard to BC technology and has led to the preparation of around 20 industrial and group standards.
Das Solar added that his “DBC 3.0 Plus” is compatible with Topcon-5.0 process flows and ready for upscaling in 2025, with an initial market focus on distributed generation and BIPV. At the level of the module, the company showed a “Diamond” DBC product on SNEC PV+ 18th (2025) International photovoltaic electricity generation and Smart Energy Conference and exhibition, advertising for an output of 670 W and 24.3% module efficiency.
Das Solar remains an active topcon player. Since the founding in 2018, the top-concrete has advanced through successive generations, with a 2024 mass production average module efficiency of 26.7% and continuous process upgrades in 2025. The company said that it has built around 40 GW battery and module capacity in various Chinese provinces and objectives of the Capacity of the Capacity of the Capacity.
According to market research agency PV Infolink, DAS Solar was the world’s ninth largest module supplier in 2024.
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