A solar module passes through quartz, polysilicon, ingot, wafer and cell before it becomes a module. LONGi links each module to its materials by batch, requires suppliers to sign a binding Code of Conduct, and checks compliance through questionnaires and on-site audits, including audits by independent third parties.
Polysilicon, wafers, cells and modules are made across several tiers and countries. Buyers are expected to know who made what, under which conditions, and to act on the risks they find. Due diligence and forced labour laws turn that expectation into a legal duty.
From quartz to module the chain has at least six stages, and buyers typically see only the last one.
The EU Forced Labour Regulation bars products made with forced labour from the EU market.
Rules such as Germany’s LkSG and the EU CSDDD require buyers to assess and act on supplier risks. See ESG compliance and bankability →
Tin, tungsten, tantalum and gold, and in some policies cobalt and mica, are screened to keep conflict financing out of supply chains.
LONGi’s traceability system links each module to its polysilicon supplier through batch numbers and purchase orders. It starts at the shipment, using the bill of lading and container number, and runs back through the silicon chain. A formal Traceability Information Report is available on request for each shipment.
The controls are a binding code, screening, audits, training and mapping beyond Tier 1.
Suppliers sign the Code and an integrity agreement before they can supply. It covers business ethics, labour and human rights, health and safety, environment and traceability, and suppliers must pass the same rules to their own suppliers.
New suppliers are screened on environmental and social criteria, using questionnaires and on-site due diligence based on the UN Guiding Principles and OECD guidance.
The audits reached 48 key suppliers. Audits of silicon and module-component suppliers use 84 criteria across 12 modules, based on SA8000 and local law.
65 training sessions covered environment, human rights and compliance. The target is 95% of Tier 1 procurement value by 2028.
Assembly, components and key raw materials. The silicon chain is traced from polysilicon to module.
New suppliers register on the supplier platform, sign the Supplier Statement and the Code of Conduct, and pass a qualification review. The review includes third-party ESG risk checks and a due diligence questionnaire on labour rights, health and safety, environment, business ethics and management systems. Suppliers with serious violations, such as forced labour, are not admitted.
Each qualified supplier gets an annual CSR risk rating of high, medium or low. High-risk suppliers are audited on site every year, medium-risk every three years and low-risk as needed, with questionnaires reviewed annually. Audits combine document review, site visits, online research and worker interviews.
Findings are rated red-line, serious or general. Red-line issues must be fixed immediately, serious issues within four months and general issues within six, with progress reports every two weeks to monthly. Suppliers that miss deadlines lose procurement share. Confirmed red-line violations lead to suspension or removal.
LONGi publishes audit results, including the issues found and how many have been closed. Silicon material suppliers passed the 2024 audits, and the audits identified no serious high-risk issue within the audited scope.
Four controls sit behind that position.
LONGi is a member of the Solar Stewardship Initiative (SSI), the industry assurance scheme for responsible solar supply chains. The Jiaxing site was also certified, and LONGi’s supplier requirements refer to the SSI ESG and traceability standards.
Documents and data LONGi provides for supplier due diligence reviews.
The formal report links the module batch to its polysilicon supplier by batch number and purchase order.
This includes the 2024 Supplier Due Diligence Report, audit ratings and corrective-action closure data.
Supplier Code of Conduct, Supplier CSR Management Measures, Responsible Mineral Procurement Policy, Human Rights Policy and Modern Slavery Statement.
Comprehensive solar lifecycle emission metrics and full-chain carbon tracking support accurate ESG evaluation for European solar investments.
Read Blog →
Operational greenhouse gas emissions at LONGi declined by 37 percent in 2024 against 2023.
Read Blog →Answers on traceability, suppliers and human rights.
What does a Traceability Information Report contain?
It links a shipment to its module, cell, wafer, ingot and polysilicon batches and to the polysilicon supplier by purchase order.
Does traceability cover materials other than silicon?
Traceability covers the silicon chain from polysilicon to module. LONGi is extending the system to the other main module materials, such as glass, encapsulant film, backsheet and frames.
Who has verified the traceability system?
In 2024 independent bodies including STS, PI Berlin, SGS, ENERT/S, CEA, TÜV Rheinland and Sinovoltaics audited it, across more than ten factories making modules, cells, ingots and wafers. The audited factories passed.
Do a supplier’s own suppliers have to comply?
The Supplier Code requires suppliers to pass its rules on to their own suppliers and not to buy materials made in breach of labour protections.
How does LONGi help suppliers improve?
Through the LONGi e-Learning Supplier Platform and training sessions on environment, human rights, health and safety and business ethics. In 2024, 228 suppliers used the platform and 65 sessions were held.
How are supplier risks rated?
Every qualified supplier is rated high, medium or low risk each year. The rating sets how often it is audited on site: yearly, every three years or as needed.
How can a concern about LONGi or a supplier be reported?
Employees, suppliers, customers and other stakeholders can report by phone, email or online, anonymously or by name. Reports are investigated independently and whistle-blowers are protected. Contact details are in the Human Rights Policy.
What does LONGi do about child labour?
Child labour is a red-line issue. The Supplier Code prohibits it and requires measures to prevent it at recruitment. Suppliers found to employ child labour are suspended or removed.
Is LONGi part of the Solar Stewardship Initiative?
LONGi is a member. Its Chuzhou site earned SSI-ESG Gold in January 2026, and the Jiaxing site is also certified.
Tell us the project, the modules and the documents your reviewers need. We will send the matching traceability and supplier evidence.
