Frequently Asked Questions

The SSI is the leading multi-stakeholder supply chain sustainability assurance initiative concentrating on the solar sector, comprising over 50 members, including buyers and manufacturers representing more than 60% of globally shipped solar PV modules. Its mission is to enhance responsible sourcing, production, and material stewardship throughout the solar value chain, in alignment with Environmental, Social, and Governance (ESG) and materials traceability principles, thereby supporting a just and inclusive energy transition.

The SSI has received endorsements from significant industry and institutional stakeholders, including international financial institutions such as the World Bank’s International Finance Corporation (IFC), the European Investment Bank (EIB), and the European Bank for Reconstruction and Development (EBRD).In January 2025, the SSI released its first ESG site certificates, with additional certifications anticipated before the end of Q1 2025. As of January 2025, the SSI’s ESG and traceability site assessment pipeline included a combined annual module production capacity of 100 GW (and cell production capacity of 20 GW), surpassing the projected demand of the European Union and the United Kingdom combined.

In December 2024, after extensive consultation with a broad range of stakeholders and piloting, the SSI agreed its Supply Chain Traceability Standard. Site certification against this standard will begin in 2025. In November 2024, the SSI approved its comprehensive multi-stakeholder governance structure which became effective as of April 2025. This governance structure guarantees parity and equal voting rights between industry and non-industry board members. Non-industry board members include civil society representatives, institutional stakeholders, international financial institutions and Human Rights experts. This structure guarantees that no single interest group can dominate decision-making. Please find more details here.

The Solar Stewardship Initiative (SSI) was created in response to growing demands from policymakers, investors, civil society, academics and industry for greater transparency, accountability, and human rights due diligence in solar PV supply chains.

The solar industry is rapidly scaling to meet global climate goals. However, this growth must be underpinned by strong environmental, social, and governance (ESG) and supply chain traceability standards to ensure the energy transition does not come at the cost of human rights or environmental harm.

The sector lacked a credible, globally applicable, and sector-specific assurance mechanism to independently verify responsible practices and traceability in solar supply chains. The SSI fills this gap. It is the first multi-stakeholder initiative specifically designed for the solar PV sector that combines robust ESG and traceability standards, international best practices, third-party verification and broad stakeholder engagement.

By certifying solar manufacturing sites and their material flows through independent, third-party audits, the SSI provides companies, buyers, and governments with a trusted mechanism to demonstrate compliance with international standards, regulations and frameworks including the OECD Due Diligence Guidance for Responsible Supply Chains of Minerals from Conflict-Affected and High-Risk Areas, OECD Due Diligence Guidance for Responsible Business Conduct, UN Guiding Principles on Business and Human Rights, the EU Forced Labour Regulation, and the Corporate Sustainability Due Diligence Directive (CSDDD).

Ultimately, the SSI helps ensure that solar deployment contributes not only to climate goals, but also to sustainable and ethical value chains, enabling a just and responsible energy transition.

The Solar Stewardship Initiative (SSI) was initially launched in 2022 by the European solar sector, through SolarPower Europe and Solar Energy UK, in response to growing demands for responsible, transparent, and traceable solar supply chains.

Since then, the SSI has evolved into a standalone organisation with its own CEO, Secretariat, a multi-stakeholder governance structure, grievance mechanism accessible to all types of stakeholders, and a dedicated and growing membership.

Delivering real impact in global solar supply chains, especially in upstream segments far removed from end markets, requires a collective effort. The SSI brings together more than 50 stakeholders across the solar value chain, including leading buyers, manufacturers, civil society organisations, institutional stakeholders, and international financial institutions.

This broad and balanced coalition gives the SSI the credibility and leverage to implement robust environmental, social, and governance (ESG) and traceability standards that drive measurable improvements and support compliance with international norms and regulations.

Multi-stakeholder Initiatives (MSIs) are robust ESG assurance and certification schemes governed by balance of stakeholders including industry representatives and civil society who are independent of the relevant industry. MSIs typically rely on third-party, independent audits conducted against international and sector-specific ESG operating practice and traceability standards.

MSIs are founded on the principle of equal representation of all stakeholders in decision making, and transparent complaints mechanisms reinforcing the legitimacy and effectiveness of such initiatives. By uniting diverse stakeholders, including civil society, these initiatives create a broader, more inclusive platform for dialogue and action, leading to more comprehensive and sustainable solutions.

If you or your organisation are interested in joining the SSI as a civil society or other non-industry stakeholder, we invite you to get in touch.

Examples of successful MSIs include Fairtrade International, the Forest Stewardship Council, the Aluminium Stewardship Initiative, or the Initiative for Responsible Mining Assurance.

The Solar Stewardship Initiative (SSI) operates through a dual-standard assurance system designed to certify responsible practices at the manufacturing site level and verify traceability of key materials throughout the solar supply chain.

Both SSI Standards complement each other and are mandatory for the SSI Manufacturer Members. Both Standards apply to the full silicon value chain from quartzite mining through metallurgical grade silicon and polysilicon to ingots and wafers to cells and modules.

The two core standards are:

• The SSI ESG Standard assesses the environmental, social, and governance (ESG) performance of individual manufacturing sites (e.g. polysilicon, ingot, wafer, cell, or module production). Sites are audited by independent, third-party assessment bodies (see the list of assessment bodies) through a process that includes site visits, unsupervised private  worker interviews, management interviews, document reviews, and external stakeholder consultations.
• The SSI’s Supply Chain Traceability Standard, which was approved in December 2024, complements the SSI ESG standard further strengthening upstream verification by requiring certified sites to implement a traceability for key materials materials, such as polysilicon, using a segregation-based Chain of Custody model.

Importantly, SSI member companies commit to progressively certifying more sites over time, ultimately working towards full operational coverage across their supply chains. This model supports continuous improvement, aligns with global due diligence frameworks like the OECD Guidelines and UN Guiding Principles, and contributes to the implementation of regulatory frameworks such as the EU Forced Labour Regulation and the Corporate Sustainability Due Diligence Directive (CSDDD).

The SSI is governed by a multi-stakeholder Board, appointed for two years, as the primary decision-making body of the initiative. The SSI Board members are stated on our website.

The daily operations of the SSI are conducted by the Secretariat led by a CEO, who reports to the SSI Board.

There are different ways to join the SSI. 

• For those interested in joining as members, we welcome applications from manufacturers, developers, installers, and purchasers in the solar value chain. More information can be found here.

• If you want to become an SSI-approved Assessment Body, more information can be found here. 

• We also receive applications from consultants. More information can be found here.

• Any other stakeholders can apply to the Stakeholder Advisory Group (SAG) and Technical Advisory Group (TAG). More information can be found here

The Solar Stewardship Initiative (SSI) has developed two independently certifiable standards which are both mandatory to the SSI Manufacturer members: the SSI Environmental, Social and Governance (ESG) Standard and the SSI Supply Chain Traceability Standard.

Together, these standards form the foundation of the SSI assurance system, designed to promote responsible production, sourcing, and stewardship in the global solar PV supply chain.

From mid-2025, all ESG certifications will be required to be accompanied by an assessment against the Traceability Standard.

These standards are aligned with leading international frameworks such as the UN Guiding Principles on Business and Human Rights, the OECD Guidelines for Multinational Enterprises, and relevant ISEAL best practices.

SSI ESG Standard

The SSI ESG Standard was first published in October 2023. Manufacturing members of the SSI are required to undergo ESG Standard assessment for at least 2 sites in the 12 months following their signature of the SSI Principles.

The SSI ESG Standard sets out a comprehensive framework to assess how solar manufacturing sites perform against a wide range of environmental, social, and governance criteria. These include, but are not limited to:

• Human and labour rights (e.g. prohibition of forced labour and child labour, freedom of association, fair recruitment practices, non-discrimination, and decent working conditions);
• Environmental performance, including resource use, emissions, waste management, and pollution prevention;
• Occupational health and safety;
• Governance, ethics, and transparency
• Responsible Sourcing

Assessments under the ESG Standard are conducted at the site level through independent third-party audits. Site certification may be awarded at Bronze, Silver, or Gold level, based on performance across defined criteria.

Sites must undergo rigorous verification, including document reviews, facility walkthroughs, confidential worker interviews, and external stakeholder consultations. Only sites meeting the requirements of the Standard are certified.

More information and access to the Standard are available on the SSI website.

SSI Supply Chain Traceability Standard

The SSI Supply Chain Traceability Standard, launched in December 2024, defines how certified manufacturing sites must demonstrate the origin and flow of key materials, particularly polysilicon, within their supply chains.

The Standard is built on a segregation-based Chain of Custody model, which requires:

• Mapping of upstream suppliers and disclosure of the regions of origin for critical materials;
• Maintenance of documentation systems that verify and segregate compliant and non-compliant materials;
• Conducting risk-based due diligence in line with international norms and regulatory expectations;
• Ensuring traceability both into and out of a certified site.

This Standard enhances supply chain transparency and helps identify and mitigate the risk of exposure to regions or suppliers linked to forced labour or lacking independent audit access. following the launch of the Standard, traceability certification is mandatory for all sites undergoing ESG certification, ensuring end-to-end visibility and accountability.

More information is available on the SSI website.

Traceability works by tracking the core materials in a product across the different sites involved in making it, at each stage of the process. It is therefore different to the SSI ESG Standard and doesn’t per se ensure sustainability, but it helps companies implement sustainability due diligence by enabling transparency and the subsequent risk mitigation as part of due diligence.

The SSI ESG Standard can certify a ‘link’ – i.e. a production site – in the solar value chain. The SSI Supply Chain Traceability Standard is the first step to show precisely where the materials used at each link come from and how they are traced. The SSI Supply Chain Traceability Standard and the SSI ESG Standard apply to the full silicon value chain from quartzite mining through metallurgical grade silicon and polysilicon to ingots and wafers to cells and modules. Supply Chain Traceability certification is mandatory for the SSI manufacturing members and complements mandatory certification against the SSI ESG Standard.

The SSI Supply Chain Traceability Standard defines requirements for entities implementing traceability management systems and currently it covers silicon and other photovoltaic semiconductor materials. It sets expectations for tracing origin of silicon through the tiers of the supply chain all the way upstream to quartzite mining. The third-party auditor will review information with regards to the origin of the silicon material used for making a solar panel. The auditor will review and assess the digital and physical documentation that shows where the polysilicon was made (including raw material extraction), how it was further processed and transported between different supply chain tiers. The auditor will review contracts, purchase orders, invoices, inbound and outbound delivery notes, and other shipping and warehouse records as needed, checking them against what is recorded in the systems used to manage resource and production processes, such as a company’s Manufacturing Execution System (MES) or Enterprise Resource Planning (ERP) system. The SSI provides a list of examples of documents which are reviewed during the SSI certification assessments against the Supply Chain Traceability Standard in Annex II.

Certification assessments conducted under the Solar Stewardship Initiative (SSI) are independent, third-party, and carried out by approved Assessment Bodies (ABs). These ABs are required to meet specific criteria, including auditor competence, independence, and safeguards against conflicts of interest.

To be able to conduct the SSI certification assessments, each auditor is subject to SSI training and must pass exams. The SSI Standards cover a comprehensive set of environmental, social, governance (ESG) topics and traceability requirements. (see list of the ABs here, and the criteria for ABs to qualify for the SSI here). Learn more about SSI-approved Assessment Bodies here.

Yes, the SSI Supply Chain Traceability Standard  traces materials, particularly silicon, throughout the entire solar value chain—from quartzite mining to solar module production. The goal is to establish an unbroken chain of custody, ensuring that certified materials remain distinct from non-certified ones.

With the implementation of both the ESG and Supply Chain Traceability Standards, the SSI seeks to provide comprehensive assurance of responsible practices across all links in the solar supply chain.

Each site assessment includes among others, documentation reviews, facility walkthroughs, interviews with external stakeholders such as civil society, local communities, governmental authorities among others, and unsupervised private interviews with workers. Depending on the size of the site, and in line with Sedex Members Ethical Trade Audit (SMETA) Best Practice Guidance, the auditing team can conduct up to 14 hours of unsupervised interviews, with more than 60 workers. (The Assurance Manual is here).

Importantly, the SSI prohibits certification in any region that is not freely accessible to independent, third-party auditors. By refusing to conduct assessments or certifications in sites or regions that are not freely accessible, whether in XUAR or anywhere else in the world, the SSI contributes to the marginalisation of businesses who fail to uphold strong ESG and traceability standards.

For ESG site certification, between 6-10 minor nonconformances = Bronze Certification, 5 minors or less = Silver Certification, No minors nonconformances = Gold Certification. More than 10 minor nonconformances, mean no certification. Any major nonconformance means no certification. A minor nonconformance could be something like an unclearly marked fire exit. Evidence of forced labour would constitute a major non-conformance.

The SSI Supply Chain Traceability Standard site certification is awarded at three levels—Gold, Silver, and Bronze—based on the number and severity of non-conformances (NCs) identified during the audit and the depth of traceability achieved:

GOLD: No major or minor non-conformances + Full traceability to quartz (raw material origin)

SILVER: No major NCs, 5 or fewer minor NCs, Improvement plan required + Traceability to metallurgical-grade silicon (MGS)

BRONZE: No major NCs, 10 or fewer minor NCs, Improvement plan required + Traceability to polysilicon

For both certifications, certified and sites with improvement plans, are subject to regular surveillance assessments to confirm progress and continued compliance.  The site’s progress with implementing improvement actions is verified by the third-party assessors and monitored by the SSI Secretariat to ensure that required improvement actions are implemented within the agreed timeframes.

To learn more about the SSI Assurance Process, read the SSI Assurance Manual.

If Assessment Bodies cannot freely access a site, or region, then those sites cannot be certified under the SSI, whether in XUAR (Xinjiang Uygur Autonomous Region) or anywhere else in the world.

The SSI is a tool to reinforce and demonstrate the credibility of sites that are freely accessible and are committed to upholding robust ESG and Traceability standards. By refusing to conduct assessments or certifications in sites or regions that are not freely accessible, the SSI contributes to the marginalisation of businesses who fail to uphold strong ESG standards.

Yes, the SSI Supply Chain Traceability Standard traces materials, particularly silicon, throughout the entire solar value chain—from quartzite mining to solar module production. The goal is to establish an unbroken chain of custody, ensuring that certified materials remain distinct from non-certified ones.  

With the implementation of both the ESG and Supply Chain Traceability Standards, the SSI seeks to provide comprehensive assurance of responsible practices across all links in the solar supply chain. 

No. The Solar Stewardship Initiative (SSI) does not replace any national or international legislation on responsible business conduct or forced labour. Nor does it exempt companies from their legal obligations under instruments such as the EU Forced Labour Regulation, the Corporate Sustainability Due Diligence Directive (CSDDD), or similar legislation in other jurisdictions. It is businesses’ responsibility to ensure compliance with these laws, and regulators’ competency to enforce these rules.

The SSI is designed to be complementary to and align with legislation. The Initiative acts as a tool to support implementation of these laws by helping companies understand and demonstrate compliance with ESG and traceability requirements in solar supply chains. The SSI assurance system provides independent, third-party verification of site-level ESG practices and traceability of critical materials such as polysilicon. This approach directly aligns with international frameworks like the OECD Due Diligence Guidance and the UN Guiding Principles on Business and Human Rights.

By aligning with these frameworks and offering a practical, credible mechanism for verification, the SSI can play a key role in helping companies operationalise legal requirements, mitigate risk, and build transparency and accountability across complex global value chains.

Beyond compliance with law and the non-negotiable respect for human rights, the SSI employs OECD Guidance on leveraging buyer pressure. Efforts like the SSI empower product buyers to join together to demonstrate demand for high-performing ESG and traceable products, supporting a race to the top for ESG and traceability standards.

Yes. The SSI does not certify sites using forced labour. This is embedded in the SSI Standards and Assurance Manual (find these here). By refusing to conduct assessments or certifications in sites or regions that are not freely accessible, the SSI contributes to the marginalisation of businesses who fail to uphold strong ESG standards.

The SSI has established a credible, independent, and verifiable certification process based on its two Standards, the ESG and Supply Chain Traceability Standards. Together, these standards provide a structured, risk-based approach to identify, assess, and mitigate exposure to forced labour across solar supply chains.

Yes. The Solar Stewardship Initiative is committed to transparency and accountability. For every manufacturing site that completes a third-party audit and achieves certification under the SSI Standards, a public summary of the assessment results is published on the SSI website here.

Breaching SSI Assessment Procedure is not tolerated. If you have a complaint, we encourage you to follow the SSI Complaints and Appeals process to ensure a fair and thorough resolution. Your feedback is crucial in maintaining the integrity and effectiveness of the Solar Stewardship Initiative.

Complainants raising a complaint with the SSI do not need to disclose their identity if they choose to maintain their anonymity. Confidential concerns will be handled with utmost discretion, and disclosure will only occur if there is a legal or regulatory obligation to do so.

The SSI certificate is valid for three years, after which re-certification takes place, regardless of the level of certification the site has achieved.  The SSI Assurance Manual provides a schedule for surveillance and re-certification depending on the level achieved on the last assessment. 

Sites that achieve Silver or Bronze during certification can request an optional reassessment after one year which may result in a grade change. Sites must undergo surveillance audits to show their progress on closing the gaps identified during the initial certification assessments.

SSI membership does not mean that a member is SSI certified. 

The SSI certification process is conducted at the site level and not company- or supply-chain wide, nor can members claim as such. Membership alone does not imply certification, endorsement, or accreditation.

Being an SSI member means that a company has signed the SSI Principles, therefore committing, in good faith, to apply the SSI Standards in its operations and encourage its adoption along its supply chain. Admission to SSI membership by the SSI Board, requires a preliminary due diligence check performed by the SSI Secretariat, as described in the SSI Policy of Association. This due diligence check is not a formal certification and does not replace the certification against the SSI Standards. 

When a manufacturer joins the SSI as a member, it commits to complete an assessment against the SSI Standards for at least two of its production sites within 12 months. 

The list of SSI-certified production sites can be accessed one the SSI website. 

The SSI assurance scheme is based on on-site, independent third-party assessments. These are more robust and credible than voluntary disclosures and self-assessments because they assess compliance to standard requirements in an impartial manner. Third-party assessments play a crucial role in enhancing consumer trust by providing independent validation.

Qualified and impartial assessors review policies, procedures and practices at a specific site to determine if they are implemented and effective. Interviews with stakeholders and workers also take place and any information received is cross-checked to support assessment conclusions and obtain an accurate picture of the site’s practices. Any gaps identified must be addressed by a fixed deadline and regular surveillance assessments take place to verify that the site continues to be in compliance with the requirements in the Standard.

No. There is no certification or standard that can substitute a company’s own environmental and human rights due diligence required by the UN Guiding Principles on Business and Human Rights, OECD Guidelines, and EU and national law.

However, SSI members can rely on the SSI for continuous guidance and support in performing their duties and once available, on the data stemming from SSI assessments.

When joining the SSI, each member commits to applying the SSI Standards within its entire operations and encouraging their adoption along its supply chain.

When a manufacturer member joins the SSI, it commits to submit at least two (2) of its production sites for assessment against the SSI Standards within 12 months.

As of January 2025, the SSI ESG and traceability site assessment pipeline included a combined annual module production capacity of 100 GW (and cell production capacity of 20 GW), surpassing the projected demand of the European Union and the United Kingdom combined.

Site certifications are kept up to date here.

It is the role of governments to set law that establishes the consequences of breaching international standards of human rights by companies and/or third countries. Accordingly, the EU has set two important pieces of legislation, the EU Forced Labour Ban and the Corporate Sustainability Due Diligence Directive (CSDDD). 

In addition, the European Commission has provided the Guidance on due diligence for eu businesses to address the risk of forced labour in their operations and supply chains. 

The SSI is designed to support companies to fulfil their obligations under EU and relevant supply chain sustainability legislation and thereby can contribute to help companies implement such legislation. 

Civil society plays a central and formal role in the governance and operations of the Solar Stewardship Initiative (SSI). The SSI’s governance was designed to ensure that civil society actors have real decision-making power.

Civil society organisations; including NGOs, human rights and environmental experts; are directly involved through:

• The Stakeholder Advisory Group (SAG): This group includes civil society representatives and elects the non-industry members of the SSI Board, ensuring stakeholder legitimacy and independence.
• The SSI Board: Civil society representatives comprise a dedicated stakeholder group on the SSI Board. There are three other stakeholder groups representing manufacturers, buyers, and institutional stakeholders/independent experts. Each stakeholder group holds three seats.
• The Complaints & Appeal Mechanism: Open to civil society organisations and any affected party to raise concerns about certification, processes, or governance.
• Consultations: Civil society actors are invited to review and contribute to the development of SSI Standards and policies through structured public consultation processes and targeted stakeholder outreach.

This inclusive approach ensures that the SSI maintains a balanced and independent governance structure and benefits from the expertise and oversight of organisations working to uphold human rights and environmental protection globally.

The SSI Complaints & Appeals Mechanism is designed to ensure accountability, transparency, and fairness in the Initiative’s certification and governance processes. It is aligned with international best practices, including the ISEAL Code of Good Practice, and is open to any stakeholder, including companies, civil society organisations, affected workers, and individuals.

Key features include:

• Scope: Complaints and appeals may concern certification decisions, conduct of assessment bodies, or the application of SSI policies and standards.
• Access: It is open to any stakeholder, including companies, civil society, and affected individuals. The mechanism is publicly accessible via the SSI website, with clear instructions for submitting a complaint or appeal.
• Process: All complaints are reviewed by the SSI Secretariat, with further escalation to the Board or an independent review panel if needed.
• Principles: The process is governed by principles of confidentiality, non-retaliation, independence, and timely resolution.

The updated Complaints & Appeals Mechanism includes a principles section, strengthens submission procedures, and is actively monitored to ensure that the process contributes to continual improvement.

Transparency is a foundational principle of the SSI and is maintained in multiple ways throughout the Initiative’s structure, processes, and communications:

1. The results of SSI assessments are published on the SSI website, including the certification level, relevant standards, and summary audit results.
2. Core Documents: The SSI’s Core Documents; including its Standards, Assurance Manual, Claims Guide, and Complaints & Appeals Mechanism; are publicly available and regularly updated.
3. The SSI conducts structured public consultations on new or revised Standards to gather input from a broad range of stakeholders. The SSI publishes the summary conclusion of public consultations and pilot testing for each Standard here.
4. SSI members are required to adhere to clear publicly available Claims Guide and can only make verified statements about certifications following independent audits.

The SSI actively engages with governments, policymakers, and regulatory bodies to promote responsible solar supply chains and help ensure that regulatory frameworks can be effectively implemented in practice.

The SSI is designed to support the implementation of key regulatory initiatives, including:

• The EU Forced Labour Regulation (FLR)
• The EU Corporate Sustainability Due Diligence Directive (CSDDD)

By providing a credible, independent, and internationally aligned assurance system, the SSI helps companies meet their due diligence and traceability obligations under these frameworks.

The Initiative also regularly contributes to policy dialogues, attends industry and institutional workshops, and provides briefings to government stakeholders.

Notably, in April 2025, the UK Government official referenced the SSI as a tool to support the implementation of its GB Energy Bill amendment on forced labour in solar supply chains. The SSI was also in a 2024 OECD report reviewing chain of custody models for critical minerals, as one of the mechanisms evaluated for its robustness, traceability design, and governance structure. These acknowledgements further reinforce the SSI’s value as a practical tool to support public policy objectives related to sustainability, human rights, and responsible sourcing in the solar sector.