Our Engineering, Procurement and Construction Business (EPC) includes engineering design, procurement of solar modules, balance-of-system components and other components, and construction contracting and management. We may engage our in-house EPC team or engage external experienced and qualified EPC contractors to handle and monitor the EPC process for our developed projects. Despite that, as the developer, we may procure the key components, such as solar modules and balance-of-system components.
We normally enter into short-term contracts with our suppliers and contractors on project-by-project basis or project portfolio basis based on the market prices.
Through engineering design, we aim to reduce the risk, reduce the costs and improve the performance of our solar power projects. The engineering design process includes the site layout, the electrical design, as well as assessing a variety of factors to choose an appropriate technology, the modules and inverters in particular. In addition to relying on our in-house EPC team, we may engage independent third party EPC contractors to conduct and monitor this process.
We procure solar modules and other key components for our developed solar power projects primarily by entering into short-term contracts to purchase at market prices. Suppliers of our solar modules and key components are primarily our related parties and third-party suppliers and contractors. Our purchasing decisions may take into consideration of technical specifications (including size, type and power output) bid price, warranty and insurance programs, spectral response, performance in low light, nominal power tolerance levels, degradation rate, technical support and the reputation of the supplier. We generally require warranties for defects in materials or workmanship for the components and a warranty for module capacity under normal testing conditions. Our in-house EPC team or external EPC contractors work in areas such as logistics, installation, construction and supervision. We maintain an updated list of qualified and reliable suppliers and third-party contractors with a proven track record with which we have established relationships. We choose our third-party suppliers and contractors through a bidding or quotation request process or through our affiliates or other cooperative arrangements with various manufacturers and contractors. The relevant departments of our local offices organize and collect bids/quotations, communicate with potential suppliers and contractors and coordinate with our local development teams to meet the local technical and legal requirements.
We engage third-party contractors for construction. We employ a number of measures to manage and monitor the performance of such contractors in terms of both quality and delivery time to ensure complying with the applicable safety and other requirements. For example, we generally have on-site supervisors and hold regular on-site meetings with the third-party contractors to monitor their work to ensure the projects progress according to schedule and adhere to quality standards. We also conduct periodic inspections to examine project implementation and quality standards compared to our project planning and prepare periodic reports for review and approval by the relevant departments in our corporate headquarters. If we identify any quality or progress issues which are attributable to the work of the third-party contractors, we will have further follow-up discussions with the third party contractors and monitor their rectification work. We also require our third-party contractors for construction and installation to comply with applicable laws and regulations regarding work safety as well as our own production safety rules and policies. We examine and keep records of the production-related safety documentation and insurance policies of our third-party contractors. All production-related tools and equipment used by our third party contractors must be compliant with and certified by applicable regulatory standards. Our third-party contractors should also regularly provide their internal records relating to production safety (for example safety production training and safety inspections) to us, and we also conduct regular safety supervision and inspection on the third-party contractors. Under our third-party contracting agreements, we are generally entitled to compensation if the third-party contractors fail to meet the prescribed requirements and deadlines under their contracting agreements. In general, our contractors require us to pay all of the contract price upon completion of the solar power projects and we require the contractor to provide a performance bond, which is usually for a period of one year to two years, in respect of the warranty obligations.
Commissioning and Warranties
When the EPC contractor notifies the regional solar power project team of on-grid operation, the regional solar power project team thoroughly tests each aspect of the solar power project. Commissioning tests generally include a detailed visual inspection of all significant aspects of the plant, an open circuit voltage test and short circuit current test prior to grid connection, and a direct-current test after connecting to the power grid. These tests are conducted in order to ensure that the plant is structurally and electrically safe and is sufficiently robust to operate as designed for the specified project lifetime. We have not experienced any material delay in construction or unsatisfactory workmanship with respect to our solar power projects. Following the commissioning, the solar power projects, which are intended for sale, will be handed over to the purchasers.
In addition to the warranties provided by the manufacturers of modules, balance-of-system components and other key components, EPC contractors also typically provide a limited warranty against defects in workmanship, engineering design, and installation services under normal use and service conditions for a period of time following the energizing of a section of a solar power plant or upon substantial completion of the entire solar power plant. In resolving claims under the workmanship, design and installation warranties, the new owner has the option of remedying the defect to the warranted level through repair, refurbishment, or replacement.