The global solar energy market has been growing exponentially over the past decade, driven by the high competitiveness reached by solar PV technology. In 2021, for the 9th consecutive year, global solar power has broken its annual installation record adding 168 GW of new solar capacity, according to Solar Power Europe. The construction activity for utility-scale PV projects, that account for most of the installed capacity worldwide, also continued at a strong pace.
In this era of massive solar technology deployment, Enertis Applus+ advises that owner’s engineering (OE) has become one of the most solicited services during the design, planning, construction, and commissioning stages of utility-scale solar PV projects, as it contributes to ensuring the projects’ quality throughout their lifetime. This is deeply related to the fact that, nowadays, investors and EPC companies have a better knowledge of the industry, therefore they are more aware of the key elements that need to be monitored from a quality assurance perspective across the different phases of the projects. Having a third party representing the project’s owner that has specialised expertise at global level is the added value when relying on an OE partner.
Today, the main challenges for owner’s engineering specialists come from the fact that the industry strives to keep increasing efficiency and reducing costs, a trend that may lead to a decrease in the project CAPEX and that has a cascading effect on the overall projects’ costs. This trend to reduce costs may imply, for example, a reduction of the budget assigned to the civil works, which makes it necessary to carry out additional studies on the roads, drainage systems, and runoff potential, as well as an exhaustive review of the solutions proposed by EPC companies to avoid serious incidents in the construction, commissioning, and operation phases of the PV project. Extreme optimizations of raw materials in the production of main components and BESS systems, which may lead to less tolerance or safety margins, are also becoming increasingly common. For this reason, one of the most demanded services is the detailed structural review of the projects.
Enertis Applus+ OE specialised experts, who are the on-site main technical responsible, have worked on projects in more than 65 countries and have wide global expertise in the industry, as well as deep knowledge of the solar photovoltaic technology, therefore they are able to identify the right solutions to the issues that may arise throughout the different phases of the projects, always protecting the owner’s interest.
MOST COMMON QUALITY ISSUES IN SOLAR PV PROJECTS THAT NEED TO BE MONITORED
It is fair to say that quality failures – with different grades of severity – occur in practically all solar PV projects. This is why a timely identification and correction, as well as an adequate implementation of the quality control program, are vital to avoid major problems.
According to Enertis Applus+ experts, based on their expertise, these are the quality issues that are most likely to be detected in solar PV projects and that need to be monitored.
In nearly 90% of solar PV projects issues with the installation of ground-mount piles are detected, where they do not reach the desired drilling depth. In this case, specific Pull Out Tests (POT) need to be performed to evaluate the behaviour of these piles when a vertical downward or an ascending vertical load is applied to make sure that the technical requirements of the support structure are met. The goal is to avoid major structural problems in case of extreme climate conditions. In this case, OE specialists work with the contractor to agree on a procedure and on the criteria to define the drilling depth level that can be considered valid, depending on the characteristics of the terrain. In case of detecting the aforementioned issues, this procedure will help to assess if the piles are suitable or if they need to be pulled out from the ground and new predrilling needs to be carried out.
The second main task for OE specialists is to continuously control in the field which piles have had incidents, verifying that the EPC company follows the acceptance/rejection criteria established in the agreed procedure, as well as carrying out the tests or repairs defined in the procedure.
Issues with the drainage design are detected in about 20% of solar PV projects and they occur because the effects of hydrology on the project ground are usually underestimated. These issues, which cause especially severe consequences in those geographic areas that have heavy rainfalls or torrential rains, are detected when the drainage system is based only on internal drainage ditches without a concrete coat. Since they get rapidly clogged, because of the sediments dissolved in the water flow, runoff tends to form shallow concentrated flow that could extend for several hundred meters and that could form rills and gullies and put the project equipment at risk. It is the OE experts’ responsibility to advise on the most appropriate drainage solutions depending on the type of terrain and the climate conditions and to review the drainage design proposed by the EPC company to ensure that it complies with the hydrology studies.
Errors in the design of trackers, mainly related to an extreme optimization of the use of steel, are detected in around 30% of the projects and they lead to an incorrect dimensioning of the structure and to early corrosion of metal components. These risks can be properly mitigated with the support of OE engineers, who carry out a detailed review of the project design and use a set of specific software to conduct both dynamic and static tests on these components. The quality control of these components is also key during the pre-manufacturing stage, to ensure that the BOM meets the required specifications, and during the post-installation phase, as the tracker’s protection against corrosion is frequently damaged during the installation.
Electrical issues or defects in the wire mounting occur in approximately 50% of the plants and they are eminently related to applying the accurate torque value to electrical terminals. This incident can cause hot spots and, eventually, small fires, especially in the Combiner Boxes or in the bridges between inverters and transformers in on-site assemblies. Also, this type of issue can also be due to insulation failure because of damages caused during the wire mounting, both in LV and AC. To avoid this type of issue, it is essential that an independent technical advisor carries out a detailed and comprehensive supervision of the quality and commissioning protocols during the construction phase.
Relying on the support and technical advice of an independent partner across all stages is key to mitigating the risks associated with quality defects and minimizing the impact on the project production and profitability.
A comprehensive OE service supports the client from the preliminary design phase to the bidding or selection of the EPC company, providing technical advice on the contracts and technical specifications, to all services related to construction supervision.
Enertis Applus+ offers a team of specialized experts that is led by an OE Site Manager with vast experience in the electromechanical field and who is supported by a remote back-office service and a supervision team of local staff.