“Forensic” examination of solar farm piles after construction

The project concerns a solar farm (one of the largest grid-connected photovoltaic power stations in the world, with thousands of photovoltaic panels on several hectares) built in New South Wales, Australia.

Unfortunately, as the project was completed in a hurry, some of the solar panels were beginning to tilt and the ground was sagging around some of the foundation piles.

The major risk identified was that the panel frame would deform, with the problem of the photovoltaic panels breaking and not working. In addition, there was also the risk of failure due to wind uplift.

It was necessary to understand, identify and quantify the problems in order to solve them, as well as to evaluate the different methods of recovery.

Initially, upwind and lateral tests required a lot of time to be carried out on the constructed solar farm (removal of the photovoltaic panels during the tests).

The company AURECON, commissioned for this diagnosis, considered the use of the PANDA® probe to be very suitable for this project. Indeed, as the solar farm was already in operation, it was necessary to use a tool that could work under the panels and very close to the piles.

The PANDA® Dynamic Variable Energy Cone Penetrometer (DCP) was therefore used to carry out soundings at the panels. It was possible to detect failures in terms of soil compaction in certain areas and a relationship could be established between the dynamic resistance qd and the tensile and lateral tests. At the same time, high strengths in the area of the piles corresponded to good results in the tensile and lateral tests.

These various tests thus enabled AURECON to diagnose pathogenic areas.