THE LATERAL LOAD CAPACITY OF GROUND SCREW PILE IN SOLAR PV FARM

Abstract

Thailand’s clean energy consumption has increased continuously due to the policy of alternative energy development, and it is intended to add more alternative energy sources which can be produced in the country, for example, solar energy. In 2015, the total installed capacity of electricity generation using solar photovoltaics (PV) was 1,419.6 MW, a 9.3% increase from the previous year. Most solar farm projects are the solar ground type in which PV panels are installed on a steel mounting structure. Ground screw steel piling is applied for the foundation because of both the convenience of installation and the fastening of the PV panels to the mounting frame. A ground screw load test was performed to prove both the vertical and horizontal pile capacity for the advantageous engineering design of the PV panels’ mounting structure. The lateral load test method conformed to the ASTM Standard D3966-90. The loading sequence and the maintenance period of different load increments were carried out and the pile head movement was also monitored. The test results revealed that the ground screw pile capacity can support and maintain a lateral load between 500 to 700 kg depending on the pile length and subsoil condition in each location. The displacements of the piling in the load direction were observed at less than 15% of the ground screw diameter.