#11 | The commissioning of a large solar thermal plant

By: Louis Hamelle, Etienne Letournel (Newheat)

The commissioning of a large solar thermal plant is a critical step. Indeed, as it was written in the previous article about solar thermal (“The operation of a large solar thermal plant explained through LIFE Remine Water pilot”), a large solar thermal plant is a 100% automated process. But, on the other hand, solar irradiation cannot be controlled. So, when ready to produce the first kWh of solar heat, operators must be sure that everything will happen as specified. This article described the steps needed to ensure this in the framework of the LIFE Remine Water solar thermal pilot plant (for a bigger project the principle will remain the same but will be more complex with several design and implementation lots).

Mechanical reception and wire-to-wire testing

This step is also called Factory Acceptance Tests for the hydraulic equipment. It happens at the workshop where the hydraulic equipment is being assembled. The objectives are the following:

  • Every hydraulic equipment (pipes, pumps, valves, expansion vessels, filters, sensors, etc.) must be there, respect the specified design and be installed at the right place as defined by the Process & Instrumentation Diagram (P&ID).
  • Every electrical connection (signals or power) between the electrical cabinet and the equipment must be connected, and at the right place.
  • The pressure tests must be validated: every connection is well sealed.

Reception of hydraulic equipment, © Newheat

Reception of the Programmable Logic Controller program

The reception of the Programmable Logic Controller program happens at the automatician’s office. Following tests are realized to ensure the program and supervision are working well:

  • The supervision contains every element (actuators, analog and digital signals, parameters, etc.) for the proper operation and monitoring of the plant.
  • Every operating mode, transition, control loop, alarm and associated emergency mode is simulated to check that it behaves as specified.

Supervision of the LIFE Remine Water solar thermal pilot plant, © Newheat

In the same way as with mechanical reception, it often happens that corrections need to be applied during this step to make the program works as expected. Indeed, gaps can sometimes exist between the realization and the understanding of the automation specification.

On site tests without solar collectors being in production

When the Factory Acceptance Tests are completed, every equipment can be shipped and assembled on site. Then, the “cold tests” can start:

  • Every loop except the solar loop (containing the solar collector), is filled with water (leaks are checked again).
  • It is checked that the installation can be controlled properly through its supervision, and that the latter gets and sends normal signal for every of its input and output.
  • Every actuator is checked to see if it behaves correctly.
  • Regulations are preset.

If all those tests are OK, the installation is ready for normal operation at this point.

On site tests with solar heat production

Solar heat production means that the solar loop is filled with its fluid and that the solar collectors are uncovered. Then starts the production of the first kWh of solar heat. This is now the time for final tests:

  • No leaks at every connection of the installation.
  • Normal behaviour in full auto mode.
  • Fine tuning of the regulations and parameters.
  • Performance checks of the installation.

Once all these steps are OK. The solar plant is ready for production of decarbonized heat over its whole lifetime.