Photovoltaics and storage for the energy mix

The success of the energy transition is partly determined by the massive deployment of photovoltaic production and connection to the electricity grids. The related challenges are both economic and technical.

CEA at INES is developing components and solutions to move towards photovoltaic systems optimised in terms of both design and operation. Our solutions aim to produce always cheaper electricity, to store it, to connect it to the grid, and to control it with increasingly reliable and more robust components.

Photovoltaic electricity is becoming always cheaper

Photovoltaic production requires the panels integrated into systems or power plants. The installation cost is composed by 40% of the PV panels and 60% of the electrical, mechanics and installation work. To this must be added the expenses, throughout the life of the plant, for its operation and maintenance. The CEA at INES is thus seeking to optimise these different cost centres as well, while seeking the best performance.

CEA at INES develops numerical tools for photovoltaic, in particular software solutions for modelling, diagnosis and production forecasting. The institute evaluates and selects panels and inverters. It also has and extends a power plant monitoring database that provides feedback on their performance and defects.

Adapting power plant architectures to new terrain

The development of solar energy requires available space to accommodate the power plants. In order to facilitate its deployment, it is necessary to avoid conflicts of land use, with agricultural and urbanisation needs as well as those of preservation of natural spaces.

The CEA at INES is developing innovative approaches to the integration of solar power plants in new environments: floating photovoltaics, agri-voltaics, photovoltaics along railways and rivers. These developments concern both mechanical integration and electrical architectures, including medium voltage.

Sizing and controlling PV+storage hybrid power plants

Coupling to storage facilitates the integration of photovoltaics into the grid. To make these hybrid systems competitive, it is necessary to be able to control the additional costs.

CEA at INES is developing digital solutions to dimension the storage as accurately as possible and to control the complete system in an optimal manner. The solutions implement modelling on the one hand and real-time and predictive controls on the other, within an information system for energy management.

New generation inverters

Photovoltaic panels and batteries are DC. An inverter is needed to connect them to the AC grid. The inverter is one of the cost items in the system and causes production losses.

CEA at the INES is developing new generation inverters to lower their cost, improve their performance and their life span. The compactness of these objects is also a challenge in order to control the impact on the installation and maintenance costs of power plants. The innovation concerns the electronic architecture (topology) and the use of the latest generation semiconductors such as silicon carbide and gallium nitride.

Selecting / optimizing storage solutions

Solar energy is an intermittent energy whose production can be partly shifted and smoothed by storage systems. Storage systems can also help with grid stability and balance.

These solutions are beginning to be deployed and require more knowledge of their behaviour in terms of performance, lifetime and safety.

The CEA at INES is recognised for its work in battery characterisation and benchmarking, modelling and diagnosis. Its developments concern experimental protocols and analysis software tools as well as battery instrumentation methods. It has and enriches a database for characterising batteries in the laboratory and monitoring systems in real conditions.

PLATFORMS AND EQUIPMENT OF EXCELLENCE

The Batteries platform has characterization benches for electrochemical storage technologies, from the cell to the battery pack: 40 climatic chambers, more than 300 channels, up to 250 kW. It also includes an abusive test chamber for batteries allowing overload, short-circuit and thermal runaway tests to be carried out.

The installations in the field of power electronics stand out with 4 R&D areas in innovative static conversion, up to 10000 V and 250 kW; calorimetric measurements, 1 inverter characterization bench, 2 double pulse dynamic characterization benches: SiC & GaN switches up to 10 kV, a static characterization bench, a characterization bench for wound magnetic components, a MPPT characterization bench; an EMC generator for fast transients and shock voltages, a photovoltaic installation in high voltage DC (3000 VDC).

Low-voltage micro-grid, equipped with SCADA, with 6 independent sub-grids, 150 kW of configurable solar fields, 120 kVA/160 kWh storage capacity, generators for 130 kVA power.

Power Hardware-In-the-Loop platform: 4 real-time targets, photovoltaic simulators (200 kW), storage (250 KVA), grid (45 kVA), and load (130 kVA).

Experimentation in real and outdoor conditions: 10,000 m² of land equipped with photovoltaic fields, 15 photovoltaic systems for monitoring the performance of innovative modules, database and digital tool for monitoring and diagnosis of 60 PV power plants in real time (200 MW across France).