The report illustrates the activities carried out and the results achieved in 2020 as part of project 1.1 High efficiency photovoltaics.

The project aims to facilitate the development of high-efficiency, reduced-cost photovoltaic (PV) generation systems, and contribute to optimising the energy production of systems installed in Italy. All this in order to allow for the achiement of the Integrated National Energy and Climate Plan (NECP) goals for 2030. The Plan envisages achieving 50 GW PV power and 72 Twh production/year, while also providing companies technological support for them to significantly participate in this PV technology development phase.

In WP1 ‘Concentrating Solar Photovoltaics’ , the activities completed concerned structural optimization and low-cost construction of concentrated PV (CPV) cells and modules, and mainly:

• the finalization of a simulation program which allowed us to define different PV cell structures, with 4 junctions and 2 or 3 terminals;
• the advancement of CPV cells realization techniques, with SiGeSn integration activities in III-V structures grown at low temperature, also achieving a better technique for measuring the concentration of Si and Sn in the deposited materials;
• the enhancement of the Spectral Response measurement system for CPV cells with up to 4 junctions and the realization of a system for controlling the temperature of CPV cells during this measurement;
• the optimization of the realization of single junction InGaP CPV cells, achieveing a 100% increase in the power of luminescent modules made with these cells compared to

modules made up of Si cells (the objective set in the Three-year Realization Plan was 50%);

• the continuation of the optimization of the biaxial shape memory sun tracking system; (6) the completion of the energy characterization methodology of CPV modules and the carrying-out of measurements in the RSE Test Field in Piacenza, where the installation of a precision biaxial sun tracker was completed;

(7) the continuation of the simulation for the innovative filter and the assessment of the performance of Germanium thermophotovoltaic cells (TPV) for domestic microgeneration.

In WP 2 ‘Flat PV’ , methods for using widely available materials in the production of innovative PV cells were developed, at RSE and UNIMIB, by optimizing the growth and finalization processes of CZTS cells, process of metal precursors deposition by sputtering and subsequent sulfuration.

As part of the activities aimed at increasing the efficiency of energy production and the management of PV systems, (1) innovative technological solutions for the predictive identification of faults in PV systems were developed, including through the creation of a

‘PV Failure Test Facility’ for simulating system failures which allows us to experiment with and optimize diagnostic techniques for the efficiency of PV systems, and implement techniques for identifying the effects of specific failures and therefore reduce O&M costs ; (2) the comparison continued between the functioning of RSE-developed MPPT ( Maximum Power Point Tracker ) algorithm and the algorithm of commercial inverters, by creating a database of I-V curves detected in real conditions on differently shaded PV strings, in order to validate the advantages of the MPPT algorithm.

Finally, in WP3 ‘The Solar Source and the Environment’, the management and enhancement of the spectral measurements of Sun Direct Normal Irradiance (SDNI) continued, with measures from the national Helios network and the processing of satellite measurements; this was done within the RdS 2.2 project ^{[1 ]}, carried out by RSE as part of this Three-year Realization Plan, in order to create DNI maps of the national territory, which is essential for identifying suitable sites for CPV systems as well as for PV systems installed on single-axis and bi-axial sun trackers. Finally, Life Cycle Analysis (LCA) activities of high-efficiency PERC cell PV systems continued in collaboration with Italian operators.

[1] ‘Architecture and management models for the evolution of the electricity system and the integration of distributed resources’