Research topics of the department Solar Energy

Solar energy can contribute greatly to the production of electricity and heat and will play an important role in the future energy system. While the combustion of fossil fuels pollutes the atmosphere with the climate-damaging CO2, solar energy does not. In many parts of the world, solar energy is already the cheapest way to supply energy. Nevertheless, the efficiency of solar cells and photovoltaic modules is still far from the physical limits in some cases, and material consumption is currently greater than necessary.

The physical knowledge of the power losses occurring in the components and the thereby enabled target-oriented optimization of manufacturing processes are the focus of our work at the Institute of Solid State Physics. For this purpose, we carry out simulation calculations for the generation, transport and recombination of electron-hole pairs. With the resulting understanding of the dominant loss mechanisms, new manufacturing processes for solar cells and modules with higher efficiencies and reduced material costs can be developed. Simulations of manufacturing processes subsequently support the transfer of the processes into production. We also analyze the optical properties of solar cells and solar modules. For example, we are also concerned with the influence of the actual weather to which installed solar modules are exposed in order to realistically simulate their behavior and to better evaluate results from laboratory tests under standard test conditions with regard to achievable performance under realistic operating conditions.

To carry out the simulation calculations, we have a powerful computing server and various software packages such as Matlab, SPICE, Sentaurus and Comsol at our disposal. For optical simulations we use, among others, the ray tracing framework Daidalos, which was developed in our group and allows simultaneous optical simulations of components with different size scales.

The activities of the group include the following research areas:

  • Coupling of optical, thermal and electrical semiconductor simulations with the aim of optimizing solar module performance under actual operating conditions
  • Analysis of light-directing elements in solar modules using three-dimensional ray tracing simulations on entire solar modules
  • Analysis of the influence of changing weather conditions (e.g. cloud cover, flat irradiation) on the output power of solar modules
  • Modelling and optical simulation of the luminescence radiation of silicon, especially with regard to measurements of electroluminescence and photoluminescence
  • Electrical transport in mono-, multi- and polycrystalline silicon
  • Recombination at doped surfaces and inside of diffused regions
  • Investigation of special contacts of the solar cells (e.g. heterojunction contacts)
  • Modelling of industrial diffusion processes
  • Simulation of phenomena that arise from new processing techniques
  • Development of new measurement methods for the characterization of solar cells
  • Detailed analysis of the synergetic loss mechanisms in solar cells for the targeted optimization of efficiency
  • Analysis of the influence of different contact geometries on the result of four-point precision measurements of the current-voltage characteristic
  • Determination of the material data required for our simulation calculations
[Translate to English:] Tageslichtquelle des Raytracing-Frameworks Daidalos [Translate to English:] Tageslichtquelle des Raytracing-Frameworks Daidalos [Translate to English:] Tageslichtquelle des Raytracing-Frameworks Daidalos
Daylight source of the ray tracing framework Daidalos for the analysis of the performance of solar modules under realistic irradiation conditions (based on irradiance measured at ISFH in the years 1992 - 2005)
[Translate to English:] Spektralellipsometer zur Bestimmung optischer Materialkonstanten von dünnen Schichten [Translate to English:] Spektralellipsometer zur Bestimmung optischer Materialkonstanten von dünnen Schichten [Translate to English:] Spektralellipsometer zur Bestimmung optischer Materialkonstanten von dünnen Schichten
Spectroscopic ellipsometer for determining optical material constants of thin layers
[Translate to English:] Bestimmung elektrischer Kenndaten von Solarzellen zur Validierung von Simulationsrechnungen [Translate to English:] Bestimmung elektrischer Kenndaten von Solarzellen zur Validierung von Simulationsrechnungen [Translate to English:] Bestimmung elektrischer Kenndaten von Solarzellen zur Validierung von Simulationsrechnungen
Determination of electrical characteristics of solar cells for validation of simulation calculations