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Table of Contents
PVM - Photovoltaic Modules
Mentor: Christopher Frank
Two photovoltaic modules are installed at IEK-8 at Forschungszentrum Jülich to measure their radiation dependent energy yield by tracking the maximum power point in the recorded I-U-Curve.
- Module type: SolarWorld SW 235-poly, polycrystalline
- Module type: Solarmodul Fist solar FS-380, thin-film
Principle - Photovoltaic
Photovoltaic modules convert radiation into electrical energy based on the so called photovoltaic effect (described by Einstein 1905). The photovoltaic effect is the stimulation of an electron to a higher energy state caused by absorption of light. Photovoltaic modules are based on semiconductors since their valence- and conduction band are completely separated, but the band gap is in the range of the energy of a photon. Thus, the photovoltaic effect causes electrons to migrate from the individual molecule structure to the conduction band. These electrons are so called free electrons. They are able to move randomly inside the crystal structure of the semiconductor. In order to produce electricity, which means to collect the excited electrons on the one side and “holes” on the other side, the semiconductors are p- and n-doped. In case of a silicon based modules P-doping means to include atoms of the 3. main group and N-doping to include atoms of the 5. main group. In the region of contact, electrons of the n-doped layer move towards the p-doped layer and induce an electric field. After a very short time this electric field reaches an equilibrium state since no more electrons can migrate to the p-doped layer. The associated area is called depletion area. If in this situation the photovoltaic effect takes place in the n-doped area and an electron migrates to the conduction band the electron is not able to cross the depletion area. At the same time the remaining hole is refilled by valence electrons reinforced by the electric field. Now there is an electron in the conduction band of the n-doped layer. If the photovoltaic effect takes place in the p-doped area the free electron mitigates to the n-doped area induced by the electric field. The remaining hole can not be refilled that easy due to repulsion of the depletion area. Thus, the negative charge is trapped in the conduction band in the n-doped layer and the positive charge is trapped in the p-doped layer. This induces an electric potential difference, which can be tapped from the solar module.
Principle - Yield measurements
- Yield measurements with 1 minute temporal resolution
- If you are interested in receiving data please contact: Christopher Frank
|5. October 2016 - today||Forschungszentrum Jülich||JOYCE|