The key components of photovoltaic (PV) systems are PV modules representing basic devices, which are able to operate durably in outdoor conditions. PV modules can be manufactured using different materials by different fabrication technologies. The main criteria supporting or limiting a successful placement of particular technologies on the market is the cost of electricity produced by PV systems. The Levelized Cost of Energy (LCOE) method takes into account the investment cost, the operating costs, and the total energy produced during the system service life. The influence of price, efficiency and service life of PV modules on LCOE (together with the availability of materials) sets limits for applicable technologies. Over the past 15 years a categorisation of generations of PV cell and module technology groups has been frequently used. The main features of individual technology groups are discussed from the view of the above criteria. Currently, PV modules are required to have: efficiency higher than 14%, price below 0.4 USD/W p and service life of more than 15 years. At present, the wafer-based crystalline silicon technologies have best met the criteria due to their high efficiency, low cost and long service time; and due to the abundance of materials, they are set to lead in future PV power generation.

There exist over 2 GW of photovoltaic (PV) systems in the Czech Republic, exposed to moderate continental climate. Although there exist many PV modules defects, thanks to the generally the same production year 2009, only some of them are usual at systems installed in Czech Republic. This work shows delamination failures that are frequent in moderate climate conditions. Special account is taken into edge delamination defect and its possible propagation in modules of standard construction. Combined PV panel and PV inverter failure is caused by edge delamination with water penetration and high string voltage. The electric discharge channel is created between the string of solar panels and the grounded PV panel frames. The result of the discharge channel created because of edge delamination is inverter switch-OFF and few months later total destruction of the inverter because of protective relay damage. The number of combined PV panel and PV inverter failures is increasing substantially after ninth year of operation of PV panels in moderate climate. Additional sealing of the PV panel frames by transparent polysiloxane gel reduced the number of combined PV panel and PV inverter failures very substantially.

Optical absorptance spectroscopy of polycrystalline CHNHPbI films usually indicates the presence of a PbI phase, either as a preparation residue or due to film degradation, but gives no insight on how this may affect electrical properties. Here, we apply photocurrent spectroscopy to both perovskite solar cells and coplanar-contacted layers at various stages of degradation. In both cases, we find that the presence of a PbI phase restricts charge-carrier transport, suggesting that PbI encapsulates CHNHPbI grains. We also find that PbI injects holes into the CHNHPbI grains, increasing the apparent photosensitivity of PbI. This phenomenon, known as modulation doping, is absent in the photocurrent spectra of solar cells, where holes and electrons have to be collected in pairs. This interpretation provides insights into the photogeneration and carrier transport in dual-phase perovskites.

Potential induced degradation (PID) is a serious threat for the photovoltaic (PV) industry. The risk of PID may increase with increasing operating voltage of PV systems. Although PID tests are currently standard tests, the expansion of floating PV power plants and installation in humid climates show that PID-free modules are still sensitive to this type of degradation. Therefore, a method that can detect PID in the initial phase before standard tests reveal it, is necessary to increase the reliability of PV systems and maintain their lifetime. One possible tool for revealing early-stage PID manifestations is impedance spectroscopy and I-V dark curves measurements. Both IS and dark current measurement methods are sensitive to cell shunt resistance (RSH), which is strongly influenced by PID before significant power loss and can act as an early stage PID detection mechanism. The paper describes the differences of the common P-type PV module parameters both during the degradation process and also during the regeneration process when diagnosed by conventional and IS and dark current measurement methods.

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