On the temperature dependence of photovoltaic module electrical performance: a review of efficiency/ power correlations

Organic photovoltaics (OPVs) evolve in an exponential manner in the two key areas of efficiency and stability. The power conversion efficiency (PCE) has in the last decade been increased by almost a factor of ten approaching 10%. A main concern has been the stability that was previously measured in minutes, but can now, in favorable circumstances, exceed many thousands of hours. This astonishing achievement is the subject of this article, which reviews the developments in stability/degradation of OPVs in the last five years. This progress has been gained by several developments, such as inverted device structures of the bulk heterojunction geometry device, which allows for more stable metal electrodes, the choice of more photostable active materials, the introduction of interfacial layers, and roll-to-roll fabrication, which promises fast and cheap production methods while creating its own challenges in terms of stability.

Stability of polymer solar cells.

As photovoltaic penetration of the power grid increases, accurate predictions of return on investment require accurate prediction of decreased power output over time. Degradation rates must be known in order to predict power delivery. This article reviews degradation rates of flat-plate terrestrial modules and systems reported in published literature from field testing throughout the last 40 years. Nearly 2000 degradation rates, measured on individual modules or entire systems, have been assembled from the literature, showing a median value of 0·5%/year. The review consists of three parts: a brief historical outline, an analytical summary of degradation rates, and a detailed bibliography partitioned by technology. Copyright © 2011 John Wiley & Sons, Ltd.

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Photovoltaic Degradation Rates—an Analytical Review

In this work we show that the rate-dependent hysteresis seen in current–voltage scans of CH3NH3PbI3 perovskite solar cells is related to a slow field-induced process that tends to cancel the electric field in the device at each applied bias voltage. It is attributed to the build-up of space charge close to the contacts, independent of illumination and most likely due to ionic displacement, which is enhanced when the device undergoes aging. This process can also lead to a reduction of the open-circuit voltage or the steady-state photocurrent and does not directly correlate with the development of the hysteresis if it is measured at a fixed voltage sweep rate.

Understanding the rate-dependent J–V hysteresis, slow time component, and aging in CH3NH3PbI3 perovskite solar cells: the role of a compensated electric field

As the solar photovoltaic (PV) matures, the economic feasibility of PV projects are increasingly being evaluated using the levelized cost of electricity (LCOE) generation in order to be compared to other electricity generation technologies. Unfortunately, there is lack of clarity of reporting assumptions, justifications and degree of completeness in LCOE calculations, which produces widely varying and contradictory results. This paper reviews the methodology of properly calculating the LCOE for solar PV, correcting the misconceptions made in the assumptions found throughout the literature. Then a template is provided for better reporting of LCOE results for PV needed to influence policy mandates or make invest decisions. A numerical example is provided with variable ranges to test sensitivity, allowing for conclusions to be drawn on the most important variables. Grid parity is considered when the LCOE of solar PV is comparable with grid electrical prices of conventional technologies and is the industry target for cost-effectiveness. Given the state of the art in the technology and favorable financing terms it is clear that PV has already obtained grid parity in specific locations and as installed costs continue to decline, grid electricity prices continue to escalate, and industry experience increases, PV will become an increasingly economically advantageous source of electricity over expanding geographical regions.

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A review of solar photovoltaic levelized cost of electricity

Potential of solar electricity generation in the European Union member states and candidate countries

All commercial manufacturers of photovoltaic modules define the expected lifetime of their products through guarantees of peak power rating of the module after 10 to 25 years of operation. These estimations are based on accelerated lifetime testing such as the IEC61215 and limited field experience. As the first installed systems and arrays are reaching 20 years plus lifetime we can now for the first time begin to associate the levels of accelerated testing of type approval with actual field behaviour. The paper presents some key behaviour of several different silicon technologies, dating back to 1982. The basis of the analysis is the JRC ESTI outdoor test field where examples of diverse generations of PV technology have been exposed to long-term outdoor exposure. The effect of performance degradation on the lifetime is explored in order to quantify the impact of degradation on performance. Results indicate that current module technologies may far exceed the nominal 20 years lifetime assumed in all financial calculations.

20 years of life and more: where is the end of life of a PV module?

Capacitance effects in high-efficiency cells

The performance of a photovoltaic module at Standard Test Conditions (STC) is valuable for comparing the peak performance of different module types. It does not, however, give enough information to accurately predict how much energy a module will deliver when subjected to real operating conditions. There are several proposals for an energy rating for PV modules which attempt to account for the varying operating conditions that one encounters in the field. In this paper, we present an approach with the emphasis on simplicity and practicality that incorporates existing standard measurements to determine the energy output as a function of global in-plane irradiance and ambient temperature. The method is applied to crystalline Si modules and tested with outdoor measurements, and a good accuracy of prediction of energy production is observed. Finally, a proposal is made for a simple Energy Rating labeling of PV modules. Copyright © 2005 John Wiley & Sons, Ltd.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/pip.658

A practical method for the energy rating of c‐Si photovoltaic modules based on standard tests

The world market for renewable energies is continuously growing. In particular, the wind energy and photovoltaic markets show yearly growth rates between 20 and over 30% in the last few years. Despite the fact that there are still discrepancies between the European Union and the USA how to deal with climate change, renewable energies will play an important role for the implementation of the Kyoto Protocol and the worldwide introduction of tradable green certificates. Apart from the electricity sector, renewable energy sources for the generation of heat and the use of environmental friendly bio-fuels for the transport sector will become more and more important in the future. This article tries to give an overview about the progress of renewable energies in Europe.

H.A. Ossenbrink

Papers

Potential of solar electricity generation in the European Union member states and candidate countries

20 years of life and more: where is the end of life of a PV module?

Capacitance effects in high-efficiency cells

A practical method for the energy rating of c‐Si photovoltaic modules based on standard tests

Progress of electricity from biomass, wind and photovoltaics in the European Union