The energy yield of a system depends largely on how the photovoltaic (PV) panels perform at different weather conditions (particularly plane of array irradiance and module temperature) summed over the hourly meteorological data for a year at the given site. Some of the PV performance parameters such as ‘efficiency at low light/efficiency at standard conditions’ and the ‘P _MAX thermal coefficient’ can vary between technologies and may be able to be improved by better production methods (for example, improving uniformity, reducing shunts, reducing series resistance or improving the thermal design). The sensitivity of energy yield (kilowatt hour/year) against PV input value will be site dependent, for example, high insolation sites will usually experience higher module temperatures so that improvements in temperature coefficients would be more beneficial at higher than at lower insolation. This study studies the effect of the sensitivity of energy yield at five different sites (from northern Europe to desert) of six different PV input values (including low-light efficiency, P _MAX temperature coefficient and nominal operating cell temperature). It quantifies the benefits at each site of good temperature coefficients or improving the low-light efficiency and also the need for wide V _MP inverter ranges at sites with wide seasonal temperature differences.

Met Office station data from 1980 to 2012 has been used to characterise the interannual variability of incident solar irradiance across the UK. The same data are used to evaluate four popular historical irradiance products to determine which are most suitable for use by the UK PV industry for site selection and system design. The study confirmed previous findings that interannual variability is typically 3–6% and weighted average probability of a particular percentage deviation from the mean at an average site in the UK was calculated. This weighted average showed that fewer than 2% of site-years could be expected to fall below 90% of the long-term site mean. The historical irradiance products were compared against Met Office station data from the input years of each product. This investigation has found that all products perform well. No products have a strong spatial trend. Meteonorm 7 is most conservative (MBE = −2.5%), CMSAF is most optimistic (MBE = +3.4%) and an average of all four products performs better than any one individual product (MBE = 0.3%).

Point source, pillbox and circumsolar ratio-dependent extended light source Sun models are used as solar source inputs into an analytical optical ray trace model for the calculation of plane restricted illumination profiles generated by three example lenses. The example lenses are: a low iron soda-lime glass plano-convex lens, a poly (methyl) methacrylate (PMMA) 3-facet Fresnel lens and a PMMA 20-facet Fresnel lens. Significant differences in illumination profiles are found with solar source description variation. Most notably, it is found that chromatic aberrations and spectrally variant effects specific to the multi-junction solar cell architecture are only identified using the extended light source Sun model. The spectral dependency of material optical properties are analysed in the context of the multi-junction cell architecture by means of spectrally weighted averages corresponding to the active range of the sub-cells.

This work describes progress towards achieving a flexible, high specific power and low-cost photovoltaic (PV) for emerging large area space applications. The study reports the highest conversion efficiency of 15.3% AM1.5G for a CdTe device on ultra-thin cerium-doped cover glass, the standard protective material for extra-terrestrial PVs. The deposition technique used for all of the semiconductor layers comprising the device structure was atmospheric pressure metal organic chemical vapour deposition. Improvements to the device structure over those previously reported led to a V _oc of 788 mV and a relatively low series resistance of 3.3 Ω·cm². These were largely achieved by the introduction of a post-growth air anneal and a refinement of the front contact bus bars, respectively. The aluminium-doped zinc oxide transparent conductive oxide, being the first layer applied to the cover glass, was subject to thermal shock cycling +80 to (−) 196°C to test the adhesion under the extreme conditions likely to be encountered for space application. Scotch Tape testing and sheet resistance measurements before and after the thermal shock testing demonstrated that the aluminium-doped zinc oxide remained well adhered to the cover glass and its electrical performance unchanged.

replace with: Currently, the impacts of wide-scale implementation of photovoltaic (PV) technology are evaluated in terms of such indicators as rated capacity, energy output or return on investment. However, as PV markets mature, consideration of additional impacts (such as electricity transmission and distribution infrastructure or socio-economic factors) is required to evaluate potential costs and benefits of wide-scale PV in relation to specific policy objectives. This study describes a hybrid GIS spatio-temporal modelling approach integrating probabilistic analysis via a Bayesian technique to evaluate multi-scale/multi-domain impacts of PV. First, a wide-area solar resource modelling approach utilising GIS-based dynamic interpolation is presented and the implications for improved impact analysis on electrical networks are discussed. Subsequently, a GIS-based analysis of PV deployment in an area of constrained electricity network capacity is presented, along with an impact analysis of specific policy implementation upon the spatial distribution of increasing PV penetration. Finally, a Bayesian probabilistic graphical model for assessment of socio-economic impacts of domestic PV at high penetrations is demonstrated. Taken together, the results show that integrated spatio-temporal probabilistic assessment supports multi-domain analysis of the impacts of PV, thereby providing decision makers with a tool to facilitate deliberative and systematic evidence-based policy making incorporating diverse stakeholder perspectives.

The likelihood of system failure of small systems is investigated in order to establish the risk associated for the investment into a photovoltaic (PV) system for small domestic applications. This is achieved by reviewing existing literature on PV system failure rates and using these as an input for a statistical PV system yield simulation tool that considers failure and repair. It is typically assumed that these systems do not require any maintenance, but it is shown that this will have near catastrophic impact on the energy production of PV systems. The no maintenance is not a likely scenario, as small systems have to register their generation to achieve a feed-in-tariff. In a later stage, when PV is used for self-consumption only, this may change but in the present market most users are forced to carry out a quarterly check and thus this catastrophic failure is avoided by the need of having to apply for the feed-in-tariff. Minimum maintenance strategies for ensuring profitable system operation are investigated and their cost-effectiveness is discussed. It is shown that the present situation where many systems are neither monitored nor is any maintenance carried out results in a high probability of unsuccessful system operation as failure detection may take a very long time. Successful system operation here is defined as not recovering the financial investment. It would be advisable to carry out at least monthly performance checks as otherwise it is likely to have more than 10% energy lost because of system downtime. This requires, however, availability of irradiance data as otherwise it is not possible to identify whether low yields are due to resource issues or really system yield issues.

The study discusses the short-term performance variations of grid-connected photovoltaic (PV) systems installed in Kanpur, India. The analysis presents a holistic view of the performance variations of three PV array technologies [multi-crystalline (multi-Si), copper indium gallium diselenide and amorphous silicon] and two inverter types (high-frequency transformer and low-frequency transformer). The analysis considers the DC–AC conversion efficiency of the inverter, system performance through performance ratio (PR) calculations, energy variations between fixed and tracking systems and the comparison between calculated and simulated data for the examined period. The energy output difference between the tracking and fixed systems of the same PV technology show that these are dependent on differences in temperature coefficient, shading and other system related issues. The PR analysis shows the effect of temperature on the multi-Si system. The difference between the simulated and measured values of the systems was mostly attributed to the irradiance differences. Regarding the inverter evaluation, the results showed that both inverter types underperformed in terms of the conversion efficiency compared with nameplate values.

A system that combines the advantages of fast global electroluminescence (EL) imaging and detailed spectrally resolved EL measurements is presented. A charge-coupled device camera-based EL imaging system is used to measure the intensity of radiative recombination of the photovoltaic (PV) device spatially resolved over its full area. A monochromator-based system is utilised to measure localised emission spectra at given points of interest. Measurements of multi-crystalline and amorphous silicon PV devices demonstrate the potential to investigate radiative defects and reveal performance variations and non-uniformities. This links inhomogeneities much closer to device physics than using camera-based EL only.

The drive to reduce reliance on fossil fuel generation in meeting power system demand is encouraging network operators to develop new methods managing network capacity while maintaining stability and security. Challenges relating to network stability are particularly acute on islanded networks. The Northern Isles New Energy Solutions (NINES) project is implementing techniques to manage the power network on the Shetland Islands in the UK. Active network management (ANM) is used to monitor and control generation in real time, and flexible demand is scheduled to minimise the use of conventional generation by reducing wind curtailment and minimising system losses. The flexible demand has the ability to respond to frequency and support system stability. This study presents the development of two modelling techniques used in the design and deployment of NINES – an ‘envelope of stability wind generation’ and the use of dynamic optimal power flow to schedule flexible demand. A case study is presented which shows that an ANM scheme managing flexible demand has the potential to increase wind capacity connected on Shetland from the existing 4 MW to 16.1 MW. Demand flexibility is shown to be capable of contributing up to 16.6 GWh towards reducing conventional generation.

In the past few years, grid-code requirements for grid-connected photovoltaic power plants have experienced a continuous evolution in different countries to ensure a reliable power system operation as the level of renewable energy penetration increases to high levels. According to several European grid-codes, PV power plants must be able to ride through specific and severe disturbances without disconnections. Under this new framework, the present study analyses intensive power quality surveys carried out from 2008 to 2011 in three different Spanish PV power plants: a fixed array installation with 4 MW PV power capacity, a PV power plant including dual axis–trackers with 1 MW PV power capacity, and one more fixed array PV power plant with 5 MW PV power capacity. Voltage dips and supply interruptions have been collected, discussing several methods to characterise the monitored disturbances and to compare these events to current Grid-Code requirements. Furthermore, the time interval around the residual voltage is proposed and defined by the authors as an additional parameter to provide a complete characterisation of the severity of the disturbances. Results from both characterisations of collected data and comparison with current requirements are also included in the study.

Recently, a special attention has been attributed to the renewable energy in Egypt. Optimal sizing of small renewable energy system has a very important role in the use of renewable energy effectively and economically. Particle swarm optimisation (PSO) is a popular stochastic optimisation method that has found in wide applications. Conventional PSO suffers from high computational complexity and slow convergence speed. This study presents a modified PSO (MPSO) technique to optimise the capacity sizes of different components of hybrid PV/wind/battery power generation system for supplying communication and information technology centre in Mansoura University-Egypt. A feasibility study for two options is investigated; stand-alone system composed of PV/wind/battery combination and a grid connected PV/wind system. The proposed MPSO technique proves faster convergence speed and shorter computational time as compared with conventional techniques.

This study focuses on the development of a supervisory control scheme for power management and operation of an isolated hybrid AC/DC micro-grid, which consists of an AC micro-grid and a DC micro-grid. In the proposed hybrid micro-grid, wind and diesel generators and AC loads are connected to the AC micro-grid, whereas photovoltaic array and DC loads are tied to the DC micro-grid. Moreover, the authors consider two independent battery banks in the AC and DC micro-grids. Furthermore, the AC and the DC micro-grids are coupled through a bidirectional converter, which can act as an inverter or rectifier. The objectives of the proposed supervisory controller are listed as follows: (i) maximum utilisation of renewable energy sources along with satisfying the load power demand in both AC and DC micro-grids, (ii) maintaining state of charge (SOC) of battery banks in both AC and DC micro-grids and (iii) managing the power exchange between the AC and the DC micro-grids while the reliability of the whole system is taken into account. The supervisory controller is formalised using a state machine approach. For these purposes, 15 distinct operation modes are considered. Furthermore, in order to extend the battery life cycle, a fuzzy controller manages the desired SOC controlling the charge and discharge currents. The effectiveness of the proposed supervisory controller is evaluated through extensive numerical simulations.

A single-switch, single-stage, three-phase ac–dc buck–boost converter suitable for medium-voltage applications is proposed. Basic relations that govern steady-state converter operation are established, confirmed using PSCAD/EMTDC simulations, and substantiated experimentally. Simulation and experimental results establish that the proposed converter has good dynamic performance in buck and boost modes, with near unity input power factor.

Current wind turbine (WT) studies focus on improving their reliability and reducing the cost of energy, particularly when WTs are operated offshore. A supervisory control and data acquisition (SCADA) system is a standard installation on larger WTs, monitoring all major WT sub-assemblies and providing important information. Ideally, a WT's health condition or state of the components can be deduced through rigorous analysis of SCADA data. Several programmes have been made for that purposes; however, the resulting cost savings are limited because of the data complexity and relatively low number of failures that can be easily detected in early stages. This study proposes a new method for analysing WT SCADA data by using an a priori knowledge-based adaptive neuro-fuzzy inference system with the aim to achieve automated detection of significant pitch faults. The proposed approach has been applied to the pitch data of two different designs of 26 variable pitch, variable speed and 22 variable pitch, fixed speed WTs, with two different types of SCADA system, demonstrating the adaptability of the approach for application to a variety of techniques. Results are evaluated using confusion matrix analysis and a comparison study of the two tests is addressed to draw conclusions.

An energy assessment was made for a novel solar cell consisting of thin film silicon on woven polyester. The total energy used in manufacture by this unique combination of textile and semiconductor processes was estimated to be 446 MJ/m², lower compared with using more conventional substrates such as glass and polymer film. The authors' substrate choice of woven polyester (53 MJ/m²) shows a cut in energy use compared with glass, which requires 150–200 MJ/m². Comparison with the energy generated by the device in a typical mid-European operating ambient showed it to have an energy payback time of 1–2 years for an energy conversion efficiency range of 10–5%.

This study presents a robust and cost-effective microgrid topology for integrating two commonly available wind and small-hydro renewable energy sources. The proposed topology has two generators, one of them is self-excited squirrel cage induction generator driven by a small-hydro turbine and other one is permanent magnet brushless DC generator driven by a small-scale wind turbine. The proposed system is integrated using a voltage source converter and a boost converter which are maintaining voltage and frequency, mitigating power quality problems and performing mechanical sensorless maximum power point tracking, respectively. A battery bank is also used to balance the load and supply power mismatch and to ensure the supply for critical loads. The proposed control algorithm is tested and verified on a developed laboratory prototype of the system. Test results verify that voltage and frequency of the system are regulated and the power-quality-related issues are also resolved in this microgrid.

The extraction of hydrokinetic energy from ocean currents or tides involves the use of marine turbines generating turbulent wakes. The prediction of the wake characteristics is essential because the velocity deficit and increased levels in turbulence intensity dictate the interaction between turbines and any environment impact. A numerical methodology combining the parabolised Navier–Stokes equations with a modified actuator-disk model is presented. The main innovation of the modified actuator-disk model is that the flow is considered to be non-uniform downstream of the turbine. The numerical method is used to reproduce the experiments of Neary et al. (2013) and Mycek et al. (2014). The computational results show that the modification in the actuator-disk model aids in the reproduction of the experimental measurements. The simulations also show that increased levels in the ambient turbulence intensity cause a faster recovery in the turbulent wake, which agrees with experiments.