Eduardo F. Fernández

• PhD in Physics
• Head Researcher at University of Jaén

The effective realization of long-distance energy transmission without the need for cables is closer than ever, thanks to advancements in Optical Wireless Power Transfer (OWPT) technology and improvements in Photovoltaic Laser Power Converter (PVLPC) performance. Although current state-of-the-art GaAs-based PVLPCs hold the highest reported efficien...

Optical Wireless Power Transfer (OWPT) has surfaced as a transformative technology among long-range wireless power transmission options, capable of delivering kilowatts of power across kilometric distances. By eliminating physical connections, OWPT enables energy supply in harsh environments such as the deep ocean, outer space, or remote terrestria...

Agrivoltaics have emerged as a viable solution to resolve conflicts arising from land-use competition between large photovoltaic solar installations and conventional agriculture. However, their implementation has not yet fully addressed the issue of social community rejection due to visual impact or making agricultural tasks more difficult. For thi...

Despite being one of the major issues that photovoltaic systems face worldwide, estimating the energy and economic magnitude of soiling of solar collectors still represents a challenge. This work presents a first European assessment of the soiling loss and of the cost-effectiveness of soiling mitigation. New soiling maps are generated through the i...

High‐power optical transmission (HPOT) technology has emerged as a promising alternative among far‐field wireless power transmission approaches, enabling the transfer of kilowatts of power over kilometer‐scale distances. Its exceptional adaptability allows operation in challenging scenarios where traditional electrical wiring is impractical or unfe...

High-power optical transmission (HPOT) enables the uninterrupted transfer of power in the order of hundreds of watts over several kilometers, freeing power systems from traditional wiring constraints. Its vast versatility of applications ranges from the ocean depths to outer space. In recent years, particular emphasis has been placed on the develop...

Soiling in photovoltaic (PV) systems is a significant factor that decreases their efficiency, resulting in lower yields and reduced revenues. However, many PV plants lack specialized equipment to monitor soiling losses. As a result, yield assessors often rely on constant annual loss assumptions to estimate yield losses caused by soiling. These assu...

This paper presents a 3D simulation model for an optical photovoltaic power converter hybridized with a thermoelectric generator and shows the potential of hybridization for applications at very low temperatures. To carry out the study, the methodology for designing the hybrid converter optimizes the thermoelectric couple height under different air...

Concentrator photovoltaic (CPV) technology offers an alternative to conventional photovoltaic systems, focusing on the concentration of solar radiation through the optics of the system onto smaller and more efficient solar cells. CPV technology captures direct radiation and requires precise module orientation. Traditional CPV systems use robust and...

Concentrator photovoltaic (CPV) technology offers an alternative to conventional photovoltaic systems, focusing on the concentration of solar radiation through the optics of the system onto smaller and more efficient solar cells. However, the surface on which the solar beam is incident must remain oriented towards the position of the sun, which req...

The state of the art in the field of high-power laser transmission is dominated by the so called Vertical Epitaxial Hetero-Structure Architecture (VEHSA), which consists of monolithically stacking p/n cells connected by tunnel junctions. This configuration distributes the current between the cells and reduces the losses due to Joule heating. Since...

In this study, the impact of pollen as a PV soiling agent is investigated. The performance data of five utility-scale PV plants in North Carolina, USA, was collected and analyzed using two soiling extraction methods. Satellite and environmental data, including pollen counts, cropland, and vegetation, was also collected and analyzed to identify impa...

Bifacial technology is attracting the attention of the photovoltaic community. Although considered premature, research and development activities still need to be carried out to improve bPV performance. In addition, the need for a standard test reference will aid bankability and increase confidence in this technology. This article describes the sta...

The demand for bifacial photovoltaic modules is continuously increasing. However, some aspects of their behaviour under realistic operating conditions still require more in-depth investigations. Indeed, the long-term analysis of the spectral impact on bifacial modules remains pending. This is particularly true for the rear incident spectrum, which...

Hybrid renewable systems increase electricity production by reducing the randomness of sources without greenhouse gas emissions. Literature indicates that further research is still required for large systems connected to the grid. The energy storage capability of hydroelectric plants provides an opportunity to develop new renewable energy generatio...

Concentrator photovoltaic (CPV) technology has achieved efficiencies above 30 %, which is approximately the double of conventional non-concentrating PV systems. However, the cost of CPV still needs to be lowered to be competitive. In these systems, ≈ 60 % of the incident energy is dissipated as heat. One way to further enhance CPV systems is to act...

In floating photovoltaics, modules are mounted on or above water surfaces in order to limit the land occupancy, an issue arising with the growing deployment of photovoltaics. The floating structures are also expected to lower the capital expenditures required by traditional in-land systems, thanks to the lack of major site preparation needs and to...

Photovoltaic (PV) performance is affected by reversible and irreversible losses. These can typically be mitigated through responsive and proactive operations and maintenance (O&M) activities. However, to generate profit, the cost of O&M must be lower than the value of the recovered electricity. This value depends both on the amount of recovered ene...

A deposição de poeira na superfície dos módulos fotovoltaicos (FV) causa perdas significativas nos sistemas fotovoltaicos, com quedas de energia de até 50% em algumas regiões. Isso significa que pode levar a grandes perdas financeiras devido ao menor rendimento de energia dos sistemas fotovoltaicos e aos custos de Operação & Manutenção (O&M) mais a...

Soiling consists of the accumulation of dust on the solar panel's surface and has a deleterious effect on solar photovoltaic devices' performance, which varies with location. However, soiling losses and rates are significantly under-reported or underestimated since regional differences and seasonal variations are overlooked. Accurate prediction of...

Soiling is a factor that impacts the performance of photovoltaic (PV) modules. Nowadays, the research related to PV soiling monitoring is focused on optical sensors, which estimate the soiling loss through a monochromatic transmittance or reflectance measurement. However, these typically neglect the spectral profile of soiling transmittance, which...

Modelling the current–voltage (I–V) characteristics of photovoltaic (PV) devices is important for understanding their behaviour and potential. Typically, the single exponential model (SEM) is used because of its simplicity and accuracy. In this work, we validate the SEM for a gallium arsenide (GaAs) vertical‐tunnel‐junction (VTJ) using TCAD softwar...

High power laser transmission technology is based on energy transfer through a monochromatic laser onto a photovoltaic receiver avoiding the limitations of conventional wiring. Current technology, headed by GaAs‐based devices, faces two limitations: the intrinsic entropic losses and the degradation at high input power densities due to ohmic losses....

Agrivoltaic (APV) systems have emerged as a promising solution to reduce the land-use competition between PV technology and agriculture. Despite its potential, APV is in a learning stage and it is still necessary to devote big efforts to investigate its actual potential and outdoor performance. This work is focused on the analysis of APV systems in...

Extracting accurate soiling loss information from photovoltaic (PV) production data first requires segmenting the time series data per natural or manually occurring cleaning events. Maintenance logs are often incomplete, rain data are often unavailable, and the debate on rain thresholds for cleaning and dew or wind cleanings is still ongoing. The p...

Soiling is the process where dust, dirt, and organic/inorganic contaminants accumulate on the surface of a photovoltaic (PV) module. It impacts the energy generation of PV systems and causes significant economic losses. It can be monitored through soiling estimation models, which evaluate its impact depending on a number of environmental parameters...

Photovoltaics (PV) has reached high level of maturity in terms of material efficiency and low production costs. For this reason, nowadays, lot of emphasis is put on the reduction of the operation and maintenance costs. Soiling is one of the issues that most affect these costs. So, the understanding of its electrical and economic implications is ess...

High-power laser transmission (HPLT) is attracting a huge interest from both the scientific and industrial community due to its large number of potential applications and future perspectives. This technology consists of the use of a monochromatic light source to power supply a remote system by using a photovoltaic converter. HPLT offers a technolog...

Operation and maintenance (O&M) and monitoring strategies are important for safeguarding optimum photovoltaic (PV) performance while also minimizing downtimes due to faults. An O&M decision support system (DSS) was developed in this work for providing recommendations of actionable decisions to resolve fault and performance loss events. The proposed...

In situ photovoltaic-thermal (PVT) solar energy generation in buildings is an effective way to cover both thermal and electrical energy demands, mimizing losses and costs associated with transportation. High-concentration PVT (HCPVT) collectors present higher electrical conversion efficiencies, lower thermal dependence coefficients and the possibil...

High power laser transmission is being intensively researched as a potential solution to transfer power to remote systems, being the power converter (PC) one of the main limiting factor to improve the system efficiency ( $\eta $ ). Current PCs are mostly horizontal structures in which the $\eta $ heavily decreases at large input power. In this w...

Several models have been presented in the recent years to estimate the magnitude of soiling from environmental parameters. However, these models are often based on data from a single site, or at most a few sites, and only limited data are, as of yet, available on their uncertainty. The present work aims to present a first comparative analysis of so...

The present paper evaluates the soiling losses of a 3.25‐MW photovoltaic (PV) system installed in central Chile, 200 km north of Santiago, and analyzes the nonuniform soiling deposition between the various strings for a period of 3 years. A robust methodology is developed to extract, in the most systematic way, 142 reliable soiling profiles from th...

This work investigates the possibility of using historical environmental parameter data to predict the typical soiling loss profile and the most convenient cleaning schedule for a PV site. The three-year performance of a 1 MW system in Southern Spain is evaluated using different soiling extraction methods. When the rainfall pattern is used to detec...

Concentrator photovoltaic technology faces the challenge of evolving toward ultra-high concentration levels (>2,000 suns) to increase the conversion efficiency of sunlight to electricity and lower the system cost. Recent studies have analysed technical issues related to optics, concentrator solar cell development, and thermal management. On the con...

Non-uniformity is a relevant concern of concentrator photovoltaic systems (CPV) due to its impact on the performance of multi-junction (MJ) solar cells. This work is focused on a state-of-the-art investigation related to the effects of shading on the irradiance profiles and electrical performance of MJ cells. For doing this, three different CPV sin...

Ultra-high concentrator photovoltaic systems aim to enhance the conversion efficiency of sunlight and to reduce the cost of electricity. However, it is still necessary to develop optical systems with higher efficiencies and angular tolerances for them to become a reality. This Letter proposes a novel design that is able to achieve a geometric conce...

The impact of soiling on the energy yield of PV systems has recently become a major concern for PV owners, as soiling losses have reduced significantly the revenues of several PV sites. However, a large number of PV plants still lack the equipment to monitor these losses. An appropriate knowledge of soiling losses in PV modules can significantly in...

The impact of non-uniform illumination on triple junction solar cells equipped with either refractive or reflective optics without secondary optical elements is characterised by varying the concentrator-to-receiver distance. Indoor experiments covering both electrical measurements and photographs with a charge-coupled device camera are performed. T...

The exponential growth of global capacity along with a reduction in manufacturing costs in the last two decades has caused photovoltaic (PV) energy technology to reach a high maturity level. As a consequence, currently, researchers from all over the world are making great efforts to analyse how different types of degradation impact this technology....

The present work investigates how the COVID-19 related lockdown imposed in Spain in between March and June 2020 affected the national electricity sector and the share of photovoltaics in the energy mix. The analysis is conducted by comparing actual electricity demand, generation and price data with forecasts based on their pre-lockdown trends. The...

This study presents indoor and field validation results for two versions of the “DUSST” optical soiling sensor, intended to be a low‐cost and low‐maintenance device for measuring photovoltaic soiling losses. Indoor testing covers irradiance calibration and temperature dependencies, which are necessary to achieve high accuracy, low uncertainty field...

The exponential growth of global capacity along with a reduction in manufacturing costs in the last two decades has caused photovoltaic (PV) energy technology to reach a high maturity level. As a consequence, currently, researchers from all over the world are making great efforts to analyse how different types of degradation impact this technology....

Soiling, which consists of dust, dirt and particles accumulated on the surface of conventional or concentrator photovoltaic modules, absorbs, scatters, and reflects part of the incoming sunlight. Therefore, it reduces the amount of energy converted by the semiconductor solar cells. This work focuses on the effect of soiling on the spectral performa...

Soiling can cause significant losses to photovoltaic systems, and therefore it is often measured for the purposes of predicting long-term energy forecasts or for monitoring real time performance and triggering maintenance events as needed. Currently, the most common soiling monitoring technologies are soiling stations that use the electrical output...

Soiling can cause significant losses to photovoltaic systems, and therefore it is often measured for the purposes of predicting long-term energy forecasts or for monitoring real time performance and triggering maintenance events as needed. Currently, the most common soiling monitoring technologies are soiling stations that use the electrical output...

b>Accepted Manuscript (Postprint): L. Micheli et al., “Improved PV Soiling Extraction through the Detection of Cleanings and Change Points,” IEEE Journal of Photovoltaics, Volume: 11, Issue: 2, March 2021.

b>Accepted Manuscript (Postprint): L. Micheli et al., “Improved PV Soiling Extraction through the Detection of Cleanings and Change Points,” IEEE Journal of Photovoltaics, Volume: 11, Issue: 2, March 2021.

Soiling is the process whereby dirt, dust and organic/inorganic contaminants deposit on the surface of a photovoltaic (PV) module. It causes significant economic losses and can have a substantial impact on the expansion of photovoltaic technologies for energy generation. The first step to address soiling adequately is monitoring, as soiling mitigat...

Photovoltaic (PV) soiling profiles exhibit a sawtooth shape, where cleaning events and soiling deposition periods alternate. Generally, the rate at which soiling accumulates is assumed to be constant within each deposition period. In reality, changes in rates can occur because of sudden variations in climatic conditions, e.g., dust storms or prolon...

The efficiency of solar cells can be enhanced by increasing the light intensity and/or the number of bandgaps of the structure. However, current solar cells cannot fully exploit these two factors because of various critical drawbacks. Here, we show a novel microscale, that is, side ≈ 0.5 mm, vertical solar cell structure that does not suffer the se...

Dust accumulation significantly affects the performance of photovoltaic modules and its impact can be mitigated by various cleaning methods. Optimizing the cleaning frequency is essential to minimize the soiling losses and, at the same time, the costs. However, the effectiveness of cleaning lowers with time because of the reduced energy yield due t...

Nowadays, photovoltaic (PV) technology has reached a high level of maturity in terms of module efficiency and cost competitiveness in comparison with other energy technologies. As PV has achieved high levels of deployment, the development of devices that can help to reduce PV operation and maintenance costs has become a priority. Soiling can be cau...

Nowadays, photovoltaic (PV) technology has reached a high level of maturity in terms of module efficiency and cost competitiveness in comparison with other energy technologies. As PV has achieved high levels of deployment, the development of devices that can help to reduce PV operation and maintenance costs has become a priority. Soiling can be cau...

The present study analyzes the soiling losses of a 1 MW photovoltaic system installed in the South of Spain. Both the Levelized Cost of Energy and the Net Present Value are used to compare the convenience of different mitigation strategies. It is found that also photovoltaic installations located in moderate regions, where the yearly soiling losses...

In this paper, the soiling impact on photovoltaic systems in Aguascalientes, in central Mexico, an area where 1.4GWp of new photovoltaic capacity is being installed, is characterised experimentally. A soiling rate of −0.16%/day in the dry season for optimally tilted crystalline silicon modules, and a stabilization of the soiling losses at 11.2% aft...

Solar photovoltaic technologies have undergone significant scientific development. To ensure the transfer of knowledge through the training of qualified personnel, didactic tools that can be acquired or built at a reasonable price are needed. Most training and research centres have restrictions on acquiring specific equipment due to its high cost....

Ultra-high concentrator photovoltaic systems (UHCPV), usually referred to CPV systems exceeding 1000 suns, are signalled as one of the most promising research avenues to produce a new generation of high-efficiency and low-cost CPV systems. However, the structure of current concentrator solar cells prevents their development due to the unavoidable s...

Soiling impacts the photovoltaic (PV) module performance by reducing the amount of light reaching the photovoltaic cells and by changing their external spectral response. Currently, the soiling monitoring market is moving toward optical sensors that measure transmittance or reflectance, rather than directly measuring the impact of soiling on the pe...

Soiling impacts the photovoltaic (PV) module performance by reducing the amount of light reaching the photovoltaic cells and by changing their external spectral response. Currently, the soiling monitoring market is moving toward optical sensors that measure transmittance or reflectance, rather than directly measuring the impact of soiling on the pe...

Ultra-High Concentrator Photovoltaic (UHCPV) designs with up to more than 6000× geometrical concentration and optical efficiency of 80% are demonstrated in this paper by means of ray tracing simulations. These are developed based on Cassegrain-Koehler concentrators [Opt. Lett. 41(9), 1985 (2016)], with four pairs of paraboloid-hyperboloid mirrors a...

The accumulation of soiling on photovoltaic (PV) modules affects PV systems worldwide. Soiling consists of mineral dust, soot particles, aerosols, pollen, fungi and/or other contaminants that deposit on the surface of PV modules. Soiling absorbs, scatters, and reflects a fraction of the incoming sunlight, reducing the intensity that reaches the act...

div> The identification and prediction of the daily soiling profiles of a photovoltaic site is essential to plan the optimal cleaning schedule. In this article, we analyze and propose various methods to extract and generate photovoltaic soiling profiles, in order to improve the analysis and the forecast of the losses. New soiling rate extraction m...

div> The identification and prediction of the daily soiling profiles of a photovoltaic site is essential to plan the optimal cleaning schedule. In this article, we analyze and propose various methods to extract and generate photovoltaic soiling profiles, in order to improve the analysis and the forecast of the losses. New soiling rate extraction m...

The identification and prediction of the daily soiling profiles of a photovoltaic site is essential to plan the optimal cleaning schedule. In this article, we analyze and propose various methods to extract and generate photovoltaic soiling profiles, in order to improve the analysis and the forecast of the losses. New soiling rate extraction methods...

Approximately 60% of the incident energy is dissipated as heat in conventional concentrator photovoltaic modules. The hybridization with thermoelectric generators (TEGs) aims to recover part of the waste heat and transform it to electricity. Recently, the feasibility of passively cooled designs has been assessed for small sized solar cells (3 mm ×...

In the frame of the Concentrator Photovoltaic (CVP) technology, to achieve ultra-high (UH) concentration levels is a promising strategy to reduce the cost of the PV electricity, since it takes advantage of the reduction of the solar cell area and also of the physical behavior of the solar cells. This work analyzes a previous optical concentrator de...

This paper presents an experimental study on the effect of soiling on CPV modules located in the south of Spain. The I-V curves of two identical modules with different cleaning schedules (i.e. one was naturally soiled and the other one was cleaned periodically) have been measured over a course of year. The effect of soiling on the short-circuit cur...