• Energy Research

The objective of this work is to analyze the possibility of compliance with the objectives committed to by the Canary Islands authorities, which aim to reach a completely decarbonized economy by 2040, meaning ten years earlier than the entire EU. Since historically, energy planning in the Canary Islands did not achieve its objectives by far, we will first identify the historical obstacles which had prevented the achievement of this planification, to later highlight the main differences between the energy transition foreseen by the current planning instruments of the government of the Canary Islands and the expected evolution of the energy transition of the archipelago. Beyond this point, and, within the frame of energy governance, we will understand how the root of this failure lies in planning instruments developed hierarchically, without including the view of the different stakeholders involved in the process. The final goal, after identifying the main barriers faced by the energy transition in the Canary Islands, is to provide a set of recommendations contributing to supporting a successful energy transition for the archipelago.

This report presents the results that have been performed based on the analysis of case studies in order to propose possible retrofitting strategies that can be used to reduce energy consumption. Retrofitting measures have been identified and described, classified by Building Typologies, Climates Zones and Types of Retrofit Strategies. Recommendations are proposed for Southern Europe, Central Europe and Northern Europe.

Abstract This paper reports the chemical and optical characterization of a cost effective down-converter polymeric film based on an Eu(III) complex embedded in polymethylmethacrylate (PMMA) which placed on conventional photovoltaic (PV) glass, used for module assembly, produces an increase in the external quantum efficiency (EQE) of a reference Si-based solar cell. Our results show that the best location of the down-converter is on the front surface of the glass. The UV absorption of the down-converter protects and enhances the stability of the PMMA film. This increase in EQE is further enlarged by placing a light trap on the device, collecting most of the down-converted photons, which are isotropically emitted. Additional increases in EQE are expected after a proper encapsulation of the solar cell and the glass. Thermogravimetric measurements show that the down-converter active specie is stable up to 275 °C and the PMMA film is stable up to 225 °C, consequently, it can be applied in any step of the lamination process in the production of PV modules. Thereby, the down-converter can be profitably applied in Si-based solar cells and modules, particularly in concentrated PV systems.

AbstractOperating distribution grids is increasingly challenging due to the increasing penetration of photovoltaic systems. To address these challenges, modern photovoltaic inverters include features for local control, which sometimes lead to suboptimal results. Improved communication infrastructure and photovoltaic inverters favour global control strategies, which receive information from all the systems in the grid. An estimation of distribution algorithm is used to optimize a global control strategy that minimizes active power curtailment and use of reactive power of the photovoltaic inverters, while maintaining voltage stability. Optimized global control outperforms every other local control evaluated in terms of apparent energy used for control (9.9% less usage compared to the second best alternative in all scenarios studied) and ranks second in terms of voltage stability (with a 0.14% of total time outside the voltage limits). Two new indicators to compare control strategies are proposed, and optimized global control strategy ranks best for both efficiency index (0.98) and average apparent power use (0.48 kVA).

Abstract As the cost of silicon-based solar cells has been decreasing sharply in recent years, photovoltaic (PV) systems have dramatically increased their attractiveness in many countries and in mall power systems. This increase of attractiveness can be objectively described in terms of grid parity reached in many areas around the world and a substantial improvement for accessing to electricity without subsidies in places where the power supply is intermittent or, simply, is not offered. One of such places around the world where power supply is limited is West Africa. On the other hand, as the PV industry is maturing and the production capacity is increasing, it is expected that PV companies will place new factories close to markets in highly solar irradiated developing countries, where the demand will grow in the near future. In this work a technical and socio-economic assessment of silicon-based low-cost solar cells produced in a manufacturing factory located in West Africa is exposed. The cost of the solar cells, in terms of USD/W p is obtained for different West African countries and compared to the production costs of a similar factory operating in China but exporting the cells to West Africa. A sensitive analysis of the final cost of the solar cells varying the cost of key input parameters (mainly labor, electricity, silicon contract price, investment and logistic costs) into a defined range is also exposed. The cost of the solar cells produced is integrated with other sensitive parameters for business competitiveness in a synthetic indicator which offers a ranking of the ten more favorable countries for the location of this PV factory.

For the first time to our knowledge, a study about the increase in external quantum efficiency (EQE) by down-shifters (DS) encapsulated by industrial procedures on photovoltaic (PV) modules is presented. EQE improves substantially in the UV range not only because of the optical path optimization for photons reaching the solar cell, but also it is attributed to the substantial reduction of DS photons scattered out of the solar cell when the outermost surface of the DS layer is embedded in ethyl-vinyl-acetate. Consequently, a proper encapsulation of DS layers is required for the optimal characterization of EQE. Moreover, the encapsulation of the DS layer substantially reduces the degradation of its luminescent properties due to UV radiation. However, the reduction of the EQE under UV radiation for the encapsulated DS layer is still high and should be substantially reduced for the integration of down-shifting properties in the lamination process of PV modules.

In this work, we compiled our research on lanthanide-based luminescent materials, prepared down-shifter layers, and studied their effect on photovoltaic (PV) mini-modules. The compounds we have prepared (C1-C17), with formulas [Eu2(phen)2(bz)6] (C1), [Eu2(bphen)2(bz)6] (C2), [Eu(tta)3bphen] (C3), [Eu(bta)3pyz-phen] (C4), [Eu(tta)3pyz-phen] (C5), [Eu(bta)3me-phen] (C6), [Er(bta)3me-phen] (C7), [Yb(bta)3me-phen] (C8), [Gd(bta)3me-phen] (C9), [Yb(bta)3pyz-phen] (C10), [Er(tta)3pyz-phen] (C11), [Eu2(bz)4(tta)2(phen)2] (C12), [Gd2(bz)4(tta)2(phen)2] (C13), [EuTb(bz)4(tta)2(phen)2] (C14), [EuGd(bz)4(tta)2(phen)2] (C15), [Eu1.2Gd0.8(bz)4(tta)2(phen)2] (C16) and [Eu1.6Gd0.4(bz)4(tta)2(phen)2] (C17), can be grouped into three families based on their composition: Series C1–6 were synthesized using Eu3+ ions and phenanthroline derivatives as the neutral ligands, and fluorinated β-diketonates as the anionic ligands. Complexes C7–11 were prepared with ligands similar to those of compounds C1–6 but were synthesized with Er3+, Yb3+, or Gd3+ ions. Series C12–17 exhibit the general formula [M1M2(bz)4(tta)2(phen)2], where M1 and M2 can be Eu3+, Gd3+, or Tb3+ ions, and the ligands are benzoate (bz–), 2-thenoyltrifluoroacetone (tta–) and 1,10–phenanthroline (phen). All compounds were characterized using X-ray techniques, and their photoluminescent properties were studied. We then examined their impact on the EQE (External Quantum Efficiency) of PV mini-modules and their durability in a climate chamber when embedded in PMMA and EVA films. This review emphasizes the methodology employed and the key findings, including enhanced mini-module efficiency. Additionally, we present promising results on the application of compound C6 in a bifacial solar cell.

Abstract The Canary Island of Tenerife is supplied by an insular power system which relies mainly on conventional thermal power plants. However Tenerife has reached grid parity in photovoltaics (PV) and wind energy. The Spanish government has just approved a new legislation to stimulate the deployment of new PV and wind energy systems in all Spanish insular systems mainly to reduce the cost of these systems. This paper analyses the current electric power system and energy production in Tenerife, especially PV and wind energy, and investigates the consequences of this new legislation and the planning initially approved by the government of the Canary Islands to substantially increase the share of both technologies in the horizon 2020. This paper shows that the Tenerife power system is technically capable of managing the ramps expected to occur in the defined near term scenarios. However, the cost per MWh will increase because of the curtailment of renewable energy generation and the operation of the thermal power system in suboptimal conditions. Some regulatory recommendations are included as conclusions.