In this paper, an autonomous photovoltaic system is going to be designed for the North Tower of Instituto Superior Técnico through the application of solar panels on its windows, using them as producers of electricity based on solar energy. The main objectives of this paper are: (1) to make the building energetically autonomous, using an integrated system of solar photovoltaic technology;(2) check the system behaviour and comment on possible system impacts on the user's lifestyle. Two solutions are going to be proposed to cover/substitute the windows of the Tower, one using amorphous silicon panels and the other using crystalline silicon panels. Taking into account this type of solution, it is possible to recognize that there are positive impacts, such as the reduction of transmission lines/grids or the decentralisation of energy supplies. However, there are also disadvantages such as the need to have an energy storage system to guarantee the continuous supply. This study, for this building in particular, shows that organic photovoltaic cells have enormous advantages in the future in terms of our environment and social needs, but they do not yet produce the energy needed to meet today's needs. Both solutions present a return estimative time of seven years, with an initial investment of approximately two million euros, but the produced energy will not be enough to create an off-grid system.The sun serves as a giant nuclear furnace in space, constantly bathing our planet as a free energy supplier. The average amount of solar energy arriving at the top of our atmosphere is 1330 W/m 2 , however about half of this energy is absorbed by the atmosphere [4]. Among several solar energy technologies of sustainable energy sources, photovoltaic (PV) appears quite attractive for electricity generation, because it is noiseless, it has no carbon dioxide emission during operation, it is scalable, and it requires simple operation and maintenance processes [5]. Furthermore, the solar energy is costless, it does not need fuel and it is very abundant and it is easily achievable in many parts of the world. The required systems are cheap in comparison with other energy sources that are more limited sources with more expensive systems. Many scientific developments have allowed PV to be an economically and technically viable solution for many applications, from satellites to remote telecommunication systems and pocket calculators. These systems are called autonomous systems, since they produce electricity for one specific need, with no other input need [6].

Nanoscience and nanotechnology are emerging fields where some phenomena were recently discovered, allowing the design of some new devices. One of these phenomena is extraordinary optical transmission - EOT -, which was discovered in 1998 by Ebbesen. He reported that light can be amplified in certain conditions, due to a resonant behaviour, using metallic arrays. Even more, he associated this behaviour to surface plasmon polaritons and suggested that devices, as optical sensors, can be designed based on this phenomenon. To understand the surface plasmon polaritons theory, classical theories will be studied and compared with it. Also, the composite diffracted evanescent waves - CDEW -, model, which is not the most accurate model in comparison with the surface plasmon polaritons, will be presented, in order to cover an important topic on the theoretical foundations. After it, the application of nanoantennas as a sensor is going to be analysed. Finally, stationary simulations for a 16-slit gold array were performed using COMSOL Multiphysics and they are going to be presented in order to observe the occurrence of EOT.

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Currently, the nine islands of the Autonomous Region of the Azores have fossil fuel-fired power stations as the main source of electric power. Each island has an independent electrical system classified as an isolated micro-system, given its size and location. The aim of this paper is to analyse the best set of technologies to have nine sustainable hybrid systems. For this purpose, some factors will be considered, such as actual data production of the island, economic scenarios, growth perspectives of consumption and reliability of supply. The results of these studies will allow us to conclude on the applicability of these systems and to quantify the consequent socioeconomic , environmental and fossil energy-saving benefits. A system is projected to the archipelago, in order to reduce the energy production due to non-renewable energies, budgeted on 783.28 million euros, which intend to instal wind farms and photovoltaic parks (using polycrystalline and cadmium telluride technologies).

Photovoltaic technology has become a huge industry, based on the enormous applications for solar cells. In the 19th century, when photoelectric experiences started to be conducted, it would be unexpected that these optoelectronic devices would act as an essential energy source, fighting the ecological footprint brought by non-renewable sources, since the industrial revolution. Renewable energy, where photovoltaic technology has an important role, is present in 3 out of 17 United Nations 2030 goals. However, this path cannot be taken without industry and research innovation. This article aims to review and summarise all the meaningful milestones from photovoltaics history. Additionally, an extended review of the advantages and disadvantages among different technologies is done. Photovoltaics fundamentals are also presented from the photoelectric effect on a p-n junction to the electrical performance characterisation and modelling. Cells’ performance under unusual conditions are summarised, such as due to temperature variation or shading. Finally, some applications are presented and some project feasibility indicators are analysed. Thus, the review presented in this article aims to clarify to readers noteworthy milestones in photovoltaics history, summarise its fundamentals and remarkable applications to catch the attention of new researchers for this interesting field.

At nano-scale new phenomena have been discovered, allowing devices' miniaturisation, energy harvesting, and power reduction. The Extraordinary Optical Transmission (EOT) phenomenon was reported in 1998 by Ebessen, who stated that the resonant peaks in the response of metallic nano antennas were more intense than predicted by classical diffraction theories. Years later, the main reason for this behaviour was attributed to the Surface Plasmon Polaritons (SPP), at least in ultraviolet and visible regions. In this article, a new method to model the radiation-matter interaction on a dielectric-metal interface is proposed, based on Maxwell's equations and Fresnel Coefficients in absorbing media. Transmission percentage, angle and propagation length are obtained for a rigorous sweep on incident angle and wavelength.The results taken using some noble metals allow us to observe the presence of surface phenomena at expected SPP resonances. First, it is noticeable huge values of transmission in ultraviolet and visible regions, meaning that the metal does not reflect all the radiation. Also, the transmission angle tends to be higher, meaning huge surface components. Furthermore, the transmission length is on orders of 50-100 nm, meaning that phenomena as EOT only occurs at the nano-scale, since waves should arrive at another interface before being absorbed.

Currently, huge opportunities for the inclusion of new optical devices in our lives have been appearing. There are evident and irrefutable examples for nanoantenna applications. They can be used to improve already developed devices or even be used as the device. In both cases, they can be applied in diverse areas, such as medicine, environment, energy, defense, and communications. A square arrayed metallic nanoantenna composed of circular holes is studied by performing simulations using COMSOL Multiphysics. This article aims to study the influence of the nanoantenna’s metal, silver, gold, copper and aluminum, but also the optical response dependence on the nanoantenna’s periodicity, its thickness, the hole diameter, and the number of holes. It is evidenced that the optical response can be tuned using the structure parameters and by choosing an appropriate material. This tuning will allow developers to fulfil the specifications, since it is proven that the response peak can be deliberately shifted, amplified, or attenuated.

In the last decade, the development and progress of nanotechnology has enabled a better understanding of the light–matter interaction at the nanoscale. Its unique capability to fabricate new structures at atomic scale has already produced novel materials and devices with great potential applications in a wide range of fields. In this context, nanotechnology allows the development of models, such as nanometric optical antennas, with dimensions smaller than the wavelength of the incident electromagnetic wave. In this article, the behavior of optical aperture nanoantennas, a metal sheet with apertures of dimensions smaller than the wavelength, combined with photovoltaic solar panels is studied. This technique emerged as a potential renewable energy solution, by increasing the efficiency of solar cells, while reducing their manufacturing and electricity production costs. The objective of this article is to perform a performance analysis, using COMSOL Multiphysics software, with different materials and designs of nanoantennas and choosing the most suitable one for use on a solar photovoltaic panel.