• Energy Research

On-site photovoltaic (PV) and battery systems intend to improve buildings energy performance, however battery costs and monetary incentives are a major drawback for the introduction of these technologies into the electricity grids. This paper proposes an energy refurbishment of an office building based on multi-objective simulations. An innovative demand-side management approach is analyzed through the PV and battery control with the purpose of reducing grid power peaks and grid imported energy, as well as improving the project economy. Optimization results of load matching and grid interaction parameters, complemented with an economic analysis, are investigated in different scenarios. By means of battery use, the equivalent use of the grid connection is reduced by 12%, enhancing the grid interaction potential, and 10% of load matching rates can be increased. Project improvements indicate the grid connection capacity can be reduced by 13% and significant savings of up to 48% are achieved on yearly bills. The economy demonstrates the grid parity is only achieved for battery costs below 100 €/kWh and the payback period is large: 28 years. In the case with only PV system, the grid parity achieves better outcomes and the payback time is reduced by a half, making this a more attractive option.

Abstract One of the main characteristics of the Solar Decathlon Europe houses is that they run exclusively on solar energy, as part of the requirements of this worldwide competition for universities. This obligation stimulates the university Teams to search for innovative solutions to integrate photovoltaic technologies in their houses, searching for the best options that combine design with energy efficiency, energy performance and construction. The main tendencies, advances and solutions are presented.

Abstract Due to its zero-marginal-cost, the high penetration of renewable energy sources in the electricity markets threatens incumbents’ business models who are gradually shifting towards fixed power charges instead of the traditional energy charges. The purpose of this study is to assess the impacts of these fixed power charges on the economics of PV systems under self-consumption schemes. Using real demand and generation data, simulations include detailed computation of annual billing savings, payback-time, self-consumption and self-sufficiency of a dwelling coupled with PV-battery system. A range of PV array and battery sizes are explored for different storage control strategies. Billing scenarios include a) only energy charges, b) Portuguese case (high energy charges and low fixed charges), c) Spanish case (low energy charges and high fixed charges), and d) only fixed charges. Results show that fixed charges require adding storage to residential PV systems. In spite of battery relative high costs, results also show that photovoltaics can be profitable with payback times below 10 years in all scenarios, as long as appropriately sized and with the suitable storage control strategy.

In this paper, a methodology for the integral energy performance characterization (thermal, daylighting and electrical behavior) of semi-transparent photovoltaic modules (STPV) under real operation conditions is presented. An outdoor testing facility to analyze simultaneously thermal, luminous and electrical performance of the devices has been designed, constructed and validated. The system, composed of three independent measurement subsystems, has been operated in Madrid with four prototypes of a-Si STPV modules, each one corresponding to a specific degree of transparency. The extensive experimental campaign, continued for a whole year rotating the modules under test, has validated the reliability of the testing facility under varying environmental conditions. The thermal analyses show that both the solar protection and insulating properties of the laminated prototypes are lower than those achieved by a reference glazing whose characteristics are in accordance with the Spanish Technical Building Code. Daylighting analysis shows that STPV elements have an important lighting energy saving potential that could be exploited through their integration with strategies focused to reduce illuminance values in sunny conditions. Finally, the electrical tests show that the degree of transparency is not the most determining factor that affects the conversion efficiency.

During the last decades, the photovoltaic (PV) modules and their associated architectural materials are increasingly being incorporated into the construction of the building envelope such as façade, roof and skylights in the urban centers. This paper analyzes the-state-of-the-art of the PV elements and construction materials which are advertised as BIPV-products at the most important companies in the world. For this purpose 136 companies and 445 PV elements have been investigated and analyzed from a technical and architectural point of view. Also, the study has been divided into two main groups according to industry which producing the product: BIPV-Modules, which comes from the PV modules manufacturers and consist of standard PV-modules with some variations in its aesthetic features, support or dimensions; and PV-Constructions Elements, which consist of conventional constructive elements with architectural features intentionally manufactured for photovoltaic integration. In advance for conclusions, the solar tile is the most common PV-constructions element, the Si-crystalline is the most widely used PV technology, and the BIPV-urban furniture is the fastest growing market experienced in recent years. However, it is clear the absences of innovative elements which meet at the same time both the constructive purpose as the quality standards of PV technology.

This paper presents the operation of an Electrical Demand-Side Management (EDSM) system in a real solar house. The use of EDSM is one of the most important action lines to improve the grid electrical efficiency. The combination between the EDSM and the PV generation performs a new control level in the local electric behavior and allows new energy possibilities. The solar house used as test-bed for the EDSM system owns a PV generator, a lead-acid battery storage system and a grid connection. The electrical appliances are controllable from an embedded computer. The EDSM is implemented by a control system which schedules the tasks commanded by the user. By using the control system, we define the house energy policy and improve the energy behavior with regard to a selected energy criterion, self-consumption. The EDSM system favors self-consumption with regard to a standard user behavior and reduces the energy load from the grid.

AbstractElectricity power systems worldwide have traditionally been designed to a vertically connected scheme characterised by centralised generation. Over the last few decades, several factors have dictated a gradual shift from the central‐control approach to a more distributed layout where distributed generation (DG) technologies are effectively integrated and not just connected (appended) to the networks; amongst others liberalisation of electricity markets, security and quality of supply and environmental issues. Photovoltaic powered distributed generation (PV‐DG), although still having a much lesser impact than other DG technologies, is increasingly being embedded into electricity distribution networks worldwide within the framework of successful regulatory state and marketing programmes. PV‐DG has added values (benefits) for the electricity systems that extend from peak power and load reduction (when deployed close to electricity consumption points) to participation in grid‐supporting or grid‐forming modes of operation. The question arises as to what the present situation of PV technology is for its optimal integration in distribution networks, whether there are still technical barriers to overcome as well as new opportunities for PV in future renewably supplied electricity systems. This paper presents the current state of knowledge concerning these topics from a European perspective with regard to different grid structures. It also discusses existing standards, new opportunities to provide grid services and research and development needs identified to fully exploit the added‐value—and still developing—benefits of PV‐DG. Copyright © 2008 John Wiley & Sons, Ltd.

The fragile ecosystem of the Galapagos Islands is being affected by population growth, intensive tourism, the exploitation of local resources and the high consumption of imported fossil fuels. This unsustainable development model makes the provision of services such as electricity a challenge. This research investigates the hybrid renewable mini-grid Baltra–Santa Cruz, which represents 62% of the electricity generation mix of the archipelago. This study aims to support the Galapagos Zero Fossil Fuel Initiative and the Sustainable Development Goal 7 through the reduction in diesel consumption and electricity generation costs. To do so, HOMER Pro, a specialized hybrid renewable mini-grid planning tool, is used to perform several techno-economic assessments, focusing on different electricity demand scenarios. Therefore, multiple pathways are compared to identify the most reliable alternatives towards the progressive decarbonization of this hybrid system. The results indicate that installing 18.25 MWp of photovoltaic and 20.68 MWh of battery capacity could reduce the Levelized Cost of Electricity (LCOE) from 32.06 to 18.95 USc/kWh, increasing the renewable energy (RE) share from 18% to 39%. Additionally, the successful application of energy efficiency measures would even reduce the LCOE to 17.10 USc/kWh. What is more, distributed energy is considered the most attractive way to involve islanders in the energy transition process. Finally, this paper offers a comprehensive business model proposal to achieve a resilient energy supply, based on a combination of auctions and energy community models, which demands high political will, reliable and innovative regulations and social awareness about energy use.