The number of Building Integrated Photovoltaic (BIPV) system installations is increasing as different new and specific solar cells and modules are developed. The great advantages of BIPV systems should be enough to achieve their massive implantation, but the difficult working conditions of the urban environment reduce the energy yield and increase the payback period of investment.In order to boost the energy yield of BIPV systems distributed PV system architectures seem to be the solution. In this sense, TECNALIA developed a new distributed DC-DC converter PV system architecture. These electronic devices, commonly called power optimizers, eliminate almost all the mismatching losses between modules and increase the system energy output.The performance of these distributed architectures is much better than centralized ones for high mismatched PV systems. However, for no mismatched cases centralized architectures present higher overall system efficiencies and energy yields. This makes the decision of which architecture is the most suitable one not so easy.In order to quantify the advantages and disadvantages in the performance of these types of architectures, the present abstract summarizes the experimental results of both architectures in real and identical working conditions. The tests have been performed in two independent PV fields, one with distributed architecture and the other one with the typical centralized one.The work carried out has consisted in generating different type of mismatching situations common in an urban environment. The tested working conditions are related to different irradiation levels, type of irradiation, orientation and inclination, shadows, dirtiness and reflexions conditions. Other aspects related to the double operation of MPPT systems (inverter and power optimizers) have also been tested.The energetic test result are presented and analyzed, showing the strengths and weaknesses of each PV system architecture.The work carried out is comprised under the Government of Bizkaia funded research project EMAITEK-FOTO. BACKGROUND

The high energy-consuming building sector needs to meet both electricity and heat demands. In a nearly zero energy building scenario, most of the consumed energy would be generated locally by means of renewable solutions that nowadays seem not to provide an attractive performance or cost-competitiveness. Solar-based technologies tend to be the most promising ones, but for high densely populated areas, the usual photovoltaic or thermal single approaches may not be efficient enough. The current work is focused on the analysis of the dual use of the solar resource by means of hybrid PVT collectors and their smart combination with direct expansion heat pumps through predictive control strategies. To that end, a system was developed, installed in a real-use single-family house at a continental climate for domestic hot water application, operated and monitored for one entire year. The average day indicator results show 83% renewable energy share, 220% self-sufficiency ratio, 41% heat pump self-consumption and 46% of the solar fraction.

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As most of PV systems, CPV systems are also affected by mismatching losses, particularly due to misalignment of optics and receivers. As a result, module level power electronics can help to increase their energy yield by making every CPV module deliver it maximum power at the output. Among the different alternatives, solutions based on DC power optimizers exhibit higher conversion efficiencies and lower costs than microinverters. However, while microinverters ensure optimal operation independently from the operating conditions, system design with DC power optimizers must be carefully examined to avoid potential underperformance. This paper describes not only the customized design and validation of a high-efficiency and economical DC power optimizer for HCPV systems, but also a comprehensive analysis of the whole system design to optimize its production under expected working conditions.