Assessing the feasibility of implementing DC-microgrids in addition to USB-C and rooftop PV in households and offices: The Cases of Sweden and Spain

Sammanfattning: This Thesis’s frame is the feasibility of DC-microgrids at buildings environment. Nowadays, there is plenty of literature available regarding the benefits of implementing DC at buildings instead of AC as a means of optimizing photovoltaic generation PV on the grounds of minimizing conversion losses, with an overall energy saving of about 5-12% [1] [2]. Studies conclude that even more energy, up to 14%, could be saved if Local Energy Storage (LES) was also integrated in the equation [1]. Basing its findings on this data and on the many papers and publications that ratify these conclusions, this Thesis aims to provide a new contribution on this issue. Thanks to the baseline discussion, where all the relevant information, inputs and facts that support the hypothesis of the Thesis had been presented, the model was developed in order to assess the feasibility of implementing DC-microgrids in addition to USB-C and rooftop PV in households and offices for both countries, Sweden and Spain. Each country represents different weather condition settings but also different sociopolitical commitments to both the environment and the renewable energy generation movements, and the model this Thesis has developed, has been capable to take all of this into account and provide coherent conclusions. Different scenarios, dependent on the DC market penetration, have been carried out through the model thanks to Microsoft Office Excel. The aim of the model per se was to provide answers about the energy, environmental and economic consequences that developing a hybrid grid with both AC and DC power infrastructure have on buildings equipped with rooftop PV. Furthermore, the profitability of creating “free storage” through USB-C have been studied in two different typologies of buildings, one with the PV generation matching the consumption in time, the offices, and other without this coincidence, the households, where the demand significantly varies after the sun goes down. After optimizing the number of PV modules and the amount of electric storage for each typology of building and country, the results of the Thesis show how non-technical aspects have strong positive or negative economic consequences in both countries but, nevertheless, the implementation of the system proposed carry considerable environmental savings independently on the DC penetration. Finally, office buildings have stated themselves as the most interesting typology of building to implement the system analysed.