Load Profiles in Grid-Connected Residential Buildings: Experimental Studies with Rooftop PV and Battery Systems

摘要

The number of photovoltaic (PV) installation in many countries has increased in the past decades. The advantages of energy from PV consists of reduction of CO2 emission, low maintenance cost, low operation cost, etc. On the other hand, the main problems of this technology consist of: (1) electrical power is relatively fluctuated and (2) the excessive energy from PV generating cannot be stored for any use in another necessary time. One of the solving solution is the integration of the PV systems with battery systems to keep the system stability. Moreover, the reduction of battery price leads the electricity users interest in the installation of battery systems with rooftop PV on their buildings. In the past, a number of works studied on PV systems with integrated batteries as the off-grid systems and evaluated by simulation programs. In this work, the load profiles of buildings in different categories (i.e. households, small offices, and home offices) of residential section are discussed. The characteristics of load profiles in residential buildings installed with a grid-connected rooftop PV system with batteries are analyzed by physical experimentations. It was found that battery systems were significantly affected the load profiles of the residential buildings. Household was found to be the highest proportion (21.68%) of excessive electricity. The ratio of PV met to load (29.15%) was smaller than the ratio of battery charging (50.17%). In addition, the excessive electricity in small office was the lowest proportion (10.39%), while the ratio of PV met to load (57.83%) was higher than the battery charging (31.78%).