Electric load in the domestic sector and its modulation by building integrated photovoltaic : findings of a detailed monitoring study of energy consumption in UK buildings

The future energy supply is highly likely to be a mix of central and decentralised energy sources, therefore knowledge of on-site generation, such as photovoltaic systems, and energy consumption patterns with a good degree of certainty will be necessary to ensure the current quality of supply that we enjoy at present from non-renewable resources. This thesis describes the outcome of a detailed electric energy monitoring campaign on 5 different sites in a total number of 81 households predominantly undertaken in the social housing sector in the United Kingdom. The 5 minute data (and 1 minute short term) have been derived during the Department of Trade and Industry Photovoltaic Domestic Field Trial Program, where over a period of two years electric energy consumption by the households and electric energy generation by their photovoltaic systems were monitored by the author as part of this study. The consumption data obtained underwent a detailed analysis in order to give an understanding of the characteristics of the electric load in terms of base load, peak load, the load fluctuation and the energy consumption. The measured electric load profiles were separated into weekday and weekend profiles, and summer and winter profiles were also derived. The results are presented as overall load profiles for the entire set of dwellings as site specific load profiles and, for a smaller number of dwellings, as dwelling specific load profiles. Another outcome of this research is the development of several publicly available measured annual data sets suitable for use in modelling (5 minute interval data). The findings of this energy consumption analysis and the long term real data sets can be used for computer modelling purposes in general, but particular in the field of on-site generation, where the need for available realistic data sets is immense. In order to create a link between the energy consumption characteristics and socio-economic factors an occupant survey was undertaken among the people living in the monitored dwellings. The survey included questions regarding the following aspects: the number of tenants living in the household, tenant's age, ownership of electrical appliances and the general times of use of appliances and occupancy in the household. The results of this survey, carried out in 46 dwellings, can be applied to improve electric load models in general and especially the parts of the models that present the social housing sector. The findings will also help to investigate the options of load shifting, based on the time of use analysis of the 17 appliances. This study has investigated the options of reducing the electric load in the domestic sector by building integrated PV-systems. Therefore the influence of simulated PV-generation profiles on the recorded electric load profiles was analysed. The outcome can help to size PV-systems when the direct use of the PV-energy in order to reduce losses in the public grid is desired. The findings of this study are also of use when knowledge is required on the electric demand of small networks when connected to a large PV-generator as opposed to the connection of one dwelling to one small PV-system. The results can be used to size storage systems (e.g. batteries) if a self sustaining schedule of dwellings is needed. The findings of this study were used in the International Energy Agency Energy Conservation in Buildings and Community Systems Annex 42 to provide the profiles needed for modeling the performance of Fuel Cells and Cogeneration systems in residential properties