Home energy management in off-grid dwellings: Exploiting flexibility of thermostatically controlled appliances

Abstract

In off-grid dwellings, proper energy management of different appliances, onsite generators and storage facilities is crucial to meet some monetary goals and environmental premises such as CO2 emissions and diesel consumption reduction. Nowadays, this task may be performed by home energy management systems, which are able to efficiently coordinate the operation of the different home assets to achieve some predefined goals. In such cases, the operation of thermostatically controlled appliances such as heating-ventilation-air conditioning systems, electric water heaters and freezers, plays a vital role as this kind of devices allow certain degree of flexibility. This way, some thermal premises (such as thermal comfort, frozen food conservation or hot water temperature set-point) can be relaxed in order to achieve other complementary goals. This work analyses this aspect by proposing a home energy management model which incorporates flexible operational modes of various typical thermostatically controlled devices. Various results are presented on a benchmark isolated home which counts with a diesel engine as backup generator. Results show that energy generated by the backup generator can be reduced by 15% by operating the thermal-based appliances in a flexible way, while other relevant indicators such as fuel consumption, fuel cost and CO2 emissions can be also improved by 12%. Other relevant aspects such as the impact of the photovoltaic array size and storage capacity are also investigated.