Power balance control and dimensioning of a hybrid off-grid energy system for a Nordic climate townhouse

This paper investigates conversion of a Nordic oil-heated townhouse into carbon-neutral by different energy efficiency (EE) improvements and an off-grid system including solar photovoltaics (PV), wind power, and battery and hydrogen energy storage systems (BESS and HESS). A heat-pump-based heating system including waste heat recovery (WHR) from the HESS and an off-grid electrical system are dimensioned for the building by applying models developed in MATLAB and Microsoft Excel to study the life cycle costs (LCC). The work uses a measured electrical load profile, and the heat generation of the new heating system and the power generation are simulated by commercial software. It is shown that the EE improvements and WHR from the HESS have a positive effect on the dimensioning of the off-grid system, and the LCC can be reduced by up to euro2 million. With the EE im-provements and WHR, the component dimensioning can be reduced by 22%-41% and 13%-51% on average, respectively. WHR can cover up to 57% of the building's annual heat demand, and full-power dimensioning of the heat pump is not reasonable when WHR is applied. Wind power was found to be very relevant in the Nordic conditions, reducing the LCC by 32%.

Automated summary

This paper investigates the conversion of a Nordic oil-heated townhouse into a carbon-neutral building by implementing energy efficiency improvements and an off-grid system with solar photovoltaics, wind power, and battery and hydrogen energy storage systems. The study uses MATLAB and Microsoft Excel to determine the dimensioning of a heat-pump-based heating system and an off-grid electrical system, based on life cycle costs (LCC). The results show that energy efficiency improvements and waste heat recovery from the hydrogen energy storage system have a positive impact on the dimensioning of the off-grid system, reducing the LCC by up to 2 million euros. Wind power is found to be highly relevant in Nordic conditions, reducing the LCC by 32%.