For renewables to be used efficiently on a large scale in buildings, we need cross-technology approaches and intelligent, optimized complete systems. Working together with research partners, experts at the Austrian firm Heliotherm Wärmepumpentechnik Ges.m.b.H. are currently investigating how to combine heat pumps with photovoltaics (PV) integrated in buildings and/or solar heating systems, and to link them up to a smart grid in an intelligent, predictive way.

Here possible ways in which heat pumps and PV can interact to level loads, and the best arrangement for feeding power into/drawing it from the grid, are being assessed and suitable strategies developed. These are based on a sophisticated algorithm for the interaction between the thermal storage masses in the building, the domestic water storage tank and a user-tuned energy management system involving predictive control. Various reference buildings, facilities and control systems are comprehensively modelled in simulation tools (such as TRNSYS, Matlab), together with their interactions. A physical model of a heat pump with advanced thermodynamic cycles (desuperheater switching, steam injection) plus predictive control algorithm is being developed. The control units are set up and fine-tuned to take user behaviour, comfort criteria, energy consumption in the building, grid requirements and weather forecasts into account.

On the basis of these simulations various approaches to using heat pumps as storage and its direct linking to the PV equipment are to be improved, so as to level loads and minimize cost for the reference buildings. A direct link between PV and heat pump, and the control strategies developed, will be tested on a prototype.