The extension of the Electricity Act 2010 - ElWOG 2010 (latest version amended by Federal Law Gazette I No. 108/2017) to include section 16a regulates the legal entitlement to operate community energy generation facilities. This makes it possible for the first time for renewable energy generated by small-scale plants to be consumed within the community by several parties.
The figure on the left shows the state of the art with centralised domestic hot water generation via natural gas (GT=gas boiler) and a circulation pipe. On the right: the approach from PrOAGE with decentralised hot water generation by means of heat pump (WP) or resistive heating elements (DE), separate smart meter per apartment and a single central community owned PV system.
As a typical application, a multi-party house (32 units) with a PV system (38 kWP) with real production and consumption profiles is balanced in an annual simulation. Since there is a time discrepancy between generation and demand, decentralised hot water storage units (DHWH) with electric heating and known consumption profiles are taken into account as shiftable and directly controllable loads. This allows for the implementation of different control strategies in order to consume the generated PV electricity within the household community.
Starting with the classic low-tariff switching of the DHWHs as a basic scenario, results are compared with the case of heating during PV surplus and other various optimization scenarios. An increase in the degree of self-sufficiency of the entire residential building from approx. 20 % to up to 40 % can be observed. The self-consumption rate of the PV yield increases from approx. 55 % to over 90 % with optimal control. If the electricity costs are balanced, a maximum saving of approx. 8 % is achieved, but only by cost-optimized operation. In all other cases the financial savings are negligible. The total energy consumption is reduced by approx. 6 % with optimized demand-oriented switching of the MRP.
The main result of the project is that energy efficiency suffers enormously under simple control systems. If hot water storage tanks are randomly switched on at times of PV surplus in addition to the typical night charging times, without including the expected demand, the self-consumption rate. Thus the degree of self-sufficiency is increased, but the energy efficiency of the entire building system is significantly reduced.