David Fischer

• Dr. Dipl.-Ing. Dipl. Wirt.-Ing
• Researcher at Fraunhofer Institute for Solar Energy Systems

The transformation of the energy system towards volatile renewable generation, increases the need to manage decentralized flexibilities more efficiently. For this, precise forecasting of uncontrollable electrical load is key. Although there is an abundance of studies presenting innovative individual methods for load forecasting, comprehensive compa...

This paper presents a stochastic bottom-up model for flexibility in the residential electric load profile. The model accounts for user-behaviour and all relevant technologies, characterising their diversity in sizing and controller settings. The flexibility of technology is mapped into a linear electrical storage equivalent model, which is parametr...

Technological progress and the ambition to de-carbonise the energy sector are changing the way electricity is generated and used. In the residential sector, more efficient electric devices, electrification of mobility and heating systems, as well as on-site PV and battery systems are the main technologies driving this change. These changes will imp...

This paper introduces a simulation framework to test agent based energy management systems during the development state. The management target is to match electrical demand and supply within a given energy community. To reach this goal, a pricing mechanism provides an economic incentive for agents to shift the controllable load to favourable times....

Long-term power-system planning and operation, build on expectations concerning future electricity demand and future transmission/generation capacities. This paper reviews current methodologies for forecasting long-term hourly electricity demand on an aggregate scale (regional or nationally), for 10–50 years ahead. We discuss the challenges of thes...

This paper introduces a control concept for aggre-gators to directly control a pool of residential heat pumps using market available technology. Smart meters are used for measuring the electric demand and the heat pumps' SG-Ready interfaces are used to trigger four different load-shifting strategies in the heat pump. The main idea of this paper is...

This paper presents the results – and the way towards them – for a field trial of a 120 kWel PEM electrolyser located within the city boundaries of Freiburg, Germany. The plant is equipped with on-site hydrogen storage and connected to the local gas and electricity network. Restrictions in gas feed-in and allowed peak electricity demand apply, and...

This paper presents a stochastic bottom-up model to assess electric vehicles’ (EV) impact on load profiles at different parking locations as well as their potential for load management strategies. The central innovation lies in the consideration of socio-economic, technical and spatial factors, all of which influence charging electricity demand and...

This paper presents a simulation study to explore the flexibility of a pool of residential combined heat and power plants (cogeneration systems) coupled with thermal storages. Flexibility is identified by sending daily trigger signals (ON and OFF) of various signal lengths to a pool of 60 micro cogeneration systems over the course of one year. A ra...

Power-to-gas (P2G or PtG) technology can provide energy storage capacity to the energy system by converting excess electrical energy into hydrogen and feeding it into the natural gas network, where it can be stored. However nowadays hydrogen feed-in has to be limited to certain percentages in order to keep the characteristics of the resulting gas m...

Der Anteil erneuerbarer Energien an der Stromerzeugung in Deutschland lag im Jahr 2017 bei rund 33 %. 2030 sollen es nach dem Willen der Bundesregierung sogar 65 % sein. Ein großer Anteil von Strom aus Wind- und Sonnenenergie macht künftig Stromspeicher erforderlich. Besonders vielversprechend ist die Konvertierung in Wasserstoff. Forschung, Indust...

The influence of different control strategies and boundary conditions on heat pump system performance are investigated in this study and the trade-off between complexity and performance of different controllers is addressed. For this purpose five different control approaches for a variable speed air source heat pump in a multi family house are comp...

Transforming our energy system towards 100% renewable energy sources requires radical changes across all energy sectors. Heat pumps as efficient heat generation technology link the electricity and heat sector. From 2010 to 2015 between 750,000 and 800,000 heat pumps have been sold every year across Europe. Those heat pumps, when connected to ther...

In this work different business models that could arise from using the flexibility of residential heat pumps in a smart grid context are analysed. The investigated applications are: operation to reduce loading of the electric distribution grid, operation at the reserve markets, operation at the EEX spot market, operation to reduce the need for bala...

In this work the response of a heat pump pool towards direct load control signals sent by an aggregator is analysed and a characteristic response is presented. The signals differ by type, duration and frequency. The used signals are based on the SG-Ready definition. It is essential to understand the reaction of heat pump pools towards direct load c...

This paper investigates heat pump systems in smart grids, focussing on fields of application and control approaches that have emerged in academic literature. Based on a review of published literature technical aspects of heat pump flexibility, fields of application and control approaches are structured and discussed. Three main categories of applic...

This paper presents and demonstrates a methodology to explore the flexibility of a heat pump pool. Three points are in the focus of this work: First the procedure to model a pool of residential heat pump systems. Second the study of the response of a large number of heat pumps when the Smart-Grid-Ready interface is used for direct load control. Thi...

Many countries in the world plan to increase their share of wind and solar power. In order to efficiently utilize large amounts intermittent renewable power, flexible consumers such as buildings with heat pumps and chillers may play a crucial role. However, it is not clear how heat pumps and chillers should be operated in order to make the best use...

Heat pump (HP) units coupled to thermal storage offer flexibility in operation and hence the possibility to shift electric load. This can be used to increase PV self-consumption or optimise operation under variable electricity prices. A key question is if new sizing procedures for heat pumps, electric boilers and thermal storages are needed when he...

Self-consumption of PV electricity has become a very important aspect for both, investment decisions as well as for calculating excessive or shortage energy supply. The objective of this paper is to identify uncertainties in the modeling process for calculating such PV self-consumption and quantify their impact. Results show: First, applying a real...

Zero Energy Buildings (ZEBs) are considered as one of the key elements to meet the Energy Strategy of the European Union. This paper investigates cost-optimal solutions for the energy system design in a ZEB and the subsequent grid impact. We use a Mixed Integer Linear (MILP) optimisation model that simultaneously optimises the building’s energy sys...

In this work the impact of a high penetration of air to water heat pumps and PV plants on the distribution grid in residential areas is investigated. Results show that increasing PV penetration increases the hours of critical states in the distribution grid. Air to water heat pumps reduce those effects slightly when they are added to the grid. With...

In 2013 83% of energy in the German residential sector is used for the preparation of domestic hot water (13%) and space heating (70%). Thermal demand profiles are essential to correctly determine operation and sizing of heating technologies. In this work, the stochastic bottom-up approach for electric loads is extended to cover domestic hot water...

Emerging infrastructure for residential meter communication and data processing carries the potential to control household electrical demand within local power system constraints. Deferral of load control can be incentivised through electricity tariff price structure which can in turn reshape a daily load profile. This paper presents a stochastic b...

Heat Pumps for heating and cooling purposes could play an important role in the future energy system. Combined with a thermal storage they offer the possibility for demand side management applications in a smart grid. Optimized utilization of local solar resources can be achieved by increasingly sophisticated control strategies. Smart gird integrat...

In the last five years the costs of photovoltaic systems have decreased considerably making it economically attractive to generate electricity locally. In many countries, self-consumption is the most attractive option to make use of the generated electricity. Variable speed heat pumps – if controlled properly – can take a share of the PV electricit...

Todays change of technical equipment in private households leads to altered domestic electric load profiles. This work investigates the change of residential electric load profiles when introducing PV, Air-Source-Heat-Pumps, CHP units and electric vehicles (EV). A modular modelling approach is presented, which allows for application on a larger sca...

Detailed knowledge of electricity demand is essential for power system planning and operation. EUs 20-20-20 targets will increase the development of more energy efficient buildings as all new buildings shall be " nearly zero energy buildings " by 2020. The result from this ambition is that so-called passive buildings and nearly-net-zero-energy-buil...

Approximately 27% of the European energy consumption is caused by the domestic sector, where 19% of the end use energy demand is caused by electric devices. To investigate the factors at play, a stochastic bottom-up model for the generation of electric load profiles is introduced in this paper. The model is designed for investigating the effects of...

The use of air source heat pumps is an efficient method to provide heat for space heating and domestic hot water in residential buildings, which cover roughly one third of the German domestic energy use. Capacity controlled heat pumps are gaining increased market share and provide high flexibility in operation. The possibility to use thermal storag...

An increased share of fluctuating renewable en- ergy generation like wind and photovoltaic (PV) in the power system has led to an increased need for capacity reserves. By providing flexibility on the demand side, balancing of fluctua- tions is possible. In this paper, air source heat pumps (ASHP) for heating and cooling in residential and office bu...

With the introduction of on-site PV production, electric cars, and more energy efficient buildings, planning and operation of energy systems are becoming more challenging as the electricity flows both to and from each customer, acting as so-called prosumers. In this context, high resolution forecasting models for both on-site production, and energy...

In the ongoing work we investigate the effects of introducing Zero Carbon Buildings (ZCB) into the energy system. In order to reach the zero balance requirement several different technologies are available. With an optimisation model we investigate the preferred technology mix needed to reach the zero carbon balance in the most cost efficient way....

Zusammenfassung Die vorliegende Arbeit befasst sich mit einem Modell zur Erstellung typischer hochaufgelöster Haushaltslastprofile. Diese stellen zur Auslegung und Regelung von dezentralen Erzeugungsan-lagen eine Alternative zu gemessenen Lastprofilen dar. Des Weiteren bieten synthetische Last-profile die Möglichkeit, verschiedene haushaltsspezifis...

Future energy supply will depend increasingly on fluctuating renewable energy generation. This requires new techniques and methods to deal with fluctuations in the grid. Thermal energy systems with thermal storage capacities linked to the electrical grid, for example, combined heat and power (CHP) and heat pump systems can provide additional and ne...