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Schematic diagram for a home energy management system that controls all thermal and electrical energy flows in the building and also incorporates the storage system for an electric car.
© EWE-Forschungszentrum NEXT ENERGY
Home energy management systems are designed to control energy flows

Optimising the personal use of solar power

Intelligent control of thermal and electrical energy flows in buildings: researchers from Oldenburg in Germany are currently developing and evaluating concepts for a home energy management system that utilises the sun as the sole energy supplier. This makes it more economically interesting for homeowners to use their own solar power. The new system is designed to store the solar energy decentralised and control the energy flows across time.

Rising energy prices are making the generation of solar power for personal use increasingly attractive for homeowners in economic terms. In order to ensure, however, that the yield from the homeowner’s own photovoltaic system is available around the clock, the energy produced must be initially stored on site before being subsequently utilised in an efficiently and intelligently controlled fashion. The EWE Next Energy Research Centre for Energy Technology is therefore currently developing and evaluating concepts for corresponding home energy management systems for supplying decentralised energy to residential buildings. The researchers are developing new software and hardware components for monitoring energy flows and for efficiently controlling the deployment and storage of the energy generated by the photovoltaic system. Besides decentralised electricity and heat generators, the newly conceived management system also controls intermediate electrical and thermal storage systems. “Its function is to optimally regulate the energy flows between generators, storage systems, loads and the electrical low voltage grid in accordance with the currently available radiant solar energy,” explains Dr Thilo Kilper, R&D Manager in the Photovoltaics Research Division at Next Energy.

Interdisciplinary concept development

Using the data from the simulation series, the scientists are recording how the system components interact. “For example, we can examine whether the photovoltaic installation and the intermediate storage system are optimally dimensioned in relation to consumer requirements in the building so as to achieve the highest possible on-site consumption of solar power,” emphasises Kilper. The charge and discharge characteristics of the storage system and the behaviour of additional system components can also be evaluated on this basis. By emulating existing home energy management systems with multifunctional inverters and batteries, it will also be possible to check manufacturers’ performance specifications.
Researchers from the research centre’s three focal areas – photovoltaics, energy storage systems and fuel cells – are working together on developing the home energy management system. For their work they are able to make use of a recently installed test rig for simulating solar modules, solar module strings and solar generators up to 30 kW. This is supplemented with a grid simulator and electrical loads for simulating consumer profiles. The data is based on generator profiles derived from the operating data provided by the institute’s own photovoltaic system and which depict the typical annual feed-in characteristics of a photovoltaic system in time-lapse mode. Based on these laboratory tests and simulations, the researchers are developing the comprehensive new management system.

From 24 to 28 September 2012, the scientists from Oldenburg will be presenting their initial project findings and further research activities in the photovoltaics sector at the EU PVSEC international photovoltaic conference in Frankfurt. In the next step, they are planning to carry out practical trials to verify the data, for example in collaboration with developers of solar housing estates. To achieve a management system that is as comprehensive as possible, their work also includes the integration of electric cars and stationary fuel cell systems with combined heat and power generation (CHP).
The Photovoltaics Research Division at Next Energy is also participating in the “SiliziumDS12plus” research project, which is being funded by the “Photovoltaic Innovation Alliance” under the auspices of the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU). This research project is concerned with developing highly efficient, thin-film silicon solar cells with a triple-junction structure and a stabilised efficiency of more than twelve per cent.



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