Transmission system operator TransnetBW is testing power grid stabilization using “Powerwall” photovoltaic home storage systems from U.S. energy and mobility company Tesla. During periods of high load or low feed-in, the power grid is relieved by postponing the charging of the batteries, with the solar plants feeding power into the public grid as needed and as instructed by TransnetBW. This helps to stabilize the power grid in a cost-efficient, resource-conserving and climate-neutral way.
“Our goal is to support the move away from fossil fuels as quickly as possible and at a reasonable cost to power grid operations by intelligently integrating decentralized flexibilities into the grid,” explains Dr. Rainer Pflaum, CFO of TransnetBW and responsible, among other things, for the Grid Business unit, which is home to the pilot project. The field trial, which will initially run for six months, also aims to gather experience on the availability and predictability of flexibility potential, which will be used in the preparation of a standardized mechanism, known as Redispatch 3.0. Through the cooperation of consumers and grid operators, renewable energies are efficiently integrated into the power grid and climate neutrality is further advanced.
For this purpose, TransnetBW took a closer look at the charging cycles of Tesla Powerwalls and found that PV home storage systems have degrees of freedom for flexible charging from the PV system in some months. This time margin between generation and load, the so-called flexibility, can be used by intelligent control: By selectively postponing the battery charging process, householders do not suffer any disadvantages. For participating PV home storage owners, this shift could even mean additional financial reward in the future. In turn, the grid operator can potentially use the generated PV power to reduce grid congestion (positive redispatch). Up to now, fossil-fired power plants have been used primarily for the latter.
“With PV Shift, we are entering new territory, which we are opening up step by step. The elimination of conventional power plants is offset by the enormous demand for e‑cars, heat pumps and solar systems with battery storage. Practical experience in the interaction between grid operators, system providers and end consumers is of central importance for the development of the electricity system of the future,” says Dr. Sabrina Ried, project manager of PV-Shift. For the field test, TransnetBW receives free flexibility potential from a limited number of stationary powerwalls. Tesla acts as an aggregator here and forms the interface between home storage owners and TransnetBW, which uses the power to stabilize the power grid when needed.
TransnetBW already had the economic potential for using decentralized flexibility for redispatch in Baden-Württemberg examined last year by a short study conducted by the University of Stuttgart. The result: In Baden-Württemberg alone, there is potential in the triple-digit million euro range. The company now intends to gradually raise these. The launch of the PV Shift project is an important building block for this. By the end of the year, the project is expected to produce its first results.