Dynamic energy management approach uses PV and batteries

02 Mar 2023

Fraunhofer ISE method to offset power fluctuations combines solar power with grid and storage.

A long-discussed challenge facing the widespread adoption of renewable energies is the fluctuating output of photovoltaic systems — for energy-intensive companies, this means that their distribution networks can rapidly become inadequate.

Now researchers at the Fraunhofer Institute for Solar Energy Systems (ISE) have come up with a solution that combines power from renewable sources with electricity from the public grid and uses batteries to compensate for fluctuations.

This approach is expected to benefit companies that aim to invest in sustainability with photovoltaics — and reduce their energy costs in the process. A living laboratory, which mimics practical conditions, will give industry customers the opportunity to test components and system solutions. The solution also allows for a more efficient management of e-car charging stations.

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Increasingly, industrial companies are using energy from renewable sources, such as photovoltaics, in addition to the public power grid. But wind and solar power outputs fluctuate, making energy management a complex task. Batteries are set to play an important role in solving this problem: They serve as buffers and compensate for fluctuations in electrical power. If industrial companies with photovoltaic systems installed on their roofs can successfully combine self-produced electricity generated from photovoltaics with electricity from public grids, they stand to benefit enormously.

There is growing demand to do just that, as energy prices are currently rising dramatically. ISE, based in Freiburg, Germany, is addressing this need with the Haid-Power project. The Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut, EMI are partners.

Comprehensive energy management

“We are developing a solution that companies in the manufacturing industry can use to combine photovoltaics with battery storage in order to supplement their energy and power needs,” said Felix Stortz, a research scientist in the Applied Storage Systems group at ISE – the largest solar research institute in Europe.

The concept is simple: The software is fed consumption data from all manufacturing machines, as well as data on the status and charging capacity of the batteries that are charged using solar power. “The energy management system can then determine how much power the on-site batteries can supply and how much power must be drawn from the public grid,” said Stortz.

By more effectively exploiting the potential of renewable energies, companies can reduce their CO₂ emissions while saving on electricity costs. Smart energy management also helps avoid the need for major investments, such as installing new power lines.

Predictive capabilities

The intensity of solar radiation can sometimes be predicted days in advance — so the same is true for the output of photovoltaic systems. This information, in combination with readily available data on typical rates of energy consumption for all the manufacturing machines, can enable the software to make predictions.

In principle, electricity prices could also be considered in this planning process: batteries could act as a buffer during pricing peaks. Current data on the machines’ energy consumption flow into the system through smart meters, as does the current status of the batteries. This means the system can react at any time, for example if a machine has to be started up at short notice.

One core component of this solution is its integrated load management. While energy management is the primary tool involved in the overall strategy of producing and consuming energy from various sources, load management serves as a tool for reacting to consumption peaks.

For example, if an energy-intensive system, such as a furnace, is put into operation when the charging capacity of the energy storage units is exhausted, then more power must be drawn from the public grid.

“It could also be possible to run machines at a later time, when the batteries are charged — provided that the production process allows for this,” said Stortz. “It is also possible to implement a system whereby operation takes place on the company’s own server and can be controlled via the internet.