What Is Peak Shaving?
Peak shaving refers to the targeted limitation of high power imports at the grid connection point. A battery energy storage system (BESS) or controllable loads can partially compensate for demand above a defined threshold or shift it to another period. At the same time, currently available local generation reduces the measured grid import. This can lower the import capacity relevant to demand-based grid charges or contractual capacity costs.
Peak Shaving at a Glance
- An energy meter measures active power at the grid connection point. An EMS controls the available flexibility based on a project-specific target value.
- A BESS requires sufficient discharge power to reduce the height of the peak and sufficient usable energy to cover its duration.
- The economic potential depends particularly on the load profile, billing methodology, and demand charges.
- Peak shaving concerns grid import and must be distinguished from limiting power export.
How Does Peak Shaving Work Technically?
An energy meter measures the current active power at the grid connection point. It transmits these measurements to the EMS at short intervals. The EMS compares grid import with a project-specific threshold. If this threshold is at risk of being exceeded, the EMS can send a discharge setpoint to the BESS. It can also reduce or shift controllable loads. Available PV generation is considered when calculating the remaining grid import.
PV output depends on the current generation conditions. It can only reduce grid import when sufficient solar irradiation and plant capacity are available. If the PV system was previously curtailed, its output can be increased within the currently available capacity. This requires suitable technical support.
With reactive control, the EMS responds directly to measured deviations. Measurement cycles, data transmission, and response times must therefore be sufficiently short. Billing, however, is often based on average power over a defined metering interval. Individual second-by-second values are usually not the basis. At German sites with registered load measurement, the highest billing-relevant grid import power during the billing year can strongly affect the demand charge. The applicable metering interval, billing period, and calculation method must be checked in the relevant contract. This may be the grid-use or electricity supply contract.
The control system can also track the average power measured so far within the current metering interval. It considers this value alongside the remaining time in that interval. This means brief threshold violations do not always require a response at maximum available power.
Predictive control additionally uses load and PV forecasts, expected charging processes, or production schedules. It can prepare the BESS for upcoming load peaks. It can also distribute the available battery energy across prolonged or multiple peaks. When recharging the BESS, the EMS considers its state of charge and permitted charging and discharging power. It also accounts for efficiency losses, available grid capacity, and other operating objectives.
Where Is Peak Shaving Used?
- Manufacturing sites: Machine start-ups, electric heating processes, or production lines operating simultaneously can cause temporary high levels of grid import.
- Logistics and commercial sites: Cooling systems, conveyor technology, building services, and charging infrastructure can create overlapping load peaks.
- Charging parks: A BESS can temporarily provide additional charging power without requiring the entire amount to be imported from the grid.
- Sites with limited connection capacity: Peak shaving can help maintain an agreed grid import limit.
If an import limit must be reliably maintained under all intended operating conditions, additional reserves and fallback strategies are required. These can include maintaining a sufficiently high BESS state of charge, prioritised load shedding, and defined behaviour in the event of communication or component failures. Peak shaving therefore does not replace the technical and contractual assessment of the grid connection.
Benefits, Limitations, and Technical Requirements
Peak shaving can reduce demand-based grid charges or contractual capacity costs and make better use of the available grid connection capacity. Whether the application is economically viable depends on factors including the magnitude, frequency, and duration of the load peaks, the applicable pricing structure, and the investment and operating costs of the flexibility used.
Two parameters are essential when selecting a BESS: Power in kilowatts determines how far a load peak can be reduced. Usable energy in kilowatt-hours determines how long this reduction can be maintained. If the threshold is set too low, the BESS may discharge prematurely, leaving insufficient reserves for a later and higher peak. If the threshold is set too high, potential savings remain unused. Conversion losses, ageing, and available charging windows must also be considered.
Other applications, such as self-consumption optimisation, backup power reserves, or market-based schedules, may compete for the same storage capacity. The EMS therefore requires clearly defined priorities and operating limits. Suitable metering at the relevant grid connection point, reliable communication interfaces, and components that can actually be controlled are also required.
How Can Peak Shaving Be Implemented with EcoPhi?
EcoPhi can collect power measurements at the grid connection point as well as operating data from PV systems, BESS, and relevant loads. Where suitable device integrations are available, the EMS can monitor a project-specific grid import threshold and transmit charging or discharging setpoints to the BESS.
Controllable loads can also be coordinated, provided that they are connected through suitable interfaces and the corresponding interventions are included in the project scope. Multiple operating objectives can be prioritised according to project-specific requirements. Whether a function is immediately available or requires additional engineering depends on the respective plant concept and functional scope.
The specific implementation is determined particularly by the metering concept, storage sizing, required response times, supported device interfaces, and defined fallback strategies.
Conclusion: When Is Peak Shaving Useful?
Peak shaving is particularly relevant to commercial and industrial sites with pronounced, cost-relevant load peaks. It requires suitable metering, sufficient available flexibility, and a control strategy that combines economic objectives with technical limits and the necessary operating reserves.
Frequently Asked Questions About Peak Shaving
What Is the Difference Between Peak Shaving and Load Shifting?
Peak shaving aims to limit the maximum grid import capacity. Load shifting deliberately moves energy consumption or storage operation to different periods, for example in response to time-varying electricity prices. Both strategies can be combined.
Is the Power Rating of a BESS Sufficient for System Sizing?
No. In addition to discharge power, the usable energy must be sufficient to cover the expected duration of the load peak. The state of charge, efficiency, operating limits, and potential consecutive peaks are also relevant.
Can PV Alone Be Used for Peak Shaving?
PV can reduce grid import when generation and the load peak occur at the same time. Without a BESS or flexible loads, however, PV power is not available on demand. Its impact therefore depends on the time of day, weather conditions, and current plant output.
How Is the Peak-Shaving Threshold Determined?
The threshold is determined based on the load profile, billing methodology, available flexibility, and economic objective. Historical measurements and, where applicable, forecasts help balance potential savings against the required technical reserve.