Amp it up: Why you need peak shaving and virtual grid expansion

What happened?

The site’s grid connection point (GCP) couldn’t handle all the vehicles plugged in at once. And to make matters worse, weeks later, the charge point operator (CPO) or car park owner isn’t just dealing with unsatisfied customer reviews — they’re also hit with a steep bill based on their highest 15-minute peak of the month. That’s a one-two punch of letting down the customer and unexpected costs… all from a momentary overload.

Smarter energy for smarter charging

As electric vehicle (EV) adoption accelerates, charging infrastructure needs to grow just as fast. But for CPOs, car park operators, and facility managers, that expansion is increasingly challenged by grid limitations and rising electricity costs.

That’s where battery energy storage and intelligent load management come into play.

Two powerful strategies – peak shaving and virtual grid expansion – can help operators deliver reliable, scalable EV charging without blowing their budget or the grid. While they work in similar ways, each approach is tailored to different site conditions. In this article, we’ll break down what they are, how they work, and how to decide which solution fits your site best.

Peak shaving and virtual grid expansion: How they’re connected

Peak shaving is designed to limit short-term demand spikes – particularly important in regions with high demand charges or time-based billing structures. It’s a cost-saving technique used to reduce electricity expenses by minimizing high demand and thereby lowering peak charges. These peaks are measured in timed intervals, which fluctuate from country to country, although many use 15-minute intervals. For example, Germany, Austria, the Netherlands and Switzerland all use 15-minute intervals, while Belgium uses 10-minutes and the UK uses 30-minutes.

For EV chargers, peak shaving works best at sites where the grid is not frequently congested, but brief peaks in load can trigger high electricity costs. By managing these short surges in demand, CPOs can significantly lower their energy bills.

Virtual grid expansion

Virtual grid expansion is an extension of peak shaving. It’s used when a charging site consistently hits its grid capacity limit or faces frequent power curtailment. In these scenarios, "virtually” expanding the GCP with a battery is an attractive option. Virtual grid expansion allows the site to operate as though it has a larger grid connection by using battery storage to buffer loads. This helps maintain full charging operations even when the physical grid can't meet the demand.

In short:

• Peak shaving = lower costs in non-congested grids with short-term demand spikes
• Virtual grid expansion = increased operational capacity in congested grids with frequent curtailment

Depending on the location, grid access and charging behavior, CPOs may benefit from one strategy or the other — or even a combination of both.

The problem with rising demand for EV charging and grid limitations

One of the most pressing issues for businesses operating EV chargers is the burden of peak demand charges. These charges are calculated based on the highest amount of power drawn from the grid during a specific period, often 15-minute intervals. In some regions, such as Germany, customers may be billed for their worst 15-minute peak of the month, with costs reaching up to €100/kW per year for industrial customers. For instance, if a site's highest 15-minute peak over the last year was 115kW, the operator would face an annual charge of €11,500. This incentivizes reducing peak demand to significantly lower costs. 

Peak shaving helps by lowering those spikes without notably affecting charging volume, either by reducing charging power or by discharging from a battery during the peak period, ensuring your grid-drawn power stays below a defined target. This approach, also referred to as “billing interval optimization” (to account for the different timing intervals across Europe), is ideal for avoiding high charges due to occasional power surges.

In more congested grid areas, the challenge isn’t just cost — it’s capacity. Many CPOs can’t install more chargers or operate them at full power because their grid connection is already maxed out – and grid upgrades can take years. In fact, industry reports show that 50–80% of potential EV charging sites face constrained or insufficient grid connections. Upgrading a grid connection to supply higher power can take 1–3 years of permitting and construction, with upfront costs often between €150,000 and €3 million (averaging around €500k per site). These steep costs and long timelines make it impractical for CPOs and car park owners to scale up charging infrastructure quickly. 

This is where virtual grid expansion comes in. By charging a battery during off-peak times or when PV energy is available, and discharging it when charging demand is high, operators can serve more EVs than the existing grid connection would normally allow. It’s a way to grow your infrastructure – virtually – without waiting on utility reinforcements.

Peak shaving and electricity curtailment

At gridX, when we talk about peak shaving, we’re really talking about intelligently curtailing power (i.e., optimizing peak shaving) – specifically, reducing EV charging load in real time to avoid exceeding costly demand thresholds.

Because demand charges are based on the highest 15-minute average consumption in a billing period, without intervention, a sudden surge – like multiple EVs starting to charge at full power – can trigger a massive spike in that window, resulting in high annual grid fees. gridX’s system avoids that by automatically limiting charging power during those moments. This Dynamic Load Management (DLM) approach ensures that the site's total power draw stays within a defined cap – without impacting the user experience over the long term. Cars may charge slightly slower during peaks, but overall energy delivery is optimized.

So rather than using a battery to fill in during high-demand periods (as in traditional battery-based peak shaving), gridX’s peak optimization strategy works by flattening the load curve through smart, software-driven curtailment.

Using virtual grid expansion in a car park

Virtual grid expansion is all about unlocking more usable capacity without upgrading the grid. A battery is installed onsite and strategically charged:

• When PV generation is high (if solar is available)
• During off-peak grid hours
• When EV charging demand is low

The stored energy is then discharged during periods of high charging activity, enabling the site to temporarily exceed its grid connection limit — without overloading the grid. This is especially useful when:

• The grid connection is frequently congested
• Charging demand regularly exceeds grid limits
• Grid curtailments force operators to throttle charging or reject new sessions

In these cases, virtual grid expansion is less about reducing costs and more about expanding capability – giving operators the flexibility to meet growing EV charging demand without having to curtail due to limited grid capacity.

Why add a battery to an EV charging site

At an EV charging site, adding a battery unlocks the ability to virtually expand your grid connection and reduce reliance on expensive grid power. This is especially useful when the existing connection can't keep up with charging demand.

The battery is charged during periods of low demand or when cheaper energy is available. This could mean either:

• Surplus solar energy from on-site PV installations
• Low-cost electricity available during off-peak hours, often through dynamic or time of use (ToU) tariffs

Instead of using costly grid power during high-demand periods, the battery stores this “cheap energy” – whether solar or ToU – for later use. Then, when charging demand spikes (e.g., several EVs plugging in at once), the battery discharges to cover the extra load. This keeps the site's grid consumption below the contracted limit, avoiding overloads, tripped breakers and demand charges based on short-term consumption peaks.

By acting as a buffer, the battery allows operators to:

• Serve more vehicles at full charging speed
• Stay within their grid connection limit
• Avoid triggering grid expansion or reinforcement projects

Just like a home battery system plus EMS saves end users money by storing cheaper energy for evening use, a battery at a charging site helps operators avoid pulling expensive power during peak periods. 

Battery-reinforced peak shaving makes otherwise costly grid expansions unnecessary. Instead of spending huge sums and waiting years to upgrade the local substation and cables, the operator can rely on the battery to buffer the power.

Benefits for CPOs and car park operators

Implementing either peak shaving or virtual grid expansion at EV charging sites yields several key benefits for charge point operators, car park owners and facility managers:

• Cost reduction: Peak shaving minimizes exposure to costly demand charges. By avoiding short-term spikes, operators reduce their monthly energy bills without affecting user experience.
• Grid independence and expansion: Virtual grid expansion lets you grow your charging footprint without waiting on utility upgrades. Add more chargers, serve more EVs — all with your existing connection.
  Improved reliability: Battery-reinforced systems ensure stable charging performance during busy periods. Whether it’s shaving a peak or covering a curtailment, batteries provide flexibility and resilience.
• Customer loyalty: Ensure better charging speeds for the EV drivers that improves overall user experience at the charging location.
  Revenue opportunity: CPOs can sell more energy with virtual grid expansion as they do not have to curtail when the limits are reached. Instead, they can use the battery energy to meet EV charging demand that is above the limit.

Peak shaving is typically relevant when you have a non-congested grid and just need to smooth out short demand spikes — like when all cars plug in at once in the morning. But virtual grid expansion is really beneficial when your grid is constantly congested and you’d otherwise have to curtail charging. It lets you serve more vehicles without overloading your connection.” – Lars Rheinemann, Solution Engineer, gridX

Which strategy to use for a charging site

Don’t leave your customers on empty

EV charging infrastructure is under pressure – from rising energy costs, grid bottlenecks and accelerating demand. Smart strategies like peak shaving and virtual grid expansion allow charge point and car park operators to meet these challenges with agility.

Remember the EV driver at the shopping center — the one who plugged in and walked away, only to find their car barely charged upon their return? With the right solution in place, that site could have avoided this situation: both the weak charge experience and the costly demand spike. With a well-implemented peak shaving system, the charging power would have automatically reduced to stay below the 15-minute threshold. A virtual grid expansion setup could have used stored battery energy to cover the excess load – keeping the chargers steady, the grid stable and the customer happy.

Ultimately, these tools aren’t just about optimizing kilowatts – they’re about ensuring seamless, reliable charging experiences that scale with demand, without breaking the grid or the budget. With gridX’s intelligent energy management solutions, CPOs can make data-driven decisions about which strategy – or combination – fits best. It’s time to move beyond constraints and unlock the full potential of your charging network.