Peak Shaving: How to avoid power cuts with solar batteries

What is peak shaving and why is it essential?

Peak shaving is a smart energy management strategy that involves reducing spikes in electricity consumption by temporarily drawing power from storage batteries. This technique prevents your installation from exceeding the power capacity contracted with your electricity supplier, thereby eliminating unwanted trips of the main circuit breaker.

Imagine a business with a 36 kVA electricity contract. When several energy-intensive appliances start up simultaneously, instantaneous consumption can reach 46 kVA for a few minutes. The meter then triggers a safety cut-out, interrupting operations and causing potentially significant financial losses.

“Outages caused by power surges last only a few minutes, but can occur two or three times a year. For a business, this is simply unacceptable.”

Peak shaving solves this problem by detecting excessive power demands in real time and instantly supplying the missing energy from lithium batteries. The electricity grid then ‘sees’ only the authorised consumption, whilst the surplus is offset by local storage.

Typical situations requiring peak shaving

• High-consumption commercial activities: car washes, production workshops, supermarkets with cold stores
• Simultaneous start-ups of equipment: pumps, compressors, industrial air-conditioning systems
• Existing photovoltaic installations without storage capacity or smart load management
• Savvy households with irregular consumption patterns (electric vehicles, heat pumps, heated swimming pools)

Why can’t all inverters perform peak shaving?

There is often confusion: simply having solar panels and an inverter does not guarantee the ability to perform peak shaving. Here’s why:

Conventional inverters: generation without storage

Standard photovoltaic inverters (such as many basic models from Sofar, SMA or Fronius) are designed to convert solar energy into usable electricity and feed it into the grid or consume it locally. Their main function is DC/AC conversion, not battery management or rapid response during consumption peaks.

These devices excel in their field, but they lack the following features:

• Communication with lithium batteries (CAN/RS485 protocols)
• Real-time detection of power demands via smart meters
• Instantaneous injection of stored energy (response time of less than 1 second)
• Management of charge/discharge cycles according to site requirements

Hybrid inverters: the key to peak shaving

Conversely, hybrid inverters incorporate these capabilities natively. They act as energy conductors, coordinating three flows simultaneously:

1. Solar generation: management of photovoltaic panels
2. Storage: intelligent charging and discharging of batteries
3. Grid: feeding into or drawing from the grid according to immediate needs

Real-life case study: securing a business

Let’s take the concrete example of an existing photovoltaic installation facing recurring power cuts:

Initial situation

Technical diagnosis

Analysis reveals that the power cuts occur when energy-intensive equipment is switched on simultaneously. The existing inverter, whilst excellent for solar generation, cannot store energy or intervene during peak demand. The solution therefore requires a partial overhaul of the installation.

Implemented solution

The strategy adopted is based on three technical pillars:

1. Replacement of the main inverter with a hybrid model

The Deye 15K inverter (15 kVA three-phase) takes over the management of the existing panels whilst providing storage and peak shaving capabilities. Its key features for this application: 🔗 See technical data sheet

• Continuous output power: 15 kW per phase
• Compatibility with high-voltage batteries (CAN/RS485 protocol)
• Input for external smart meter (total consumption measurement)
• Feed-in response time: < 500 ms
• Programmable operating modes (peak shaving, backup, self-consumption)

2. Storage sizing: power before capacity

A crucial point that is often misunderstood: for peak shaving, discharge power takes precedence over total capacity. It must be possible to supply 10 kW instantly to bridge the gap between the 36 kVA contracted and the 46 kVA consumed.

The chosen configuration: 6 Pylontech US5000 batteries (4.8 kWh each, totalling 28.8 kWh).

Why 6 units and not 4? Two compelling technical reasons:

• Cumulative discharge power: 6 × 1.6 kW = 9.6 kW available continuously, covering the required 10 kW with a safety margin
• State of Charge (SOC) protection: even at 50% charge, the batteries can still supply the required power without triggering safety shutdown

“Insufficient power capacity would cause the BMS (Battery Management System) to halt discharge during a significant peak, negating the intended protective effect.”

3. Installation of a smart meter for real-time detection

The challenge with this installation: the inverter is located 56 metres from the main meter. For the system to detect spikes instantly and activate the batteries, the following is required:

1. Install a three-phase smart meter immediately after the main circuit breaker
2. Connect this meter to the inverter via a communication cable (RS485 or Ethernet)
3. Configure the inverter to ‘peak shaving’ mode with an intervention threshold (36 kVA)

The communication cable can be a standard Cat5e/Cat6 network cable (Ethernet type), or even a wireless connection via RS485 wireless modules to avoid long-distance cabling work. Although the latter option is more expensive, it greatly simplifies installation in existing buildings.

Results achieved

The multiple benefits of peak shaving with storage

Beyond peak shaving, this solution offers additional benefits that are often underestimated:

Optimisation of photovoltaic self-consumption

The batteries store surplus solar energy generated at midday to be released in the evening or during morning peak periods. The self-consumption rate typically rises from 30–40% (without storage) to 70–80% (with batteries), reducing the electricity bill by the same proportion.

Backup function (emergency power supply)

In the event of a grid outage, the hybrid inverter automatically switches to off-grid mode. Critical loads remain powered by the batteries (autonomy of 3 to 6 hours depending on consumption). This function is invaluable for activities that cannot tolerate any interruption (cold rooms, security systems, computer servers).

Avoiding tariff penalties

Some network operators charge for exceeding contracted power levels or impose progressive tariff brackets. Peak shaving keeps consumption below the contractual threshold, avoiding these additional costs.

Deferral of network investment

Rather than upgrading to a higher contract tier (high recurring costs) or upgrading the electrical connection (a significant investment), local storage solves the problem at a controlled cost.

Sizing your peak shaving installation correctly

A successful peak shaving project requires adherence to a rigorous methodology:

Step 1: Consumption analysis

Obtain your load profiles from your electricity supplier (ideally with data at 10-minute intervals). Identify:

• The maximum power demand (in kW or kVA)
• The frequency and duration of the peaks
• The times at which they occur (correlation with specific equipment)

Step 2: Determine the gap to be bridged

Calculate the difference between your contracted power and the actual peaks. This is the minimum discharge power required for your batteries. Add a 20% safety margin to account for unforeseen events and the gradual degradation of the batteries.

Step 3: Choose the right components

Hybrid inverter: its rated power must cover your base load + the discharge power of the batteries. Opt for proven brands (Deye, Victron, Goodwe) with native smart meter input.

Lithium batteries: opt for LiFePO4 technology (longer lifespan, enhanced safety). Check the continuous discharge power per module and the number of stackable units. The Pylontech US5000 has become the European standard for its reliability and universal compatibility.

Smart meter: check compatibility with your inverter (usually Modbus RTU protocol over RS485). The meter must measure the site’s total consumption, not just solar production.

Step 4: Software configuration

Commissioning requires configuring the inverter via its interface (LCD screen or mobile app):

• Operating mode: ‘Peak Shaving’ or ‘Zero Export’ depending on the model
• Activation threshold: contracted power (e.g. 36 kVA)
• Time slots: define the periods of active peak shaving (usually 24 hours a day)
• Priorities: backup > peak shaving > self-consumption (depending on your needs)

Alternatives and technical considerations

Long-distance cabling: wired or wireless?

When the distance between the meter and the inverter exceeds 50 metres, there are two options:

Wired solution (Cat6 network cable): more economical (a few euros per metre), reliable, but requires cable routing work. Ensure protected cable trays are used and comply with electrical standards (separation of high and low voltage circuits).

Wireless solution (RS485 wireless modules): eliminates the need for cabling work, range of up to 100 metres in open space. Higher cost (€150–300 per pair of modules), requires a power supply at both ends. Check compatibility with your inverter before purchasing.

Peak shaving vs. tariff increase

The return on investment for peak shaving generally occurs within 7 to 12 years, depending on local tariffs and system usage. However, additional benefits (backup, self-consumption, increased property value) accelerate this return on investment.

Common mistakes to avoid

Under-specifying discharge capacity

Prioritising capacity (kWh) at the expense of power (kW) is the most common mistake. For peak shaving, a 10 kWh / 5 kW battery pack is more effective than a 20 kWh / 3 kW pack if your peaks exceed 3 kW.

Neglecting to measure total consumption

Measuring only solar production (via the inverter’s internal meter) is not enough. The smart meter must be installed after the main circuit breaker to capture the site’s total consumption.

Choosing an incompatible inverter

Not all ‘hybrid’ inverters support peak shaving. Check for an external meter input (RS485/Modbus) and a dedicated operating mode before purchasing.

Ignoring scalability

Plan from the outset for the possibility of adding additional batteries. Modular systems (such as Pylontech units, which can be stacked up to 15 units) offer this flexibility without requiring a complete replacement.

Maintenance and lifespan

A correctly sized peak shaving system requires little maintenance:

• LiFePO4 lithium batteries: 6,000 to 10,000 cycles (15–20 years in daily use), no preventive maintenance
• Hybrid inverter: annual check of connections, firmware update every 2–3 years
• Smart meter: calibration check every 5 years (depending on local regulations)

Remote monitoring via a mobile app (SolarMAN, VRM Portal, etc.) allows anomalies to be detected in real time and settings to be optimised without the need for on-site intervention.

Frequently Asked Questions (FAQ)

Can I add peak shaving to my existing solar installation?

Yes, provided you replace your current inverter with a compatible hybrid model. The existing solar panels are retained and reconnected to the new inverter. The investment therefore covers the inverter, the batteries and the smart meter.

Does peak shaving work at night or when there is no sun?

Absolutely. Peak shaving uses the energy stored in the batteries, whether it comes from the sun (midday surplus) or the grid (off-peak night-time charging if configured). The system kicks in as soon as a peak is detected, regardless of current solar production.

How responsive is the system during a sudden peak?

Modern hybrid inverters (Deye, Victron, Goodwe) react in under 500 milliseconds. The smart meter measures consumption in real time (updated every 200–500 ms), the inverter analyses the data and triggers battery discharge instantly. This responsiveness is more than sufficient for typical industrial peaks (motor start-ups, compressors).

Do batteries wear out more quickly with peak shaving?

Peak shaving does indeed place a strain on the batteries, but modern lithium technologies (LiFePO4) can withstand 6,000 to 10,000 full cycles. A 10-minute peak consuming 30% of the charge represents 0.3 cycles. Even with three daily peaks, the service life exceeds 15 years. Generous sizing (6 batteries instead of 4) further reduces the load on each individual battery.

Am I eligible for financial support for this installation?

Support schemes vary by country and region. Consult local organisations (network operators, energy authorities) to find out about available grants. Some regions promote decentralised storage as part of the energy transition.

Can the system handle several simultaneous peaks?

Yes, provided the cumulative discharge power of the batteries covers the shortfall. For example, with 6 Pylontech US5000 batteries (9.6 kW continuous discharge), you can cover 10 kW peaks for several tens of minutes. If the batteries reach their minimum threshold (usually 10–20% charge), the inverter temporarily stops feeding into the grid to protect the battery pack’s lifespan.

Wattuneed support and guidance

Wattuneed supports its customers at every stage of the project:

• Free preliminary study: analysis of your load profiles and customised sizing
• Technical support: French-speaking team available by phone, email and chat for configuration and troubleshooting
• Manufacturer’s warranties: 10-year warranty on Pylontech batteries, 5-year warranty on Deye inverters (extensions available)
• Comprehensive documentation: commissioning guides, video tutorials, detailed technical data sheets

Conclusion: securing your business intelligently

Peak shaving with a hybrid inverter and lithium batteries is much more than just a solution to prevent power cuts. It is a strategic investment that secures your business, optimises your energy bills and enhances the value of your property.

Current technologies (Deye inverters, Pylontech batteries) offer proven reliability and modularity, allowing the system to be adapted to your future needs. Whether you are a business facing recurring power cuts or a savvy homeowner looking to maximise your energy independence, this solution is well worth serious consideration.

“The best system is one that operates seamlessly: you no longer need to think about electricity; the system manages everything intelligently in the background.”

Don’t wait for the next power cut to take action. Contact the Wattuneed experts today for a personalised analysis of your situation and a bespoke solution.

Wattuneed SPRL
Rue Henripré, 12 – 4821 Andrimont, Belgium
Tel.: +32 87 45 00 34 | Email: info@wattuneed.com
www.wattuneed.com