Energy Storage for Commercial Buildings: BESS & Peak Shaving in Singapore

A Battery Energy Storage System (BESS) helps commercial buildings slash peak demand charges, which can account for 30% to 50% of a factory’s monthly electricity bill in Singapore. By charging during off-peak hours or when solar generation is high, then discharging during the few 15-minute intervals when demand spikes, a properly sized BESS can deliver payback in 3 to 5 years. This guide explains how peak shaving works and what to consider when sizing a BESS for your industrial or commercial facility.

Understanding Singapore’s Commercial Demand Charges

Contracted Capacity vs. Maximum Demand

SP Group bills large commercial consumers based on two key components: energy charges (cents per kWh) and demand charges (dollars per kW of contracted capacity or maximum demand). If your building’s peak demand exceeds the contracted capacity, excess demand charges apply. Even a short spike during the 15-minute demand window can trigger a higher monthly bill. A BESS smooths these spikes, keeping the grid draw within the contracted limit.

Real Cost Impact of Peak Demand

For a factory with a contracted capacity of 500 kW, excess demand above that level may be billed at approximately S$0.30 to S$0.50 per kW per day, depending on tariff class. A 50 kW overshoot sustained over one demand window could add around S$750 a month. Over a year, that’s S$9,000. A BESS sized to shave that 50 kW peak often costs less than the cumulative excess charges over a few years.

How BESS Enables Peak Shaving

Load Shifting Strategy

The BESS charges gradually during low-demand periods—overnight, weekends, or when your solar PV system is generating surplus. When the building’s load rises near the contracted capacity limit, the battery discharges to cover the excess, flattening the peak. The grid sees a stable, lower maximum demand. The result is a lower demand charge and better utilisation of your solar investment.

Co-locating BESS with Solar PV

A commercial solar array often peaks at midday, but many factories have a demand peak in the morning or late afternoon. A BESS time-shifts that solar energy to the period when it’s needed most, maximising self-consumption and reducing export. This matters because Singapore’s export rates are not designed for large commercial systems, so using every kWh on-site is more profitable.

Sizing a BESS for a Commercial Building

Step 1: Analyse Your Demand Profile

Pull 15-minute interval data from your SP Power billing portal. Identify the highest demand peaks each month and their duration. Most peak shaving applications need 1 to 2 hours of discharge at the required power level. A factory with a recurring 80 kW excess peak for 30 minutes would need at least 40 kWh of usable battery capacity plus safety margin.

Step 2: Choose the Power-to-Energy Ratio

A BESS rated at 100 kW / 150 kWh can deliver 100 kW for 1.5 hours. Lithium iron phosphate (LFP) batteries are the preferred chemistry for commercial projects in Singapore because they handle the heat better and have a long cycle life. For peak shaving, a 1C to 2C discharge rate is typical, meaning the battery can discharge its full capacity in one hour or 30 minutes.

Step 3: Factor in Round-Trip Efficiency and Degradation

LFP systems typically operate at 90–95% round-trip efficiency. Over 10 years, the battery may lose 20% of its capacity. I advise clients to oversize the BESS by 15–20% on day one so it still meets peak shaving targets later. This avoids installing a second unit prematurely.

Regulatory and Fire Safety Considerations

• SCDF fire safety requirements: Indoor BESS installations must comply with SS 638, the Singapore standard for electrical installations, and SCDF’s fire code for battery rooms. Adequate ventilation, smoke detection, and an emergency shutdown system are mandatory.
• EMA and SP connection: A BESS connected to the grid requires a generation licence if it exports. For most peak shaving setups, you operate behind-the-meter without export, simplifying approvals. Still, notify SP Group as per the Transmission Code.
• Structural loading: Battery cabinets are heavy. A 200 kWh system can weigh over 2 tonnes. A qualified PE must certify the floor loading capacity.

Pros and Cons of Installing a BESS for Peak Shaving

Expert Insights on Commercial BESS in Singapore

I have seen BESS proposals fail because the client underestimated the cooling load. Singapore’s ambient temperature averages 28°C, but inside a factory or electrical room it can hit 35°C. LFP batteries degrade faster above 30°C. We always include an active air-conditioning unit or liquid cooling in the BESS enclosure. The HVAC cost adds about 5% to the project but extends battery life significantly.

Another insight: align your battery charging with the lowest electricity price period. If your building is on a contestable contract with a retailer offering time-of-use pricing, you can charge the BESS at night at a low rate and discharge during the day to avoid high peak rates and demand charges simultaneously. This dual benefit slashes payback to under four years in some cases.

Is a BESS Worth It for Your Facility?

If your monthly maximum demand regularly breaches 150 kW and you face excess charges, a BESS is worth a detailed feasibility study. Buildings with high air-conditioning or motor loads—cold rooms, manufacturing lines, data centres—stand to gain the most. A rooftop solar system plus a BESS creates a microgrid that can run essential loads even during grid flickers, which is becoming a priority for factories with sensitive processes.

To model your specific load profile and get a custom BESS proposal, Enquire with Akando Solar. Our team integrates solar and storage design so the two systems work as one coherent asset.

References

• SP Group, Demand Charges and Tariff Structure, https://www.spgroup.com.sg/our-services/utilities/business/tariff-information
• Energy Market Authority, Energy Storage Systems, https://www.ema.gov.sg/
• SCDF Fire Code 2023 (SS 638), https://www.scdf.gov.sg/