What the evidence says
Energy charges measure kWh while demand charges can depend on the highest kW interval or a minimum billing demand. Reducing energy does not automatically reduce billed demand.
Meralco’s business guidance is useful inside its franchise, but Philippine distribution utilities and customer classes can use different approved tariffs. The current account documents govern.
A BESS must hold the target below the threshold for the complete billing interval and peak duration. Too little kW misses the spike; too little usable kWh rebounds before the peak ends.
Practical decision guide
Model the billed peak before buying the battery
Begin with the tariff and bill, not the battery catalogue. Separate energy charges based on kWh, demand charges based on kW, fixed charges, power-factor or reactive-energy items, taxes, supply and distribution components, and any minimum or contracted-demand rule. Identify the exact meter, service class, voltage level, demand interval, billing calendar, ratchet or minimum, peak/off-peak window and current approved schedule. Meralco’s business guide explains billed and minimum demand for applicable accounts in its franchise, but another Philippine distribution utility or customer class may use a different structure. Even inside one utility, current account documents and monthly approved rates govern. A BESS cannot reduce a charge that is fixed, already below a billing floor, based on a different measurement point or excluded from distributed-energy offset.
Use interval data at the same resolution and boundary as the bill. Twelve monthly totals cannot show whether a peak lasted one interval, several hours or multiple consecutive shifts. Obtain at least twelve months where possible, align timestamps and holidays, remove missing or duplicated intervals, reconcile interval kWh with billed energy and map each monthly maximum to the operating event that caused it. Examine start-up sequences, compressors, chillers, furnaces, pumps, EV charging, production batches, weekend recovery, solar variability and simultaneous loads. Build a duration curve and event library: magnitude above a candidate threshold, duration, time of day, recurrence, season and warning time. One exceptional incident should not size a battery until the owner compares process changes, staggered starts, demand-limit settings, contract correction or other lower-cost measures.
Size power and energy separately. The PCS kW rating and overload capability determine how far the net load can be pulled down and how quickly the controller can react. Usable battery kWh determine how long that reduction can be held after accounting for SOC window, temperature, conversion and auxiliary losses, degradation and operating reserve. A narrow high spike may need substantial kW but little energy; a broad plateau may need many kWh even at a modest reduction. Monthly consumption divided by days is not a peak-shaving calculation. Simulate the complete billing interval so a late rebound does not establish the very peak the system intended to avoid. Check transformer and feeder limits, phase balance, ramp rates, charge availability, thermal derating, warranty throughput and whether charging creates a new peak in another tariff window.
Design the controller for uncertainty and competing objectives. A simple fixed threshold works only when the BESS starts with enough charge and can anticipate the complete peak. Real facilities face forecast error, unexpected production, consecutive peaks, cloud-driven PV changes, generator tests, outages, tariff-window transitions and communication gaps. Define the meter of control, sampling and command latency, target threshold, reserve SOC, recharge rule, solar priority, maximum cycles, export limit, generator interaction and what happens when data are stale. If the same BESS also provides resilience, the economic dispatch must not consume emergency reserve without an approved rule. Test graceful degradation when the utility meter, weather forecast, EMS, BMS link, cloud or internet is lost. Safe local limits and a bounded fallback mode matter more than an attractive remote-portal demonstration.
Build the business case from avoided billed charges over the project life, not from one peso-per-kWh multiplier. Model the no-project bill and BESS bill under the current tariff, then test production growth and decline, tariff and contract changes, weather and solar output, battery efficiency, auxiliary use, degradation, augmentation, downtime, maintenance, software and communications, insurance, financing, taxes and end of life. Distinguish demand reduction from energy arbitrage, power-factor support, backup value and other services so one benefit is not counted twice. Apply the minimum-billing floor and any charges that distributed resources cannot avoid. Compare operating changes, contract right-sizing, power-factor correction, solar, thermal storage, process scheduling and a smaller BESS. Report ranges and sensitivities instead of promising a fixed saving or payback; economics can reverse when the peak pattern changes.
Specify measurement and verification before award. Define the baseline period, exclusions, meter boundary, interval, time source, data quality, weather or production adjustments, BESS availability, target calculation and how an avoided peak is valued under the bill. Acceptance should prove the controller can hold several representative events below the threshold without violating SOC, temperature, protection, export or reserve limits. After operation, reconcile monthly utility bills with high-resolution facility and BESS data; investigate missed peaks, false dispatch, excessive cycling, unavailable power and charging peaks. Keep the original raw data and settings history. A vendor portal’s estimated saving is not an invoice and may use a different baseline. The performance warranty must align with the power, energy, throughput, availability and environmental duty the peak-shaving model actually needs.
S3’s free initial peak-shaving evidence screen asks for the current tariff and service class, twelve months of bills, available interval demand, contracted and minimum demand, facility operating calendar, major flexible and inflexible loads, existing solar or generator, proposed BESS power and energy, controller description, resilience reserve, warranty and decision deadline. We return a bounded gap map showing whether the next useful step is tariff confirmation, data cleaning, peak-event diagnosis, operational change, interval simulation, control specification or independent proposal review. It is not a savings guarantee, tariff ruling, energy audit certificate or design approval. A later paid scope can be limited to interval-data modelling, tariff and scenario comparison, power/energy sizing, control and M&V specification, bid comparison or acceptance-test support with the responsible Philippine parties.
Meralco — understand your business bill
Discuss the engineering scope →What a business should do next
- Collect at least the current tariff and twelve months of bills plus interval data at the billing meter; identify monthly peaks, duration, recurrence, minimum demand and operating causes.
- Simulate the controller under forecast errors, consecutive peaks, solar variation, outages, reserve constraints, auxiliary loads, efficiency loss and degradation; compare against operational and tariff alternatives.
- Request a free S3 peak-shaving evidence screen to identify whether the tariff, interval data, peak shape, control rule or BESS limit should be tested first.