C&I ESS Peak Shaving Data Checklist: 15-Minute Loads, Demand Charges and Dispatch Limits

Project-development note: A C&I battery quote cannot be validated from a monthly electricity bill alone. Peak shaving depends on when the peak occurred, how long it lasted, whether it repeats, what caused it, and how much battery power and energy remain available at that moment. Buyers should request interval data before treating an estimated saving as a project result.

This checklist is for facility owners, EPC teams, distributors and energy consultants preparing a C&I ESS project. It also connects the analysis with Solar Panel, Solar Inverter, and smaller Home Energy Storage product paths. Use the Battery Storage Buyer Resources hub and send the interval file through Contact for a pre-quotation review.

Why monthly bills are not enough for peak shaving

A bill may show total kWh, maximum demand and tariff charges. It usually does not show the shape of the load that created the demand peak. Two sites can report the same maximum kW and require very different battery systems. One may have a brief compressor start; another may hold a high load for three hours. The first is mainly a power problem, while the second needs both power and substantial usable energy.

Interval data reveals the difference. For many tariffs, 15-minute data is the practical starting point, although the correct interval must match the utility demand calculation. The analysis should cover enough months to capture production seasons, weather changes, holidays, maintenance shutdowns and unusual events.

C&I ESS peak shaving data checklist

Data item	Minimum information	Decision it supports
Interval load	Timestamped site import in kW or kWh for each utility interval, ideally 12 months.	Peak duration, frequency and required discharge profile.
Tariff	Demand-charge rule, billing interval, time-of-use periods, ratchet and taxes.	Value of reducing each qualifying peak.
PV generation	Existing or proposed PV profile, inverter clipping and export restriction.	Daytime charging and net-load forecast.
Operating schedule	Shifts, weekends, seasonal production, planned expansion and shutdowns.	Whether historical peaks represent future operation.
Large loads	Motor, chiller, compressor, furnace, charger or process load rating and start pattern.	Power requirement and controllable-load options.
Battery limits	Usable kWh, continuous kW, SOC window, efficiency, temperature derating and degradation.	Achievable dispatch rather than nameplate output.
Control rules	Target demand, reserve SOC, charging window, PV priority and backup requirement.	Dispatch strategy and service conflicts.

Match the data interval to the tariff

Do not assume every utility uses the same demand interval. The project team should obtain the tariff sheet and identify how maximum demand is calculated. The interval may be 15, 30 or 60 minutes, and some tariffs use time-of-use demand windows, monthly ratchets or seasonal rules. A simulation based on the wrong interval can overstate savings.

Keep the raw timestamps, units and time zone. Check daylight-saving changes, missing intervals, duplicated rows and meter resets before modeling. If the file contains energy per interval rather than average power, convert it consistently. Document every cleaning step so another reviewer can reproduce the result.

Find peak duration, not only peak magnitude

Rank the highest demand intervals for each month and inspect the hours around them. A single maximum value does not show whether the battery must discharge for one interval or a long production cycle. Calculate how much energy would have been required to hold the site below several target levels.

For example, a target that removes only the highest few percent of peaks may need less energy and deliver a better use of the battery than an aggressive flat ceiling. The project should show a target-demand curve and the corresponding battery kW, discharged kWh, cycle count and remaining SOC. This makes the tradeoff visible before equipment is selected.

Separate site load, PV and battery behavior

Peak shaving should be modeled on net grid demand, but the underlying site load and PV generation should remain separate in the working file. Otherwise a cloudy-day peak may be mistaken for a production change. Separate profiles also help the team test future PV expansion, export limits and battery charging strategies.

The Solar Panel and Battery Storage Matching guide explains PV recharge and inverter constraints. The battery should not be assumed to recharge fully every day if the site load consumes most of the PV output or the tariff discourages grid charging.

Model usable battery limits

Nameplate kWh and kW are not the same as dispatchable energy and power. The model should include the permitted SOC window, inverter efficiency, auxiliary load, temperature derating, BMS current limit and degradation assumption. If backup reserve is required, that reserved energy cannot also be counted as freely available for peak shaving.

Power and energy must be checked together. A battery may have enough kWh but insufficient kW to hold the demand target during a sharp peak. Another system may have enough power but reach its minimum SOC before a long peak ends. Review How to Size a LiFePO4 Battery Bank for a Small Commercial Project for the basic relationship between load, runtime and usable capacity.

Account for overlapping services

A C&I ESS may be expected to support peak shaving, self-consumption, backup and tariff arbitrage. Those services compete for the same SOC and inverter capacity. The control plan should state which service has priority and what happens when conditions conflict. A site that requires 40% backup reserve has less flexible energy for daily demand management.

Ask for a dispatch hierarchy, not just a list of features. The hierarchy should cover reserve SOC, demand threshold, grid-charging permission, PV charging, outage preparation and recovery after a deep discharge. It should also define who can change settings and how changes are logged.

Test sensitivity instead of promising one savings number

A useful proposal shows several cases. Change the target demand, battery size, degradation rate, tariff escalation, operating schedule and PV profile. Report annual discharged energy, equivalent cycles, peak reduction by month, unmet target intervals and estimated savings. A sensitivity table is more credible than a single payback number built from optimistic assumptions.

Historical data also needs context from site staff. Mark production expansions, temporary shutdowns, equipment failures and unusual weather. If a new chiller or production line will be added, include its expected schedule rather than assuming last year's meter file represents the future.

Define measurement and verification before installation

The project team should agree how performance will be checked after commissioning. Save the original interval file, tariff version, simulation assumptions and expected monthly target. After installation, compare meter demand, battery dispatch, SOC, alarms, PV output and operating schedule for the same intervals.

Commissioning should include communication, metering direction, current-transformer ratio, time synchronization, charge and discharge commands, reserve SOC and alarm handling. The C&I Battery Energy Storage Commissioning Checklist and C&I ESS Maintenance Checklist provide records for the operating phase.

For independent background on storage evaluation and safety, buyers can consult the U.S. Department of Energy energy storage resources and UL Solutions energy storage system testing and certification.

What to send before requesting a peak-shaving quote

Prepare at least 12 months of interval data, 12 months of bills, the current tariff, site operating schedule, large-load list, existing PV information, planned expansion, backup requirement, available installation space, ambient conditions and a basic single-line diagram. State whether the buyer is optimizing demand charges, energy cost, resilience or a combination.

SolarStorageHub reviews the supplied load and project assumptions for quotation support; final tariff interpretation, electrical design and financial approval remain with the responsible local parties. Use the C&I ESS Quote Checklist, then submit the data package through Contact.

FAQ

How much interval data is needed for a C&I peak-shaving study?

Twelve months is a practical minimum because it captures seasonal operation and tariff changes. More history is useful when production varies significantly by year.

Is a monthly electricity bill enough to size the battery?

No. The bill shows charges and maximum demand but not the duration and shape of the peaks. Interval data is needed to estimate battery power and usable energy.

Why is 15-minute load data often requested?

Many demand tariffs use a 15-minute billing interval. The analysis interval should match the actual utility rule rather than using 15 minutes automatically.

Can the same battery provide backup and peak shaving?

Yes, but the services share battery energy and power. The control plan must reserve enough SOC for backup and state which service has priority.

How does solar PV affect peak shaving?

PV can reduce daytime net load and recharge the battery, but clouds, export limits and site consumption affect the result. PV and site-load profiles should be modeled separately.

What causes an unrealistic savings estimate?

Common causes include using monthly data, ignoring tariff details, assuming full daily recharge, omitting degradation, and treating nameplate kWh as fully usable energy.

What should a peak-shaving proposal report?

It should report assumptions, target demand, monthly peak reduction, required battery kW and kWh, cycle count, unmet intervals, reserve SOC and sensitivity cases.