What data do you need to size a BESS?

Twelve months of interval metering, the tariff structure, the peak you want to cap, the backup loads and their required duration, the solar generation profile if present, and the available space and grid connection capacity.

Indoor cabinets or an outdoor container?

Cabinets suit systems up to a few hundred kWh where a suitable room and fire strategy exist. Containers suit larger systems, keep the energy outside the building and arrive with cooling, fire detection and protection integrated.

Can a BESS also serve as the UPS?

Only with a power conversion system rated for that duty and an appropriate transfer arrangement. Most BESS have a transfer time in the tens of milliseconds, which is too slow for loads that require a UPS.

What is a realistic payback in the region?

It depends entirely on the tariff and the load profile. With a demand charge and a pronounced daily peak, payback is usually a small number of years. Without a demand component, self consumption alone is slower. We calculate it from your own metering data before you commit.

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BESS use cases compared

6 min readLast reviewed: September 2026

Short answer

A BESS is sized by the job it does. Peak shaving needs high power for short periods and cycles daily. Backup needs energy and rarely cycles. Solar self consumption needs one full cycle a day and pays back on the tariff difference. Grid services need fast response and accurate control. Getting the use case wrong is what makes a storage project underperform, not the battery.

Battery storage is not one product. The same cabinet serves five different jobs, and each job sets a different ratio between power and energy. Here is the comparison, with what each case actually requires.

The comparison table

The power to energy ratio, written as C rate, is the number that decides the hardware. A 1 MW system with 1 MWh is a 1C system for short bursts. A 1 MW system with 4 MWh is a 0.25C system for long duration. The same cells cannot serve both economically.

What each use case requires
Use case	Duration	Cycles per year	Drives the sizing	Revenue or saving
Peak shaving	15 minutes to 2 hours	250 to 365	Power in kW	Lower demand charge
Backup and continuity	1 to 8 hours	5 to 50	Energy in kWh	Avoided downtime
Solar self consumption	2 to 6 hours	300 to 365	Daily surplus in kWh	Tariff difference
Grid services	Seconds to 1 hour	Hundreds, partial	Response speed and control	Service contract
EV charging support	10 to 60 minutes	200 to 365	Peak power in kW	Avoided grid upgrade

Peak shaving is an arithmetic exercise first

Before any hardware discussion, you need 12 months of interval metering data. The load profile shows how high the peaks are, how long they last, how often they repeat and how much of the bill they cause. From that you get the required power and the required energy directly, and you can calculate the saving before you commit. Without metering data, peak shaving sizing is guesswork and the payback figure is fiction.

Stacking cases is normal, but not free

Most commercial systems serve two or three jobs: shave the peak, hold a reserve for backup, absorb solar surplus. That is good economics, because the asset earns from more than one source. It also means a share of the energy is reserved and cannot be traded, and the control strategy has to arbitrate between the jobs. Decide the priority order at design stage and write it into the control specification, not after commissioning.

Degradation belongs in the sizing, not in the disappointment

A lithium system loses usable capacity with cycles and with time. If the case needs 500 kWh in year ten, the system is sized above that today, or an augmentation step is planned. Specify guaranteed end of life capacity, the cycle count it assumes and the temperature it assumes. A capacity warranty tied to conditions that the site will not meet is not a warranty.

Frequently asked

What data do you need to size a BESS?: Twelve months of interval metering, the tariff structure, the peak you want to cap, the backup loads and their required duration, the solar generation profile if present, and the available space and grid connection capacity.
Indoor cabinets or an outdoor container?: Cabinets suit systems up to a few hundred kWh where a suitable room and fire strategy exist. Containers suit larger systems, keep the energy outside the building and arrive with cooling, fire detection and protection integrated.
Can a BESS also serve as the UPS?: Only with a power conversion system rated for that duty and an appropriate transfer arrangement. Most BESS have a transfer time in the tens of milliseconds, which is too slow for loads that require a UPS.
What is a realistic payback in the region?: It depends entirely on the tariff and the load profile. With a demand charge and a pronounced daily peak, payback is usually a small number of years. Without a demand component, self consumption alone is slower. We calculate it from your own metering data before you commit.