Battery Storage Module Guide
Battery Energy Storage Sizing & Lifecycle TEA
A battery only pays for itself if it is sized and dispatched against the real tariff and load. Here is how to pick the value strategy, size power vs energy, and model degradation and resilience honestly.
Technology Overview
The economics of a behind-the-meter battery are almost entirely a function of dispatch. The same battery can shave a demand peak, arbitrage a time-of-use spread, soak up excess solar, or ride through an outage — and its value depends on how well those actions line up with the site’s tariff and load. Rule-of-thumb sizing (“two hours at the peak”) misses the peaks that actually drive the bill.
Value stacks, but not all value is equal. Demand-charge management is usually the largest and most predictable stream on a commercial bill; TOU arbitrage adds value where the price spread is wide; solar co-optimization shifts midday generation into peak-price hours and manages export under NEM 2.0, Net Billing, or Buy-All-Sell-All; and resilience buys avoided-outage value that is real but harder to monetize.
Batteries also fade. Cycle and calendar degradation erode usable energy and round-trip efficiency over the warranty life, so a business case built on year-one throughput over-states the return. Any credible model tracks degradation and re-prices the value each year.
The CogenS™ Battery Energy Storage Module sizes and operates the battery with a linear-program dispatch against your actual rate structure and 8,760-hour load. It models DC blocks and power-conversion systems (inverters) from real manufacturer data, cycle and calendar degradation, PCS part-load curves, and outage resilience — then reports NPV, IRR, payback, TCO, and levelized cost of storage (LCOS) from both the building-owner and Energy-as-a-Service provider perspectives.
Module Specs at a Glance
Chemistry
Utility-scale lithium-ion (LFP) DC blocks from major OEMs, with energy (kWh) and power (kW) ratings and round-trip efficiency.
Power vs Energy
Independent power (kW, set by the PCS) and energy (kWh, set by the DC blocks) sizing — the ratio is the key design lever.
Dispatch Strategies
Demand-charge management, time-of-use arbitrage, and self-consumption, solved with a linear program against the real tariff.
Degradation
Cycle and calendar degradation with round-trip efficiency and ambient derating, re-priced across the study period.
Metering & Export
NEM 2.0, Net Billing, and Buy-All-Sell-All, with grid import limits and monthly export caps respected by the dispatch.
Output
TEA report with NPV, IRR, payback, TCO, LCOS, dispatch and state-of-charge charts, and multi-vendor comparison.
How to Design a Project
A high-level workflow that mirrors how the CogenS™ platform structures the analysis end-to-end.
Build the load profile and pull the tariff
An 8,760-hour (or sub-hourly) load profile and the real rate structure — energy, demand, and metering policy — are the inputs that matter most. Demand charges, not energy price, usually decide the sizing.
Pick the value strategy
Decide what the battery is primarily for: demand-charge management, TOU arbitrage, self-consumption, or resilience. Most projects stack several; the dispatch engine optimizes across them, but the dominant stream drives the sizing.
Size power and energy separately
Power (kW) is set by the PCS and the peak you need to shave; energy (kWh) is set by how long you must sustain it. A demand-shaving battery is power-heavy; an arbitrage or backup battery is energy-heavy.
Add solar co-optimization (if applicable)
Pair with on-site PV and co-optimize. Model export value under the correct metering policy and the benefit of shifting midday solar into peak-price hours.
Model degradation and resilience
Apply cycle and calendar degradation and round-trip efficiency so the economics reflect real throughput. For backup value, define a critical-load fraction and outage duration and price the cost of unserved energy.
Run the lifecycle TEA and structure the deal
Compare 2-3 vendors on NPV/IRR/payback/LCOS over a 20-year study period. For third-party ownership, model the Energy-as-a-Service structure — energy concession or capacity tolling — with a dual-MARR solve.
Related Guides
Microgrid DER Guide
Combine storage with on-site generation and solar for a full behind-the-meter microgrid.
DER Co-Optimization & EaaS
Structure the deal: building-owner vs Energy-as-a-Service provider contracts.
EV Charging Feasibility Guide
Storage often pairs with fast charging to manage demand-charge spikes.
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