Levelized Cost of Storage vs. Duration Calculator
The single most important concept in long-duration energy storage economics is that every storage technology carries a fixed, power-related cost (inverters, controls, turbines, stack hardware) that does not change with how many hours of energy you need, plus an energy-related cost that scales directly with duration. This calculator takes a power rating, a power-related cost, an energy-related cost, and a discharge duration, then reports the total installed cost, the energy capacity, and the effective blended cost per kWh — letting you watch that blended cost fall as you extend duration. It pairs naturally with our Flow Battery LCOS Calculator for translating these physical quantities into levelized cost of storage, and our planned LDES Technology Comparison Calculator for comparing how different technologies' cost structures shift the duration-cost curve.
The system's continuous power output rating.
This represents the fixed cost tied to power output (inverters, controls, stack hardware) -- independent of how many hours of storage you need. Default values here are representative of vanadium flow battery cost structure.
This represents the cost tied to energy capacity (cells, electrolyte, reservoir, etc.) -- this is the cost that scales directly with duration.
Try different duration values to see how the effective blended cost per kWh changes -- this is the core dynamic behind why storage technology choice depends so heavily on required duration.
(power rating (MW) × 1000 × power-related cost ($/kW)) + (power rating (MW) × duration (hours) × 1000 × energy-related cost ($/kWh))
power rating (MW) × 1000 × duration (hours)
total installed cost ($) ÷ energy capacity (kWh)
Results update live as you type. For planning and field-check estimates — always verify against applicable standards and equipment ratings.
How we calculate this →This is the single most important concept in long-duration energy storage economics: because power-related cost is fixed regardless of duration, extending discharge duration spreads that fixed cost over more kWh, pulling the effective blended cost per kWh down. Using this calculator's default cost structure, a 1-hour system costs about $600/kWh effectively, while the identical technology at 10 hours drops to around $330/kWh -- a 45% reduction from duration alone, with no change in underlying technology or unit costs. This is exactly why storage technologies with high power-related cost but low energy-related cost (like pumped hydro and CAES) become increasingly attractive as required duration grows, while technologies with the opposite cost structure favor short-duration applications.
How the levelized cost of storage vs. duration is calculated
This calculator separates a storage system's installed cost into a power-related component (fixed regardless of duration) and an energy-related component (scaling directly with duration), then divides the total by the resulting energy capacity to show the effective blended cost per kWh. Three quantities tie the calculation together.
Total Installed Cost ($) = (Power Rating (MW) × 1000 × Power-Related Cost ($/kW)) + (Power Rating (MW) × Duration (hours) × 1000 × Energy-Related Cost ($/kWh)). The first term is the fixed power cost: converting the power rating from megawatts to kilowatts (× 1000) and multiplying by the cost per kW of power-handling hardware (inverters, controls, stack, turbines) gives a cost that does not change with how many hours of energy the system stores. The second term is the energy cost: the energy capacity in kWh (power rating in MW × 1000 × duration in hours) multiplied by the cost per kWh of energy-storage medium (cells, electrolyte, reservoir volume, cavern volume) gives a cost that scales directly with duration. Summing the two gives the all-in installed cost. At the defaults (100 MW, $300/kW, $300/kWh, 4 hours), that is (100 × 1000 × $300) + (100 × 4 × 1000 × $300) = $30,000,000 + $120,000,000 = $150,000,000.
Energy Capacity (kWh) = Power Rating (MW) × 1000 × Duration (hours). Converting the power rating from megawatts to kilowatts (× 1000) and multiplying by the discharge duration in hours gives the total energy the system can store and deliver. At the defaults, that is 100 × 1000 × 4 = 400,000 kWh.
Effective Blended Cost ($/kWh) = Total Installed Cost ($) ÷ Energy Capacity (kWh). Dividing the all-in installed cost by the total energy capacity gives the average cost per kWh of storage capacity -- the single figure that shows how duration dilutes the fixed power cost. At the defaults, that is $150,000,000 ÷ 400,000 = $375.00/kWh.
Two notes on the model. First, the power-related and energy-related cost figures are the two most consequential inputs, and their ratio (not just their absolute values) drives how steeply the blended cost falls with duration: a technology with high power cost and low energy cost (like pumped hydro or CAES) shows a much steeper duration-cost decline than one with the opposite ratio (like lithium-ion, where the cells dominate). The default values are representative of vanadium flow battery cost structure, so the editable fields let you substitute technology-specific or vendor-specific figures. Second, this calculator isolates the installed-cost-vs-duration relationship and excludes round-trip efficiency, cycle life, operating cost, charging energy cost, financing, and revenue -- all of which matter for real project economics, and which our Flow Battery LCOS Calculator addresses for a full levelized-cost treatment. Data sources: Storage system cost decomposition (power-related vs. energy-related cost) from DOE (Department of Energy), NREL (National Renewable Energy Laboratory), and IRENA (International Renewable Energy Agency) energy storage technology assessments; vanadium flow battery cost structure from industry benchmarks and NREL studies; duration-cost relationship methodology from standard levelized cost of storage frameworks. Verification: with defaults (100 MW, $300/kW, $300/kWh, 4 hours), Total Installed Cost = $150,000,000, Energy Capacity = 400,000 kWh, Effective Blended Cost = $375.00/kWh.