Flow Battery LCOS Calculator
This calculator estimates the levelized cost of storage (LCOS) for a vanadium redox flow battery (VRFB) project -- the all-in cost to store and re-deliver one megawatt-hour of electricity across the system's full operating life, rolling upfront capital, charging energy, round-trip efficiency losses, and operating costs into a single cost-per-MWh figure. It pairs naturally with our Flow Battery Sizing Calculator for translating a target power and duration into the energy capacity this calculator needs, and our LCOS Calculator for a direct lithium-ion comparison over the same lifecycle.
See the Flow Battery Sizing Calculator to estimate this for your target power and duration.
2026 vanadium redox flow battery (VRFB) installed costs commonly run $400-800/kWh -- and notably, unlike lithium-ion, this cost falls meaningfully as duration increases, since adding energy capacity mainly means more (relatively cheap) electrolyte.
VRFBs typically achieve 65-80% round-trip efficiency, somewhat lower than lithium-ion's 85-92%.
How many full charge/discharge cycles the system performs per year. Once-daily cycling is about 365; capacity-only or arbitrage-light duty cycles less.
VRFB calendar life is commonly cited at 20-25 years. Notably, VRFB cycle life (often 15,000-20,000+ cycles with minimal degradation) frequently exceeds what typical daily cycling would use within that calendar life -- meaning calendar life, not cycle-driven degradation, is often the binding constraint.
Annual operating and maintenance cost as a percentage of total installed cost, applied each year over the plant life.
The price of the electricity bought to charge the battery. Off-peak, curtailed solar, or surplus wind commonly runs $10-40/MWh.
system energy capacity (kWh) × installed cost ($/kWh)
(system energy capacity (kWh) × cycles per year × plant life (years)) ÷ 1000
(total installed cost + lifetime charging cost + lifetime O&M cost) ÷ lifetime energy discharged (MWh)
Results update live as you type. For planning and field-check estimates — always verify against applicable standards and equipment ratings.
How we calculate this →At 300 cycles a year over a 20-year system life, this flow battery only uses 6,000 of its rated 15,000+ cycle life -- meaning calendar life, not cycle-driven wear, is the real constraint on its economic life, unlike lithium-ion, where cycle count typically dominates degradation and replacement timing. That long, stable operating life helps offset flow batteries' higher upfront cost: this example lands around $157/MWh LCOS, a genuinely competitive figure once you account for decades of reliable, minimally-degrading operation rather than just comparing sticker price per kWh. Compare this figure against our LCOS Calculator for a lithium-ion project over the same lifecycle.
How flow battery LCOS is calculated
This calculator estimates the levelized cost of storage (LCOS) for a vanadium redox flow battery (VRFB) project -- the total cost to store and re-deliver electricity across the system's full operating life, divided by the total energy discharged over that life. Eight quantities tie the calculation together.
Total Installed Cost ($) = System Energy Capacity (kWh) × Installed Cost ($/kWh). Multiplying the system's energy capacity by the all-in installed cost per kWh gives the upfront capital cost. At the defaults (8,000 kWh and $500/kWh), that is 8,000 × $500 = $4,000,000.
Lifetime Cycles = Cycles per Year × Plant Life (years). Multiplying the annual cycle count by the operating life gives the total number of charge/discharge cycles the system performs. At the defaults (300 cycles/year and 20 years), that is 300 × 20 = 6,000 cycles.
Lifetime Energy Discharged (MWh) = (System Energy Capacity (kWh) × Lifetime Cycles) ÷ 1000. Multiplying the energy capacity by the lifetime cycle count gives the total energy discharged in kWh; dividing by 1,000 converts it to MWh. At the defaults, that is (8,000 × 6,000) ÷ 1000 = 48,000 MWh.
Lifetime Charging Energy Required (MWh) = Lifetime Energy Discharged (MWh) ÷ (Round-Trip Efficiency (%) ÷ 100). Because round-trip efficiency means you always get back less than you put in, the charging energy required exceeds the energy discharged. At the defaults (48,000 MWh and 75% RTE), that is 48,000 ÷ 0.75 = 64,000 MWh.
Lifetime Charging Cost ($) = Lifetime Charging Energy Required (MWh) × Charging Electricity Price ($/MWh). Multiplying the total charging energy by the price of that electricity gives the lifetime cost of the energy bought to charge the battery. At the defaults (64,000 MWh and $30/MWh), that is 64,000 × $30 = $1,920,000.
Lifetime O&M Cost ($) = Total Installed Cost ($) × (Annual O&M Cost (%) ÷ 100) × Plant Life (years). Applying the annual O&M percentage to the installed cost and multiplying by the operating life gives the total operating and maintenance cost over the project. At the defaults ($4,000,000, 2% and 20 years), that is $4,000,000 × 0.02 × 20 = $1,600,000.
Total Lifetime Cost ($) = Total Installed Cost ($) + Lifetime Charging Cost ($) + Lifetime O&M Cost ($). Summing the upfront capital, the lifetime charging cost, and the lifetime O&M cost gives the all-in cost of owning and operating the system across its full life. At the defaults, that is $4,000,000 + $1,920,000 + $1,600,000 = $7,520,000.
LCOS ($/MWh) = Total Lifetime Cost ($) ÷ Lifetime Energy Discharged (MWh). Dividing the total lifetime cost by the total energy discharged gives the levelized cost per megawatt-hour delivered -- the single all-in figure that lets you compare this flow battery project against other storage technologies or against the revenue you expect it to capture. At the defaults, that is $7,520,000 ÷ 48,000 = $156.67/MWh.
Two notes on the model. First, this is a simplified undiscounted LCOS: it does not apply a discount rate to future costs, does not model capacity degradation or augmentation, and treats cycles, O&M, and charging price as constant across the full life -- a more detailed model would discount future cash flows and account for any year-over-year changes. Second, the result is most sensitive to installed cost per kWh and plant life (which together drive the capital cost amortized over the life) and to charging electricity price (which compounds across thousands of cycles), so the editable fields let you substitute project-specific values. Data sources: VRFB installed cost ranges and calendar/cycle life from DOE (Department of Energy), NREL (National Renewable Energy Laboratory), and IRENA (International Renewable Energy Agency) energy storage technology assessments; VRFB round-trip efficiency ranges from industry benchmarks and NREL studies; LCOS methodology from standard levelized cost of storage frameworks. Verification: with defaults (8,000 kWh, $500/kWh, 75% RTE, 300 cycles/yr, 20 years, 2% O&M, $30/MWh), Total Installed Cost = $4,000,000, Lifetime Energy Discharged = 48,000 MWh, LCOS = $156.67/MWh.