AMPROTEQHow we calculate LCOS.
The method behind “lowest cost per delivered kilowatt-hour”: inputs, formula and the assumptions that move it.
Published 13 October 2026
Levelised cost of storage (LCOS) is the cost of every kilowatt-hour a storage system will deliver over its life. It is how we compare configurations, durations and offers on one basis, and it is the number our claim “engineered for the lowest cost per delivered kilowatt-hour” refers to. We do not publish a market-wide ranking; we publish the method, so any offer can be compared on it.
The formula
Costs and energy are both discounted at the same rate r over the same N years, so a kilowatt-hour delivered in year 15 counts for less than one delivered in year 1.
What goes in
- Capex: the installed system, including power conversion, the medium-voltage skid where used, civils, connection and commissioning.
- Opex: maintenance, monitoring, insurance and the auxiliary energy for cooling and controls.
- Augmentation: modules added or replaced to hold contracted capacity, timed from the degradation curve.
- Charging cost: the energy bought to charge the battery, at the off-peak or solar price, grossed up for round-trip losses. Some comparisons leave it out to show the cost of the storage alone; we always say which we have done.
- Energy discharged: usable capacity (90 % depth of discharge) × cycles per year × state of health in that year × efficiency.
What moves it most
- Degradation. Energy delivered in later years depends on how fast the cells fade. We use the cell manufacturer's measured 20-year test set by dispatch duty, published on the Systems page, not an assumed end-of-life figure.
- Thermal design. Cells age at the rate of the hottest cell. Liquid cooling holding the spread to about 3 °C is what lets cells reach their rated cycle life.
- Duty. Running at 0.5C or below and one cycle a day trades a little power for a lot of life.
- Efficiency. 94.0 % DC round trip at beginning of life; at least 88 % AC to AC for the whole system.
- Discount rate. Your cost of capital, or the rate in the PPA.
Ask for it
Every AMPROTEQ proposal states its LCOS with these inputs listed. If you have another offer, send it with your enquiry and we will put both on the same basis.
Start with your meter data.
Twelve months of interval data, your tariff schedule and your notified maximum demand are enough for a first sizing, an indicative capex and a PPA rate, within five working days, at no cost.