AC-Coupled

A solar-plus-storage configuration in which the solar array and the battery each have their own inverter. It adds flexibility and is well suited to retrofitting storage onto existing solar. Compare with DC-Coupled.

All-Electric Vessel

A ship or boat propelled entirely by electric motors drawing on onboard batteries, with no direct fuel combustion. Well suited to short-route ferries, harbor craft, and inland vessels.

Atmospheric Water Generation

Technology that extracts drinking water directly from humidity in the air, typically using condensation or desiccant materials. Provides a decentralized source of potable water for homes, resorts, and remote sites without wells or pipelines.

Augmentation

Adding battery capacity to an existing storage system over time to offset natural degradation and keep usable capacity at target levels through the project’s life.

Bankability

The degree to which a project’s technology, contracts, and projected returns are solid enough for lenders and investors to finance it on reasonable terms.

Baseload

The minimum continuous level of power demand on a grid over a given period, traditionally met by always-on generation. Storage and renewables increasingly reshape how baseload is served.

Behind-the-Meter / Front-of-the-Meter

Describes where an energy asset sits relative to the utility meter. Behind-the-meter systems (rooftop solar, on-site batteries) serve a single customer and reduce their utility bill; front-of-the-meter assets connect directly to the grid and sell power or services wholesale.

BESS

Battery Energy Storage System. Large-scale batteries that store electricity from solar, wind, or the grid and discharge it when demand is high. Used to stabilize grids and provide backup power.

Bidirectional Charging

Charging that lets energy flow both into and out of an EV battery, enabling vehicle-to-grid (V2G) and vehicle-to-load applications where parked vehicles become a power source.

Black Start

Restarting a grid or facility after a total outage using local generation or storage, without drawing power from an external source.

BMS

Battery Management System. Onboard electronics that monitor and protect each battery cell — balancing charge, regulating temperature, and preventing over-charge or over-discharge.

BOOT

Build-Own-Operate-Transfer. A project delivery model where Mystic finances, builds, and operates the energy asset for a contracted period before transferring ownership to the client.

Brackish Water

Water saltier than fresh water but less salty than seawater, commonly found in estuaries and some groundwater. It requires less energy to desalinate than seawater.

Brine

The concentrated salt solution left over after desalination. It must be managed or discharged responsibly to protect surrounding ecosystems.

C-Rate

A measure of how fast a battery charges or discharges relative to its capacity. A 1C rate fully charges or discharges in one hour; 0.5C takes two hours.

Capacity Factor

The ratio of an asset’s actual output over time to its maximum possible output, expressed as a percentage. A useful way to compare how hard different generation or storage assets actually work.

CapEx / OpEx

Capital Expenditure is the upfront cost to build or acquire an asset. Operating Expenditure is the recurring cost to run and maintain it. Both feed into a project’s total cost of ownership.

CCS

Combined Charging System. A widely used DC fast-charging connector standard for electric vehicles in North America and Europe.

Cold-Ironing

Shore-to-ship power supply. Allows docked vessels to shut down onboard diesel generators and connect to grid or stored electricity, eliminating port emissions and noise. See also Shore Power.

Containerized BESS

A battery energy storage system pre-engineered inside a standard shipping container for rapid transport and deployment. Mystic’s Energy in a Box™ is a containerized BESS, designed for rapid deployment in remote, island, and infrastructure settings.

Curtailment

Deliberately reducing renewable output when generation exceeds what the grid can absorb. Storage captures this otherwise-wasted energy for later use.

Cycle Life

The number of full charge-and-discharge cycles a battery can complete before its usable capacity falls below a defined threshold (commonly 80 percent). Higher cycle life means a longer service life.

DC-Coupled

A solar-plus-storage configuration in which the solar array and the battery share a single inverter, reducing conversion losses and improving efficiency. Compare with AC-Coupled.

DC Fast Charging

High-power charging that delivers direct current straight to an EV battery, bypassing the onboard converter to recharge in minutes rather than hours. Also referred to as Level 3 charging.

Demand Charge

A utility fee based on a customer’s highest rate of power use during a billing period, separate from total energy consumed. Storage can lower it through peak shaving.

Depot Charging

Charging infrastructure installed where fleets park — bus yards, truck depots, ferry terminals — to recharge multiple vehicles on a schedule, often paired with on-site storage to manage demand.

Depth of Discharge

The percentage of a battery’s capacity that has been used (DoD). Operating at a lower depth of discharge generally extends cycle life.

Desalination

The process of removing salt and minerals from seawater or brackish water to produce fresh, usable water.

Distributed Energy Resources

Small, decentralized energy assets — rooftop solar, batteries, EV chargers — located near where power is used rather than at a central plant. Often abbreviated DER.

EMS

Energy Management System. Software that controls how and when a storage system charges and discharges, optimizing for cost, grid demand, or backup priorities.

Energy Arbitrage

Buying or storing electricity when prices are low and discharging or selling it when prices are high. A core revenue stream for battery storage, especially in markets with time-of-use rates or volatile wholesale prices. See Mystic’s containerized BESS → Explore Mystic’s desalination solutions →

Energy Recovery Device

Equipment that captures and reuses pressure energy from the brine stream in reverse-osmosis systems, sharply reducing the energy needed for desalination.

EPC

Engineering, Procurement, Construction. A contract model where a single provider handles design, sourcing, and construction of a project and delivers it ready to operate.

EVSE

Electric Vehicle Supply Equipment. The formal term for EV charging hardware — the unit, connector, and controls that deliver power to a vehicle. Charging is commonly tiered as Level 1 (standard outlet), Level 2 (240V), and Level 3 / DC fast charging.

eVTOL

Electric Vertical Take-Off and Landing aircraft. Battery-powered aircraft that take off and land like helicopters, used in emerging air-mobility and emergency-response applications.

Frequency Regulation

Rapid charging and discharging of storage to keep grid frequency stable as supply and demand fluctuate moment to moment. One of the fastest-responding grid services batteries provide.

Geothermal Energy

Power and heat generated from the Earth’s internal temperature, either through deep wells that drive turbines or ground-source systems for heating and cooling. Delivers steady, around-the-clock renewable output independent of weather.

Grid Resilience

A grid’s ability to withstand and recover quickly from disruptions such as storms, cyberattacks, outages, or sudden demand spikes.

Hybrid Power System

A system that combines two or more sources — typically solar generation paired with battery storage — to deliver reliable power around the clock, including where grid access is limited.

Interconnection

The process—and the physical connection—by which a generator, battery, or microgrid is approved to link to the utility grid. Interconnection studies, agreements, and queue timelines are often the pacing item in commercial energy projects.

Inverter

A device that converts the direct current (DC) produced by solar panels and batteries into the alternating current (AC) used by the grid and most equipment.

IP Rating

Ingress Protection rating. A two-digit code indicating how well an enclosure resists dust and water — for example, IP55 denotes protection against dust and low-pressure water jets.

Islanding

The ability of a microgrid or storage system to disconnect from the main grid and keep powering local loads during an outage.

ITC (Investment Tax Credit)

A U.S. federal tax credit that offsets a percentage of the capital cost of qualifying solar, storage, and other clean-energy systems. Project timing matters: credit levels step down based on when construction starts and when equipment is placed in service.

kWh

Kilowatt-hour. A unit of energy equal to one kilowatt of power sustained for one hour — the unit most utilities use to bill electricity. 1,000 kWh equals one MWh.

LCOE

Levelized Cost of Energy. The average cost per unit of electricity over a project’s full lifetime, accounting for upfront, operating, and financing costs. Used to compare energy options on equal footing.

LFP

Lithium Iron Phosphate. A lithium-ion battery chemistry known for safety, long cycle life, and thermal stability. Widely used in grid-scale BESS due to low fire risk. Compare with NMC.

Load Shifting

Storing energy when it is cheap or abundant and using it later when prices or demand are higher.

Marine BESS

A battery energy storage system engineered for shipboard or port use, built to maritime safety, vibration, and corrosion standards. Powers all-electric and hybrid vessels and supports shore power.

Marine Hybrid Propulsion

A propulsion system that combines a conventional engine with batteries and electric drive, letting large vessels run on stored power for low-speed or zero-emission zones and cut fuel use and emissions overall.

Megawatt Charging System

A high-power charging standard (MCS) designed for heavy-duty vehicles, marine vessels, and aircraft that need far more power than passenger-car chargers can deliver.

Microgrid

A self-contained power network that can run connected to the main grid or independently, balancing local generation, storage, and demand.

MW

Megawatt. A unit of power measuring the rate of energy transfer. Used to describe the maximum output capacity of a BESS or generation asset.

MWh

Megawatt-hour. A unit of energy measuring total output over time. A 10 MW system running for 4 hours delivers 40 MWh of energy.

NACS

North American Charging Standard. The EV connector standard, originally developed by Tesla, now adopted across much of the North American market.

Nameplate Capacity

The maximum rated output of a generation or storage asset under ideal conditions, as stated by the manufacturer.

Net Metering

A billing arrangement that credits owners of on-site generation for surplus electricity they export back to the grid.

NFPA 855

A US fire-safety standard governing the installation, spacing, and protection of stationary energy storage systems.

NMC

Nickel Manganese Cobalt. A lithium-ion chemistry with high energy density, common in EVs. Compared with LFP, it stores more energy per kilogram but runs hotter, which is why grid-scale storage often favors LFP.

Off-Grid

A power system that operates entirely independent of any utility grid, relying on local generation and storage.

Offshore Wind

Wind generation sited in seas or large lakes, where stronger, steadier winds support larger turbines and higher output than most onshore sites.

O&M

Operations & Maintenance. The ongoing servicing, monitoring, and upkeep that keep an energy asset performing reliably over its life.

Onshore Wind

Land-based wind generation, generally the lowest-cost form of new wind power.

Osmotic Power

Also called Pressure-Retarded Osmosis (PRO). A method of generating electricity from the salinity difference where fresh water meets seawater.

OTEC

Ocean Thermal Energy Conversion. A method of generating electricity from the temperature difference between warm surface seawater and cold deep water.

PCS (Power Conversion System)

The bidirectional inverter hardware that converts a battery’s DC power to grid-ready AC—and back again for charging. The sizing and efficiency of the PCS determine how fast a BESS can charge and discharge.

Peak Shaving

Discharging stored energy during periods of highest demand to reduce the costliest grid draws and avoid demand charges.

Potable Water

Water that is safe for human consumption.

PPA

Power Purchase Agreement. A long-term contract between an electricity generator and a buyer, typically a utility or large consumer, to purchase energy at a predetermined price.

Reverse Osmosis

The most common desalination method (RO), forcing water through a semi-permeable membrane under pressure to separate out salts and impurities.

Round-Trip Efficiency

The percentage of energy retained after a complete charge and discharge cycle. For example, 90 percent round-trip efficiency means 10 percent of the energy is lost during storage and retrieval.

Safe Harbor

An IRS provision that lets a project lock in its Investment Tax Credit rate by “beginning construction”—starting physical work or incurring at least 5% of project costs—before a deadline. Widely used to preserve credit eligibility as ITC rules step down.

Shore Power

Grid or stored electricity supplied to a docked vessel so it can switch off its onboard engines. The enabling technology behind cold-ironing.

Solar-Plus-Storage

A combined system pairing solar PV with battery storage so daytime generation can be shifted to evening peaks or outages. Improves solar economics, enables backup power, and can qualify the battery for tax credits when charged from the solar array. Explore Mystic’s renewable energy systems →

Solar PV

Solar Photovoltaic. Technology that converts sunlight directly into electricity using semiconductor panels.

State of Charge

The amount of energy remaining in a battery, expressed as a percentage of its full capacity (SoC) — the battery equivalent of a fuel gauge.

TDS

Total Dissolved Solids. A measure of all dissolved minerals and salts in water, used to gauge water quality and desalination performance.

Thermal Runaway

A chain reaction in which a battery cell overheats and triggers further heating in neighboring cells. LFP chemistry and proper battery management greatly reduce this risk.

Tidal Energy

Electricity generated from the predictable rise, fall, and flow of ocean tides, using underwater turbines or barrages. Its predictability sets it apart from many other renewables.

UL 9540 / 9540A

A North American safety standard for energy storage systems. The companion 9540A test method evaluates how a system behaves during thermal runaway.

UN 38.3

A United Nations testing standard that lithium batteries must pass to be transported safely by road, sea, or air.

V2G

Vehicle-to-Grid. Technology that allows electric vehicle batteries to discharge power back to the grid, turning fleet vehicles into distributed energy resources.

Virtual Power Plant

A network of distributed batteries, solar systems, and flexible loads coordinated by software to act as a single power plant (VPP).

Wave Energy

Electricity generated from the motion of ocean surface waves, captured by devices that convert that movement into power.

Wind Power

Electricity generated by converting the kinetic energy of moving air into rotational energy via turbines. See Onshore Wind and Offshore Wind.

Wind Turbine

A machine that converts wind into electricity, using rotor blades to drive a generator. Output scales with blade length and wind speed.