eCactus Solar

Professionals in the solar photovoltaic (PV) and battery storage sectors must possess a comprehensive understanding of industry-specific terms to effectively navigate the continually changing landscape of this discipline. The technology, strategies, and mechanisms that underpin our industry exhibit a wide range of diversity and complexity.

It is imperative to establish a common understanding of the accompanying terminology in order to facilitate straightforward communication and foster productive collaboration. In light of this recognition, we have compiled an extensive “Glossary of Terms” to function as a readily accessible resource for solar installers and other relevant parties possessing expertise in solar installations.

This glossary is intended to facilitate the process of accessing information, whether you are an experienced installer in need of a quick review or a technical specialist aiming to enhance your understanding of certain terminology.

The objective of this initiative is to enhance informed discussions and decision-making in the solar PV and battery storage industries by centralising key terms. We cordially extend an invitation to fully leverage this resource, so guaranteeing utmost clarity and precision in your professional pursuits.

Global Terminology

AC (Alternating Current)

Electric current where the flow of electric charge periodically reverses direction.

ACAN (Amperex CAN)

A proprietary communication network that interconnects the Main Battery Management Unit (MBMU) with the Power Conversion System (PCS).

AGM (Absorbent Glass Mat)

A type of VRLA battery in which the electrolyte is absorbed into a mat of fine glass fibres.

BESS (Battery Energy Storage System)

A system that stores energy from the grid or renewable resources like wind or solar for use at a later time.

BEV (Battery Electric Vehicle)

A type of electric vehicle that uses chemical energy stored in rechargeable battery packs.

BMS (Battery Management System)

An electronic system that manages a rechargeable battery by protecting it from operating outside its safe operating parameters. It monitors its state, calculates secondary data, reports data, controls its environment, and potentially balances it.

BMU (Battery Management Unit)

A device or subsystem responsible for managing a rechargeable battery, ensuring safe operation and longevity by monitoring and controlling its state and parameters.

BOL (Begin of Life)

The initial phase in the life cycle of a product or system when it is first put into service.

BOS (Balance of System)

In a photovoltaic system, it signifies all components other than the photovoltaic panels.

C&I (Commercial & Industrial)

Relating to commerce and industry.

CAN (Controller Area Network)

A robust vehicle bus standard allowing microcontrollers and devices to communicate with each other (through applications) without a host computer.

CATL (Contemporary Amperex Technology Limited)

A China based company that manufactures lithium-ion batteries for electric vehicles and energy storage systems.


A communication network between the Battery Management Unit (BMU) and the Cell Supervision Circuit (CSC).

CSC (Cell Supervision Circuit)

An electronic circuit that monitors and manages both the performance and safety of an individual battery cell or groups of cells.

CSP (Concentrated Solar Power)

Technology that uses mirrors or lenses to concentrate a large area of sunlight.

CSU (Current Sensor Unit)

A device that measures the electrical current flowing through a conductor and provides a signal accordingly.

CT (Current Transformer)

A type of transformer that is used to measure alternating current (AC).

DC (Direct Current)

Electric current that only flows in one direction.

DCAN (Diagnostic CAN)

An internal Controller Area Network used for debugging.

DER (Distributed Energy Resource)

Distributed Energy Resources are technologies that produce, store, and distribute energy as and when it is required, monitored by an energy management system.

DoD (Depth of Discharge)

Signifies how much of a battery’s capacity has been used.

ENS (Electrical Network Service)

Refers to services related to electrical grids.

EOL (End of Life)

The final stage in the life cycle of a product or system when it is no longer functional or economically viable to continue using.

EPC (Engineering, Procurement, and Construction)

A contracting arrangement where the EPC contractor is responsible for all project activities.

EPS (Emergency Power Supply)

A backup power supply that allows uninterrupted operation during power outages.

ESS (Energy Storage System)

A system designed to store electrical energy on a large scale.

ETH (Ethernet Module)

A hardware component that provides networking capabilities to a device or system using Ethernet communication protocols.

EV (Electric Vehicle)

A vehicle that uses electric motors for propulsion.

FIT (Feed-in Tariff)

A policy mechanism designed for renewable energy technologies producers.

FSS (Fire Suppression System)

An integrated system designed to detect fires and mitigate damage by automatically extinguishing or containing them. These systems are commonly used in buildings, aircraft, ships, and other environments where a rapid response to fire is necessary to protect lives and property.

IBC (Interdigitated back contact cells)

A solar cell design for increased efficiency.

IPP (Independent Power Producer)

An entity which owns facilities to generate electric power for sale.

IRR (Internal Rate of Return)

A metric used to estimate the profitability of potential investments.

kW (Kilowatt)

A measure of 1,000 watts of electrical power.

kWh (Kilowatt hour)

A measure of electrical energy equivalent to 1,000 watts for 1 hour.

LCOE (Levelised Cost of Energy)

The unit-cost of electricity over the lifetime of a generating asset.

LFP (Lithium Iron Phosphate)

A type of lithium-ion battery known for its safety and longevity.

Li-ion (Lithium-ion)

A type of rechargeable battery for portable electronics and EVs.

MBMU (Master Battery Management Unit)

The primary control unit within a battery management system that oversees and coordinates all battery-related functions. It communicates with other battery management units or cell supervision circuits and is responsible for the battery pack’s overall performance, safety, and efficiency.

MPPT (Maximum Power Point Tracking)

A technique used to extract maximum power from PV modules.

MSD (Manual Switch Disconnector)

A manually operated safety device used to disconnect the electrical circuit of a battery or other power source for safety and servicing.

MWh (Megawatt hour)

A unit of energy equivalent to one megawatt for one hour.

NMC (Nickel Manganese Cobalt)

A type of lithium-ion battery balancing energy density and safety.

O&M (Operation and Maintenance)

Tasks related to a photovoltaic system’s operation and upkeep.

PCS (Power Conversion System)

The Power Conversion System is an electrical device that facilitates the bidirectional conversion of energy between the battery system and/or load. Charge and discharge capabilities, active and reactive power regulation, and off-line switching capabilities should be included in this device.

PHEV (Plug-in Hybrid Electric Vehicle)

A vehicle that uses rechargeable batteries and can be plugged in.

PPA (Power Purchase Agreement)

A contract between an electricity generator and purchaser.

PT (Potential Transformer)

Used to scale down voltage in high voltage systems.

PV (Photovoltaic)

The conversion of light into electricity using semiconducting materials.

PVC (Photovoltaic Cell)

A diode that converts visible light into direct current.

RE (Renewable Energy)

Energy from naturally replenished sources.

RPS (Renewable Portfolio Standards)

Regulations for increased production of energy from renewable sources.

SBMU (Slave Battery Management Unit)

A secondary battery management unit that operates under the direction of a primary battery management system to oversee additional battery modules.

SCAN (Slave CAN)

A Controller Area Network used between the Slave Battery Management Unit (SBMU) and the Current Sensor Unit (CSU).

SOC (State of Charge)

Equivalent to a fuel gauge for a battery pack in EVs.

The current charge level of a battery expressed as a percentage of its total capacity.

SOE (State Of Energy)

A measurement representing the total energy a battery can store or deliver at a given time.

SOH (State of Health)

An estimation of a battery’s remaining capacity and performance compared to its new condition.

SOP (State Of Power)

The available power capacity of a battery, which may vary according to the battery’s condition, age, temperature, and other factors.

SPD (Surge Protection Device)

A device or appliance that protects electrical equipment from voltage surges and spikes. An SPD limits transient voltages by blocking or redirecting surge current to the ground, safeguarding connected electronics from damage.

TMS (Thermal Management System)

A system or set of mechanisms that regulate the temperature of a device or an environment. Thermal management systems are critical in electronics, vehicles, and machinery to ensure that components operate within safe temperature ranges and to maintain efficiency and performance.

TUV (Technischer Überwachungsverein)

A German organisation that validates product safety.

UPS (Uninterruptible Power Supply)

Provides emergency power during mains power failures.

VRLA (Valve-Regulated Lead-Acid)

A type of rechargeable battery with minimal electrolyte and a pressure valve.

UK-Specific Terminology

BEIS (Department for Business, Energy & Industrial Strategy)

A UK government department.

CCL (Climate Change Levy)

An environmental tax on electricity and gas.

CfD (Contract for Difference)

A financial tool for renewable energy generators.

COP (Coefficient of Performance)

A ratio measuring the efficiency of a heating system.

CPI (Consumer Price Index)

A measure of consumer price inflation.

DECC (Department of Energy and Climate Change)

A former UK government department.

DNO (Distribution Network Operator)

Companies licensed to distribute electricity.

DUoS (Distribution Use of System)

Costs for the UK’s electricity distribution networks.

ECO (Energy Company Obligation)

A UK government scheme.

EMR (Electricity Market Reform)

A program established by the UK government.

ESCo (Energy Services Company)

A commercial business providing energy solutions.

FiT (Feed-in Tariff)

A policy mechanism for renewable energy technologies.

LZC (Low or Zero Carbon)

Technologies or measures producing low or zero carbon emissions.

MCS (Microgeneration Certification Scheme)

A quality assurance scheme in the UK.

Ofgem (Office of Gas and Electricity Markets)

The UK government regulator.

REE (Renewable Energy Exporter)

Refers to those who generate renewable energy for the grid.

RHI (Renewable Heat Incentive)

A UK Government scheme.

RPI (Retail Price Index)

An inflation measure.

RO (Renewables Obligation)

A scheme for electricity generation from renewable sources.

ROC (Renewables Obligation Certificate)

A green certificate for renewable electricity generation.

SAP (Standard Assessment Procedure)

Methodology to assess energy and environmental performance.

SEG (Smart Export Guarantee)

A UK government obligation for electricity suppliers.

ST (Solar Thermal)

A technology for harnessing solar energy for heat.


Refers to the three highest system demand periods between November and February.

VAT (Value Added Tax)

A consumption tax.

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