UK Solar Panel Glossary

Your Guide to Key Terms & Concepts

Understanding the terminology surrounding solar panels can seem daunting, but this glossary aims to provide clear, concise explanations of currently relevant terms, abbreviations, governing bodies, industry organisations, and other UK-specific considerations like grant schemes and planning regulations.

Term / Abbreviation	Category	Definition & UK Relevance
AC (Alternating Current)	Technology	The type of electricity used in homes and businesses in the UK. Solar panels generate DC (Direct Current) electricity, which is then converted to AC by an inverter for household use and export to the grid.
Amorphous Solar Cell	Technology	A type of thin-film photovoltaic (PV) cell made from non-crystalline silicon, giving it a more glassy structure. Less efficient than monocrystalline or polycrystalline, but can perform better in low light and are more flexible.
Array	Technology	The common term for an arrangement of multiple solar panels connected together to form a solar PV system. The size of an array is usually measured in kWp.
Azimuth	Technology	The horizontal direction a solar panel array faces, measured in degrees clockwise from North. For optimal performance in the UK, a south-facing azimuth (180 degrees) is generally ideal, though East and West can still be suitable.
Battery Storage (Solar Battery)	Technology	A system that stores excess electricity generated by solar panels for later use, such as during the evening or on cloudy days, rather than exporting it all to the grid. This increases self-consumption and energy independence.
Building Regulations	Planning/Regulations	National standards for the design, construction, and alteration of buildings in the UK, including requirements for the structural integrity and electrical safety of solar panel installations. Approval may be needed for roof loading and electrical works.
Conservation Area	Planning/Regulations	An area of special architectural or historic interest in the UK. While planning permission is often not required for solar panels in these areas, special considerations apply, especially for panels on walls fronting a highway or on listed buildings.
DC (Direct Current)	Technology	The type of electricity generated directly by solar panels. An inverter is required to convert this to AC for use in typical UK homes.
DNO (Distribution Network Operator)	Industry Organisation	The company responsible for operating and maintaining the electricity distribution network in a specific geographical area of the UK. Your solar panel installer will typically register your system with your DNO.
ECO4 (Energy Company Obligation)	Grant Scheme	A UK government energy efficiency scheme running until March 2026. It requires large energy suppliers to provide funding for energy efficiency improvements, including solar panels, to eligible low-income and vulnerable households.
Energy Performance Certificate (EPC)	Planning/Regulations	A certificate that rates a property’s energy efficiency from A (most efficient) to G (least efficient). Historically, an EPC rating was sometimes required for certain solar panel grant schemes (e.g., Feed-in Tariff).
Energy Saving Trust (EST)	Industry Organisation	An independent organisation providing impartial advice and information on energy saving, renewable energy, and related financial incentives in the UK.
Export (Electricity)	General Term	Excess electricity generated by your solar panels that is not used by your home and is instead sent back to the national grid. Under the Smart Export Guarantee (SEG), energy suppliers pay for this exported electricity.
Feed-in Tariff (FiT)	Grant Scheme (Closed)	A UK government scheme that ran from 2010 to March 2019. It paid homeowners for the electricity they generated from renewable sources (generation tariff) and for any excess electricity exported to the grid (export tariff). Closed to new applications but existing recipients continue to receive payments.
Gigawatt-hour (GWh)	Measurement	A unit of energy equal to one billion (1,000,000,000) watt-hours or one million kilowatt-hours (1,000 MWh). Used for measuring large-scale electricity generation.
Green Mortgages	Financial	Specialised mortgage products offered by lenders that provide financial incentives (e.g., lower interest rates, cashback) for purchasing, building, or renovating homes to meet certain environmental and energy-efficiency standards, including solar panel installation.
Hybrid Inverter	Technology	An inverter that can manage inputs from both solar panels and a solar battery simultaneously. It can charge batteries with solar-generated power or grid power, offering more flexibility for energy management.
Import (Electricity)	General Term	Electricity drawn from the national grid when your solar panels are not generating enough power to meet your home’s demand.
Inverter	Technology	A crucial component of a solar PV system that converts the DC electricity produced by solar panels into AC electricity, which can then be used in the home or exported to the national grid.
Irradiance	Technology	A measure of the power of sunlight (solar radiation) falling on a surface, typically measured in watts per square metre (W/m²). Higher irradiance generally means more electricity generation.
Kilowatt (kW)	Measurement	A unit of electrical power, equal to 1,000 watts. Used to measure the instantaneous power output of a solar system or appliance.
Kilowatt-hour (kWh)	Measurement	A unit of energy consumption or production over time, commonly known as a “unit” of electricity. For example, a 1kW appliance running for one hour uses 1 kWh. Your electricity bill is based on kWh usage.
Kilowatt-peak (kWp)	Measurement	A standard unit used to measure the maximum electrical power a solar panel or system can produce under ideal “Standard Test Conditions” (STC). It indicates the system’s potential generating capacity.
Listed Building	Planning/Regulations	A building in the UK that has been given special legal protection because of its historic or architectural interest. Installing solar panels on a listed building typically requires Listed Building Consent in addition to any necessary planning permission.
MCS (Microgeneration Certification Scheme)	Governing Body/Standard	A UK-based quality assurance scheme that certifies microgeneration technologies (like solar PV) and installers. To be eligible for many government-backed incentives (e.g., SEG), your solar installation must be MCS-certified and installed by an MCS-accredited installer.
Megawatt-hour (MWh)	Measurement	A unit of energy equal to one thousand (1,000) kilowatt-hours (kWh). Used for larger solar installations and commercial energy measurement.
Monocrystalline Solar Panel	Technology	A type of solar panel made from a single, pure crystal of silicon. These panels are typically more efficient and have a uniform black appearance.
Mounting System	Technology	The framework and components used to securely attach solar panels to a roof (roof-mounted) or to the ground (ground-mounted).
NAPIT (National Association of Professional Inspectors and Testers)	Industry Organisation	A UK Accreditation Service (UKAS) approved membership scheme for tradespeople, including solar panel installers. A NAPIT-registered installer indicates adherence to certain quality and safety standards.
NICEIC (National Inspection Council for Electrical Installation Contracting)	Industry Organisation	A non-profit independent regulatory body for the electrical contracting industry in the UK, administering a register of qualified electricians and solar panel installers. An NICEIC logo suggests high standards of work and safety.
Ofgem (Office of Gas and Electricity Markets)	Governing Body	The UK government regulator for the electricity and natural gas markets. Ofgem oversees various environmental and social schemes, including the administration of the Smart Export Guarantee (SEG).
Optimiser (Power Optimiser)	Technology	A device installed on individual solar panels to maximise their performance. They help to mitigate the impact of shading or differing panel performance, ensuring the rest of the array continues to operate effectively.
Permitted Development Rights	Planning/Regulations	Rules that allow certain types of development (including solar panel installation) without needing to apply for full planning permission, provided specific conditions are met (e.g., panel protrusion, height, location in relation to highways in conservation areas).
Photovoltaic (PV)	Technology	The technical term for the conversion of light (photo) directly into electricity (voltaic). Solar PV panels are the most common type of solar panels, converting sunlight into electricity.
Pitch (Roof Pitch)	Technology	The angle of a roof slope. For solar panels, the optimum pitch for maximum sunlight absorption varies across the UK, but generally, between 10 and 50 degrees is considered adequate.
Planning Permission	Planning/Regulations	Formal consent required from a local planning authority for certain building work or changes of use. While many domestic solar panel installations fall under “permitted development,” planning permission is required if certain conditions are not met, or for listed buildings and some commercial properties.
Polycrystalline Solar Panel	Technology	Also known as multicrystalline, these panels are made from multiple silicon crystals. They are generally less efficient than monocrystalline but can be more cost-effective and have a fragmented, reflective appearance.
Power Purchase Agreement (PPA)	Financial	A contractual agreement between a solar energy generator and a power buyer, where the buyer agrees to purchase electricity generated by the solar system at a pre-agreed price over a set period. Often used for larger commercial or community projects.
REA (Renewable Energy Association)	Industry Organisation	A not-for-profit trade association representing a wide range of renewable energy and clean technology companies in the UK, promoting a future based on renewable energy.
RECC (Renewable Energy Consumer Code)	Industry Organisation	A consumer protection code approved by the Chartered Trading Standards Institute. RECC members commit to high service standards for domestic renewable energy installations, providing consumers with assurance. Installers registered with MCS are often required to adhere to an approved consumer code like RECC.
Renewable Heat Incentive (RHI)	Grant Scheme (Closed)	A UK government scheme that paid participants for generating renewable heat for their homes or businesses. While the domestic RHI closed in March 2022, it was relevant to solar thermal installations.
Self-Consumption	General Term	The amount of electricity generated by your solar panels that you use directly in your home, rather than exporting it to the grid. Maximising self-consumption reduces reliance on grid electricity and can lead to greater savings.
SEG (Smart Export Guarantee)	Grant Scheme	A UK government-backed initiative, introduced in 2020, that requires larger energy suppliers to pay homeowners for any surplus renewable electricity (including solar PV) they export to the national grid. An MCS certificate is usually a prerequisite.
Solar Farm (Solar Field)	Technology/Industry	Large-scale solar installations consisting of numerous ground-mounted solar panels, typically used to generate electricity for the grid or large industrial consumers.
Solar PV (Photovoltaic)	Technology	The most common type of solar technology, directly converting sunlight into electricity.
Solar Thermal	Technology	A technology that uses solar energy to heat water or a heat-transfer fluid, rather than generating electricity. Often used for domestic hot water systems.
Solar Together	Grant Scheme/Initiative	A group-buying scheme for solar panels organised by local councils in partnership with providers. It aims to make solar installations more affordable by leveraging collective purchasing power.
Solar Trade Association (STA)	Industry Organisation (Renamed)	Formerly the main UK solar industry body, now known as Solar Energy UK.
Solar Energy UK	Industry Organisation	The leading trade association for the UK solar energy industry, representing companies across the solar sector and working to influence policy and drive market growth.
Stand-alone Solar Panel	Technology	A solar panel that is not attached to a building, often located in a garden or on agricultural land. Specific planning permission rules apply based on height and proximity to boundaries.
TWh (Terawatt-hour)	Measurement	A unit of energy equal to one trillion (1,000,000,000,000) watt-hours or one billion kilowatt-hours (1,000,000 MWh). Used for measuring very large-scale energy production or consumption.
Warm Homes: Local Grant	Grant Scheme	A government scheme expected to deliver from Spring 2025, funding eligible local authorities to provide energy performance upgrades (including solar panels) to low-income households in privately owned homes in England.
Watt (W)	Measurement	The basic unit of electrical power.
Watts-peak (Wp)	Measurement	The peak power output of a single solar panel under Standard Test Conditions (STC). Often used to describe the capacity of individual panels, while kWp is used for entire systems.
Zero-rate VAT	Tax Allowance	A UK government incentive that applies a 0% VAT rate to the supply and installation of certain energy-saving materials, including solar panels, until March 31, 2027, for installations in England, Scotland, and Wales.

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