Common Solar Terms Made Simple

Solar can feel full of jargon. This glossary explains the key terms you’ll see in your paperwork, apps, and handover pack — all in plain English. Keep it handy whenever you need a quick reference.

Certificates, Approvals & Organisations

MCS (Microgeneration Certification Scheme)

A UK quality standard for renewable energy installations.

If your installer and products are MCS-certified, it means they meet strict standards.
You’ll get an MCS Certificate in your handover pack — needed for export payments.

DNO (Distribution Network Operator)

The company that manages the local electricity network in your area (cables, substations, and the grid).

They approve how much electricity your system can export.
You’ll see “DNO approval” in your paperwork.

G98 / G99

UK rules for connecting generators like solar to the grid.

G98 – For smaller systems (up to 3.68kW per phase). Usually just a notification after installation.
G99 – For larger systems or batteries. Requires approval before installation.

MPAN (Meter Point Administration Number)

A unique 13-digit number that identifies your electricity supply.

Found on your electricity bill.
Needed when applying for SEG export tariffs.

Tariffs & Payments

SEG (Smart Export Guarantee)

The scheme that pays you for exporting solar electricity back to the grid.

Run by energy suppliers, not the government.
You need your MCS Certificate and DNO approval to apply.

Export Tariff

The rate your energy supplier pays you per unit of electricity you export to the grid.

Feed-in Tariff (FiT)

An older government scheme (closed in 2019). If you already receive FiT, you’ll continue — new customers join SEG instead.

System Components

Solar PV (Photovoltaic)

The technical name for solar panels — devices that convert sunlight into electricity.

Inverter

The device that converts DC electricity (from your panels) into AC electricity (used by your home and the grid).

Hybrid Inverter

An inverter that manages both solar panels and battery storage in one unit.

String Inverter

A standard inverter where panels are connected in series (“a string”). If one panel underperforms, it can affect the whole string.

Micro-Inverter

A small inverter fitted to each solar panel, allowing them to work independently. Helpful for shaded or complex roofs.

Optimiser

A device fitted to panels to reduce shading issues and improve overall system efficiency.

Battery Storage

A home battery stores spare solar energy for later use — helping you buy less from the grid and take advantage of cheap overnight tariffs.

Diverter

A device (e.g. MyEnergi Eddi, iBoost) that diverts spare solar energy to heat your hot water tank instead of exporting it.

Generation Meter

A meter that measures how much solar electricity your system generates.

Smart Meter

A digital electricity meter that records what you import (from the grid) and export (to the grid). Needed for SEG payments.

Technical Terms

AC (Alternating Current)

The type of electricity used in your home and supplied by the grid.

DC (Direct Current)

The type of electricity generated by solar panels and stored in batteries before being converted into AC.

Export Limit

The maximum amount of electricity your DNO allows you to send back to the grid at one time.

Example: An 8kW system may have a 6kW export limit.
You can still use the full 8kW at home.

kW (Kilowatt)

A measure of power — how much energy is being generated or used at a moment in time.

kWh (Kilowatt-hour)

A measure of energy — the amount of power used or generated over time.

Example: A 1kW kettle running for 1 hour uses 1kWh.

Depth of Discharge (DoD)

The percentage of a battery’s capacity that can be safely used.

Example: A 10kWh battery with 90% DoD gives 9kWh usable.

Cycle Life (Battery)

The number of times a battery can be charged and discharged before its capacity starts to reduce.

Financial & Performance Terms

Self-Consumption

The percentage of solar energy you use directly in your home instead of exporting it.

Payback Period

The time it takes for your system’s savings and export payments to equal the upfront installation cost.