Solar & renewables glossary

Key terms explained

Bookmark this page — you can come back whenever you encounter an unfamiliar term in your quote.

01MCS (Microgeneration Certification Scheme)

An industry-led quality assurance scheme for renewable energy installations. MCS certification is required for your installer to register your system on the MCS Installation Database, which in turn is required to claim the Smart Export Guarantee. We install through MCS-certified partners. You can check the register at mcscertified.com.

02SEG (Smart Export Guarantee)

A UK government scheme requiring licensed energy suppliers to offer a tariff for small-scale electricity exported to the grid. You must have an MCS-certified installation and a smart meter or approved export meter. Rates vary by supplier — we help you find the right tariff.

03DNO (Distribution Network Operator)

The company that owns and operates the local electricity distribution network. In Scotland, this is either SPEN (SP Energy Networks) covering the Central Belt and south, or SSEN (Scottish & Southern Electricity Networks) covering the Highlands and north-east. You must notify your DNO before connecting a generator to the grid.

04kWp (Kilowatt Peak)

The peak power output of a solar panel or array under standard test conditions (STC: 1,000 W/m² irradiance, 25°C cell temperature). A typical domestic system in Scotland is 4–8 kWp. Real-world output varies with irradiance, temperature, shading, and orientation.

05EPC (Energy Performance Certificate)

A rating of a property's energy efficiency from A (most efficient) to G (least efficient). Required for selling or renting a property. Installing solar panels, insulation, or a heat pump can improve your EPC rating.

06G98

The Engineering Recommendation that covers the connection of small generators (up to 16A per phase, typically up to 3.68 kW single-phase or 11.04 kW three-phase) to the distribution network. Most domestic solar installations fall under G98, which requires only a notification to the DNO — not a full application.

07G99

The Engineering Recommendation for larger generators exceeding the G98 thresholds. G99 requires a formal application to the DNO and may involve a network study, which can take 6–12 weeks. Larger domestic systems and most commercial installations require G99.

08SPEN (SP Energy Networks)

The Distribution Network Operator for the Central Belt, south of Scotland, and parts of England and Wales. If your property is in SPEN's area, your DNO notification or G99 application goes to them. We handle this as part of the process.

09SSEN (Scottish & Southern Electricity Networks)

The Distribution Network Operator for the Highlands, north-east Scotland, and parts of southern England. If your property is in SSEN's area, your DNO notification or G99 application goes to them. We handle this as part of the process.

10ASHP (Air Source Heat Pump)

A heating system that extracts heat from the outside air and uses it to heat your home and hot water. ASHPs work efficiently even at sub-zero temperatures. Installation is carried out through our MCS-certified partners.

11Hybrid Inverter

An inverter that manages both solar panel generation and battery storage in a single unit. It converts DC electricity from the panels and battery into AC for use in the home, and directs surplus energy to the battery or grid. Simpler and often more cost-effective than separate solar and battery inverters.

12LiFePO4 (Lithium Iron Phosphate)

A lithium-ion battery chemistry known for its long cycle life, thermal stability, and safety. LiFePO4 batteries do not suffer thermal runaway under normal conditions and contain no cobalt.

13Smart Export Tariff

Another name for the Smart Export Guarantee (SEG). Energy suppliers offer varying rates for exported electricity — some are fixed, some track wholesale prices. We help you compare tariffs and sign up after installation. A smart meter or approved export meter is required.

14Permitted Development

Planning rules that allow certain types of building work to be carried out without applying for planning permission. In Scotland, most domestic solar panel installations fall under permitted development, subject to conditions on protrusion, roof height, and property type (listed buildings and conservation areas may require consent).

15Inverter

A device that converts the direct current (DC) electricity generated by solar panels into alternating current (AC) electricity used in the home. String inverters handle multiple panels as one; microinverters are fitted to individual panels.

160% VAT

A reduced rate of VAT that applies to solar panels and battery storage installations until 31 March 2027. It is applied automatically — you do not need to apply separately.

17Interest-free credit up to £30,000, subject to status

Finance may be available for your installation, subject to status. Contact us to discuss options.