Glossary

Solar panel jargon explained: 25 terms in plain English

Installers' quotes are full of terms like kWp, G98, SEG and hybrid inverter. Here is what each one means, in a sentence or two. Last updated 21 October 2026.

0% VAT on solar ends 31 March 2027. That's under six months away, and it's due to go back to 5% after.

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All terms A–Z

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AC and DC: Solar panels make direct current (DC) electricity. Your home and the grid use alternating current (AC), so an inverter converts one to the other.
Battery storage: A home battery stores spare solar power made during the day so you can use it in the evening. A typical home battery holds 4–10kWh.
Conservation area: An area of special historic or architectural interest chosen by the local council. Roof panels are often still allowed, but panels on a wall facing the road need planning permission.
DNO (distribution network operator): The company that runs the local electricity network. In Nottinghamshire it is National Grid Electricity Distribution. Your installer tells the DNO about your system.
ECO4: A government scheme that funded energy upgrades through energy suppliers. It is winding down and only runs to 31 December 2026 to finish existing work.
EPC (Energy Performance Certificate): A rating of a home's energy efficiency from A (best) to G (worst). Many grants, such as the Warm Homes: Local Grant, are for homes rated D to G.
Export: Solar electricity your home doesn't use that flows out to the grid. You can be paid for it under the Smart Export Guarantee.
G98 and G99: The forms used to connect a generator such as solar panels to the grid. Most home systems use the simpler G98 notification. Larger systems, often over about 3.68kW per phase, need a G99 application approved before install.
Hybrid inverter: An inverter that can manage both solar panels and a battery. It is a common choice if you want a battery now or later.
Inverter: The box that turns DC electricity from the panels into AC for your home. Inverters usually last 10–15 years, so most systems need one replacement.
kW and kWp: A kilowatt (kW) measures power. A system's kWp (kilowatt peak) is its maximum output in ideal conditions. A typical three-bed home has a 4kWp system.
kWh: A kilowatt hour is a unit of energy, the measure on your electricity bill. Running a 1kW heater for one hour uses 1kWh.
Listed building consent: Permission needed for changes to a listed building, including fitting solar panels. It is separate from, and can be needed as well as, planning permission.
MCS (Microgeneration Certification Scheme): The UK standard for small renewable systems and installers. You usually need an MCS-certified installer and system to get Smart Export Guarantee payments.
Microinverter: A small inverter fitted to each panel instead of one central inverter. Microinverters can help roofs with partial shade.
Optimiser: A small device fitted behind each panel to get the most from it, especially when some panels are shaded. Optimisers work alongside a central inverter.
Payback period: How long it takes for bill savings and export payments to cover the cost of a system. For a typical 4kW system in Nottinghamshire it is roughly 9–14 years.
Permitted development: Building work you can do without applying for planning permission. In England, most roof solar panels qualify if they stick out no more than 200mm and stay below the highest part of the roof.
Self-consumption: The share of your solar electricity that you use in your own home. Without a battery it is often about 30–50%; a battery can raise it to about 70–90%.
Smart Export Guarantee (SEG): The scheme that requires larger energy suppliers to pay you for electricity you export. Rates vary by supplier, roughly 5–15p per kWh.
Solar diverter: A device that sends spare solar electricity to your hot water tank instead of exporting it. It can be useful if you have an immersion heater.
Solar PV: Short for solar photovoltaic: panels that turn daylight into electricity. Solar thermal panels, which heat water directly, are a different technology.
Time-of-use tariff: An electricity tariff with cheaper rates at certain times, often overnight. It can work well with a battery or an electric car.
Warm Homes: Local Grant: A government grant run by local councils that can pay for insulation, heat pumps and solar panels for eligible lower-income households in homes rated EPC D to G.
0% VAT on solar: Home solar panels and batteries have no VAT until 31 March 2027. After that the rate is due to return to 5%.

Next: read our 10-point quote checklist or the 15 most-asked solar questions.