Solar and battery jargon explained
Plain-English meanings for the words on your paperwork and in your app, from kWp to G98.
The words you'll come across on your paperwork and in your app, in plain English.
Your system
| Word | What it means |
|---|
| Panels (PV, photovoltaic) | Turn daylight into electricity. They need daylight, not direct sun. |
| Inverter | Turns the panels' electricity (DC) into the kind your home uses (AC). It's the brain of the system. |
| Hybrid inverter | An inverter that also charges and discharges a battery. Fox ESS and Duracell Energy systems use one. |
| Battery | Stores spare electricity for later. A Tesla Powerwall 3 has the inverter built in. |
| Dongle | The small Wi-Fi stick that connects the inverter to your app. |
| Isolator | A switch that safely disconnects part of the system. There's an AC isolator and a DC (solar) isolator. |
| CT clamp | A sensor around your main electricity cable that tells the inverter what your home is using. |
| Optimiser | A small box behind a panel that lets each panel work at its best, for example when part of the roof is shaded. |
| Bird barrier | Mesh around the edges of the panels to stop birds nesting underneath. |
| Consumer unit | Your fuse box. |
Numbers
| Word | What it means |
|---|
| W / kW | Power: how fast electricity is being made or used right now. |
| kWh | Energy over time: what bills and batteries are measured in. |
| kWp | The size of your panels: number of panels × watts ÷ 1000. |
| SoC | State of charge: how full the battery is, as a percentage. |
| Min SoC / Backup Reserve | The level a battery keeps back and won't go below day to day. |
| Usable capacity | How much of a battery you can actually use. A little less than its total (nominal) size. |
In the app
| Word | What it means |
|---|
| Generation / PV / solar | What your panels are making. |
| Load / home / consumption | What your house is using. |
| Import | Electricity you're buying from the grid. |
| Export | Spare electricity going out to the grid. |
| Work mode / operational mode | How the battery behaves, for example Self-use or Savings. |
| EPS / backup | Power from the battery to some or all circuits during a power cut. |
Paperwork
| Word | What it means |
|---|
| MCS certificate | Shows a certified installer fitted your system to the MCS standard. You need it for export payments. |
| EIC | Electrical Installation Certificate: shows the electrical work was tested and is safe. |
| G98 / G99 | How your network operator is told about your system. G98 is a notification after installation; G99 is an approval before it. |
| DNO | Distribution network operator: the company that runs the power lines in your area. |
| MPAN | The 13-digit number for your electricity supply, on your bill. An export MPAN is a second one for the electricity you export. |
| SEG | Smart Export Guarantee: how you get paid for electricity you export. |
| SMETS2 | The current kind of smart meter, which sends half-hourly readings. |
| HIES | Our consumer code, which protects your deposit and backs our workmanship guarantee with insurance. |
| Handover pack | Your page on handover.rest-uk.com with all your documents. |
