Inverter
The unit that turns into , such as the one between a solar PV array and the board. It takes the DC from the strings and produces AC that can run alongside the supply, and battery systems can use one too. On a schematic it's the dividing line: everything before it is the DC side, which stays live while light falls on the modules, even with the AC side isolated.
Using Inverter in context
Reviewed
A distinction worth remembering
Battery storage adds a source of supply that keeps going when the grid doesn't, so switching off at the main switch doesn't make the installation dead. Under Amendment 4 of BS 7671, regulation 551.7.2.1 treats a stationary battery as a generating set and not a load. Most of what's different about this work follows from that.
Questions to take further
- How can I revise Inverter beyond the definition?
- Explain what Inverter describes, compare it with a related term and use it in a topic question. State any assumptions and what evidence you would need before applying the idea to real work.
Sources
- SELECT: So what's new? Amendment 4:2026 — A trade body's overview of Amendment 4. Regulation 110.1.1, what Section 716 covers, regulation 716.414.1.1 on sources, the 60 V and 15 V limits, cable categories and the 750 mA design current.
- BSI: PAS 63100:2024, protection against fire of battery storage in dwellings — In effect from 31 March 2024. Scope, where a battery can't go, ventilation, fire separation, alarms, and what the user is left with.
- GOV.UK: register energy devices in homes or small businesses — Telling the network operator about energy devices including battery storage, building rules, and checking with building standards in Scotland.
- ENA: distributed generation connection guide, G98 for single premises — For Great Britain. The 16 A per phase limit including storage, 3.68 kW on a single phase, the total at the premises, and notifying within 28 days of commissioning.
- National Grid: generation (G99) — Generation above 16 A, or 3.68 kW, per phase has to comply with G99.
- legislation.gov.uk: Building Regulations 2010, regulation 12 — In England, the electrical work in a home that has to be notified to building control (a new circuit, a replacement consumer unit, or work on existing circuits in a special location), and what counts as a special location.
- IET: current BS 7671 edition and updates — BS 7671:2018+A4:2026 and the main subject areas updated by Amendment 4.
- HSE: electrical safety questions — Isolation, competence and precautions before electrical work.
Where Inverter fits in the learning path
The Low-Carbon Electrics section covers these units:
- EV Charging
- Solar PV and Batteries in Depth
- Heat Pumps, Smart Loads and the Supply
See this section in the full curriculum
This section is on the Plus path. Lesson availability depends on content review and your learning path.
Read, practise, return
1. Read it in context
- Battery Energy Storage SystemsThe Regs and Practice Papers
2. Try recalling, then explore practice
Use the memory prompt below to connect the vocabulary.
- 18th Edition — quiz previewPlus · The Regs and Practice Papers
3. Return to the meaning
After reading or practising, explain the idea in your own words, then check what you remembered.
Recall a related term
Which term fits this definition? Say it to yourself, then reveal it. This is a memory prompt, with no score or saved result.
Direct current flows in one direction, although its size can vary. A battery supplies DC, while an inverter can convert DC from a battery into AC for suitable loads. DC does not mean low voltage or harmless: direction of flow and voltage level are separate ideas. Insulation resistance instruments use a DC test voltage, but that is not the normal supply voltage of the circuit.
Compare related terms
Open a meaning to compare its role with Inverter, or follow its full entry.
DC — Direct Current
Direct current flows in one direction, although its size can vary. A battery supplies DC, while an inverter can convert DC from a battery into AC for suitable loads. DC does not mean low voltage or harmless: direction of flow and voltage level are separate ideas. Insulation resistance instruments use a DC test voltage, but that is not the normal supply voltage of the circuit.
Read the DC entryAC — Alternating Current
Alternating current reverses direction repeatedly, unlike direct current. An AC voltage also changes polarity over its cycle. Frequency, measured in hertz (Hz), tells you how many complete cycles occur each second. In a three-phase system, the three AC waveforms are offset in time; three-phase does not mean three times the frequency.
Read the AC entryPV string
A set of solar photovoltaic modules wired in series, so their voltages add up while the current stays about what one module gives. A string can reach hundreds of volts DC, and it's live whenever light falls on the modules. Switching off at the board doesn't make the DC side dead, so it gets its own isolator.
Read the PV string entryBattery energy storage system — BESS
A battery and its control equipment, installed to store electricity and release it later. Often fitted alongside solar PV, it adds an energy source that can stay live when the supply is off, and running it in parallel with the network brings in the network operator's connection rules. BS 7671's Chapter 57 covers stationary batteries, and in homes PAS 63100:2024 deals with fire safety, including places a system doesn't go.
Read the Battery energy storage system entryG98 — Engineering Recommendation G98
The rules for connecting small, fully type-tested generation of up to 16 A per phase to the public network. It runs in parallel with the low-voltage network, and 16 A per phase works out at 3.68 kW per phase, counting all the plant at the premises. In Great Britain, for a single premises, the installer can usually commission first and then notify the network operator within 28 days. Northern Ireland uses NIE Networks' own version, G98/NI.
Read the G98 entryA definition is a start. Using it in a real question is where it sticks.