PV string
A set of solar photovoltaic modules wired in series, so their add up while the stays about what one module gives. A string can reach hundreds of volts , 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.
Using PV string in context
Reviewed
A distinction worth remembering
The current teaser names the interfaces between sources, loads, controls and protection. The Low-Carbon Electrics part of the electrical course goes further on charge points, heat pumps and the supply, and the electrical foundations are what it builds on.
Questions to take further
- How can I revise PV string beyond the definition?
- Explain what PV string 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
- HSE: electrical safety questions — Isolation, competence and precautions before electrical work.
- IET: current BS 7671 edition and updates — BS 7671:2018+A4:2026 and the main subject areas updated by Amendment 4.
- IET: automatic disconnection of supply for island mode prosumer installations — Prosumer installations, island mode, earthing, system referencing and limited fault current from inverters.
- legislation.gov.uk: Electric Vehicles (Smart Charge Points) Regulations 2021 — Which charge points are covered, smart functionality, default charging hours, safety and where the rules extend.
- NIE Networks: generation connections — Northern Ireland's G98/NI and G99/NI connection routes.
- Ofgem: Smart Export Guarantee — Who the Smart Export Guarantee covers in Great Britain and how rates are set.
- GOV.UK: domestic battery energy storage systems — A 2020 government-published review of the safety risks of home batteries.
- 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.
- GOV.UK: domestic electrical safety guidance — England guidance on domestic electrical safety; other nations require their own checks.
Where PV string 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
- Smart, safe and low-carbon homesInstallation
2. Try recalling, then explore practice
Use the memory prompt below to connect the vocabulary.
Follow a topic above to explore how the term is used, then use the learning entry below to find your path.
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 PV string, 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 entryInverter
The unit that turns DC into AC, 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.
Read the Inverter 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 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 entryA definition is a start. Using it in a real question is where it sticks.