Panel installation and wiring
What Goes Into a UK Solar PV Electrical Setup
A solar PV installation is more than panels on a roof. There is a complete electrical system connecting the DC output from your panels through an inverter and generation meter to your consumer unit, with a mandatory notification to your Distribution Network Operator before the system can go live.
Helpful video reference. Blue Ape Renewables' "Real Electrical Setup of a UK Solar PV Install!" walks through the actual electrical components on a completed UK install, showing how each part connects and where isolators, meters and inverter sit. Blue Ape Renewables is a UK MCS-accredited solar and battery storage installer.
All the AC work is notifiable
Everything on the AC side of a solar install, including the consumer unit connection, generation meter, and DNO notification, is notifiable under Building Regulations Part P and must be carried out by a qualified and registered electrician. The DC string wiring on the roof also involves high voltages that are live whenever there is daylight. Do not attempt any part of this work yourself: it is not a grey area.
1. The DC side: panels, strings and isolators
Panels are wired together in series to form strings. The voltage of a string is the sum of the individual panel voltages: a string of 10 panels rated at 40V each has an open-circuit string voltage of around 400V. DC cables must be rated for outdoor use and UV exposure (typically twin-core solar cable to EN 50618), and all connections use MC4 connectors rather than screw terminals.
A DC isolator sits between the string cables and the inverter, and must be clearly labelled and mounted as close to the inverter as practicable under current UK wiring regulations. On rooftop installs there is usually a second DC isolator fitted at roof level as well. These isolators are not the same as domestic AC switches: they must be rated for DC voltage and current, because DC arcs behave very differently from AC arcs and will destroy an inappropriately rated switch.
2. The inverter: converting DC to AC
The inverter is the central component of the system. It takes the variable DC voltage from the strings, finds the maximum power point for the current irradiance conditions (this is called MPPT, maximum power point tracking), and inverts the result to 230V 50Hz AC to match the grid. Most residential inverters include one or two MPPT inputs, which lets the installer connect strings of different orientations or with different amounts of shading to separate inputs so they don't drag each other down.
A hybrid inverter adds a battery charge controller: it manages both the solar input and the battery charge and discharge, and in some configurations can provide a backup supply if the grid fails. Hybrid inverters are larger and more expensive, but for a system that includes battery storage they are usually the tidier and more capable solution compared with adding a separate AC-coupled battery later.
The inverter is mounted indoors or in a well-ventilated outdoor enclosure, close to the consumer unit to keep AC cable runs short. It generates some heat and noise during peak generation: factor this in when agreeing on placement with your installer.
3. The AC side: generation meter and consumer unit connection
The AC output from the inverter runs to the consumer unit via a dedicated circuit protected by a suitably rated MCB. A generation meter is fitted on this circuit, usually between the inverter and the consumer unit, to record how many kWh the system produces. This meter reading is the basis for Smart Export Guarantee calculations and is what most electricity suppliers ask for when you register for SEG export payments.
The generation meter should be MID-approved (Measuring Instruments Directive) to be accepted by most SEG suppliers. Your MCS installer will fit a suitable meter as part of a standard install. Some modern inverters include internal energy monitoring that is accurate for monitoring purposes, but is not always accepted as a metering point by suppliers for SEG, so a standalone generation meter is the safer option.
4. DNO notification and going live
Before the system is energised, your installer must notify your local Distribution Network Operator (DNO). The DNO is the company that owns and operates the cables and substations in your area: in East Kent, that is typically UK Power Networks. The notification requirement protects the grid from unmanaged power flows and is a legal requirement, not optional.
For most residential solar systems without battery export, the relevant standard is G98. Under G98, notification can be submitted at the same time as or after installation, and the system can go live on the day of install. Your installer sends a technical notification pack to the DNO, and you should receive a copy. For larger systems or systems where the battery can export to the grid, G99 applies: this requires prior approval from the DNO, which can take from a few days to several weeks depending on your network operator's workload and local grid capacity.
Frequently Asked Questions
What is a DC isolator and why does it matter?
A DC isolator is a safety switch fitted between the solar panels and the inverter, allowing the DC circuit to be safely interrupted for maintenance or in an emergency. UK wiring regulations require it to be positioned as close to the inverter as practicable and clearly labelled. DC isolators must be rated specifically for DC use: an AC-rated switch will arc and fail dangerously under DC conditions because the current does not cross zero in the same way AC does.
Do I need a separate generation meter?
Yes, if you want to register for the Smart Export Guarantee (SEG). Most suppliers require a MID-approved generation meter as part of SEG registration, and many do not accept inverter monitoring data alone. Your MCS installer will fit a standalone generation meter as part of a standard installation. This meter also gives you an independent record of how much your system produces, separate from your inverter's own monitoring.
What is the difference between G98 and G99 notification?
G98 covers smaller systems (up to 3.68kW per phase) with no battery export: your installer notifies the DNO on or after the day of installation and the system can go live immediately. G99 covers larger systems or those where a battery can export to the grid: the DNO must give prior approval, which can take from a few days to several weeks. Your MCS installer will confirm which standard applies to your system and handle the notification.