Solar panel electrical requirements for a UK home
The panels are the easy part. What decides whether a solar installation goes smoothly is the state of the consumer unit, the earthing arrangement and whether the network operator has been told what you are connecting.
What has to be in place before panels go up
A solar PV system is a generator connected to your installation, so the existing installation has to be fit to receive it. That means a consumer unit with capacity and adequate protection, sound earthing, correct main protective bonding, and circuits in a condition that will not cause nuisance tripping once an inverter is added.
In a lot of older South Wales housing stock, the honest sequence is an EICR first, then remedial work or a board upgrade, then solar. Fitting generation onto a tired installation does not improve the installation, it just adds another thing to it.
- Consumer unit with a spare way and adequate protection
- Verified earthing arrangement suitable for the inverter type
- Main protective bonding present and correctly sized
- An assessment of existing circuit condition before commissioning
AC and DC sides, isolation and labelling
A PV installation has a DC side from the panels to the inverter and an AC side from the inverter into your consumer unit. Both need means of isolation, clearly labelled, and both need to be accessible to anyone who might need to shut the system down, including the fire service.
The AC connection is usually a dedicated way in the consumer unit with appropriate protection. Labelling matters more than it sounds: a board with an unlabelled generator supply is genuinely hazardous, because switching off the main switch does not necessarily make everything dead.
Notifying the network operator
Connecting generation to the grid involves the distribution network operator. Smaller domestic systems are generally connected under a notification arrangement where the installer informs the operator after commissioning, while larger systems or those with substantial battery output need permission before connection.
Your installer handles this, but you should see evidence it has happened. If you later add a battery or a second array, that changes the total and can change the process, so it needs revisiting rather than assuming the original notification still covers it.
- Smaller systems: notify the operator after connection
- Larger systems and big batteries: apply before connecting
- Adding storage later changes the picture and needs rechecking
- Export payment arrangements need a smart meter and a supplier tariff
Batteries and EV chargers alongside solar
Battery storage moves the value of solar considerably, because it lets you use evening electricity you generated at midday. Electrically it needs its own considerations: a suitable location with ventilation and temperature stability, protection and isolation, and enough space at the board.
If you have or want an EV charger, plan the two together. A charger that can be told to draw only surplus generation is worth having, and load management between a charger, a battery and a house drawing heavily is a design question, not something to bolt on afterwards. Doing both at once also avoids paying twice for the same board work.
Roof, cable routes and the practical side
DC cabling from the array runs from the roof down to the inverter, and where that cable goes matters. A route through a loft is normal, but it should be supported properly, protected from rodents and kept clear of anywhere someone might stand on it while retrieving Christmas decorations. Cable that has been draped over a joist and forgotten is the thing that causes problems in year six.
Inverter position is a real decision too. Inverters make a low hum, they are happiest somewhere cool and ventilated, and they need to be accessible for service and isolation. A garage or utility room usually beats a loft on all three counts, particularly during a South Wales summer when a slate roof loft becomes an oven and the inverter throttles its output.
- DC cable routes supported, protected and documented
- Inverter sited somewhere cool, ventilated and accessible
- Roof mounted isolation clearly labelled for emergency services
- Monitoring equipment needs a network connection to be useful
Paperwork you should end up with
Expect an Electrical Installation Certificate covering the new circuits, commissioning records for the inverter and array, the network operator notification, the manufacturer documentation and warranties, and where applicable the certification associated with the installer's scheme membership.
Keep all of it together. It is what a surveyor asks for when you sell, what an insurer may ask for after a claim, and what the next electrician needs to work safely on your board.
Common questions
Do I need a new consumer unit for solar?
Not always, but the board needs a spare way, adequate protection and sound bonding. Where those are missing, a board upgrade usually comes first.
Does the network operator need to be told?
Yes. Smaller domestic systems are typically notified after commissioning, larger systems and substantial batteries need approval beforehand. Your installer arranges it and should show you the evidence.
Can I charge an EV from solar?
Yes, with a charger that supports solar diversion or surplus only charging. It is far easier to design the charger and the array together than to retrofit the interaction.
Should I get an EICR before solar?
On an older installation with no recent testing, it is money well spent. It finds the problems that would otherwise appear as nuisance tripping the week after commissioning.
Do batteries need special isolation?
Yes. Storage needs clearly labelled isolation, appropriate protection and a suitable location. It is not a plug in appliance.