Common Questions About Solar Panel System Size Limits in the UK
Is there a limit on how many solar panels I can have on my roof in the UK?
No, there is no legal limit on the number of solar panels you can install on a domestic property in the UK. This is one of the most common misconceptions in the solar industry, and it often prevents homeowners from maximising their energy savings.
While you may have heard about a “4kWp limit,” this is a myth that stems from outdated information about Feed-in Tariff rates and DNO (Distribution Network Operator) approval processes. Most Naked Solar customers choose to install solar systems well above 4kWp on their homes.
Why do people think there’s a 4kWp solar panel limit?
The 4kWp misconception comes from two main sources:
- Historical Feed-in-Tariff structure: Before the Feed-in Tariff scheme closed to new applicants in 2019, installations above 4kWp received a lower payment rate. This led to many installers recommending staying at or below 4kWp. However, this payment rate difference no longer exists for new installations under the Smart Export Guarantee (SEG).
- Different DNO approval processes: The process for registering your solar installation with your local DNO is more complex for systems over 4kWp, extra paperwork that some installers like to avoid.
What is the maximum solar panel system size for domestic properties in the UK?
There is no limit to the size of a domestic Solar panel system in the UK, several Naked Solar customers have systems over 50kWp connected to their domestic supply. The only difference is the DNO process. The DNO (Distribution Network Operator) are the people responsible for keeping your local grid working.
- 0-4kWp: Fit and inform process with your installer submitting the paperwork after the installation is commissioned.
- Above 4kWp: Your installer is required to submit a pre-application to your DNO prior to installation and the DNO response times can take a couple of months.
The practical limit is usually determined by your available roof space or budget, rather than regulations. Typical domestic solar installations range from 3kWp to 6kWp, and systems of 8kWp, 10kWp, or even larger are increasingly common, especially when combined with Battery Storage or Electric Vehicle charging requirements.
Can I add more solar panels to my existing system?
Yes, you can extend your existing solar panel system. This is called a “system extension” and is a popular option when:
- You’re adding battery storage (more on this below)
- You have scaffold up for roof repairs
- Your energy needs have increased
- You want to maximise your roof space
- You’re adding an Electric Vehicle
- You want to take advantage of Solar Grid Trading to reduce system payback timescales
What you need to know about system extensions:
If you have existing Feed-in Tariff (FIT) payments: You need to notify your FIT provider about the extension. They’ll pay you proportionally for the energy generated. For example:
- Original system: 4kWp
- Extension: 1kWp
- Total: 5kWp
- FIT payment: You’ll receive 4/5ths (80%) of the total generation reading
DNO notification: Your installer will need to follow the appropriate DNO process based on your new total system size.
How much does VAT affect solar panel and battery installations?
There has been some changes in recent years so here’s the current situation with VAT on Solar PV & Battery Storage systems for your home:
VAT rates for domestic installations:
- Solar panels alone: 0% VAT (returning to 5% VAT on 1st April 2027)
- Battery storage installed separately: 0% VAT
- Battery storage installed with solar panels: 0% VAT
On 1st February 2024, the UK Government extended the 0% VAT rate to include stand alone and retrofitted battery storage systems. This is also set to increase to 5% on 1st April 2027.
How many solar panels do I need for my home?
There’s several factors Solar owners consider when choosing the right Solar system size for their circumstances:
- Your energy goals
- Reducing electricity bills
- Achieving energy independence
- Preparing for Electric Vehicle charging
- Environmental concerns
- Securing your Energy future
- Powercut Cover
- Becoming an energy supplier with Solar Grid Trading
- Your electricity consumption
- Average UK households: 2,700-10,000 kWh per year
- Typical system size chosen: 3-8kWp (approximately 7-20 panels)
- Your roof
- Available space, some Solar owners also utilise North facing roofs now that Solar Panel prices are so low
- Shading from trees or neighbouring buildings
- Roof condition and structure
- Your budget
- Typical costs: £5,000-£18,000 depending on system size
- Higher capacity systems offer better cost per kWp
What questions should I ask my solar installer about system size?
When discussing system size with potential installers, ask:
- “What’s the maximum system size my roof can accommodate?” – They should not automatically cap at 4kWp
- “What DNO approval process will be needed?” – Understand any additional steps
- “What are the benefits of a larger system for my specific situation?” – Get personalized forecasts using software like PV Sol
- “Can I add more panels in the future?” – Understand your expansion options
- “Should I consider battery storage now?” – Explore financial advantages
Real-world example: Moving beyond the 4kWp myth
We recently worked with a customer who needed to relocate their existing 4kWp system from a garage roof (which had started bowing under the weight) to their main house roof. They assumed they were “at their limit” with 4kWp.
Naked Solar explained that:
- They could expand beyond 4kWp
- The scaffold costs would be incurred anyway
- They could add battery storage to maximise benefits from Solar Grid Trading.
- They’d generate significantly more energy and reduce their bills
They decided to extend their system to 6kWp and add battery storage, dramatically increasing their energy independence and making better financial use of their investment.
Summary: Key takeaways about solar panel limits in the UK
- There is no 4kWp limit on domestic solar installations in the UK
- Systems over 4kWp require a pre-application with your DNO and are perfectly legal
- Installing battery storage with solar panels saves 20% VAT compared to adding it separately
- If you have an existing system, you can extend it while maintaining your Feed-in Tariff (with proportional payments)
- The right system size depends on your roof space, energy consumption, and goals – not artificial limits
Ready to explore your solar potential?
If you’ve been told you’re limited to 4kWp, or you’re interested in extending your existing system, we’d be happy to discuss your options. At Naked Solar, we’ve been helping South West homeowners maximise their solar potential since 2010.
If you’re not in Naked Solar’s current coverage region, inline with our mission to “Improve the Solar Industry” we’re happy to give advice to help you choose the right system and avoid the many solar pitfalls.
