Can I Add to My Solar PV System if I Have a FiT Tariff?

Understanding the FiT Scheme

The Feed-in Tariff (FiT) was introduced by the UK government on 1st April 2010 to encourage the adoption of Solar PV in the UK. Unfortunately, the scheme was closed for new registration in March 2019. Anyone who had an accepted registration prior to the scheme closure is guaranteed payment from the scheme for up to 20 years from the date of registration. However, the early adopters to the scheme were eligible to receive the subsidy for 25 years and therefore potentially have at least another 10 years of the subsidy.

The scheme paid an inflation-protected rate for the electricity generated irrespective of whether the electricity is consumed on site or exported to the grid.

In addition:
An additional sum is paid for electrical energy exported back to the grid.

• Although the scheme closed to new applicants in March 2019, many homeowners still benefit from long-term agreements.
⚠️ Your original FiT agreement is based on your system’s size (measured in kWp) at the time of the original registration. Any change to that system can impact your eligibility or payment rate.

So, Can You Add to Your System?

Yes — but how you do it is crucial:

🛑 Option 1: Extend the Existing FiT System
Not recommended if you want to preserve your FiT payments.
• You must notify your FiT provider prior to any work being carried out.
• Adding panels to your registered FiT system counts as a system modification.
o Your FiT provider will not allow FiT payments for the additional panels installed. The FiT provider will confirm a fixed percentage of the future generation meter reading.
• If the proper process is not followed, you may invalidate your FiT contract or reduce your tariff rate.

✅ Option 2: Install a Separate New System
This is the preferred approach.
• Install a completely independent PV system alongside your existing one.
• It must have its own inverter and generation meter.
• It must be electrically separate from your FiT-registered system.
You won’t receive FiT payments for the new system, but you can:
• Benefit from self-consumption savings.
• Qualify for Smart Export Guarantee (SEG) payments.

⚡ Can I Add Battery Storage?

Yes — and it’s one of the best upgrades you can make.
You can install a battery storage system without affecting your FiT, as long as:
• You notify your FiT provider prior to any modifications being made.
• Your generation meter remains unaltered.
• It’s installed correctly.

This allows you to:
• Store excess solar energy during the day.
• Use that stored energy in the evening or during peak-rate periods.
• Reduce your electricity bills and increase energy independence.

🔧 Technical Setup: AC vs. DC Coupling

• AC Coupling: The battery connects via its own inverter, separate from the solar inverter. Ideal for retrofitting.
• DC Coupling: The battery connects before the inverter. More efficient but requires careful design to maintain FiT compliance.
Both methods are allowed under FiT rules, provided accurate metering is in place.

🧾 Don’t Forget the Paperwork

To stay compliant with FiT regulations, you may need to notify your FiT licensee with:
• Your FiT accreditation number.
• Battery specifications (e.g., capacity, AC/DC coupling).
• Installation date.
• Updated system schematic.
Proper documentation ensures your FiT payments continue without interruption.

📋 Other Key Considerations

🏘 Planning & Electrical Regulations
• You may need to notify your Distribution Network Operator (DNO) using a G98 or G99 form.
• Planning permission may be required in some cases (e.g., listed buildings, conservation areas).

📄 Check Your FiT Agreement
• Always review your original contract or speak to your FiT provider before making any changes.
• Talk to the experts; Chiltern Solar Limited.

✅ Summary: What You Need to Know

• ✅ You can expand your solar capacity — but with care and the proper advice.
• ✅ Installing a separate system is the safest route to benefit from SEG payments and self-consumption.
• ✅ Battery storage is allowed and can significantly increase your savings.
• ⚠️ Always seek professional advice to avoid risking your FiT payments.

Need Expert Advice?

At Chiltern Solar, we’ve helped hundreds of UK homeowners upgrade their solar systems while protecting their FiT income. Whether you’re considering adding panels, installing a battery, or exploring the Smart Export Guarantee, we’re here to help.
📞 Get in touch today for a no-obligation consultation.