A Complete Guide to Modernising Your FiT Solar Setup Without Losing Your Payments
If your solar panel system was installed under the Feed-in Tariff (FiT) scheme, you’ll already be earning payments for every unit of clean energy your system generates, but solar technology has advanced significantly since the FiT scheme closed in 2019 and many homeowners across Essex, Kent and London are now asking the same question:
“Can I upgrade my system without losing my FiT payments?”
The good news is yes, with the right guidance and documentation, you can upgrade your solar inverter, add solar batteries or even install additional solar panels, all while protecting your FiT eligibility. Here’s how.
Why Upgrade Your FiT Solar Inverter?
Most original FiT installations used traditional string inverters, a simple, affordable setup where all your solar panels are linked in a single chain. There are disadvantages to a string inverter, if one panel is shaded, dirty or faulty, it reduces the output of the whole string. Since Feed-in Tariff payments continue for 20-25 years and standard inverters usually last only 10-15 years, upgrading makes financial sense.
At SolarTherm UK, we recommend switching to a SolarEdge power optimised system if your solar PV panels are affected by shading. Power optimisers generate more power from each panel as they perform independently of one another, preventing one shaded or faulty panel from reducing the system’s total output.
If your system isn’t affected by shade, you can still upgrade your solar inverter for a newer, more efficient string inverter, boosting your savings and reducing your reliance on the grid.
How to Keep Your Feed-in Tariff Payments When Upgrading
Ofgem allows inverter upgrades, even to a higher capacity as long as your FiT provider grants permission first. For example, you can replace an old 3kW inverter with a new 5Kw solar inverter and continue receiving your FiT payments. SolarTherm UK will help you complete the necessary paperwork and ensure full compliance.
Typically, your FiT provider will need:
- The declared net capacity of your new and old inverters
- The increase in capacity (e.g. 3kW to 5kW)
- A commissioning certificate or invoice confirming what’s been installed
⚠️ Important: Always get written permission from your FiT provider before any inverter upgrade to protect your Feed-in Tariff payments.
Can You Add a Solar Battery to a FiT System?
This is a question we get asked a lot at SolarTherm UK and yes it is possible to add solar battery storage to your FiT system, making it even more efficient in the process. Storing excess power for evening use helps you save more on your energy bills and maximise self-consumption.
Your battery setup must avoid double-counting generated or exported energy. There are two main types:
AC-coupled solar batteries:
Installed after your generation meter with their own inverter – simple and FiT compliant.
DC-coupled solar batteries:
Integrated directly with your panels, usually when replacing your inverter. Requires a hybrid inverter and specialist metering setup.
⚠️ You must inform your FiT provider before installing a battery and include a wiring diagram showing how it connects to your existing system.
Can You Add More Solar Panels to a FiT System?
As long as you have permission from your FiT provider, you can add additional solar panels. You can also replace or add solar panels to your existing solar setup to increase capacity. However, only a proportion of your generation will continue to earn FiT payments. If you expand from a 4kW to 5kW system you’ll receive FiT payments on 80% of your total generation, not on the remaining 20% of generation from your additional power.
⚠️ Always discuss planned upgrades with your FIT provider before work begins.
Can You Improve Your FiT Export Payments?
Most homeowners on the Feed-in Tariff receive around 5-7p per kWh for their generated solar power and up to 40p per kWh for exported electricity. Switching to a modern export tariff could earn you up to 15p per kWh for exported electricity, but there is no equivalent payment for generated electricity.
Avoid Solar Upgrade Scams
Unfortunately, some companies target homeowners with outdated solar panels. To stay safe:
- Use an MCS-certified installer like SolarTherm UK, this guarantees quality, safety and compliance.
- Never sign under pressure. A reputable installer will provide a written quote and give you time to decide.
- Check reviews and accreditations. Always research your solar company before signing the contract.
- Speak to your FiT provider if you’re ever unsure, they can confirm what upgrades are allowed.
Is It Worth Upgrading Your FiT Solar System?
Absolutely, with the right approach, upgrading your inverter, adding solar batteries or installing extra panels can significantly increase your system’s performance, helping you make more from your investment and reduce your reliance on the grid.
At SolarTherm UK, our team of expert solar installers are working across Essex, Kent, Suffolk, Hertfordshire and the wider South East or East Anglia to help households upgrade their old FiT scheme solar PV systems for modern, high quality solar systems, all while protecting your FiT payments.
Ready to Modernise Your FiT Solar System?
Contact SolarTherm UK today for a free, no obligation upgraded quote and design, tailored to your property, FiT payments and new energy needs. No hard sell, just honest, expert advice – and the time you need to make an informed decision.
Your home. Your energy. Your future.
Frequently Asked Questions
Yes. In many cases, you can upgrade your inverter, add battery storage or expand your solar array while retaining your Feed-in Tariff payments. However, you should always obtain approval from your FiT provider before making changes.
Yes. An inverter can usually be replaced, including with a higher-capacity model, provided your FiT provider approves the change and the required documentation is supplied.
Yes. Battery storage can be added to many existing FiT systems, but the installation must be designed correctly to ensure generation and export payments are not incorrectly calculated. Your FiT provider should be informed before installation.
Potentially, yes. Additional panels can be installed with the appropriate approval, although the proportion of generation eligible for FiT payments may change following an expansion.
It can, depending on the type and extent of the upgrade. Always speak to your FiT provider before work begins so you understand how the proposed changes could affect your payments.
For many homeowners, upgrading an ageing inverter or adding battery storage can improve system performance, increase self-consumption and reduce reliance on grid electricity, while allowing you to continue benefiting from your existing FiT arrangement.
