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.
What Can You Upgrade on an Existing Solar PV System?
If you already have solar panels installed, you may not need to replace your entire system to improve its performance. Depending on the age, condition and configuration of your existing installation, a targeted solar PV upgrade could help you generate, store or use more electricity.
Common solar panel upgrades include:
- Replacing an old solar inverter: Older inverters can develop faults or reach the end of their working life. A compatible replacement can restore normal operation and may offer improved monitoring.
- Adding solar battery storage: A battery can store surplus electricity for use later, helping you make better use of the energy your panels generate.
- Installing additional solar panels: Expanding your array may increase generation, provided your roof, inverter, electrical installation and grid connection can accommodate the additional capacity.
- Improving system monitoring: Modern monitoring can help identify faults, track generation and highlight unexpected changes in performance.
- Preparing for an electric vehicle or heat pump: A system review can establish whether your existing solar installation can support higher household electricity demand.
If your installation is registered under the Feed-in Tariff (FiT), the proposed changes need additional consideration. Before replacing equipment, adding panels or changing the system configuration, contact your FiT licensee to confirm the applicable requirements and how the work could affect your payments.
The most suitable upgrade will depend on your existing equipment, electricity consumption, available roof space and the value of your current FiT arrangement. A professional assessment can help determine whether upgrading individual components or installing a separate additional system is the better option.
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
If your solar PV system is registered under the Feed-in Tariff (FiT) scheme, you may be able to replace your inverter or upgrade other components while continuing to receive your existing payments. However, the effect on your FiT arrangement depends on the type of work being carried out and the requirements that apply to your installation.
Before making any changes, contact your FiT licensee to confirm whether the proposed upgrade is permitted and whether any notification, documentation or approval is required. Do not assume that a replacement inverter with a higher capacity will automatically leave your payments unaffected.
Your FiT licensee may ask for information such as:
- The make, model and capacity of the existing and replacement inverter.
- The declared net capacity of the installation before and after the proposed work.
- Details of any additional solar panels or other equipment being installed.
- An updated system diagram, commissioning documentation or installation certificate, where required.
Your installer should also check inverter compatibility, electrical safety and any applicable Distribution Network Operator (DNO) requirements.
⚠️ Important: Obtain confirmation from your FiT licensee before work begins. Written confirmation can help you understand how the proposed changes will affect your registration and payments, but it does not replace any other approvals or notifications that may be required.
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
An AC-coupled battery uses a separate battery inverter and connects to your property’s AC electrical system. This can make it a suitable option for some existing solar installations because the original solar inverter may remain in place.
However, the battery’s location in relation to your generation meter does not, by itself, guarantee FiT compliance. The complete system design and metering arrangements must meet the applicable scheme requirements.
DC-coupled solar batteries
A DC-coupled battery connects to the DC side of a solar PV system, often using a compatible hybrid inverter. This can be an efficient way to integrate solar generation and battery storage, but the existing installation may require changes to its inverter, wiring or metering arrangements.
Before installing either type of battery, ask your installer to confirm how generation and export will be measured and whether the proposed configuration complies with your FiT arrangements. Contact your FiT licensee before work begins and obtain confirmation of any requirements that apply to your installation.
⚠️Important: Battery storage does not automatically invalidate FiT payments, but incorrect system design or metering can affect payment eligibility. Have your installation assessed before proceeding.
Can You Add More Solar Panels to a FiT System?
Adding solar panels to an existing FiT installation requires careful consideration because increasing your system’s capacity can affect the treatment of your generation and payments.
Do not assume that all additional electricity will qualify for the same FiT payments as your original accredited installation. Equally, do not assume that a simple calculation based on the original and expanded system capacities will always determine the proportion eligible for payment. The correct treatment depends on the applicable scheme rules and the circumstances of your installation.
Before expanding your array, ask your installer to assess the proposed capacity, inverter compatibility and grid connection requirements. Contact your FiT licensee to confirm how the expansion would affect your existing registration, generation payments and export arrangements.
⚠️Important: Obtain confirmation before adding or replacing panels. If you want to increase your solar generation while retaining your existing FiT arrangement, establish the applicable requirements before committing to the work.
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
You may be able to upgrade your solar PV system while retaining your existing Feed-in Tariff (FiT) payments, but the outcome depends on the changes being made and the requirements applicable to your installation. Replacing an inverter, adding battery storage or increasing panel capacity can have different implications. Contact your FiT licensee before work begins to confirm how the proposed upgrade will affect your registration and payments.
An inverter replacement may be possible without affecting your existing FiT payments. However, you should check the replacement inverter’s specifications, the system’s declared net capacity and any applicable notification requirements. Obtain confirmation from your FiT licensee before proceeding.
Yes, battery storage can be compatible with an existing FiT installation. The system must be configured so that electricity generation and, where applicable, exported electricity are measured in accordance with the relevant scheme requirements. Ask your installer to assess the metering arrangements and confirm the position with your FiT licensee before installation.
Additional panels may be possible, but increasing your installation’s capacity can affect your FiT arrangements and the generation eligible for payments. Do not assume that all electricity generated by the expanded system will qualify for your original tariff. Your FiT licensee should confirm how the proposed changes will be treated before work begins.
In many cases, you can transfer your FiT arrangement to another eligible licensed supplier without automatically losing your existing entitlement. However, you should confirm that the new provider accepts FiT transfers and follow the required process. Keep your existing agreement and payment records, and confirm the transfer arrangements before switching.
Changing the company that supplies your household electricity does not necessarily mean you have to transfer your FiT payments. Your electricity supply contract and FiT arrangement can be administered separately. Check who currently manages your FiT payments and whether any action is required before changing your electricity supplier.
You may be able to receive FiT generation payments while receiving Smart Export Guarantee (SEG) payments for eligible exports, subject to the applicable requirements. However, you cannot receive FiT export payments and SEG payments for the same installation and generation capacity at the same time. If you want to move to SEG export payments, contact your FiT licensee to discuss opting out of the FiT export tariff.
The value of upgrading depends on your existing equipment, electricity consumption, the cost of the proposed work and the value of your current FiT payments. Replacing a failing inverter may be necessary to restore performance, while battery storage could help you use more of your own solar electricity. Compare the expected savings and costs before deciding which upgrade is right for your property.
Many domestic solar panel installations fall under permitted development rights in England, but conditions and restrictions apply. Listed buildings, properties in conservation areas and certain other locations may have additional requirements. Increasing system capacity may also require electrical or grid connection notifications, which are separate from planning permission. Check the requirements for your property and proposed work before installation.
