Feed-in Tariff Solar in Wales: Protecting Your Payments 10 Years On

If your solar panels went up between 2010 and 2019, there's a good chance you're still receiving Feed-in Tariff payments from your energy supplier. For many homeowners across Wales, those quarterly payments have become so routine that the system behind them barely gets a second thought. That's understandable, but it's also a risk. Feed in tariff Wales solar maintenance is a topic that doesn't get nearly enough attention, and after ten or more years of wind, rain, and UV exposure, neglected systems are quietly underperforming without their owners ever realising.

This article looks at why your FiT payments may not be as secure as you think, what happens to solar panels as they age, and what practical steps Welsh homeowners should take right now to protect a financial asset that still has years of earning potential left in it.

How the Feed-in Tariff Still Works in 2026

The Feed-in Tariff scheme officially closed to new applicants in March 2019, but existing participants continue to receive payments for the full term of their agreement, which is typically 20 to 25 years from the date of installation. Ofgem oversees the scheme and sets the rules that suppliers must follow when processing generation and export payments.

There are two payment components most FiT recipients receive. The generation tariff pays you for every unit of electricity your system produces, regardless of whether you use it yourself or export it. The export tariff pays an additional amount for the electricity you send back to the grid. Both figures were locked in at the rate applicable when you registered, meaning early adopters who signed up in 2010 and 2011 secured some of the most generous tariffs ever offered in the UK.

What the scheme does not guarantee, however, is that your system will keep generating at the level it was producing when you first registered. Your payments are based on actual metered generation or, in many cases, a deemed export figure calculated as 50% of your recorded generation. Either way, if your panels are producing less electricity than they should, your income falls. The tariff rate stays the same but the number of units it applies to quietly shrinks.

What Ten Years of Welsh Weather Does to Solar Panels

Wales has a reputation for rain, and that reputation is well earned. Met Office data consistently shows Wales receiving some of the highest annual rainfall totals in Great Britain, particularly across Snowdonia and the western valleys. While solar panels are designed to handle wet weather, the cumulative effect of persistent moisture, temperature cycling, and airborne contamination takes a measurable toll over time.

Soiling is the most immediate issue. Panels coated in a layer of lichen, moss, bird droppings, or general atmospheric grime can lose anywhere between 5% and 25% of their generating capacity depending on the severity of the buildup. In coastal and valley areas of Wales, where organic growth is accelerated by humidity, that figure tends toward the higher end. It's not dramatic or sudden, it just creeps up year after year.

Beyond surface soiling, there are structural concerns that become more common as systems age. Microcracks in the silicon cells, degraded junction box seals, and deteriorating frame seals all become more likely after a decade of thermal expansion and contraction. Solar panel degradation is a real and measurable process, and most manufacturers quote an annual efficiency loss of around 0.5% per year. After ten years that's a potential 5% reduction from the panels themselves, before you account for any maintenance-related losses.

The inverter is perhaps the component most likely to cause a significant drop in output. String inverters, which were the standard fitting for most FiT-era installations, have a typical operational lifespan of ten to fifteen years. If your system was installed in 2011 or 2012, your inverter may be approaching or already past its expected service life. A struggling inverter can cause your system to produce well below its rated capacity, or stop generating entirely. Understanding the warning signs of inverter trouble is something every FiT recipient should be familiar with.

Feed in Tariff Wales Solar Maintenance: Why It's a Financial Decision

There's a tendency to think of solar panel maintenance as a cost. In the context of a FiT system, it's better understood as an investment protection strategy. The maths are fairly straightforward. A typical 4kWp system installed in 2011 at a generation tariff of around 43p per kWh has been earning its owner several hundred pounds a year for over a decade. That income stream has potentially another ten to fifteen years to run.

If poor maintenance has caused that system to operate at, say, 80% of its potential output, the owner is losing roughly 20% of their annual FiT income every single year. Over the remaining term of the agreement, that adds up to a substantial sum. Spending a modest amount on a thorough Solar MOT and addressing any identified faults is almost always cost-effective when measured against the generation losses it prevents.

The Energy Saving Trust has long recommended periodic professional checks for solar installations, particularly as systems enter their second decade. The reasoning is simple: small problems that are cheap to fix when caught early become expensive faults if left alone. A loose cable connector, a partially shaded cell string, or an ageing isolator switch won't necessarily stop your system working overnight, but each one chips away at the generation figures that determine your quarterly payment.

For anyone unsure whether their system is performing as it should, our free 60-second solar health check is a quick way to get an initial sense of where things stand before committing to a full inspection.

The Specific Challenges Facing Welsh FiT Systems

Welsh installations face some challenges that are less pronounced in drier parts of the UK. Moss and lichen growth is a particular concern on pitched roofs across mid and north Wales, where persistent damp creates ideal conditions for biological colonisation. Once established, these growths are surprisingly difficult to remove without professional equipment and the right chemical treatments. Attempting to scrub panels clean without the correct approach risks surface micro-abrasions that accelerate future soiling.

In south Wales and along the coast toward Cardiff and Swansea, salt-laden air contributes to accelerated corrosion of mounting hardware and frame components. The specific demands of coastal solar servicing in Swansea and similar environments differ from inland installations, and it's worth using a maintenance provider who understands those differences.

Storm damage is another factor that's statistically more likely after ten years simply because of the accumulated exposure. A panel that sustained minor frame damage in a storm three years ago may have developed water ingress since then. Knowing what to do when storm damage affects your solar panels is genuinely useful, but prevention through regular inspection is always preferable.

There's also the question of bird nesting. Starlings and sparrows commonly take up residence beneath solar panel arrays, particularly in Wales where rural and semi-rural properties are widespread. Nesting material blocks ventilation, creates fire hazard risks, and can cause physical damage to cabling and panel undersides. Dealing with birds nesting under solar panels requires professional handling to avoid both roof access risks and wildlife protection issues.

What a Professional Inspection Should Cover

Not all solar maintenance services are equal. A thorough inspection of a FiT-era system should go well beyond a quick visual check and a wipe of the glass. No1 Solar Care's Solar MOT service covers the full system from panel surface condition and mounting integrity through to electrical connections, isolators, generation meters, and inverter performance.

The inspection should include thermal imaging where possible. Thermal cameras identify hotspots within panels that are invisible to the naked eye but indicate cell-level faults, bypass diode failures, or early-stage delamination. These are precisely the kinds of issues that reduce generation gradually over time without triggering any obvious alarm.

Cabling and junction boxes deserve particular attention on older systems. The wiring standards applicable when most FiT installations were carried out have since been updated, and some early installations used DC cabling that degrades faster under UV exposure than modern alternatives. Damaged or degraded cabling is both a performance issue and a safety concern. The Health and Safety Executive is clear that electrical work on solar installations must be carried out by competent persons, which is another reason why roof-level maintenance should never be a DIY job.

Generation meter accuracy is also worth checking. Meters on FiT systems are required to be MCS-compliant and accurate to the standards set by the scheme. If a meter has developed a fault or is recording incorrectly, your payment submissions to your energy supplier could be based on inaccurate figures. MCS certification standards apply to both the original installation and the ongoing compliance of system components.

Should Welsh FiT Owners Consider Battery Storage?

One of the most common questions from FiT system owners in Wales right now is whether adding battery storage makes financial sense. The answer depends on several factors, including your current tariff rate, your household consumption patterns, and whether your system's inverter is compatible with battery retrofit.

It's worth understanding that adding a battery to a FiT system doesn't affect your generation tariff payments, since those are calculated on what your panels produce rather than what you personally consume. What a battery can do is increase the proportion of your own generation that you actually use, reducing what you buy from the grid. Given current electricity prices, that has real financial value. The case for solar battery storage in 2026 is increasingly persuasive for legacy system owners who want to extract more value from an already-paid-for asset.

If your FiT contract runs for another ten or more years, retrofitting storage while your system is still healthy makes considerably more sense than waiting until the inverter fails and necessitates a full system overhaul anyway.

Protecting a Welsh FiT System Into Its Second Decade

FiT-era systems across Wales face a demanding mix of Atlantic weather, high humidity, and the particular maintenance needs of mature solar installations. From the wet uplands of Snowdonia and the valleys through to the salt-laden air along the Cardiff and Swansea coast, Welsh conditions are hard on ageing panels. Having serviced hundreds of legacy solar systems, our team understands exactly what those systems need, and what tends to go wrong when maintenance has been put off too long.

The principle for every Welsh FiT owner is the same. Keeping a legacy FiT solar system running well into its second decade requires consistent professional attention, not just reactive repairs when something obviously breaks. The real cost of neglecting solar panels only becomes painfully apparent when you start comparing your actual generation figures against what the system should be producing.

If you're in Cardiff, Newport, Swansea or anywhere across South Wales and your FiT system hasn't had a professional inspection in the last two years, it's time to change that. Book a professional inspection and get a clear picture of what your system is actually doing.

Frequently Asked Questions

What is feed in tariff Wales solar maintenance and why does it matter?

Feed in tariff Wales solar maintenance refers to the routine servicing and inspection of solar panel systems registered under the now-closed FiT scheme in Wales. It matters because these systems are now ten or more years old, and without proper upkeep they produce less electricity, which directly reduces the quarterly generation payments their owners depend on.

Can poor maintenance actually reduce my FiT payments?

Yes, directly. Your FiT generation payments are calculated on the electricity your system actually produces. If soiled panels, a struggling inverter, or degraded cabling are causing your system to underperform, you generate fewer kilowatt hours and receive less income. Ofgem's FiT rules do not compensate for output lost through lack of maintenance.

How often should a FiT solar system in Wales be inspected professionally?

For systems that are ten or more years old, a professional inspection every one to two years is advisable. Annual cleaning is recommended as a minimum given Wales's high rainfall and the tendency for organic growth on panels. If your system hasn't been checked in more than two years, booking a thorough assessment soon is a sensible step.

Is my FiT system likely to need inverter replacement at this age?

Possibly. String inverters fitted to systems installed between 2010 and 2014 are now approaching or past their typical ten to fifteen year service life. If your inverter is showing error codes, making unusual noises, or your generation figures have dropped noticeably, it may be failing. Replacing an ageing solar inverter is usually worthwhile when you still have years of FiT income ahead.

Does adding battery storage affect my Feed-in Tariff payments?

Adding a battery does not reduce your generation tariff payments, since those are based on what your panels produce. However, it can affect your export tariff situation depending on how your metering is set up. It's worth speaking to a qualified installer before proceeding, and checking the terms of your specific FiT agreement with your energy supplier.

Are solar panel maintenance costs in Wales tax deductible or subsidised?

For residential properties, solar panel maintenance is generally not tax deductible. However, since April 2022, VAT on solar panel maintenance and repair has been reduced to 0% for most homeowners, making professional servicing more affordable than it was previously. Always confirm the applicable rate with your service provider.

Book your Solar MOT today. Call 029 2002 6002 or visit no1solarcare.co.uk/solar-mot