Solar Panel Maintenance

Key Takeaways

• Solar panels require minimal maintenance, the most important task is keeping the panel surface clean, which may only need doing once or twice a year in the UK.
• Annual or bi-annual professional servicing costs £100–£200 and covers panel inspection, inverter health, and cable/connection checks.
• Solar panels degrade at around 0.3–0.5% per year, monitoring your generation output is the best way to spot if something is wrong early.
• Inverters typically need replacing after 10–15 years at a cost of £500–£1,500, which is the main significant maintenance cost over a panel’s 25-year life.
• MCS-certified installers or RECC-registered companies should carry out any work that requires accessing the panels or electrical components.

How Much Maintenance Do Solar Panels Actually Need?

The good news is: not much. Solar panels have no moving parts, no fuel to replenish, and no combustion process to maintain. Most of the time, they simply sit on your roof and generate electricity without any intervention.

That said, “minimal maintenance” doesn’t mean “no maintenance.” There are a handful of checks and tasks that keep a solar system performing at its best and spot problems before they become expensive. This guide covers everything you need to know, organised by season and task type.

Annual Maintenance Checklist for UK Solar Panels

Use this checklist as a reference for annual maintenance. Most tasks can be done yourself; those marked with (Pro) should be carried out by a qualified installer.

Seasonal Maintenance Calendar for UK Solar Systems

Spring (March–May)

Spring is the ideal time for a thorough annual maintenance visit. Days are lengthening rapidly and generation is beginning to climb, you want the system in best condition as the peak summer season approaches.

Key tasks:

• Panel cleaning to remove winter grime, algae, and bird droppings that accumulate over the darker months.
• Check for bird nesting activity under panels, pigeons nest from March onwards and can cause significant cable damage.
• Commission a professional inspection if you haven’t had one in the past 12 months.
• Review your monitoring data from the winter months, compare generation to previous years to spot any performance decline.

Summer (June–August)

Peak generation season. Your monitoring app is your primary tool.

Key tasks:

• Monitor generation output weekly and compare to the same weeks in previous years. In the UK, June–July should be your highest-generation months.
• Check the inverter area has adequate ventilation, inverters run warmer in summer and need airflow to operate efficiently.
• If generation is significantly below expected, check for new shading (trees and hedges grow rapidly in summer) and report to your installer if panels are suspected to have faults.

Autumn (September–November)

A good time for a second panel clean after summer pollen and dust, and before the darker winter months.

Key tasks:

• Second cleaning of the year if in a polluted area or if leaves/pollen are visible on panels.
• Check for moss growth at panel edges, more common in Scotland and the North West where rainfall is higher. Moss can lift panel edges over time.
• Review SEG readings for the year and compare to your estimate, if export is significantly lower than expected, it may indicate self-consumption has changed (new appliances, EV charger) rather than a system fault.

Winter (December–February)

Lower generation but panels still work, and still need basic monitoring.

Key tasks:

• Check panels are clear of snow if heavy snowfall occurs. Light dustings can be left to melt naturally. Heavy accumulations can be gently cleared with a soft broom (never ice scrapers or tools that could scratch the surface).
• Don’t expect high generation, a 4kWp system in December may generate only 200–400 kWh for the whole month compared to 500–600 kWh in June.
• Check your inverter display is showing normal operation, faults are more common in cold, damp conditions.

How to Clean Solar Panels

Dirty panels generate less electricity. Bird droppings in particular cause significant localised losses, a single bird dropping covering 5% of a cell can reduce that cell’s output by more than 5% due to the disproportionate effect on cell strings.

In much of the UK, rainfall handles basic cleaning reasonably well, panels are installed at an angle and rain runs across the surface. But in dry spells, low-angle pollution (traffic, agriculture) or bird activity areas, manual cleaning is worthwhile.

DIY cleaning method:

• Use warm (not hot) water with a small amount of washing-up liquid.
• A soft long-handled squeegee or soft brush on an extendable pole works well for panels accessible from ground or a stable ladder.
• Rinse with clean water to avoid soap residue streaking.
• Never use abrasive cloths, pressure washers, or chemicals, these can damage the anti-reflective coating on the panel glass.
• Clean in the early morning or evening, cleaning panels that are hot from midday sun can cause thermal shock to the glass.

Professional cleaning: Panel cleaning companies typically charge £50–£150 for a residential array, using pure water fed through long-handled poles, no access to the roof required. If your panels are difficult to access, this is well worth the cost.

How to Spot Inverter Problems

The inverter is the component most likely to need attention during the life of your solar system. Here’s what to watch for:

Normal operation: Green light or “feeding in” / “generating” status on the display or app. Some inverters beep or change display overnight when entering standby, this is normal.

Warning signs:

• Error codes on the inverter display, note the code and Google it or call your installer. Common codes include earth fault, grid disconnection, and over-temperature warnings.
• Generation consistently 15–20% below expected output for the time of year.
• Inverter running hot to the touch or showing over-temperature errors, check ventilation around the unit.
• Inverter display blank or inverter not responding, may indicate a power supply fault or component failure.

Inverter lifespan: Most inverters are warranted for 10 years, with extended warranties available. In practice, quality string inverters often last 12–15 years. When replacement is needed, current string inverter costs are £500–£1,200 for residential systems, plus installation.

Microinverters (installed behind each panel rather than in a central unit) are warranted for 25 years, the same as the panels, which removes the mid-life replacement cost.

Degradation: What to Expect Over Time

Solar panels degrade gradually over their lifespan. Standard degradation is:

• Year 1: Up to 2% degradation (LID, Light Induced Degradation) as the silicon stabilises
• Years 2–25: 0.3–0.5% per year for quality panels
• Year 25: Most quality panels retain 80–88% of original rated output

In practice, this means a 4kWp system generating 3,400 kWh in year one might generate around 2,900–3,000 kWh by year 25, still producing substantial electricity.

If your generation data shows faster-than-expected decline, investigate soiling, shading changes, or inverter health before assuming panel degradation.

When to Call an MCS Engineer

Contact your MCS-certified installer or a qualified solar engineer if you notice:

• Persistent error codes on your inverter that don’t resolve
• Generation drops of more than 20% compared to the previous year (adjusted for weather)
• Any visible physical damage to panels, cracks, delamination (cloudy bubbles under the glass), burn marks
• Discolouration or burning smell from the inverter
• Water ingress around the panel mounting or inside the inverter/junction box
• Any electrical tripping associated with the solar circuit

Never attempt to access roof-mounted panels or electrical components yourself unless you are a qualified electrician. Solar panel systems involve high DC voltages (up to 600V or more) that are potentially fatal.

Cost of Professional Solar Panel Servicing

Over a 25-year system life, total maintenance costs for a well-functioning residential system are typically £3,000–£5,000, predominantly the inverter replacement at year 10–15. This compares favourably to the £30,000–£50,000 in electricity savings a well-maintained system provides over the same period.

Case Study: A Homeowner in Yorkshire Catches a Fault Early

Background

A homeowner in Leeds, Yorkshire, installed a 3.5kWp solar system in 2019. Their monitoring app showed generation figures that had been declining steadily for two years, from around 3,000 kWh in 2021 to 2,500 kWh in 2023, a 17% drop that couldn’t be fully explained by weather variation.

Project Overview

An annual inspection booked in spring 2024 revealed a failing string of panels, three panels in one string had developed micro-cracks, reducing their output significantly. The cause was traced to thermal expansion and contraction stress at a mounting point.

Implementation

The three affected panels were replaced (£480 for panels plus £250 fitting). The mounting points were reinforced. Generation in 2024 recovered to 2,900 kWh.

Results

The repair cost of £730 was recovered in under a year through restored generation income. Without the monitoring and annual inspection, the fault might have gone undetected for years, costing significantly more in lost generation and potentially allowing the fault to worsen.

Expert Insights From Our Solar Panel Installers About Maintenance

One of our senior solar panel installers with over fifteen years of UK residential experience advises:

“The most valuable thing a solar owner can do is monitor their generation data. It’s not complicated, you just need to know roughly what you should be generating in each month, and whether you’re hitting it. Most modern inverters have an app that shows this automatically. The clients who call us when something’s wrong are almost always the ones who check their app regularly. The ones who leave it for years are the ones who end up with faults that have quietly been costing them money for a long time.”

Frequently Asked Questions

Summing Up

Solar panel maintenance is simpler than most homeowners expect. Regular monitoring via your inverter app, an annual professional inspection, and cleaning once or twice a year keeps most systems in excellent condition. The main significant cost over a panel’s 25-year life is inverter replacement at around the 10–15 year mark.

If you’d like advice on maintaining your existing system or want to understand what maintenance to expect when installing solar for the first time, our MCS-certified team is happy to help.

Updated April 2026