8 Things to Know Before Installing Solar Panels in the UK

The honest, day-to-day details most buying guides skip — from squirrels chewing cables to why your panels go dark in a power cut, even at midday.

On this page

• Birds and squirrels
• Cleaning
• Cloudy days & winter
• Power cuts
• Inverter replacement
• Selling your home
• Hot water diversion
• FAQ

Things to Know Before Installing Solar Panels — Quick Summary

Things to Know Before Installing Solar Panels: 1. Birds — and Squirrels — Love the Space Underneath

The gap between your roof and the underside of a solar panel is warm, dry and sheltered — exactly what pigeons and starlings look for when nesting. It's a genuinely common enough issue that some UK pest control firms now report it's become their single largest source of residential bird-related work. Beyond the noise, nesting debris can block the panel's ventilation gap, and droppings genuinely reduce output over time. The more serious version of this problem: squirrels are known to chew through the DC cabling that runs between panels, which is a genuine fire and safety hazard, not just a nuisance.

Bird and pest-proofing mesh, fitted around the edge of the array at installation, solves this cheaply and permanently. Worth asking your installer to quote it upfront rather than retrofitting it after birds have already moved in — removing an established nest is a genuinely more awkward job than preventing one.

2. You'll Clean Them Far Less Than You Think

Most people picture regular ladder trips with a squeegee. In practice, UK rain does the majority of the cleaning work, and a well-angled roof-mounted system typically only needs a full clean every five years or so. An annual visual check — looking for obvious dirt, bird mess or debris — is the real routine maintenance most installers recommend.

Dust and grime accumulation typically costs around 1% of output per year on a well-positioned system — genuinely minor, and far less than most new owners expect. That figure isn't the same for everyone, though. Drier regions get less natural rinsing from rain, urban and industrial areas accumulate more airborne grime, and homes near farmland, busy roads, trees or with regular bird activity will all need attention sooner than a steeply pitched, exposed rural roof. If your system is in one of these categories, a rough annual check rather than the standard five-year rule of thumb is the safer habit.

3. Cloudy Days Aren't the Enemy — Short Days Are

Solar panels respond to light, not heat — a genuinely counterintuitive fact worth knowing before you install. Cold weather doesn't reduce output; if anything, cooler cell temperatures slightly improve efficiency. Panels still generate meaningful electricity on an overcast day, just less than in direct sun.

The real driver of winter's lower output is simply fewer daylight hours — roughly 8 hours around the December solstice versus 16-plus in midsummer — not the panels somehow switching off or "not working" in the cold. Heavy snow is the one genuine winter blocker, stopping generation entirely until it's cleared; a foam-headed brush (never a stiff bristle one, which can scratch the glass) is the safe way to clear it if you can reach safely. The Energy Saving Trust's guidance on solar panels is a good independent reference if you want to dig further into seasonal output variation.

4. Solar Panels Don't Work in a Power Cut — Even in Full Sun

This is arguably the single most misunderstood fact about home solar, and it genuinely surprises most new owners. A standard grid-tied inverter has a legally required safety feature called anti-islanding — it automatically shuts your system down the moment the grid loses power, specifically so it can't feed electricity back into lines that engineers might be working on to restore supply.

In plain terms: owning solar panels alone does not give you backup power during a blackout, no matter how sunny it is outside. Genuine outage backup needs a battery system with a specific backup gateway or whole-home switchover feature — see our best home battery comparison for which systems actually support this, since not every battery does by default.

5. The Inverter Won't Last as Long as the Panels

Panels genuinely can last 25 years or more with only gradual, gentle degradation. The inverter — the component converting DC panel output into usable AC electricity — has a shorter working life, typically needing replacement around year 10 to 15, at a cost of roughly £800 to £1,500 depending on system size.

This isn't a sign anything's gone wrong — it's a normal, predictable part of system ownership. Worth budgeting for as a mid-life cost rather than being caught off guard by it a decade from now.

6. Keep Your MCS Certificate — You'll Need It to Sell Your House

Conveyancing solicitors now routinely ask for your MCS (Microgeneration Certification Scheme) installation certificate when you come to sell your home — it's become a standard part of the paperwork trail buyers and their solicitors expect to see. Losing it means chasing your original installer years later, which can genuinely delay a sale.

File it somewhere permanent alongside your other home ownership documents — not in an installer's email that's easy to lose track of a decade on.

7. Ask About Hot Water Diversion Before Installation, Not After

A hot water diverter (myenergi's Eddi is one of the best-regarded names, particularly if you're already using or considering their Zappi EV charger or Libbi battery) automatically redirects surplus solar generation you're not using into your hot water cylinder, effectively using free daytime electricity to heat water rather than exporting that surplus to the grid for a fraction of its value — see our SEG tariff comparison to see exactly how little that "fraction" often is.

Most diverters are sold and fitted through solar installers rather than bought and self-installed, and they're a genuine several-hundred-pound purchase either way — typically £450 to £900 fitted. The real saving isn't in the unit price, it's in timing: adding one to a job an installer is already doing on-site is meaningfully cheaper than paying for a completely separate visit and labour charge later. Worth raising it as a specific question during your original quote, rather than discovering the option exists only after the fact.

8. Shading Changes Over the Years, Even If Your Roof Started Clear

A roof with no shading at installation can genuinely lose meaningful output a decade later — trees on a neighbouring property grow, extensions get built next door, nothing about your own roof needs to change for your system's performance to drift downward over time.

Taking a few photos of your roof's shadow pattern at different times of day when the system is first installed gives you a genuine reference point — if output drops unexpectedly years later, you'll have something concrete to compare against rather than just a vague sense something's changed.

Frequently Asked Questions — Things to Know Before Installing Solar Panels