Best Time of Year to Install Solar Panels UK (2026)
Is it worth waiting for spring, or is a winter install fine? This guide uses month-by-month UK generation data to show what each season really means: how much power you’d miss by waiting, when installers are busiest, how weather affects the job, how long it takes from first enquiry to switching on, and the best month to book so you’re ready for the sunny months.
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How much solar generates each month
Using PVGIS data for a south-facing system averaged across the UK, here’s what each month produces, and what that means for a typical 4kW system:
| Month | kWh per kW | Share of the year | 4kW system | Value* |
|---|---|---|---|---|
| January | 33 | 3.5% | 130kWh | £25 |
| February | 49 | 5.2% | 195kWh | £38 |
| March | 82 | 8.6% | 330kWh | £63 |
| April | 110 | 11.6% | 440kWh | £84 |
| May | 119 | 12.5% | 475kWh | £91 |
| June | 117 | 12.3% | 470kWh | £90 |
| July | 117 | 12.3% | 470kWh | £90 |
| August | 105 | 11.1% | 420kWh | £80 |
| September | 87 | 9.2% | 350kWh | £67 |
| October | 61 | 6.4% | 245kWh | £47 |
| November | 40 | 4.2% | 160kWh | £31 |
| December | 29 | 3.1% | 115kWh | £22 |
| Year | 949 | 100% | 3,800kWh | £730 |
*At the October–December 2026 price cap of 26.32p/kWh and 12p export, with about half the output used at home. May produces roughly four times as much as December. Southern England does a little better than these UK averages and Scotland a little worse. See solar panel output and solar panels in winter.
Each season compared
| Season | Installer availability | Weather for fitting | Generation in the first months | Verdict |
|---|---|---|---|---|
| Autumn (Sept–Nov) | Easing after the summer rush | Mostly good, with shorter days | Modest, but you’re ready for spring | Best all-round time to book |
| Winter (Dec–Feb) | Quietest, quickest slots | Occasional wind, ice or rain delays | Low, but you miss very little | Good, especially for a quick install |
| Spring (Mar–May) | Getting busy, longer waits | Good | Rising fast | Good to install, late to start booking |
| Summer (Jun–Aug) | Busiest, longest waits | Best, though roofs get hot | Highest straight away | Fine if you can get a slot quickly |
The pattern is simple: demand peaks when the sun does. Interest in solar rises in spring and summer, so lead times stretch just as generation is at its best. Booking in the quieter months lets you get through survey, design and any grid paperwork while it costs you least.
What waiting really costs
- Installing in October instead of next March gains you October to February’s generation: about 850kWh, or roughly £160, from a 4kW system.
- Each month you’re not generating between April and August costs £80–£90 on a 4kW system, and roughly twice that on an 8kW system.
- Starting your enquiry in spring can mean waiting two months or more at busy installers. Missing April and May, or April to June, is worth roughly £175–£265 on a 4kW system.
Over a 25–30-year lifespan, a few weeks either way isn’t make-or-break. But there’s no advantage to waiting for spring to begin, and missing the summer costs the most.
Get a quote now, choose your fitting date
A vetted local installer will survey your roof, give you a fixed price, and book a date that suits you, whether that’s next month or early spring. It’s free, with no obligation.
Get My Free Solar Quote →Can solar panels be installed in winter?
Yes. Installers fit panels all year round. What changes in winter:
- Wind: roof work stops in high winds for safety, so a stormy day can push the job back a day or two.
- Frost and ice: icy roofs and scaffolding are dangerous, so early starts may wait for a thaw.
- Rain: light rain rarely stops mounting work, but electrical connections are done in the dry.
- Short days: fewer working hours, so a job that takes one day in June might run into a second in December.
None of this affects the finished system. Panels are designed for UK weather, and a good installer simply works around the forecast. Cold weather actually suits the panels themselves, which are more efficient when cool. See how long installation takes and how solar panels are installed.
How long it takes: enquiry to switch-on
| Step | Typical time |
|---|---|
| Enquiry to survey | A few days to 2 weeks |
| Survey to fixed quote | A few days |
| Grid approval (G99, for systems with an inverter over 3.68kW) | Often several weeks, applied for before installation |
| Quote accepted to fitting date | 2–8 weeks with a local installer, longer at busy times or with national brands |
| Installation | 1–2 days once scaffolding is up |
| Export payments (SEG) set up | Up to about 6 weeks after installation |
Overall, expect about 4–10 weeks from first enquiry to generating, at the shorter end in winter and the longer end in spring and summer, or if a G99 application is needed. Smaller systems connect under G98, so the installer just notifies the network operator afterwards. Register for export payments as soon as you have your MCS certificate (SEG tariffs compared).
The ideal timeline
- September–November: get your quote and survey, and choose your kit.
- October–February: install, using the quieter slots, and sort out any G99 application.
- By March: be fully live with SEG set up, ready for the jump in output from March into April.
If you’re reading this in spring or summer, don’t wait for autumn. Book now, because every sunny month matters more than the season you install in.
Batteries: why autumn suits them
A battery earns its keep in winter as well as summer, because it can charge on a cheap overnight tariff and run the house through the evening peak (off-peak charging). Fitting panels and a battery together in autumn means you start saving straight away, and one visit saves on scaffolding and labour. If you already have panels, autumn is a good time to add a battery. See are solar batteries worth it.
What about prices and the VAT deadline?
This page is about the time of year. Whether to buy now or wait for cheaper panels is a separate question, and the main date to know is that 0% VAT on installed solar ends on 31 March 2027, rising to 5% after that. That’s roughly £350 more on a £7,000 system. If you want the 0% rate, book so your installation is completed before then, and check the invoice timing with your installer. For prices, technology and whether waiting pays, see our buy now or wait guide and VAT on solar panels.
Want to be generating by spring?
Get a fixed price from a vetted installer now and pick a fitting date over the quieter months. It’s free, with no obligation.
Get My Free Solar Quote →The bottom line on the best time to install solar panels
The best time to install solar panels in the UK is autumn or winter, so you’re generating by spring. Installers are quieter, slots come sooner, and you miss very little generation, because November to January produces only about 11% of the year’s output. The worst plan is waiting until spring to start, because queues lengthen just as April to August’s 60% of output arrives. Weather causes the odd short delay but never harms the finished system. Remember too that 0% VAT ends on 31 March 2027. Whatever the month, the best time to get a quote is now. See solar panel cost UK and how to choose an installer.
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Best time to install solar panels: frequently asked questions
What is the best time of year to install solar panels in the UK?
Autumn or winter, so your system is fitted and generating before spring. Installers are usually quieter from September to February, so slots come sooner, and you miss very little generation, because a UK system makes only about 22% of its yearly output from October to February. Waiting until spring to start can mean a queue just as the sunniest months arrive.
When is the best time to install solar panels?
As soon as you’ve found the right installer and price, ideally so you’re live before April. April to August produces about 60% of a UK system’s yearly output, so being up and running by spring matters more than the exact month you install. For a 4kW system, each month you’re not generating in late spring and summer costs around £80–£90 in missed savings.
Can solar panels be installed in winter?
Yes. Installers fit panels all year round. High winds, ice or heavy rain can delay roof work by a day or two, and short days mean a job may run over two days, but none of this affects the finished system. Winter is often the quickest time to get a slot, and cold weather actually makes panels slightly more efficient.
How long does it take to get solar panels installed?
Typically 4–10 weeks from first enquiry to generating. The survey and quote take a week or two, the fitting date is usually 2–8 weeks after you accept with a local installer, and the installation itself takes one to two days. Systems with an inverter over 3.68kW need G99 grid approval first, which can add several weeks. Waits are shortest in autumn and winter.
Is it worth waiting until spring to install solar panels?
No. November to January produces only about 11% of a UK system’s yearly output, so installing in winter costs you very little, while waiting until spring to start often means a longer queue just as output peaks. Installing in October rather than the following March gains about 850kWh, roughly £160, from a 4kW system.
Do I need to install before the VAT deadline?
If you want the 0% VAT rate, yes. Installed residential solar is zero-rated until 31 March 2027, and 5% VAT applies after that, roughly £350 more on a £7,000 system. Book so your installation is completed before the deadline and check the invoice timing with your installer.
Monthly generation figures are PVGIS typical-year outputs for a 1kW south-facing system averaged across UK postcodes, as published by Solar by Postcode. Values use the Ofgem price cap for 1 October to 31 December 2026 (26.32p/kWh) and a 12p export rate. Lead times are typical and vary by installer, region and season. 0% VAT on installed residential solar applies until 31 March 2027 per HMRC. Always confirm timings with your installer.