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If you're a solar owner heading into your first winter, or you're thinking about getting solar installed and wondering whether it's even worth it in the colder months, here's the honest picture.
UK solar systems generate around 15-20% of their annual total between November and February. That's not nothing — but it's a big drop from the summer peak. A 4kWp system that pulls 350-400 kWh in June will typically do 80-120 kWh in December. The good news: it doesn't need much from you to keep running properly.
Open up your inverter app (SolarEdge, Sigenergy, Solis, whichever you've got) and check it's still connecting. The most common winter issue we get called out for isn't a fault — it's a Wi-Fi router that's been swapped, moved, or had its password changed, and the inverter has lost its connection. If you can see live readings, everything's fine.
If your system is showing an error or warning, don't ignore it. The most common ones in winter are:
Snow on panels is annoying — output drops to near zero — but it almost always slides off within a day or two as the panels warm up. Do not climb up to brush it off. Roofs are dangerous in winter, brushes can scratch the glass, and the lost generation in those couple of days is genuinely tiny compared with annual output.
If you've got a battery, winter is when it does its best work — especially if you're on Octopus Go or Octopus Flux. Make sure it's charging overnight on cheap rate and discharging during the day. If it's just sitting at 50% and not doing anything, something's wrong with the schedule or the tariff configuration.
Solar panels are rated to operate down to -40°C. UK winters don't come close. In fact, panels actually run slightly more efficiently in cold conditions — the issue isn't temperature, it's daylight hours and overcast skies. Modern lithium iron phosphate (LFP) batteries — like the Sigenergy SigenStor — are happy down to -10°C operational, which is well below anything you'll see in Leigh or anywhere else in the North West.
This catches people out, because they expect solar to need annual servicing like a boiler. It doesn't. There are no moving parts. The panels themselves carry a 30-year performance warranty, and a quick visual check from the ground each year is plenty.
If you've got bird mesh fitted, give it a once-over after autumn — leaves and small branches can build up behind it and need clearing. If you don't have bird mesh and you've started seeing pigeons or seagulls nesting under your panels, get it fitted before spring. Once they're settled in, it's a much bigger job.
Here's the thing most installers don't tell you about winter solar: with the right battery and tariff setup, your bills can actually be lower in winter than you'd expect.
On Octopus Go, you pay around 8.5p per kWh between 00:30 and 05:30. If you've got a battery, you can charge it up overnight at that rate, then run your house off it through the day — even when your solar isn't producing much. Combined with whatever your panels do generate, this can keep your daytime electricity bill close to zero through the darkest months.
If you haven't set this up yet, it's a 10-minute job in the battery app. Or give us a shout and we'll talk you through it.
If you don't have solar yet but you're reading this thinking about it, the winter is actually the best time to get a quote and book in. Installers are quieter, lead times are shorter, and you'll be live in time for the spring generation pick-up — which usually starts around mid-February in the North West.
If you'd like a no-pressure quote, drop us a line. We won't try to sell you a system you don't need.
