The quickest way to check your solar panels are working is to look at your inverter’s display or app: a green or solid light and a generation figure that rises through the day means it’s working. Beyond that first glance, the real test is whether today’s generation is roughly in line with what similar weather should produce for a system your size – not zero, and not dramatically lower than the same time last year.
The Quickest Checks: Inverter Light and Monitoring App
Every inverter has a status indicator, usually a light or small screen, that shows whether it’s actively converting DC from the panels into AC for your home. A solid green light generally means normal operation; flashing, red, or an error code means something needs attention. Most systems installed in the last several years also come with a monitoring app tied to the inverter or a separate optimiser brand, showing live and historical generation in kWh – this is the more useful check day to day, since it tells you not just “is it on” but “is it producing what I’d expect.”
What “Normal” Generation Looks Like by Season
| Season | Typical daily generation (4kWp system) | What’s driving it |
|---|---|---|
| Summer (Jun–Aug) | Roughly 14–20 kWh on a clear day | Long daylight hours, high sun angle |
| Spring/Autumn (Mar–May, Sep–Oct) | Roughly 8–14 kWh | Moderate daylight, more variable cloud cover |
| Winter (Nov–Feb) | Roughly 1–5 kWh | Short days, low sun angle, frequent cloud |
These are rough guides for a well-sited, south-facing 4kWp system with no significant shading – your own figures will vary with system size, orientation and local weather. The point isn’t to hit an exact number; it’s to notice if a sunny summer day is producing what a sunny summer day produced last year. A big, unexplained gap between comparable days is the real signal something’s wrong, not a single low reading on an obviously overcast day.
A Rough Calculation for What Your System Should Produce
A useful rule of thumb: annual generation in kWh is roughly your system’s size in kWp multiplied by 850–1,000, depending on where in the UK you are and how well the panels are sited (the south of England sits at the higher end, Scotland and the north generally lower). A 4kWp system might reasonably produce 3,400 to 4,000 kWh across a year. If your actual generation is running well below this over a full 12 months, that’s worth investigating – though give it a full year before judging, since month-to-month swings are normal and expected.
Checking Your Electricity Meter and Bill
If you have a smart meter and export electricity, your energy supplier’s app or portal should show export readings that move in line with sunny days, giving you a second data point separate from the inverter’s own display. Your electricity bill itself is a slower but still useful signal: if your import (electricity bought from the grid) hasn’t dropped at all since installation, especially across summer months when generation should be highest, that’s a sign to check the system rather than assuming everything’s fine.
Warning Signs Your Solar Panels Aren’t Working Properly
Watch for: zero generation showing on a clear, sunny day; an error code or warning light on the inverter that wasn’t there before; one section of the array reading much lower than another with no shading explanation; or a steady decline over weeks that isn’t explained by the season. Any of these are worth checking against our guide to fixing underperforming solar panels, or worth a call to your installer if the cause isn’t obvious. A solar monitoring system makes all of this far easier to track, since it flags anomalies automatically rather than relying on you noticing.
What If You Don’t Have a Monitoring App?
Older systems, or ones installed without a smart inverter, might only offer a basic generation meter with a running total and no app or historical breakdown. In that case, write down the reading at the same time each week and compare the weekly increase against the same week the previous year, weather allowing. It’s more manual than an app, but it achieves the same goal: catching a gradual decline before it becomes a big one.
Frequently Asked Questions About Checking If Solar Panels Are Working
How can I tell if my solar panels are generating electricity right now?
Check your inverter’s display or app for a live generation figure in kW – anything above zero on a daylight hour, even under cloud, means the system is active. A reading stuck at exactly zero during daylight, especially on a clear day, is the clearest sign something’s wrong.
Is it normal for solar panels to produce very little in winter?
Yes. Short days, a low sun angle and more frequent cloud cover mean UK solar panels commonly generate a fifth or less of their summer output through November to February. This is expected and isn’t a sign of a fault on its own.
My inverter light is on but generation seems low. What’s wrong?
A working inverter with lower-than-expected generation usually points to shading, dirt on the panels, or a partial fault affecting one string rather than the whole system, rather than a total failure. Compare today’s figure against a similar weather day from a previous month to see how big the gap really is before assuming a serious fault.
How often should I check my solar panel generation?
A quick glance at the monitoring app once a week is enough to catch most problems early, with a closer look if you notice a run of unusually low readings on otherwise sunny days. There’s no need to check daily – day-to-day variation from weather is normal and not something to react to.
Can I check if my solar panels are working without an app?
Yes. Most inverters have a basic display showing current generation even without an app, and older systems often have a simple meter with a running total you can note down and compare over time. It’s less convenient than an app, but it works for spotting an obvious problem.
