What solar noon is, in plain terms
Solar noon is the instant the sun reaches its highest point in your sky each day. In the UK that is when it sits due south. It is the moment a fixed, south-facing balcony or wall panel hits its daily peak, because the panel is pointed closest to the sun. It is not usually 12:00 on your clock, and the gap is predictable, not random.
Why it is rarely exactly 12:00
Three things move it. Your longitude shifts solar noon by four minutes per degree, so a western city like Cardiff or Plymouth reaches it later than London. The equation of time, a wobble caused by the Earth's tilt and its elliptical orbit, moves it by up to about 16 minutes either way across the year. And from late March to late October, British Summer Time adds an hour to the clock, so solar noon reads closer to 13:00 than 12:00 in summer.
Why this matters for plug-in solar
A plug-in or balcony kit only pays when you use the power as it is generated, because most early UK kits do not pay for export. Generation peaks around solar noon and tapers towards sunrise and sunset, so the more of your daytime usage, the fridge, the washing, the work-from-home load, you can line up with the hours either side of solar noon, the higher your self-consumption and the better the maths. Day length sets the outer limits: a long June day gives a wide window, a short December day a narrow one. If you are choosing hardware, a fixed south-facing mount aimed for solar noon is the simplest setup, and the kits and microinverters pages cover the options.
What time is the sun at its highest point today?
The sun is at its highest point at solar noon. Across the UK that falls somewhere between about 12:00 and 13:10, depending on the date, how far west you are, and whether British Summer Time is in force. For the exact minute at your location today, use the calculator above.
Is the sun at its highest at exactly 12 noon?
No. Clock noon and solar noon only line up a few times a year. Three things separate them: your longitude, which shifts solar noon by four minutes for every degree west of Greenwich; the equation of time, which moves it by up to about 16 minutes across the year; and British Summer Time, which puts solar noon closer to 13:00 from late March to late October. So at 12:00 on the clock the sun is usually still climbing in the east.
Sunrise, sunset and day length
Sunrise and sunset bracket the daily generating window for a fixed panel, and day length is simply the gap between them. Both swing hard with the seasons and with latitude: a June day in Plymouth runs far longer than a December day in Aberdeen. The calculator above returns sunrise, sunset and day length for any UK city and date alongside solar noon.
How high is the sun at noon? The noon sun angle
The sun's elevation at solar noon, its angle above the horizon, sets how strong the midday sun is and the ideal tilt for a fixed panel. It depends on your latitude and the sun's declination on the day, so it peaks around the June solstice and bottoms out in December. The calculator shows the approximate noon elevation for your city, a useful starting point for the angle to set a balcony or wall panel.
Common questions
-
Solar noon is the moment each day when the sun is at its highest point in the sky for your location, due south in the UK. It is when a fixed, south-facing panel produces the most, and it rarely lands exactly at 12:00 because of your longitude, the equation of time, and British Summer Time.
-
Your longitude shifts it: places west of the Greenwich meridian, like Cardiff or Plymouth, reach solar noon a little later than London. The equation of time moves it by up to about 16 minutes across the year. British Summer Time then adds an hour to the clock reading from late March to late October.
-
Solar noon and day length tell you when and for how long a fixed panel sees the strongest sun. A south-facing balcony or wall peaks around solar noon, so matching your daytime usage to that window raises self-consumption, which is what makes plug-in solar pay. For a location-specific yield, use the postcode calculator.
-
Peak sun hours are the equivalent number of hours per day at full 1,000 W per square metre that would give the same total energy as the real day. It is a modelled figure from satellite irradiance, not a clock time, and it varies by location and season. The postcode calculator uses PVGIS data to estimate yield from peak sun hours for your address.
-
The sun is highest at solar noon, which in the UK falls roughly between 12:00 and 13:10 depending on the date, your longitude and British Summer Time. Enter your city and today's date above for the exact minute.
-
Rarely. Solar noon drifts from clock noon because of your longitude, the equation of time and British Summer Time, so the sun is usually still rising at 12:00, especially in summer when solar noon sits near 13:00.
-
It depends on the date. In London solar noon is near 12:00 in midwinter and close to 13:00 under British Summer Time, shifted by the equation of time. Select London and today's date in the calculator for the exact time.
How this is calculated
Solar noon, sunrise and sunset use the standard NOAA solar position equations: the equation of time and the sun's declination for the chosen date, combined with your city's latitude and longitude. British Summer Time is applied automatically for dates between the last Sunday of March and the last Sunday of October. Sunrise and sunset use the conventional 90.833 degree zenith, which includes atmospheric refraction and the sun's radius. Figures are to the nearest minute and are a model, so they can differ from an almanac by a minute or so.
Sources
- NOAA Global Monitoring Laboratory solar calculations, the equations used here.
- European Commission PVGIS, the satellite irradiance behind the yield figures on the postcode calculator.
- Plug Solar Hub: how we track the sun.