Solar Generation in Northern Ireland: 27 April to 3 May 2026

Last week in Belfast, a typical 4kW solar installation produced 88.5 kWh of electricity. That is around £29.70 of value, in seven days, on a roof that does not need anyone to remember it is there.

A 6kW system, the size more common on detached homes and houses with an EV or heat pump, produced just under 133 kWh. Worth £44.54.

These figures come from our new Solar Today tracker, which publishes daily generation estimates for seven towns across Northern Ireland. If you already have solar on your roof, this gives you a fair benchmark to check your system against. If you are still deciding, it answers the most common question we hear: does solar actually work in NI?

Last Week, Day By Day

Northern Ireland’s weather rarely sits still for long, and last week was no exception. Belfast saw two genuinely brilliant solar days, three good ones, and two duller days bookending the week.

Day	Weather	4kW kWh	4kW value	6kW kWh	6kW value
Mon 27 Apr	Mixed cloud	6.3	£2.13	9.5	£3.19
Tue 28 Apr	Bright skies	13.1	£4.40	19.7	£6.60
Wed 29 Apr	Brilliant sun	20.7	£6.93	31.0	£10.39
Thu 30 Apr	Brilliant sun	20.4	£6.84	30.6	£10.26
Fri 1 May	Bright skies	13.2	£4.42	19.8	£6.63
Sat 2 May	Mixed cloud	8.4	£2.82	12.6	£4.23
Sun 3 May	Mixed cloud	6.4	£2.16	9.7	£3.24
Total		88.5	£29.70	132.9	£44.54

Wednesday alone delivered more than £10 of electricity for a 6kW system. Compare that to Monday, which produced barely a third of that. The variation matters, and it is normal.

What This Means If You Already Have Solar

If you have solar panels installed, the value of a daily benchmark is simple. You can check your inverter app against the typical output for your nearest town and tell quickly whether your system is performing roughly as expected, or whether something is worth a closer look.

A few things to keep in mind when comparing:

• Our figures assume south-facing panels at a typical NI roof pitch. If your roof faces east or west, expect roughly 85% of these numbers.
• We model a 4kW or 6kW system. Scale up or down for your own size.
• Panels lose a small amount of efficiency over time. A ten-year-old system will generate around 5 to 10% less than these estimates.
• Dirty panels, new tree growth, or even bird mess all reduce output.

If your readings are consistently 20% or more below the Solar Today figures over a sunny week, that is worth investigating. It might be a dirty panel, an inverter fault, or a shading issue that has crept in since installation.

What This Means If You Are Considering Solar

The most common piece of solar misinformation in Northern Ireland is that we do not get enough sun for it to be worthwhile. Last week tells a different story. On the two best days, a 6kW system generated more than £10 of electricity each. Even on the dullest day of the week, it produced 9.5 kWh, enough to run a typical household’s daytime appliances.

NI sunshine hours are lower than southern England. They are also higher than Glasgow and roughly equal to Dublin, both of which have thriving solar markets. The honest answer to “does it work here?” is: yes, with realistic expectations. A typical NI install pays for itself in 7 to 10 years and continues to generate for 25 or more.

How Solar Today Works

Each morning, Solar Today pulls weather data for seven NI towns from Open-Meteo. We model what a typical 4kW and 6kW solar installation would produce that day, applying a 0.78 performance ratio to account for inverter losses, panel temperature, and soiling. Today’s value is a forecast. Once the day closes, it firms up to the observed weather.

The seven towns we currently cover are Belfast, Derry, Armagh, Newry, Enniskillen, Lisburn, and Ballymena. Each gets its own daily estimate based on local cloud cover and irradiance.

A few honest caveats:

• These are modelled estimates, not live readings from physical systems.
• Forecast days update as the weather firms up.
• Your actual generation will vary by roof orientation, system size, panel age, and any shading.

The point is not to replace your inverter app. It is to give NI homeowners a fair, locally relevant benchmark that did not exist anywhere else.

See Your Town

Visit Solar Today to see the latest week for your nearest NI town. We update it every morning, and from now on we will publish a recap like this one each Monday.

If you do not have solar yet and last week’s numbers got you curious, our solar savings calculator will give you a personal estimate based on your own home, roof, and current bill.