Northern Ireland's Best Solar Run of 2026: Three Days Over £11

Northern Ireland is in the middle of its strongest solar spell of 2026. In Belfast, a 6kW rooftop system produced 34.5 kWh on Sunday, 35.3 kWh on Monday and 35.8 kWh by Tuesday: electricity worth £11.55, then £11.83, then £11.98 at Power NI’s 33.5p unit rate. Three days running above £11, each one a shade brighter than the last.

That clears the previous high point of the year. On 9 May a 6kW system managed £10.30 in a single standout day. This late-May run has beaten that figure three times over, on the back of 16 hours of sunshine on both Monday and Tuesday and cloud cover down at 9 per cent.

The run, day by day in Belfast

Day	Weather	4kW kWh	4kW value	6kW kWh	6kW value
Sat 23 May	Bright, 13.2h sun	16.8	£5.61	25.1	£8.42
Sun 24 May	Clear, 13.9h sun	23.0	£7.70	34.5	£11.55
Mon 25 May	Clear, 16.0h sun	23.5	£7.89	35.3	£11.83
Tue 26 May	Clear, 16.0h sun	23.9	£7.99	35.8	£11.98

What £11.98 a day actually means

The headline number is the electricity the panels made, valued at what you would otherwise pay to import it. A real household does not bank all of that. You keep the share you use while the sun is up, and you export the rest, and exported units earn far less: around 4 to 6p under the Smart Export Guarantee, against the 33.5p you save on every unit you use yourself.

So the cash in your pocket depends on how much of that midday peak you can use or store. A home that is empty until six in the evening keeps less of it than one running a dishwasher, an immersion or an EV charger through the afternoon. A battery shifts the balance further in your favour. The £11.98 is the ceiling, not the cheque, but on a clear day in late May the kit is working flat out, and the ceiling is high.

A purple patch, not an average

This is the top of the range. We are days from the longest day of the year, and this run sat under clear high pressure that does not visit often. A NI December delivers a small fraction of these numbers, and an honest look at whether solar is worth it rests on the annual total and your own usage, not the best week of the year.

What a week like this does show is what a roof in Northern Ireland is capable of when the Atlantic steps aside. The cliche that it is “too cloudy here for solar” does not survive a 16-hour day in Ballymena. Most months from April to August carry at least a few days like these, and they do the heavy lifting in the yearly figure.

It was not just Belfast

Across the full week of 18 to 24 May, all seven towns we track in our Northern Ireland solar guide landed within 16 per cent of each other. Belfast topped it at 164 kWh on a 6kW system, with Newry, Armagh and Lisburn a short step behind and Enniskillen lowest at 138 kWh. The south and east edged the week, but every part of NI had a good one. Over a full year those town gaps shrink as the weather averages out.

For anyone weighing up panels, a run like this is the part of the year the savings are built on. The sensible next step is to see what your own roof and postcode would have produced, rather than a Belfast benchmark: a like-for-like estimate is the only figure that decides whether solar pays for your home.

How these figures are worked out

Daily solar radiation for each town comes from Open-Meteo. We apply the standard PV model: radiation multiplied by system size multiplied by a 0.78 performance ratio, a conservative allowance for inverter, temperature, orientation and shading losses. Generation is valued at the Power NI unit rate of 33.5p per kWh, the price of a unit you do not have to buy. Figures are modelled estimates for a well-sited south-facing array, not meter readings from a specific install.