How much will solar panels produce in Letterkenny?

A 4 kWp system facing south at 35° tilt in Letterkenny produces about 3,391 kWh a year. In a weak year that is 2,836 kWh, in a good one 3,947 kWh — 848 kWh per kWp.

That’s about 81% of a typical home’s yearly use (4,200 kWh).

Calculate for my roof

Based on 2014–2023 satellite weather data

Production by month

0200400600JanJanuary: 4 kWp 87 kWh, range 67–108FebFebruary: 4 kWp 162 kWh, range 124–199MarMarch: 4 kWp 297 kWh, range 237–357AprApril: 4 kWp 401 kWh, range 311–490MayMay: 4 kWp 498 kWh, range 399–597JunJune: 4 kWp 419 kWh, range 327–511JulJuly: 4 kWp 414 kWh, range 342–485AugAugust: 4 kWp 399 kWh, range 316–482SepSeptember: 4 kWp 304 kWh, range 243–365OctOctober: 4 kWp 205 kWh, range 156–253NovNovember: 4 kWp 120 kWh, range 91–149DecDecember: 4 kWp 67 kWh, range 47–87

kWh per month

A typical day in May

The sunniest month in Letterkenny. Output peaks around 11:00 solar time, at about 1.7 kWh in the best hour.

0:006:0012:0018:0023:00 1.7 0

Month by month

Month Weak year, kWh Typical year, kWh Good year, kWh
January 67 87 108
February 124 162 199
March 237 297 357
April 311 401 490
May 399 498 597
June 327 419 511
July 342 414 485
August 316 399 482
September 243 304 365
October 156 205 253
November 91 120 149
December 47 67 87
Year 2,836 3,391 3,947

The months don’t add up exactly to the yearly figure, because each one is the typical value across many years.

Common questions

How much do solar panels produce in winter in Letterkenny?

From November to February the system produces about 436 kWh, which is 13% of the year. The weakest month (December) gives roughly 67 kWh.

Is an east-west roof worth it in Letterkenny?

An east-west system typically produces 10–25% less per kWp than one facing south, but spreads production more evenly through the day. The exact difference depends on tilt and shading.

Compare an east-west roof for Letterkenny

Ground mount or roof in Letterkenny?

A ground mount can be tilted and aimed freely, which can add some yield, but it costs more and needs space. Compare both for your own plot.

Check a ground-mounted system in Letterkenny

Your roof is not an average roof

Set your own tilt, direction, shading and inverter limit and get a range for your address.

Calculate for my roof

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Climate data: Photovoltaic Geographical Information System (PVGIS) — European Commission, Joint Research Centre