What is Peak Sun Hours?
The number of hours per day when solar irradiance averages 1,000 W/m² — used to estimate daily panel output.
Quick Answer
Ireland averages 2.5–3.0 peak sun hours per day annually. This varies from 1.0 PSH in December to 5.0 PSH in June. While lower than southern Europe (4.5–6.0 PSH), Ireland's moderate temperatures and long summer days mean solar panels perform well year-round. The southeast averages about 3.0 PSH, the northwest about 2.5 PSH.
Fact-checked by John Rooney, Solar Energy Editor. Editorial policy
Peak Sun Hours Explained
Peak sun hours (PSH) is a standardised measure that represents the total solar energy received in a day as if it were concentrated into hours of full sunshine (1,000 W/m²). For example, a location receiving 4.5 kWh/m² per day has 4.5 peak sun hours. This simplifies output calculations: a 1kWp system × 4.5 PSH = 4.5 kWh per day. PSH varies by location, season, and weather patterns.
How Does Peak Sun Hours Work in Ireland?
Ireland averages 2.5–3.0 peak sun hours per day annually. This varies from 1.0 PSH in December to 5.0 PSH in June. While lower than southern Europe (4.5–6.0 PSH), Ireland's moderate temperatures and long summer days mean solar panels perform well year-round. The southeast averages about 3.0 PSH, the northwest about 2.5 PSH.
Frequently Asked Questions
How many peak sun hours does Ireland get?
Ireland averages 2.5–3.0 peak sun hours per day across the year. June averages 5.0 PSH, December averages 1.0 PSH. The southeast gets the most.
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John Rooney is the founder of Solar Info and has been covering the Irish solar energy market since 2023. He fact-checks all content against official SEAI data and maintains relationships with SEAI-registered installers across Ireland.