Definition and Solar Context
Peak Sun Hours (PSH) is a standardized metric used in solar energy system sizing and production modeling. It represents the equivalent number of hours per day during which solar irradiance reaches a reference level of 1,000 watts per square meter (W/m²).
Peak Sun Hours serve as a simplified translation of cumulative daily solar energy into a format suitable for photovoltaic system performance calculations. GetSunScore applies PSH data, sourced from NREL's publicly available datasets, as a core input to the SunScore™ Projection Engine.
What Does Peak Sun Hours Mean?
A Peak Sun Hour is defined as one hour of sunlight at an irradiance of 1,000 W/m², equivalent to 1 kWh of solar energy per square meter. The concept normalizes variable daily irradiance profiles into a single production-relevant figure.
For example, a location with 5.5 Peak Sun Hours per day receives a total daily solar energy equivalent of 5.5 kWh/m². This metric directly informs how many kilowatt-hours a given solar panel system is estimated to produce in a day.
Why Peak Sun Hours Matters in Modeling
Peak Sun Hours are the direct bridge between location-specific irradiance data and estimated system output in kilowatt-hours. The SunScore™ Projection Engine applies PSH values at the ZIP code level to calculate estimated daily production for a modeled system size.
PSH also affects modeled payback period — higher PSH locations produce more energy per installed kilowatt, improving estimated ROI metrics and shortening break-even windows in modeled scenarios.
How Peak Sun Hours Applies in Texas
Texas has strong Peak Sun Hours across most of its geographic range. Western Texas locations — including El Paso and Midland — consistently record average PSH values in the 6.0–6.5 range. Central Texas cities such as Austin typically average in the 5.5–6.0 PSH range.
The SunScore™ Projection Engine uses NREL-derived PSH data calibrated to Texas climate conditions, applying seasonal adjustment factors where relevant to capture the full multi-decade production profile.
Frequently Asked Questions
Peak Sun Hours represents the equivalent number of hours per day during which sunlight intensity reaches 1,000 W/m². A location with 5.5 PSH receives enough daily solar energy to produce 5.5 kWh per square meter per day.
The SunScore™ Projection Engine applies PSH values at the ZIP code level to estimate daily and annual solar production for a modeled system. Higher PSH results in higher estimated energy production and larger estimated savings ranges.
Texas Peak Sun Hours generally range from approximately 5.0 in the Houston area to over 6.5 in far West Texas. GetSunScore uses location-specific NREL data rather than statewide averages to reflect geographic variation.
Yes. Cloud cover reduces effective irradiance and lowers average PSH values. The SunScore™ Projection Engine uses multi-year historical PSH averages that account for typical regional cloud cover patterns, sourced from NREL's NSRDB dataset.
Solar Irradiance measures instantaneous sunlight power (W/m²). Peak Sun Hours converts cumulative daily irradiance into a simplified equivalent-hours metric. The two are related: PSH is derived from annual or daily irradiance totals. See the Solar Irradiance glossary entry for additional context.
All PSH benchmarks sourced from NREL. Projections referenced on this page are modeled scenarios based on publicly available datasets including NREL, EIA, and Texas utility rate filings (reference year: 2024).