As more homeowners and businesses turn to solar energy, one of the most critical and often misunderstood factors influencing the profitability of a solar system is solar hours. Whether you're considering installing rooftop panels or investing in a large-scale solar farm, understanding solar hours can help you make smarter, more profitable decisions.
In this post, we’ll break down what solar hours are, why they matter, and how they directly affect your potential savings and return on investment.
What Are Solar Hours?
Solar hours, sometimes referred to as peak sun hours (PSH), represent the number of hours per day when sunlight intensity averages 1000 watts per square meter — the standard condition under which solar panels are rated.
1 solar hour = 1 hour of sunlight at 1000 W/m²
For example, 5 solar hours mean that over the course of a day, your system receives enough sunlight equivalent to 5 full hours at peak intensity.
Why Solar Hours Are Critical for Profitability
Solar profitability depends on how much electricity your panels generate vs. your energy costs. More solar hours mean:
- Higher daily production
- Faster return on investment
- Lower payback period
- Increased lifetime savings
On the other hand, areas with fewer solar hours will require careful sizing, storage, or hybrid systems to maximize profitability.
How Solar Hours Vary by Location
Location is the single largest factor affecting solar hours:
City - Average Daily Solar Hours
Los Angeles (USA)5.5 - 6.0 hours
Phoenix (USA)6.5 - 7.0 hours
Munich (Germany)3.0 - 3.5 hours
London (UK)2.5 - 3.0 hours
Stockholm (Sweden)2.0 - 2.5 hours
Johannesburg (South Africa)5.0 - 6.0 hours
Nairobi (Kenya)5.5 - 6.5 hours
Dubai (UAE)6.5 - 7.0 hours
New Delhi (India)5.5 - 6.5 hours
Sydney (Australia)5.0 - 6.0 hours
Tokyo (Japan)4.0 - 4.5 hours
São Paulo (Brazil)4.5 - 5.5 hours
Buenos Aires (Argentina)4.5 - 5.0 hours
Moscow (Russia)2.0 - 2.5 hours
This is why personalized calculations matter. Tools like Sunort - solar hours calculator help you analyze your specific location using historical solar data.
Solar Hours Affect System Sizing
In lower solar hour regions:
- You may need a larger system to meet the same demand.
- Adding a battery can increase self-consumption efficiency.
In higher solar hour regions:
- Smaller systems may deliver high returns.
- Excess production can generate income (net metering, feed-in tariffs).
How to Accurately Estimate Solar Hours
- Historical Solar Data: 5-10 year average
- Satellite & Ground Measurements: (PVGIS, Solargis, NASA SSE)
- Software Tools: Sunort, PVWatts, or local solar calculators
Tip: Always account for shading, orientation, and panel tilt for the most accurate estimate.