Peak Sun Hours
Peak Sun Hours (PSH) is a standardized metric that represents the total solar energy received at a location in a day, expressed as the equivalent number of hours during which solar irradiance averages 1,000 W/m² (standard test condition). Rather than counting daylight duration, PSH converts fluctuating sunlight intensity into a single, comparable value used in professional solar designing, system sizing, production modeling, and financial forecasting.
In modern solar engineering workflows, Peak Sun Hours play a critical role in estimating system output, optimizing panel count, validating production assumptions, and improving modeling accuracy within platforms such as Solar Layout Optimization and Shadow Analysis.
Key Takeaways
- Peak Sun Hours express total daily solar energy as equivalent full-sun hours.
- PSH is essential for PV sizing, production modeling, and financial forecasting.
- Higher PSH delivers more energy for the same installed capacity.
- PSH varies by geography, climate, shading, and season.
- Accurate PSH improves proposal quality, ROI calculations, and system reliability.
What It Is
Peak Sun Hours provide a simplified way to express how much usable solar energy a site receives over a full day.
For example, if a location receives 5 kWh/m²/day of solar energy, that equals 5 peak sun hours—meaning the total daily energy is equivalent to 5 hours of perfect 1,000 W/m² sunlight.
Solar professionals use PSH to:
- Accurately size PV systems during solar designing
- Validate feasibility for residential solar and commercial solar projects
- Estimate savings, payback periods, and long-term ROI
- Build production-backed proposals using Solar Proposals
- Optimize array layouts through Solar Layout Optimization
How It Works
Peak Sun Hours translate total daily solar irradiation into equivalent full-sun hours.
Practical Process
- Measure Total Daily Solar Irradiation
- Solar resource data is collected using satellite models, weather stations, or integrated datasets inside solar design platforms. Values are expressed in kWh/m²/day, closely tied to solar irradiance.
- Normalize to 1,000 W/m² (1 Sun)
- The daily irradiation value is divided by 1 kWh/m², representing one hour of peak sunlight.
- Convert to Peak Sun Hours
- The result equals the total Peak Sun Hours for that day.
- Apply PSH in Design & Financial Tools
- Designers multiply PSH by array size to estimate daily energy output.
- EPCs apply PSH when modeling generation and system losses.
- Sales teams use PSH-based outputs inside Solar ROI Calculator and Solar Proposals to justify system sizing.
Types / Variants
1. Daily Peak Sun Hours
Used for short-term analysis, shading impact studies, and troubleshooting—often evaluated alongside Solar Shading Analysis.
2. Monthly Average Peak Sun Hours
Monthly PSH values support accurate proposal generation, seasonal forecasting, and performance comparisons.
3. Annual Average Peak Sun Hours
The most common PSH value used in feasibility studies, capacity planning, and ROI modeling.
4. Derated Peak Sun Hours
Adjusted PSH values that account for system losses such as:
- Shading
- Soiling
- Tilt or orientation mismatch
- Electrical inefficiencies
Frequently calculated during Shadow Analysis and electrical design reviews.
How It’s Measured
Formula
[
\text{Peak Sun Hours} = \frac{\text{Daily Solar Irradiation (kWh/m²)}}{1 \text{ kWh/m²}}
]
Units
- Expressed in hours
- Based on 1 peak sun = 1,000 W/m²
Data Sources Used by Designers
- Global and regional irradiance databases
- Local weather stations
- Integrated irradiance engines inside solar designing software
Practical Guidance
For Solar Designers
- Use annual PSH for early-stage feasibility and capacity planning.
- Apply monthly PSH when building detailed proposals and energy yield forecasts.
- Adjust PSH using shading insights from Shadow Analysis.
For EPCs & Installers
- Verify roof tilt and orientation using tools like the Roof Pitch Calculator.
- Align PSH-based generation estimates with real-world site conditions before finalizing Solar Proposals.
For Sales Teams
- Explain PSH clearly to justify system size and savings projections.
- Use Solar Panel Sizer and Solar ROI Calculator to visualize optimized designs for customers.
For Developers & Utility-Scale Teams
- Compare PSH across multiple land parcels during site selection.
- Use long-term PSH averages for P50/P90 energy modeling inside solar project planning & analysis workflows.
Real-World Examples
1. Residential Rooftop (California)
A home with 5.8 PSH annually installs a 6 kW system:
[
6,000 \text{ W} \times 5.8 = 34.8 \text{ kWh/day (before losses)}
]
This estimate feeds directly into Solar Proposals to calculate monthly savings.
2. Commercial Rooftop (Germany)
With 3.6 PSH, designers rely on Solar Layout Optimization to maximize usable roof space and compensate for lower solar availability.
3. Utility-Scale Solar Farm (India)
A site with 6.2 PSH is prioritized for development, with PSH comparisons integrated into broader solar project planning and financial analysis.
.svg)
