Solar PV Estimator
Estimate rooftop solar system capacity, annual energy production, and potential cost savings based on your location, roof area, and local electricity rates.
Input Parameters
Results
Capacity = Area × Efficiency | Annual kWh = Capacity × PSH × 365 × PR. Performance ratio accounts for inverter losses, wiring, soiling, shading, and temperature derating. Typical panel area ~1.7 m² at ~400W.
Solar PV System Sizing and Energy Estimation
Estimating solar photovoltaic (PV) system output is one of the first steps in evaluating whether solar energy makes sense for a residential or commercial building. This calculator provides a quick, engineering-grade estimate of system capacity, annual energy production, and potential cost savings based on readily available parameters.
How Solar Energy Production Is Calculated
Solar energy production depends on three primary factors: the amount of sunlight your location receives (measured in Peak Sun Hours or PSH), the total panel area and efficiency, and the system's real-world performance ratio. The performance ratio (PR) typically ranges from 75% to 85% and accounts for losses from the inverter, wiring resistance, panel soiling, shading, and temperature degradation. Modern monocrystalline panels achieve efficiencies of 20-23% under standard test conditions (STC) of 1000 W/m² irradiance.
Understanding Peak Sun Hours
Peak Sun Hours (PSH) is not the same as hours of daylight. PSH represents the equivalent number of hours at full 1000 W/m² irradiance that would deliver the same total daily solar energy. Halifax, Nova Scotia receives approximately 3.8 PSH per day annually, while sunnier locations like Calgary get about 4.5 PSH. Natural Resources Canada provides detailed solar resource maps through their RETScreen tool.
Who This Calculator Is For
This tool is designed for electrical engineers, solar installers, building owners, and students who need a preliminary estimate before conducting a full site assessment. For accurate project proposals, a detailed analysis using PVsyst, SAM (System Advisor Model), or RETScreen is recommended, incorporating actual site-specific shading analysis, roof orientation, tilt angle, and local utility rate structures.
Frequently Asked Questions
How many solar panels do I need for my home?
The number of panels depends on your electricity consumption and available roof area. An average Canadian home uses about 10,000 kWh per year. With modern 400W panels and 4 PSH, you would need approximately 20-25 panels (about 35-45 m² of roof space) to offset most of your consumption. This calculator estimates panel count based on your roof area and standard 400W (~1.7 m²) modules.
What is Performance Ratio and what value should I use?
Performance Ratio (PR) represents the fraction of energy actually delivered relative to theoretical maximum output. A well-designed system typically achieves 75-85%. Use 75-78% for conservative estimates in cold climates with snow, or 80-85% for optimally oriented systems in temperate climates. Factors reducing PR include inverter losses (~3-5%), wiring losses (~1-2%), soiling (~2-5%), shading, and temperature derating.
How do I find my local Peak Sun Hours?
Natural Resources Canada's RETScreen tool and the NREL PVWatts calculator provide solar resource data by location. General estimates: Maritime provinces 3.5-4.0 PSH, Ontario/Quebec 4.0-4.5 PSH, Prairies 4.5-5.0 PSH, US Southwest 5.5-7.0 PSH. These are annual averages; summer months are significantly higher than winter.
Does this account for net metering or feed-in tariffs?
This calculator uses a simple savings estimate by multiplying annual production by your electricity rate. It does not model net metering credits, time-of-use rates, feed-in tariffs, or demand charges. Actual savings depend on your utility's rate structure and how much of the solar production you consume on-site versus exporting to the grid.