Solar planning

Solar Panel Output Calculator

Estimate monthly and annual solar panel output for your location using system size, panel details, orientation and a location-aware PVWatts model. Add your coordinates before calculating; no generic production value is substituted.

Estimate solar production

Quick System Sizes:

How much electricity do solar panels produce?

Solar production depends on system size, location, tilt, azimuth, weather and system losses. This calculator sends your validated assumptions to PVWatts V8 and reports the provider's modeled AC output by month and year.

How to use this solar production calculator

Enter latitude and longitude manually or use your location, choose a system size or calculate one from panels and watts, review the orientation and then select Calculate Solar Output. Advanced PVWatts assumptions remain editable when you know more about the system.

Solar production by month

Monthly output is taken directly from the PVWatts response rather than spreading annual production evenly across the year. The result identifies the highest and lowest modeled months so seasonal variation is visible.

kW versus kWh

System size is measured in kilowatts (kW), while solar energy produced is measured in kilowatt-hours (kWh). A 10-panel system with 400 W panels has a calculated capacity of 4.00 kW before modeling.

How tilt, azimuth and losses affect output

Tilt is the panel angle and azimuth is its compass direction. Losses include system effects represented in the PVWatts inputs. These assumptions are editable and should be replaced with known project values when available.

How the PVWatts estimate works

PVWatts V8 models location-based solar production from system capacity, coordinates, array and module assumptions, tilt, azimuth and losses. Its annual and monthly AC outputs remain the authoritative modeled values; actual production can differ because of weather, shading, equipment and site conditions.

Worked calculation example

If PVWatts returns 7,500 kWh/year for a modeled 5 kW system, the average annual-production day is 7,500 ÷ 365 ≈ 20.55 kWh/day and the specific yield is 7,500 ÷ 5 = 1,500 kWh/kW-year. This is an illustrative provider-output fixture, not a prediction for every 5 kW system.

Limitations and methodology

The result is a modeled historical-weather estimate, not a production guarantee or financial forecast. Read the methodology and sources for model context and assumptions.

Solar Panel System Production Reference Matrix

Estimated annual and monthly electricity generation across standard residential system capacities and regional solar insolation levels:

Estimated annual & monthly AC generation (14% typical system losses)
System Size (kW DC)	Panel Count (400W)	Moderate Sun (3.5 PSH / ~1,200 kWh/kW-yr)	High Sun (5.0 PSH / ~1,650 kWh/kW-yr)
4.0 kW System	10 panels (~200 sq ft)	~4,800 kWh / yr (~400 kWh/mo)	~6,600 kWh / yr (~550 kWh/mo)
6.0 kW System	15 panels (~300 sq ft)	~7,200 kWh / yr (~600 kWh/mo)	~9,900 kWh / yr (~825 kWh/mo)
8.0 kW System	20 panels (~400 sq ft)	~9,600 kWh / yr (~800 kWh/mo)	~13,200 kWh / yr (~1,100 kWh/mo)
12.0 kW System	30 panels (~600 sq ft)	~14,400 kWh / yr (~1,200 kWh/mo)	~19,800 kWh / yr (~1,650 kWh/mo)

Solar AC Energy Yield & System Sizing Formulas

Estimates practical solar electricity output based on DC nameplate capacity, regional irradiance (solar insolation), and derating factors including wiring, inverter efficiency, and temperature coefficients.

FormulaDaily_kWh = System_Size_kW × Peak_Sun_Hours × (1 - System_Losses)

Variable Definitions

System_Size_kWArray DC Nameplate Rating(kW): Total panel wattage sum in kilowatts (e.g. 15 × 400W panels = 6.0 kW).
Peak_Sun_HoursDaily Solar Insolation (PSH)(hours/day): Equivalent hours per day at standard solar irradiance of 1,000 W/m² (typically 3.5 to 5.5 hours).
System_LossesAggregate Derate Factor(fraction): Standard combined losses for soiling, shading, wiring, inverter AC conversion, and thermal derate (typically 14% to 18%).

Engineering Notes & Standards

NREL PVWatts V8 performs hourly solar irradiance simulations using typical meteorological year (TMY3/NSRDB) climate records.
Specific Yield (kWh/kWp/year) measures how many kilowatt-hours each kilowatt of installed solar generates annually.

Frequently Asked Questions (FAQ)

How much electricity does a 400W solar panel produce per day?

In a region with 4.5 peak sun hours per day, a single 400W solar panel produces approximately 1.44 to 1.62 kWh (1,440–1,620 Wh) of usable AC electricity per day, accounting for typical inverter and temperature losses (~10%–20%).

How much power does a standard 5 kW or 7.6 kW home solar system produce per year?

A standard 5 kW solar array produces roughly 6,000 to 8,000 kWh per year depending on latitude and climate. A larger 7.6 kW array typically generates between 9,500 and 12,500 kWh annually.

What is the difference between solar kW rating and kWh output?

kW (kilowatts) measures the instantaneous DC power rating of your panels under Standard Test Conditions (STC). kWh (kilowatt-hours) measures the actual electricity energy produced and delivered to your home or grid over time.

How do seasonal changes affect monthly solar output?

Due to shorter days and lower sun angles in winter, monthly output during winter months can be 40%–60% lower than peak summer production in temperate latitudes.

Related solar calculator

Use the Solar Panel Tilt Calculator to explore a latitude-based starting angle and compare roof orientation, or Solar Battery Bank Size Calculator for energy storage.