Solar Production Calculator: annual & monthly kWh
Instant solar panel kWh / production calculator: enter array kW, peak sun hours, and system loss → planning annual and monthly energy. For industrial screens—not PVWatts weather-year simulation or residential shopping.
Quick answer
How much energy will my array produce? Lead with kWh: Daily kWh ≈ Array kW × PSH × (1 − Loss); Annual kWh ≈ Daily × 365. Example: 10 kW, 5.0 PSH, 15% loss → ~42.5 kWh/day and ~15,513 kWh/yr (~1,293 kWh/month flat). Pick loss % with the solar system losses & derating guide—this is a linear planning screen, not NREL PVWatts. Need panel count first? Use the solar panel calculator. Confirm PSH in peak sun hours. Hub: Solar calculators hub.
Quick PV Energy Production Calculator
Defaults: 10 kW array · 5.0 PSH · 15% system loss.
10 kW × 5.0 × 365 × 0.85.
Advanced PV Energy Production Calculator
Presets
PV Energy Production Results
Engineering disclaimer
Simplified estimate—not NREL PVWatts. Real yield varies with weather year, tilt, shading, and OEM curves. Use for planning screens only.
Results
~15,513 kWh/yr — default example.
Annual kWh by peak sun hours
| PSH | kWh/yr | kWh/month |
|---|
People also ask
- How do I estimate solar kWh? Array kW × PSH × days × (1 − loss).
- Daily production? Daily kWh ≈ Array kW × PSH × (1 − loss)—e.g. 10 × 5 × 0.85 = 42.5 kWh/day.
- 20 kW system? At 5.0 PSH / 15% loss ≈ 85 kWh/day ≈ 31,025 kWh/yr (flat).
- Is this PVWatts? No—simplified planning formula with explicit loss %.
- Monthly vs annual? Monthly ≈ annual ÷ 12 for a flat screen; seasonality needs site data.
Planning guidance
This page estimates yield from a known array. If you still need array kW, start with panel sizing. Treat results as a linear planning screen—not a weather-year bid.
- Size first: Get array kW from the solar panel sizing calculator.
- PSH: Confirm with peak sun hours / irradiance guides.
- Loss band: 12–20% is common for commercial rooftops before weather uncertainty—see losses & derating.
- Cost link: Carry kWh into the energy estimator.
- Hub: Solar calculators hub.
Last updated: 2026-08-07. Simplified estimate—not NREL PVWatts.
Typical scenarios
- 10 kW office roof: ~12–18 MWh/yr depending on PSH and soiling.
- 50 kW warehouse: Scales linearly here—confirm inverter clipping separately.
- High-loss site: Dusty / long DC runs—raise loss % before quoting savings.
Daily, monthly, and annual yield
Daily kWh ≈ Array kW × PSH × (1 − loss). Annual multiplies by days/year. Monthly on this page is annual ÷ 12 (flat)—useful for bill screens, not seasonal design.
| Example (10 kW · 5.0 PSH · 15% loss) | Energy |
|---|---|
| Daily | 10 × 5 × 0.85 = 42.5 kWh/day |
| Monthly (flat) | ≈ 1,293 kWh/month |
| Annual | ≈ 15,513 kWh/year |
This calculator vs NREL PVWatts
- This tool: Explicit kW × PSH × days × (1 − loss)—fast, transparent, linear.
- PVWatts / SAM: Weather-year irradiance, tilt/azimuth, temperature, and inverter models.
- Use this page for screening; confirm bids with NREL PVWatts or SAM.
Formula (quick reference)
Annual kWh = Array kW × Peak sun hours × Days × (1 − Loss fraction)
Monthly ≈ Annual ÷ 12 (flat average). How to choose loss %: solar system losses & derating.
Formula and sources
Not equivalent to PVWatts. Use for planning screens; confirm with site irradiance and OEM software.
kWh per kWp by US City (Annual & Monthly)
Specific yield (kWh/kWp/year) = annual energy output per kW of installed PV capacity. This is the key metric for comparing solar productivity across locations. Values below assume fixed tilt at latitude, 14% system losses, from NREL PVWatts v8.
| City | Annual kWh/kWp | Best Month (Jun/Jul) | Worst Month (Dec/Jan) | 5 kW System Annual | 10 kW System Annual |
|---|---|---|---|---|---|
| Phoenix, AZ | 2,050 | 235 kWh/kWp | 130 kWh/kWp | 10,250 kWh | 20,500 kWh |
| Los Angeles, CA | 1,820 | 225 kWh/kWp | 105 kWh/kWp | 9,100 kWh | 18,200 kWh |
| Miami, FL | 1,640 | 185 kWh/kWp | 110 kWh/kWp | 8,200 kWh | 16,400 kWh |
| Houston, TX | 1,580 | 190 kWh/kWp | 95 kWh/kWp | 7,900 kWh | 15,800 kWh |
| Atlanta, GA | 1,510 | 180 kWh/kWp | 85 kWh/kWp | 7,550 kWh | 15,100 kWh |
| New York, NY | 1,320 | 170 kWh/kWp | 60 kWh/kWp | 6,600 kWh | 13,200 kWh |
| Chicago, IL | 1,260 | 165 kWh/kWp | 55 kWh/kWp | 6,300 kWh | 12,600 kWh |
| Seattle, WA | 1,100 | 165 kWh/kWp | 35 kWh/kWp | 5,500 kWh | 11,000 kWh |
US average: ~1,450 kWh/kWp/year. World record: ~2,400 kWh/kWp/year (Atacama Desert, Chile). Values assume no shading, south-facing (or azimuth ±30°), tilt = latitude. East/west split arrays lose ~5–10% annual output.
PV System Losses Breakdown (Where the 14% Goes)
A PV array rated at 1 kW STC (Standard Test Conditions: 1,000 W/m², 25°C cell, AM 1.5) never produces 1 kW in real operation. The standard "14% system losses" assumption breaks down as follows. Understanding each component helps you optimize system design and estimate real output more accurately.
| Loss Component | Typical % | Cause | Mitigation |
|---|---|---|---|
| Temperature (PTC) | 5–10% | Cells operate 25–35°C above ambient; power drops ~0.4%/°C above 25°C | Choose high PTC-rated panels; ensure airflow under panels; avoid black roofs |
| Inverter efficiency | 2–4% | DC→AC conversion losses; peak efficiency 96–98%, but weighted ~96% | Use high-efficiency inverters (≥97% CEC weighted); right-size inverter (DC:AC ratio 1.1–1.3) |
| DC wiring (ohmic) | 1–2% | Resistive losses in PV wire, home runs, and combiner boxes | Use appropriately sized wire (≤2% voltage drop); minimize string length |
| AC wiring | 0.5–1% | Resistive losses from inverter to main panel / grid interconnection | Size AC feeder for ≤1% drop; locate inverter near main panel |
| Soiling (dust/dirt) | 2–5% | Dust, pollen, bird droppings, leaves on panel surface reduce light transmission | Annual cleaning (or rain in wet climates); tilt ≥10° for self-cleaning; avoid overhanging trees |
| Mismatch | 1–2% | Slight manufacturing tolerance differences between panels in a string; partial shading | Use microinverters or power optimizers; avoid shading; match panel models/ages |
| Light-induced degradation (LID) | 1–2% | First few months of exposure cause permanent efficiency drop (especially p-type silicon) | Choose low-LID panels (n-type TOPCon/HJT); account in production estimates |
| Availability / downtime | 0.5–1% | Inverter faults, maintenance, grid outages, snow cover | Quality components; monitoring system; snow-shedding panel design |
Total typical system losses: 14–25%
Well-designed residential systems: ~14%. Commercial systems with optimizers/microinverters: ~10–12%. Poorly designed systems with shading and long wire runs: 20–25%. Use the higher end for conservative estimates, lower end for optimized designs.
Frequently Asked Questions
How do I calculate solar production per day?
Daily kWh ≈ Array kW × Peak sun hours × (1 − Loss). Example: 10 kW × 5.0 PSH × 0.85 ≈ 42.5 kWh/day. Annual ≈ daily × 365 (or use the calculator’s annual field). Choose loss % via losses & derating.
How much does a 20 kW solar system produce per day?
At 5.0 PSH and 15% loss: 20 × 5 × 0.85 = 85 kWh/day ≈ 31,025 kWh/year (flat monthly ≈ 2,585 kWh). Lower PSH or higher soiling reduces output—re-run with your site inputs above.
How do I calculate solar panel kWh production?
Multiply array kW by peak sun hours, days per year, and (1 − system loss). Example: 10 × 5 × 365 × 0.85 ≈ 15,513 kWh/yr.
How many kWh does a 10 kW solar system produce?
At 5.0 PSH and 15% loss ≈ 15,513 kWh/year (~1,293 kWh/month flat). Raise or lower PSH/loss in the calculator for your site.
Is this the same as NREL PVWatts?
No. This is a simplified planning estimate with an explicit loss percentage—not a weather-year simulation. Use PVWatts/SAM for deeper studies.
What loss percentage should I use?
Often 12–20% for commercial systems covering inverter, wiring, soiling, and mismatch. See solar system losses & derating.
How does this differ from solar panel sizing?
This page = production (kWh) from a known array. The solar panel calculator finds how many panels / array kW from daily load. Do not use production to size panel count.
Why is monthly just annual divided by 12?
Flat average for quick bill screens. Real seasonality needs monthly PSH or a weather-year model—start with peak sun hours.
What is the next step?
Size MPPT controllers for string current, or screen energy cost with the energy estimator.
How it works
Daily full-sun equivalent hours are scaled across the year and reduced by a combined system loss fraction. The model is linear in array kW—clipping, seasonal PSH, and tilt are out of scope here.
Worked examples
- 10 kW · 5.0 PSH · 15% loss
10 × 5 × 365 × 0.85 = 15,512.5 kWh/yr (~1,293 kWh/month).
- 50 kW · 4.5 PSH · 18% loss
50 × 4.5 × 365 × 0.82 ≈ 67,342 kWh/yr.