Solar Sizing & Calculators
Interactive calculators and sizing guides for every step of solar system design. How many panels do you need? How much will they produce? How many fit on your roof? What tilt angle is optimal? Every calculator uses NREL PVWatts v8 formulas with real-world derate factors.
Start with How Many Solar Panels to Power a House — the hub article that links to every sizing calculator on the site. If you already know your monthly kWh, jump to the specific calculator for 500, 1,000, 2,000, or 2,500 kWh/month.
Benchmarks: U.S. avg 4.98 · Phoenix 6.54 (highest) · Seattle 3.95 · Anchorage 3.17 (lowest). Above ~5.5 = sunny · 4.5–5.5 = average · below 4.5 = cloudy.
Tap to see sensitivity analysisSensitivity analysis
| Scenario | Value |
|---|---|
| Low (-20%) | 1.2 kWh |
| Expected | 1.5 kWh |
| High (+20%) | 1.8 kWh |
Your daily production scales linearly with both panel wattage and peak sun hours. A 10% change in either input changes your result by 10%.
All 18 Articles
How Many kWh Does A Solar Panel Produce Per Day? (Calculator + 2026 Tables)
A 100W panel produces ~0.4 kWh/day, a 400W panel ~1.7 kWh/day, a 6 kW system ~25 kWh/day. Full lookup tables for every panel size and system size at 4–7 peak sun hours, plus city-specific numbers for 12 U.S. locations and a 'what can it actually power' appliance comparison. Built on NREL PVWatts v8.
Read article →Average Peak Sun Hours By State: All 50 + DC (2026)
NREL peak sun hours for all 50 states plus DC. The U.S. average is 4.98 PSH/day, ranging from Arizona’s 6.54 to Alaska’s 3.17. Sortable table + kWh output.
Read article →Solar Rooftop Calculator: How Many Solar Panels Fit On Your Roof? (2026)
How many panels physically fit on your roof — based on NFPA 1 §11.12 fire-code setbacks, modern panel dimensions, and roof type. The current rule of thumb is roughly 1 kW of solar per 70 sq ft of total roof area, or about 28 sq ft per modern 400W panel after fire-code clearances. Includes lookup table for 300–5,000 sq ft roofs and conversion from house square footage.
Read article →How Many Solar Panels In A 1, 3, 5, 10, And 20 kW System (2026 Panel Sizes)
A modern 5 kW residential system uses 12 × 410W panels. 10 kW uses 24. 20 kW uses 47. Full table with 2026 Tier 1 panel options (LONGi, REC, Maxeon, Trina, Jinko), roof area, weight, and 2026 cost per system size.
Read article →How Many Solar Panels Do I Need For 500 kWh Per Month? (Calculator + 2026 Numbers)
500 kWh/month is about 57 % of U.S. average household use — a small home, apartment, or gas-heat house. At average sun you need about 10 × 410W panels (~4 kW DC). Full state table, 2026 cost, and a live calculator.
Read article →How Many Solar Panels Do I Need For 2,500 kWh Per Month? (Calculator + 2026 Numbers)
2,500 kWh/month is 30,000 kWh/year — a large all-electric home with EVs, heat pump, and/or pool. At U.S. average sun, that needs about 45 × 410W panels (~18.5 kW DC). State-by-state table, cost, and payback for 2026.
Read article →How Much Power Does A 5 kW Solar System Produce Per Day, Month, And Year? (2026)
A 5 kW DC residential solar system produces 17–27 kWh/day depending on location — about 6,200–10,000 kWh/year. Full PVWatts v8 numbers for 12 U.S. cities, monthly seasonal breakdown, 2026 cost and payback math (no federal tax credit).
Read article →How Much Power Does A 4.5 kW Solar System Produce Per Day, Month, And Year? (2026)
A 4.5 kW DC solar system produces 15–25 kWh/day depending on location — about 5,400–9,000 kWh/year. PVWatts v8 numbers for 12 U.S. cities, what this system size is best suited for, 2026 cost and payback.
Read article →How Many Solar Panels Do I Need For 2,000 kWh Per Month? (Calculator + 2026 Numbers)
2,000 kWh/month is 24,000 kWh/year — a large home with electric heat, EVs, or both. At U.S. average sun (4.98 PSH), that needs roughly 36 × 410W panels (~14.8 kW DC) using PVWatts v8 derates. Full state-by-state table and 2026 cost breakdown.
Read article →Solar Panel Calculator (2026): Size, Cost & Payback
Enter your ZIP and electric bill to get system size, panel count, cost, and payback. Built on NREL PVWatts v8 — most U.S. homes pay back in 9-14 years.
Read article →How Many Amps Does A 100 Watt Solar Panel Produce? (PWM vs MPPT, 2026)
A 100 W solar panel produces ~5.55 A at the panel itself (Imp) and up to ~8.33 A at the battery through an MPPT charge controller. PWM controllers are stuck at 5.55 A. Full explainer with real Renogy/BougeRV datasheet numbers.
Read article →How Much Power Does A 10 kW Solar System Produce Per Day, Month, And Year? (2026)
A 10 kW DC residential solar system produces 33–54 kWh/day depending on location — about 12,000–20,000 kWh/year. Full PVWatts v8 numbers for 12 U.S. cities, seasonal breakdown, 2026 cost (no federal tax credit), and the critical derate factor most articles skip.
Read article →How Many Solar Panels Do I Need For 1,000 kWh Per Month? (Calculator + 2026 Numbers)
1,000 kWh/month is roughly the U.S. average household. At average sun you need about 20 × 410W panels (~8 kW DC). Full PVWatts v8 math, state-by-state table, 2026 cost (no federal tax credit), and a live calculator.
Read article →Solar Panel Direction Calculator: Which Way to Face (2026)
Enter your ZIP and roof direction to see your annual yield vs true south, from NREL PVWatts. East/west keeps about 83%, not 50% — plus your compass fix.
Read article →Solar Wire Size Calculator: Find The Right AWG For Your Solar System
Calculate the correct wire gauge for any solar circuit: panels to controller, controller to battery, battery to inverter. Input amps, distance, and voltage to get AWG, voltage drop, power loss, and fuse size. Includes voltage drop calculator, quick-reference chart, and component-by-component sizing guide.
Read article →Solar Panel Tilt Angle Calculator: Best Angle by ZIP (2026)
The optimal solar panel tilt runs a few degrees below your latitude — about 33° in New York, facing true south. Enter your ZIP for the exact PVWatts angle.
Read article →How Many Solar Panels To Power A House? (2026 Guide)
The average US home needs 15-25 solar panels (400W) to cover 10,500 kWh/year. Arizona needs 13; Massachusetts needs 22 for the same energy. See the math.
Read article →How To Calculate Solar Panel Output (Watts → kWh, Day / Month / Year)
The exact formula every solar installer uses, explained line by line. Includes the PVWatts v8 derate breakdown (the authoritative 14% number), temperature coefficient math, year-1 vs year-25 degradation, worked examples, and lookup tables for 50W to 15 kW systems. Built on NREL methodology.
Read article →More Topics
How solar panels convert sunlight to electricity, panel types (monocrystalline, polycrystalline, thin-film), datasheet specs (STC, NOCT, NMOT), efficiency, voltage, and everything you need to understand before buying.
How much solar panels cost, how much they save, the now-expired federal tax credit, lease vs buy comparison, net metering explained, home value impact, and the all-in-one solar savings calculator.
Battery sizing calculator, LiFePO4 guide, MPPT vs PWM charge controllers, wiring panels to batteries, charge time calculators, and Tesla Powerwall specs. Everything for battery-based solar systems.
Complete solar panel installation guide: DIY vs professional, step-by-step process, permits, roof mount vs ground mount, series vs parallel wiring, and string inverter vs microinverter comparison.
How to maintain solar panels for maximum lifetime production: cleaning, monitoring, degradation tracking, performance in snow and clouds, and when to call a professional.
Solar sizing guides for specific applications: RV and campervan solar, EV charging, air conditioner sizing, well pump systems, and Tesla charging. Interactive calculators included.