Free Tools for US Homeowners
Free Solar
Calculators Hub
8 precision tools to estimate your system size, monthly savings, payback timeline, roof capacity, and 25-year ROI — no login, no guesswork.
All Solar Calculators
Solar Watt-Hour Calculator
List your appliances and daily usage hours to instantly calculate your total daily and monthly kWh — the foundation of every solar decision you’ll make.
Net Metering & 25-Year ROI Calculator
Model 25 years of solar savings, payback period, NPV, and IRR with your local utility export/import rates and the 30% federal ITC built in.
Solar Roof Area & Layout Estimator
Input your usable roof dimensions and panel size to get max panel count, total system wattage, and an optimized placement layout.
Solar Power Per Square Foot
Calculate how many kWh your available roof area can realistically generate, accounting for efficiency, peak sun hours, and system losses.
Solar Performance Loss Breakdown calculator
Analyze solar panel efficiency losses from shading, dust, temperature, wiring, and aging to optimize overall system performance.
Solar Time-of-Use (TOU) Optimization Planner
Optimize solar energy usage against utility TOU rates to reduce bills, maximize savings, and improve battery scheduling.
How to Use Them (In Order)
Audit Your Energy
Use the Watt-Hour Calculator to get your daily kWh — the foundation of every other calculation.
Size Your System
Feed daily kWh into the System Size Calculator with your ZIP code for a kW and panel count recommendation.
Check Your Roof
Confirm panels fit using the Roof Layout Estimator, accounting for setbacks and shading.
Run the Financials
Open the Net Metering ROI Calculator for your 25-year savings, payback, and NPV after incentives.
Which Calculator Do You Need?
| Your Question | Use This Tool | Key Output | Best For |
|---|---|---|---|
| How much energy does my home use? | Watt-Hour Calculator | Daily & monthly kWh | All homeowners |
| How many panels do I need? | System Size Calculator | kW size, panel count | Grid-tied |
| How much will I save on my bill? | Savings Calculator | Monthly & annual $ savings | Bill-reduction focus |
| When will solar pay for itself? | Payback Period Calculator | Break-even year | Pre-purchase |
| What’s my 25-year solar ROI? | Net Metering ROI Calculator | NPV, IRR, 25-yr savings | Deep analysis |
| How many panels fit on my roof? | Roof Area Estimator | Panel count & layout | Pre-installation |
| How much power does my roof produce? | Power Per Sq Ft Calculator | kWh output per sq ft | Roof planning |
| I want to go completely off-grid. | Off-Grid Solar Calculator | Panels, battery, inverter | Off-grid / rural |
Frequently Asked Questions
The average US home uses about 886 kWh/month. At 5 peak sun hours and 400W panels, that’s roughly 17–21 panels (6–8 kW system). Your exact number depends on state sunlight, roof direction, and how much of your bill you want to offset. Use our System Size Calculator for a ZIP-code-specific result.
The Solar Investment Tax Credit (ITC) lets you deduct 30% of your total solar installation cost from your federal taxes. It covers panels and battery storage. The 30% rate is locked through 2032, dropping to 26% in 2033 and 22% in 2034. All our financial calculators include the ITC automatically.
Most US homeowners break even in 6–10 years. High-rate states like Massachusetts, California, and Hawaii often see 5–7 year paybacks. Lower-rate states may see 10–14 years. After payback, every remaining year of your 25-year panel warranty is pure savings. Use our Payback Calculator for your specific situation.
Our tools use NREL peak sun hour data and industry-standard performance ratios (75–85%). Estimates are accurate within 10–15% for most homeowners. Real-world results vary based on shading, panel brand, and inverter quality. Always confirm with 2–3 installer quotes before purchasing.
Yes. Our Off-Grid Solar Calculator sizes your battery bank, array, charge controller, and inverter based on your daily load and autonomy days needed. Works for rural homes, cabins, RVs, and boats.
Ready to Run Your Numbers?
All tools are free, require no login, and give instant results — so you walk into any installer conversation fully prepared.