Rooftop Solar Calculator
Free solar PV panel calculator & production estimator — enter your address for panel count, annual kWh, and savings, powered by Google Solar API with NREL PVWatts fallback.
Your Address
Start typing and select your address from the dropdown
Enables payback period estimate
Default 400W, range 300–500W
Analyzing your roof geometry…
Pulling satellite data and crunching numbers
Your Roof Can Produce
Panel Count
—
panels
System Size
—
kilowatts
Usable Roof Area
—
m² / sq ft
Annual Production
—
kWh / year
Annual Savings
—
Monthly Average
—
kWh / month
Financial Projection
Estimated System Cost
—
Payback Period
—
years
25-Year Savings
—
Payback estimate uses the federal cost benchmark of $2.70/W after federal incentives and excludes state and local rebates, property tax exemptions, and performance payments, which can shorten payback in incentive-rich states (CA, NY, MA, CO, and others).Check available incentives in your state →
Compared to your ZIP average
Roof Segment Breakdown
Each roof face analyzed for orientation and energy contribution. South-facing segments (azimuth ~180°) perform best in the US.
| Facing | Pitch | Azimuth | Panels | Energy/yr |
|---|
Detailed satellite data isn't available for this address yet. These estimates use regional solar irradiance averages. For roof-level precision, try a nearby address or get a professional assessment.
Ready to see real quotes?
Get a free, no-obligation assessment from certified solar installers using your roof's actual solar potential.
Enter your street address above to analyze your roof's solar potential using satellite imagery.
Estimates are based on satellite imagery (Google Solar) or regional solar irradiance (NREL PVWatts) and local utility rates. Actual production varies with shading, equipment, and installation. This is an estimate, not a quote.
Also Interested In
What Is a Solar PV Calculator?
A solar PV calculator (photovoltaic calculator) estimates how much electricity a solar array will generate from a handful of inputs: your location, your roof's area and orientation, and the system size in kilowatts. It takes the solar irradiance at your latitude and runs it through a standard loss model — the same NREL PVWatts V8 defaults this site uses everywhere, including a14% system-loss derate for inverter inefficiency, wiring, soiling, and temperature. If you are looking for a solar PV panel calculator, a PV panel calculator, or a plain solar array calculator, this is the same tool: type your address, and the panel count and annual kilowatt-hours come back in seconds.
Solar Electricity Calculator: What It Estimates
A solar electricity calculator goes one step further than raw production and converts kilowatt-hours into dollars at your local utility rate. This page is both a solar energy calculator and a solar power calculator in one run: after the production math resolves, it pulls the residential rate for your resolved location from NREL Utility Rates data and reports annual savings, a monthly average, and (when you enter your monthly bill) a payback period. The result is a complete solar production calculator and solar output calculator view — kWh and dollars side by side, so you can see what the array makes and what it is worth.
How the Solar PV Estimator Works
As a solar PV estimator, the pipeline is: address → Google Solar satellite roof geometry (roof segments, azimuth, and pitch) with an NREL PVWatts V8 fallback when satellite data is not available for your location. The production run applies the PVWatts 14% loss derate canon and 0.5%/yr panel degradation. Sizing defaults to an 8 kW array of 400 W panels when no monthly bill is provided; with a bill entered, the system is right-sized to roughly offset your annual usage. The financial projection uses the federal cost benchmark of$2.70/W after federal incentives for the payback and 25-year savings figures. In a single run, the tool does the work of a solar calculator, a solar array calculator, and a solar panel system calculator: it sizes the array from your roof rather than asking you for a system size up front.
Solar Calculator vs Solar Estimator: What's the Difference?
The two terms get used interchangeably, but there is a meaningful difference. A solar calculator does the production and savings math from a system size you hand it. A solar estimator sizes the array for you from your address — measuring your roof and picking a panel count before doing any math. This tool does both, which is why it ranks as a rooftop solar calculator and a solar PV estimator at the same time.
| Capability | Solar Calculator | Solar Estimator | This Tool |
|---|---|---|---|
| Production & savings math | Yes | Yes | Yes |
| Roof-aware sizing from your address | No — you enter kW | Yes | Yes |
| Address-level roof geometry | No | Yes (Google Solar, with PVWatts fallback) | Yes |
Frequently Asked Questions
What is a solar PV calculator?
A solar PV (photovoltaic) calculator estimates how much electricity a solar array will produce from three inputs: your location, your roof's area and orientation, and the system size in kilowatts. It applies standard loss factors (the NREL PVWatts V8 default is a 14% system-loss derate) and panel degradation (about 0.5% per year) to convert raw irradiance into realistic annual kilowatt-hour output. This page is a solar PV calculator: enter your address and it sizes an array to your roof, then runs the production math automatically.
What is a solar electricity calculator?
A solar electricity calculator translates solar production into dollars at your local utility rate. It takes annual kilowatt-hours and multiplies by your residential rate (pulled from NREL Utility Rates data for your location) to estimate annual and monthly savings, and — when you enter your monthly bill — a payback period. This page does both: the production side is the PV calculation, and the savings side is the electricity calculation, so you see kWh and dollars together.
How accurate is the rooftop solar calculator?
When Google Solar data exists for your address, the calculator uses your roof's actual segment geometry — orientation, pitch, and azimuth — for an address-level estimate. When satellite data is not available, it falls back to NREL PVWatts regional irradiance at your resolved latitude and longitude. Either way, actual production varies with shading, equipment choice, and installation quality, and the result is an estimate, not a quote or a guarantee. The PVWatts 14% loss factor and 0.5%/yr degradation are the same defaults used across this site.
What's the difference between a solar calculator and a solar estimator?
A solar calculator does the production and savings math from a system size you give it. A solar estimator goes one step further and sizes the array for you using your address — measuring your roof and picking a panel count. This tool does both: it estimates a roof-aware system size from your address, then runs the calculator math on it. That is why we call it a rooftop solar calculator and a solar PV estimator in the same breath.
How do I use the solar PV panel calculator without signing up?
Type your street address and select it from the dropdown, then click Analyze. There is no account, no email, and no phone-number gate — the calculator runs entirely in your browser and calls NREL PVWatts and Utility Rates directly. An optional monthly-bill field unlocks the payback and 25-year savings projection, and an optional panel-wattage field lets you override the default 400W panel, but neither is required.
Does the solar calculator work for any address in the US?
Yes. Google Solar satellite coverage varies by location, so some addresses get full roof-segment geometry and others fall back to NREL PVWatts regional irradiance — but every US address resolves to a latitude and longitude and returns a production and savings estimate. If you get a regional fallback result, try a more specific street address or a nearby address for roof-level precision.