Estimate your home solar panel system size, installation costs, annual savings, and payback period. Enter your electricity usage and location to get a personalized solar analysis.
Your Electricity Usage
Location & System
Cost Breakdown
| Item | Amount |
|---|
Estimated Monthly Production (kWh)
25-Year Savings Projection
Assumes 2.5% annual electricity rate increase and 0.5% annual panel degradation.
| Year | Production (kWh) | Elec. Rate ($/kWh) | Annual Savings | Cumulative Savings | Net Position |
|---|
Environmental Impact (25 Years)
Average Peak Sun Hours by US Region
Peak sun hours represent the number of hours per day when solar irradiance averages 1,000 watts per square meter. This is the standard measure used to estimate solar panel production, not simply daylight hours.
| Region | Peak Sun Hours | Example Cities |
|---|---|---|
| Southwest | 5.5 - 6.5 | Phoenix, Las Vegas, Albuquerque, Tucson |
| Southeast | 4.5 - 5.5 | Miami, Atlanta, Houston, Charlotte |
| Midwest | 4.0 - 5.0 | Chicago, Denver, Kansas City, Minneapolis |
| Northeast | 3.5 - 4.5 | New York, Boston, Philadelphia, Pittsburgh |
| Pacific Northwest | 3.0 - 4.0 | Seattle, Portland, Spokane |
| California | 5.0 - 6.0 | Los Angeles, San Diego, Sacramento |
| Hawaii | 5.5 - 6.5 | Honolulu, Maui, Kauai |
How This Calculator Works
This calculator estimates your solar panel system needs using the following methodology:
Step 1: Determine monthly kWh usage. If you enter your monthly bill, we divide by your electricity rate to find your kWh consumption. For example, a $150 bill at $0.16/kWh means you use about 938 kWh per month.
Step 2: Calculate system size. Your annual usage is divided by the number of peak sun hours, a system efficiency factor (typically 80% to account for inverter losses, wiring, temperature, and shading), and 365 days. The formula is:
System kW = Annual kWh / (Sun Hours x 365 x 0.80)
Step 3: Determine panel count. The system size in watts is divided by individual panel wattage (default 400W). We round up since you cannot install a fraction of a panel.
Step 4: Estimate costs. System cost is calculated at $2.85/watt (national average), then the 30% federal Investment Tax Credit is applied. Annual savings are based on the system's estimated production multiplied by your electricity rate.
Step 5: Calculate payback period. Net system cost (after tax credit) is divided by first-year savings. The 25-year projection accounts for 2.5% annual electricity rate increases and 0.5% annual panel degradation.
Average Solar Panel System Costs (2024-2025)
Installed costs vary by system size, equipment quality, and local market conditions. These are national averages before incentives.
| System Size | Avg. Cost (Before ITC) | After 30% ITC | Typical Home Size |
|---|---|---|---|
| 3 kW | $8,550 | $5,985 | Small / Apartment |
| 5 kW | $14,250 | $9,975 | 1-2 Bedroom |
| 6 kW | $17,100 | $11,970 | 2-3 Bedroom |
| 8 kW | $22,800 | $15,960 | 3-4 Bedroom |
| 10 kW | $28,500 | $19,950 | Large Home |
| 12 kW | $34,200 | $23,940 | Very Large Home |
About Residential Solar Panels
Residential solar panels convert sunlight into electricity using photovoltaic (PV) cells. Modern monocrystalline panels typically achieve 20-22% efficiency and produce 350-450 watts each. A complete solar system includes panels, an inverter (which converts DC to AC power), mounting hardware, and wiring.
Panel lifespan and warranty: Most solar panels come with a 25-year performance warranty guaranteeing at least 80% of original output. In practice, panels often produce electricity for 30-35 years. Degradation averages about 0.5% per year, meaning panels at year 25 still produce roughly 87.5% of their original capacity.
Net metering: In many states, net metering allows you to sell excess solar electricity back to the grid at retail rates. When your panels produce more than you use during the day, your meter runs backward. You draw from the grid at night and on cloudy days, only paying for your "net" usage. Net metering policies vary by state and utility.
Federal tax credit (ITC): The Inflation Reduction Act extended the 30% Investment Tax Credit through 2032. This credit applies to the full cost of your solar system, including equipment and installation. For a $20,000 system, the ITC saves you $6,000 on your federal taxes. The credit steps down to 26% in 2033 and 22% in 2034.
Additional incentives: Many states, utilities, and municipalities offer additional incentives including state tax credits, rebates, Solar Renewable Energy Credits (SRECs), and performance-based incentives. Check the DSIRE database for incentives available in your area.
Frequently Asked Questions
How many solar panels do I need for my home?
The number of solar panels depends on your electricity usage and location. A typical US home uses about 900 kWh per month and needs a 6-8 kW system, which is 15-20 panels at 400W each. Homes in sunnier regions like the Southwest need fewer panels than those in the Northeast because each panel produces more energy per day.
How much does a residential solar panel system cost?
The average cost of a residential solar panel system in 2024-2025 is $2.50-$3.50 per watt before incentives. A typical 6 kW system costs $15,000-$21,000 before the federal tax credit. The 30% federal Investment Tax Credit (ITC) can reduce the cost by $4,500-$6,300, bringing the net cost to $10,500-$14,700.
What is the payback period for solar panels?
The average payback period for solar panels in the US is 6-12 years, depending on electricity rates, sun exposure, system cost, and available incentives. In states with high electricity rates like California or Massachusetts, payback can be as short as 5-7 years. With a 25-30 year panel lifespan, homeowners typically enjoy 15-20 years of essentially free electricity after payback.
How much can I save with solar panels over 25 years?
Over 25 years, a typical residential solar system can save $20,000-$60,000 or more, depending on electricity rates and rate increases. Solar panels typically have a 25-year warranty and can produce electricity for 30+ years. Savings increase over time as utility rates rise, typically 2-3% per year.
Do solar panels work on cloudy days?
Yes, solar panels still produce electricity on cloudy days, though at reduced output (10-25% of full capacity). Modern solar panels are designed to capture diffuse sunlight. Even in cloudy climates like Seattle or Portland, solar panels can be a worthwhile investment because the annual average production accounts for all weather conditions.
What is the federal solar tax credit?
The federal Investment Tax Credit (ITC) allows homeowners to deduct 30% of their solar installation cost from their federal taxes. This credit applies to systems installed through 2032 and steps down to 26% in 2033 and 22% in 2034. The credit covers panels, inverters, mounting equipment, wiring, and installation labor.
Privacy & Limitations
- All calculations run entirely in your browser -- nothing is sent to any server.
- Results are computed using standard formulas and should be verified for critical applications.
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Solar Panel Calculator FAQ
How many solar panels do I need for my home?
The number of solar panels depends on your electricity usage and location. A typical US home uses about 900 kWh per month and needs a 6-8 kW system, which is 15-20 panels at 400W each. Homes in sunnier regions like the Southwest need fewer panels than those in the Northeast because each panel produces more energy per day.
How much does a residential solar panel system cost?
The average cost of a residential solar panel system in 2024-2025 is $2.50-$3.50 per watt before incentives. A typical 6 kW system costs $15,000-$21,000 before the federal tax credit. The 30% federal Investment Tax Credit (ITC) can reduce the cost by $4,500-$6,300, bringing the net cost to $10,500-$14,700.
What is the payback period for solar panels?
The average payback period for solar panels in the US is 6-12 years, depending on electricity rates, sun exposure, system cost, and available incentives. In states with high electricity rates like California or Massachusetts, payback can be as short as 5-7 years. With a 25-30 year panel lifespan, homeowners typically enjoy 15-20 years of free electricity after payback.
How much can I save with solar panels over 25 years?
Over 25 years, a typical residential solar system can save $20,000-$60,000 or more, depending on electricity rates and rate increases. Solar panels typically have a 25-year warranty and can produce electricity for 30+ years. Savings increase over time as utility rates rise, typically 2-3% per year.
Do solar panels work on cloudy days?
Yes, solar panels still produce electricity on cloudy days, though at reduced output (10-25% of full capacity). Modern solar panels are designed to capture diffuse sunlight. Even in cloudy climates like Seattle or Portland, solar panels can be a worthwhile investment because the annual average production accounts for all weather conditions.
What is the federal solar tax credit?
The federal Investment Tax Credit (ITC) allows homeowners to deduct 30% of their solar installation cost from their federal taxes. This credit applies to systems installed through 2032 and steps down to 26% in 2033 and 22% in 2034. The credit covers panels, inverters, mounting equipment, wiring, and installation labor.