Online solar calculators provide reasonable estimates but typically have an accuracy range of ±15-20% compared to professional quotes. This variation occurs because calculators use regional averages, while actual quotes incorporate property-specific factors such as roof complexity, electrical panel conditions, local permitting costs, and current market pricing. Our calculator aims to provide midrange estimates based on national and regional data, but we recommend getting 3-5 professional quotes from reputable solar installers for exact pricing. These quotes are free and will include a detailed site assessment and production estimate tailored to your specific property.

Standard grid-tied solar panel systems without battery storage will not operate during power outages. This is a safety feature called anti-islanding, which prevents solar systems from sending electricity to the grid during outages, protecting utility workers making repairs. To maintain power during outages, you need either battery storage or a special transfer switch with a secure power supply feature. Battery systems typically add $10,000-$20,000 to installation costs but provide resilience during grid disruptions. Some newer inverters offer limited emergency power (1-2 outlets) during daylight hours without batteries, but this capability is restricted to small loads. Our calculator includes battery storage options if backup power is a priority for your installation.

Multiple studies have found that owned solar panel systems increase home values. According to research by the Lawrence Berkeley National Laboratory, homes with owned solar systems sell for approximately 3-4% more than comparable non-solar homes. For a median-priced $350,000 home, this represents an added value of $10,500-$14,000. The value increase depends on system size, age, remaining warranty period, and local electricity rates. Higher electricity prices generally correlate with higher value premiums for solar homes. However, leased systems or PPAs don’t typically add value and may complicate real estate transactions because the agreements must be transferred to new homeowners. This home value increase isn’t directly factored into our calculator’s financial projections but represents an additional financial benefit to consider.

Yes, solar panels generate electricity in both cloudy and cold conditions, though with some differences in performance. In cloudy weather, panels typically produce 10-25% of their rated capacity, depending on cloud density. Contrary to intuition, solar panels actually perform more efficiently in cold temperatures, as semiconductor properties improve in cooler conditions. Germany, which has a climate similar to the Pacific Northwest or New England, has been a world leader in solar adoption despite having moderate sunlight levels. Our calculator accounts for local climate conditions when estimating production, using historical solar irradiance data for your region. Even areas with frequent cloud cover can be economically viable for solar, especially when combined with high electricity rates or strong incentive programs. To maximize production in cloudy regions, system designs may incorporate east-west orientations to capture more diffuse light throughout the day.

When your solar system produces more electricity than you’re consuming, the excess flows back to the grid, and your utility company typically compensates you through one of several methods. Under full retail net metering, you receive credits at the same rate you pay for electricity, which you can use when your production is lower than consumption. Some utilities use avoided cost or wholesale rate net metering, providing credits at a lower rate than retail. Credit rollover policies vary—some utilities allow indefinite credit carryover, while others reset annually or monthly. If you consistently overproduce throughout the year, some utilities will pay you for excess annual production, though often at wholesale rates. Battery storage can help you retain excess production for later use. Our calculator assumes standard net metering practices but check with your utility for their specific policies, as these vary widely and can significantly impact the economics of oversized systems.

Solar panels have demonstrated remarkable longevity, with modern panels designed to last 25-40 years while continuing to produce electricity. Manufacturers typically offer 25-30 year “production warranties” guaranteeing that panels will maintain at least 80-85% of their original output capacity after this period. Studies of early solar installations from the 1970s and 1980s show many systems still operating at 80% capacity or better after 30-40 years. The primary mode of degradation is a slow, predictable decline in output (typically 0.5% per year for quality panels), not sudden failure. This means a quality solar installation should continue producing valuable electricity long after it has paid for itself. Solar panels have no moving parts, which contributes to their durability. The most common system repairs involve the inverter (typically lasting 10-15 years) rather than the panels themselves. Our calculator’s 25-year financial analysis is conservative; many systems will produce substantial additional value beyond this timeframe.