Grid-Tied Solar System Calculator

A grid-tied solar system connects directly to your utility grid. Your panels produce DC electricity, an inverter converts it to AC, and that power flows first to your home's loads. Any surplus is exported to the grid for a credit (net metering). When your panels aren't producing enough — at night or on cloudy days — you draw from the grid normally. Grid-tied systems are the most common, most cost-effective, and simplest residential solar configuration.

Net metering is a billing mechanism where your utility credits you for the excess solar electricity you export to the grid. When your system produces more than you use, the meter 'spins backward' (or logs a credit). At night, you draw that credit down. At the end of the billing period, you pay only the net difference between what you used and what you produced. Net metering policies vary by state and utility — some offer full retail rate credits, others use a lower 'avoided cost' rate.

No — standard grid-tied systems automatically shut off during outages for safety. This prevents live electricity from backfeeding into utility lines where workers may be repairing them. If backup power during outages is important, you need to add a battery system (creating a 'hybrid' or battery-backup configuration). Some newer inverters (like the Enphase IQ8) can provide limited island-mode power without a battery.

The typical payback period for a grid-tied system in the US is 6–12 years, depending on your state's electricity rate, available sun hours, system cost, and local incentives. States with high electricity rates (California, Massachusetts, Hawaii) tend to see 5–8 year paybacks. States with lower rates (Texas, Florida) are more commonly in the 9–12 year range. After payback, electricity is essentially free for the remaining 15–20+ year panel life.

Under most net metering programs, excess annual production is either rolled over to the next month, paid out at a lower 'avoided cost' rate, or simply forfeited. Very few utilities pay full retail rate for annual excess. This is why sizing your system to offset 90–100% of your usage (rather than 110–120%) generally maximizes ROI on a grid-tied system.