How Many Solar Panels Do You Need for Net Metering?

Calculating System Size

To calculate the required system size for net metering, start by determining your daily energy consumption in kilowatt-hours (kWh). For example, if you use 30 kWh of electricity per day, and you want to offset 80% of it, you’ll need a system that produces at least 24 kWh per day. Next, consider your local solar irradiance, which can range from 4 to 7 peak sun hours (PSH) per day. For an average irradiance of 5 PSH, you’ll need a system with a total DC capacity of 4.8 kW (24 kWh / 5 PSH). Finally, consider a 10-20% efficiency margin to account for shading, panel degradation, and other losses.

Choosing the Right Panels

When selecting solar panels for a net metering system, look for high-efficiency modules with a minimum of 300 watts (W) per panel. Consider panels with a power tolerance of ±3% to minimize losses due to temperature and voltage fluctuations. A good starting point is a 60-cell solar panel with a nominal power rating of 320-350 W. For a 4-6 kW system, you’ll need 12-18 panels, depending on their wattage and the system’s voltage requirements.

Net Metering Considerations

When designing a net metering system, keep in mind that your local utility company may have specific requirements for system size, voltage, and inverter type. Be sure to check with your utility before selecting a system, as they may have specific requirements for grid-tie inverters and system monitoring. Additionally, consider the cost of any additional equipment, such as a grid-tie inverter, mounting hardware, and wiring, when calculating the total system cost. A reputable solar installer can help you navigate these requirements and ensure a successful net metering installation.