What Else Does a Grid-Tie Solar Kit Need Before It Can Connect to the Grid?
Summary
Panels only generate the power. To make it usable at home, the system needs mounting and an inverter, and a grid connection adds equipment that DOE calls balance-of-system: power conditioning, safety equipment such as a disconnect switch, and meters. Most homeowners also sign an interconnection agreement with the utility. Without a battery and an inverter designed for backup, the house gets nothing from the array during an outage.
Three add-ons named by Energy Saver
DOE's Energy Saver lists the extra items a grid-connected home system may need to deliver power safely and meet the utility's connection rules.
| Item | What Energy Saver says it does |
|---|---|
| Power conditioning equipment | Makes the system's output match the voltage and frequency of the electricity on the grid |
| Safety equipment | Switches that disconnect the system from the grid during a power surge or failure, so repair crews are not electrocuted |
| Meters and instrumentation | One bi-directional meter under net metering, or two uni-directional meters under net purchase and sale |
The panels themselves are, in DOE's words, "only one of the many parts in a complete photovoltaic (PV) system." The racking has to withstand wind, rain, hail, and corrosion over decades, and DOE expects the inverter to be replaced at least once in a 25-year array lifetime.
Standards and pre-certified models
IEEE 1547-2003 sets the technical requirements and tests for grid-connected operation. UL 1741 certifies inverters, converters, charge controllers, and output controllers, and verifies that inverters comply with IEEE 1547. The National Electrical Code covers wiring and equipment safety, and some states pre-certify specific models as safe to connect. Which models a given utility accepts is set by the utility, the state, and the equipment maker's specifications. SolarPanelX does not rule on compatibility.
Paperwork that comes before the purchase
Energy Saver tells buyers to contact the utility about its grid-connection requirements before purchasing any part of the system. An interconnection agreement is the likely next step. The page notes that most homeowners carry at least $100,000 of liability coverage through their homeowner's policy and that the utility may require more. Possible charges include permitting fees, engineering and inspection fees, metering charges if a second meter goes in, and stand-by charges.
Sources
- U.S. Department of Energy — Solar Photovoltaic System Design Basics
- U.S. Department of Energy, Energy Saver — Grid-Connected Renewable Energy Systems
- U.S. Department of Energy — Solar and Resilience Basics
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