Grid-Connected System explained
A grid-connected system (also called an on-grid or grid-tied system) is the standard setup for the vast majority of residential and commercial solar installations. Your solar system remains connected to the public electricity network at all times.
How it works:
- During the day (high solar output): solar powers your home first. Any surplus is automatically exported to the grid, earning SEG payments
- During the day (low solar output): your home draws additional power from the grid as needed, topped up by any battery if you have one
- At night: your home runs entirely on grid power (plus battery discharge if installed)
The main advantage of a grid-connected system over an off-grid setup is reliability and cost: you don't need enough battery capacity to see you through cloudy weeks, so the system is significantly cheaper. The grid acts as a virtually unlimited "backup" and "storage" mechanism.
The main disadvantage: if the grid goes down, your solar system automatically shuts off for safety reasons (to prevent back-feeding into lines that engineers may be working on). Some hybrid inverters have "backup mode" or islanding capability that can power critical loads during an outage, but this requires specific hardware.
For UK homeowners, grid connection requires notification to or approval from your DNO, and your installation must comply with G98 or G99 engineering requirements.