In conjunction with black lines, red lines often represent the bus bars that are crucial for the solar panel's energy transmission. The grid lines are essential for the panels to generate usable electricity, and without them, your panel would be little more than a glorified sunlight. Here are design tips for methods of PV system utility interconnection. You may also scroll to the bottom to see the table of all one-line diagram symbols. Understanding these symbols is a necessary step to deciphering and designing. So at around 9:30am I turned the AC on at full power hence there's a little spike in load (yellow line). © 2025 - 2026 Solar Diagram Tool.