Those lines are called the grid lines, and they're actually doing some serious work to light your house and keep you cool during the summer. . Look closely at a solar panel, and you'll see a series of thin metallic lines running across the surface. They're not there to look nice — they have a specific purpose. Familiarize yourself with panel layout, 2. Use appropriate tools for. . The answer lies in the way PV panels are designed and constructed. The white lines on photovoltaic modules serve one of three important purposes, depending on whether they're the gaps, the fingers or the busbars.