Hi Product Hunt, I'm Michael, a solo developer in Germany. I built Tegrona Lite because laying panels out on a roof is either done in CAD that costs four figures a year, or on paper with a tape measure. It starts from a photo - a drone shot, or just something taken from the ground. The hard part wasn't packing the panels, it was the perspective. A photo of a roof is projectively distorted and you can't measure anything on it. The usual fix is to drag four corners onto a rectangle, but that only works if the roof section actually is a rectangle - a trapezoid or a triangular hip gets mangled by it. So it reads the tiles instead. Roof tiles run in rows and columns, so the photo contains two families of parallel lines, and each family converges to its own vanishing point. Send those two points to infinity and the distortion is gone - and the roof outline never enters the math, which is why odd-shaped sections work. It finds the families by looking for periodicity in directional projections rather than gradient energy (the step where rows overlap can be an order of magnitude fainter than the grooves between tiles, and a gradient histogram simply doesn't see it), takes the median over nine patches so a chimney or a dormer sitting in the middle of the frame can't sink the whole run, and then checks its own work: each candidate transform is applied to a copy and scored by how evenly the tile pitch comes out. If it didn't actually improve anything, it says so instead of handing you back a warped picture. Scale comes from the tiles too - you pick the tile type, it counts tiles in a box, and now you have centimetres. After that it's the boring useful part: fill the roof, nudge with arrow keys, rotate with space, export a PNG/PDF spec sheet for the customer. It's free and there's no account. The web version runs entirely in your browser - nothing is uploaded, which matters more than it sounds, because aerial photos carry the GPS point of someone's house in EXIF. There are native apps for macOS, Windows, iPad and Android as well, and the project file is byte-compatible across all of them. What it is not: no shading simulation, no yield calculation, no string design. It answers one question - how many panels fit on this roof, and where. Try it without installing anything: https://tegrona.com/planner/?utm... I'd really like to hear what breaks. Especially if you have a roof photo it fails on - the detector is the part I keep working on, and awkward photos are what it learns from.

Tegrona Lite

Plan a solar panel layout from one photo of the roof

Plan a solar panel layout from one photo of the roof