Solar Builder started as a personal side project, built for fun out of a genuine interest in how solar systems work. It began as a simple helper for planning component wiring for my own setups, but quickly took on a life of its own. What started as basic layout and wire sizing grew into a full simulation engine, fault detection, a component database, and more.
From the start, one thing was important: keep it free, open, and frictionless. No accounts, no sign-ups, no installs. Just open a browser and start building. The goal was to make it as quick and accessible as possible so anyone curious about solar can just jump in and start playing around.
The main goal was always understanding. Solar setups can feel intimidating. There are a lot of components, a lot of specs, and a lot of ways things can interact with each other in ways that aren't obvious until something goes wrong. This tool exists to make that easier to see.
Place a panel, connect a charge controller, add a battery and a load, and watch how the numbers flow. See how changing the battery voltage affects wire sizing. See what happens when you add a second panel in series versus parallel. See which wire is the bottleneck.
The simulation is meant to give you a realistic feel for how a system will perform, not a certified engineering analysis. It models irradiance over the course of a day, battery state of charge, power flow through each wire, and basic fault conditions like blown fuses and short circuits. It's accurate enough to be useful for planning and learning, but it's not a substitute for a professional assessment on a real installation.
If this tool helps you understand your system better, figure out what components you need, or just gives you a clearer picture of how everything fits together, that's exactly what it's here for.
If you found this tool useful and have a little extra to spare, I accept donations through Buy Me a Coffee. It's completely optional and the tool will always be free, but it's appreciated more than you know.
Have a question, found a bug, or want to suggest something? Get in touch.