Partial Shading & Hotspots in a Solar Panel

Solar cells in a panel are wired in series, so the whole string can only carry as much current as its weakest cell. This simulator models an 18-cell string with a real single-diode equation per cell, lets you shade individual cells with a shadow pattern, and shows exactly what happens electrically: a shaded cell is forced into reverse bias by the healthier cells around it and starts dissipating power as heat instead of generating it — the physical origin of solar-panel hotspots. Toggle the three per-row bypass diodes to see how real panels prevent this by routing current around a shaded substring, at the cost of losing that substring's output.