Enter your panel's Voc, panels per string, and record low temperature to check your string voltage against your controller's max input.
Cold weather raises panel voltage — this is the calculation installers use to avoid frying an inverter on the coldest morning of the year, not just average conditions.
Solar panel voltage rises as temperature drops, the opposite of what most people expect — a string that's safely within range on a warm afternoon can exceed an inverter's maximum input voltage on a freezing morning and trip a fault, or worse, cause damage. This check uses your site's record low temperature, not just STC ratings, to size the string safely for the coldest realistic day.
Solar cells are semiconductors whose voltage output rises as temperature falls, roughly the inverse of how their current behaves — it's a physical property of the cell, not a malfunction.
Most inverters and charge controllers will fault out or shut down for protection, and in the worst case sustained overvoltage can damage the input circuitry — always keep a safety margin, not just barely under the limit.