High altitude

At high altitude the air is thinner, so it cools electronics less well and insulates less well than air at sea level. Inverters that rely on natural or forced convection run hotter for the same output. This makes them more likely to derate because of high internal temperature. Thin air has lower dielectric strength, so high DC input voltages can cause electric arcs that damage the inverter. Designs must allow for larger conductor and component clearances. Manufacturers warn that cosmic radiation makes the failure rate of some electronic components rise exponentially as altitude increases. Datasheets give a maximum operating altitude, often 2000 m but 3000 m or 4000 m for some models. Some inverters reduce rated output power above about 2500 m, following a derating curve. Above 2000 m, some manufacturers say each installation must be assessed case by case, and one forbids such installations entirely. In high-altitude deserts, strong UV and wide daily temperature swings speed up degradation of modules, cables, junction boxes and mounting structures. This can lead to hotspots, insulation failures and arc flashes. To reduce exposure: derate power devices or fit larger heat sinks and more forced airflow, choose equipment rated for the site altitude, and schedule work around the risk of altitude sickness for crews.

<!-- review notes

• sentence 3: support check: partial - Arcing from reduced dielectric strength at high DC voltage is stated, and clearances must be considered, but the passages say 'appropriate' clearances rather than 'larger' ones. -->