Separate the key voltage limits
Maximum DC voltage is a hard ceiling, while startup voltage is the level needed for the inverter to begin operating and the MPPT range is where it can actively track the array. A string can be below the maximum voltage yet still be poorly matched if its normal operating voltage sits outside a useful MPPT range.
Check the cold-voltage case
Module open-circuit voltage rises as cell temperature falls. Designers use the exact module Voc and its temperature coefficient with a credible local low temperature to make sure the string remains below the inverter’s maximum DC voltage. Guessing from nominal operating voltage is unsafe.
Check the hot operating-voltage case
Module operating voltage falls as cells become hot. A string that looks comfortable at standard test conditions may approach the lower MPPT boundary on a hot roof. Use the exact module and inverter data rather than a generic volts-per-panel rule.
Current limits matter with modern high-current modules
Inverter datasheets may state operating input current and a separate maximum short-circuit current per MPPT. Parallel strings add current. Confirm the exact topology, connector limits and whether each MPPT input is independent or internally combined.
Oversizing is not permission to ignore electrical limits
Manufacturers may allow a DC array larger than the inverter’s AC rating, but that does not override voltage, current, short-circuit, connector or regional code limits. Treat each limit independently.
Related Melnti checks
inverter sizing guide panel datasheet guide products
Keep the string calculation with the project file
A saved calculation showing module count, temperature assumptions and the inverter limits makes later module replacement or troubleshooting easier than a system record that contains only total array kW.