The sofware developped by SMA is SUNNY DESIGN. By simply entering some basic system parameters, this free software helps solar installers and system planners visualize possible PV plant designs and select the optimum configuration quickly and easily. Sunny Design offers a user-friendly interface and a practical input wizard for assistance. It also provides data for an economic evaluation of the system along with a technical analysis of the included components. Sunny Design saves solar professionals valuable time and results in a customized PV system for the end user. You can also assess losses in AC and DC cables.
Now SMA propose also a version online of Sunny design called "Sunny Design web"
Link to use Sunny Design Web