A string sizer and voltage drop calculator all-in-one

Over 1000 downloads!

It's free

Our tool is free and available for download, just fill out the form below and you'll be sent a link to download the excel tool.


  • Excel-based tool
  • Calculate allowable string sizes
  • Voltage drop calculator
  • Performance calculator
  • Dual MPPT configuration
  • Quick writing features
  • Thousands of modules
  • Hundreds of inverters
  • Add your own modules or inverter
  • 5000+ worldwide ASHREA locations
  • Create your own custom sites