BK Precision SASPVS Solar Array Simulator Software USB Dongle for PVS/MR Programmable DC Power Supplies. The BK Precision SASPVS Solar Array Simulator Software USB Dongle is designed for use with the PVS or MR Programmable DC Power Supplies (not included). This USB-type dongle allows for the use of the Solar Array Simulator software after the 30 day trial period of it expires on the main unit.