This module is a LM2577 DC-DC Automatic Buck or Boost Converter 3-35V to 2.2-30V LM2596 Voltage Step-Down Power Supply. IN+ is for positive voltage input. IN- is for negative voltage input. That means after you set the output voltage, it can output your desired voltage no matter the input voltage is LESS or GREATER than your desire voltage. Step-up or Step-down action is automatic.

Specification:
Module properties: Non isolated, Automatic Buck-Boost (SEPIC)
Rectifier type : Non synchronous rectifier
Input voltage : 3V-35V
Output voltage: 2.2V-30V
Output current: 2A MAX
Conversion efficiency: 92% ( max)
Switching frequency: 50KHz
Output ripple : 40mV MAX
Load regulation rate: 0.5% Voltage regulation rate: 0.5%
Working temperature: - 40 C to +85 C
Dimension: 48 x 24 x 14mm

Application:
Great for solar panel supply, solar panel input voltage is not constant. Therefore it can output constant voltage

Specs: