Victron's Blue Solar PWM USB-LCD charge controllers offer a low cost solution for solar charge regulation with the benefit of an LCD display for setup and system monitoring, plus integrated USB charging ports. A selectable charge algorithm allows optimised charging for wet, AGM, GEL and LiFePO4 batteries (LiFePO4 batteries must have on-board battery management) and built-in battery protection prevents over discharge of the battery by consumers connected to the 'Load' terminals of the controller.
PWM controllers are most effective in warmer climates where clear skies are expected and partial shading of the panel is not likely to occur (e.g. under trees). In these conditions, and when used in smaller systems, they have a performance comparable with MPPT controllers. 
This controller is recommend for panels up to around 125W output with a maximum solar voltage of 28V (12V systems) or 55V (24V systems). For a 12V battery system the solar panel should be 36 cells and for a 24V system the panel should be 72 cells or 2 x 36 cells in series.
Features

PWM Technology
LCD display
Twin USB sockets - 5V, 2A (total for both outputs)
Programmable charge algorithms for wet, AGM, GEL and LiFePO4 batteries
Programmable dusk/dawn control of load output (useful for controlling exterior lights)
Low voltage battery protection (when using controller load output)
Battery reverse polarity protection (fuse)
Output short circuit protection
Over-temperature protection
5-year manufacturer's warranty