Good product, but cannot deliver charging current of 5A, unless there is proper heatsink on the two diodes and the two mosfets. This may also be due to RCS being bigger than 0.04Ω. In any case the existing heatsink is not correctly glued underneath the components, as it touches only partially some of the heated parts. Even worse, the metal heatsink touches the pins of some other components and there is danger of shorts and damage. Furthermore, in my unit, the dual led is soldered the other way around, and as a result, when it charges a battery, the blue led is on, and when the battery gets full, the red led comes on. Nevertheless, it is a good mppt charger. I attach the Charging Profile and its Diagram, taken from CN3722 datasheet.

This device works quite well at lower currents (< 3A). MPPT via panel voltage tracking seems to work quite well. I have mine outputting an almost consistant 10 Watts(2.8A @ 3.6v) into a 1s20p Lithium battery(nom. 3.6v, 45Ah) from a 12.5 Watt panel (21Voc, 17Vmp), so approx. 80% efficiency, even in 42 degree celcius ambient heat with panel temperature above 60 deg C !! (Australian summer). In 'cooler' summer weather (mid 20's) I get maybe an extra Watt out at mid day (~11W -ish).
Although this is advertised as working up to 5A, even after extensive testing I was not able to get much above 4A with a 25Watt(measured) panel and very good heatsinking: I only get 15 Watts out (4.2A@3.6v) so efficiency at higher currents suffers badly (25W in, 15W out = ~60% efficiency)
This item, as shipped, will NOT work with 1S lithium because the regulation voltage can only be adjusted down to ~6.5v, however, it is relatively easy to modify it for 1S operation. To do this, simply replace the 22k resistor (R7, marked 223, 0603 size) with something around 75k to 100k. I used an 82k resistor which alows me to adjust regulation from ~3.0v to ~9v.
Note that the supplied heatsink itself is okay, but it is useless as supplied because it is mounted with a thick dob of silicone adhesive. This is because A) the current sense shunt resistor is thru-hole and protrudes, and B) the PCB tracks under it have exposed solder pads. Poor design/lack of forethought by whoever did the PCB layout!. Therefore, mounting the heatsink directly to the PCB would cause a short circuit. I have modified mine with heatsinks on the top side packages(Mosfets and Diodes), and also a heatsink with a drilled hole (to clear the shunt solder pad) un the underside using double-sided tape as insulation to avoid shorts with the board tracks. Not exactly ideal, but much better than as-supplied.