Described as a "small hydraulic," the unit is 4 times more efficient than a basic propeller-based dam system, although it's still a slow, steady output.
At 160 Watts optimal output, the Japanese-designed Cappa isn't the holy grail of residential-sized hydroelectric, but it's a step forward. A solar PV system is much cheaper on a watt-for-watt basis, but keep in mind that the Cappa runs 24 hours a day, rain or shine, so depending on your local climate, it could provide a much greater overall power output than a significantly larger sized PV array.
Cappa, which is supposed to come to market soon, is being developed by Japanese company Ibasei. Here are the relevant specs. They didn't give a weight, but they assert that two people can carry and install one.
●Water depth: 50cm or more
●Waterway width: 1.1~4.5m
●Target current speed: 1.5~2.0m/s (2-point method)
●Continuous rated output (Single waterwheel system): 160W at 1.75m/s
●Rated output when operating by battery only (fully charged): 450W/1hr; 250W/3hrs; 180W/5hrs; 120W/10hrs
That's low enough that it may make the unit very much a niche energy source, especially given the much lower cost of installed solar panels.
Company fact sheet downloadable HERE