per the article: 0.2kW/M2

No fucking way! Rain drops impact at 9m/s. To get 200W, even at 100% efficiency, you'd need 200 (kg m2/s3) * 2 / (9 (m/s))**2 = 4.94 kg/s of rainwater! That's 3600 (s/hour) * 4.94 (kg/s) / 1000 (kg/m) = 17.8 meters of rainfall per hour! (700 inches/hour in freedom units). The most rain ever recorded in 1 hour ever has been 0.305m.

If they actually built some kind of microturbine or piezoelectric array system (there is no way to tell which from the fucking article), good for them, but it's useless for rooftop power generation unless you gonna be blasting it with a firehose personally. But given the nonsense language and the quite specific "green house powered by rainfall" graphics, this is a scam.