It's good to think outside the box, but unfortunately the theoretical amount of energy available (that others have calculated in the comments here) just make it

It's good to think outside the box, but unfortunately the theoretical amount of energy available (that others have calculated in the comments here) just make it a non-starter. For comparison, even on the rainiest day I've measured in the last year from my 6.6 kW photovoltaic array on my house, I made 8 kWh of energy (on a good summer's day I get around 40 kWh), with the lowest output across most of the day being 450W (less at sunrise and sunset obviously). Other have posted calculations of the maximum energy that can be expected to be collected from raindrops, and from those calculations, I doubt that with a raindrop capture device as large as my PV array you could make 8 kWh in a month.