Surely it costs the environment the same, no matter what time it's generated? And about the 50% efficiency in 20 years who cares I'll be dead thing....if my current system was working at 50% I (and maybe most of us) woukd find that unusable so would either have to use the grid more (which will have been the case all through as the efficiency decreases) or replace the batteries. Assuming replacement, hasn't that just handed a huge problem to the next but one generation.
Don't both the above scupper the eco argument and expose the true motives for all this...financial gain?
