Thanks for explanation! :D I got too focused with intensity and forgot about power storage.

If you would not mind, I have another question that hit me while I was reading some more on ISS. Among them was a series of articles like Staying Cool on the ISS that talks about thermal control. Apparently ISS uses ammonia to 'vent' the excess heat by forcing it to radiate IR outside of the station. It's completely understandable to have such system, not only because of their power consumption, population and amount of active machinery. Even more importantly, ammonia is pretty much unparalleled as far as heat transfer goes (at least in the concerned range of temperature). But wouldn't ammonia cause a hazard in the long run? I could not find anything more serious than this false alarm about ammonia leak, but to my understanding the more people and space are involved the higher are the chances of something going wrong. It's harder to contain, able to linger undetected before concentration gets close to hazardous levels, and isn't all that easy to filter out from the air (although not impossible, as detailed in patent of continuous electrochemical scrubber… but that requires a similarly dangerous H3PO4 chemicals so we have a Catch 22 ;)).

So, after all this long-winded rambling: are the hazards linked to ammonia simply something that astronauts must accept and deal with (and I'm getting waaaay too concerned about minutia) or does it pose some real problem to long-term manned missions?