You can put it on your roof, but unlike other systems where you have 20 to 30 solar panels and the only option is to putthem on your roof, here's a situation where you have two or three and you can putthem wherever you like.
In that sense, you can putthem firmly on the 'fresh water' side of the arguments within economics that I have discussed here in the past (see my posts of 17 July and 2 November 2009).