This was the topic of heated discussion at home over the last month or so. Several Vastu experts (virtually people who'd read one book on Vastu - by which definition I'm almost half a Vastu expert) had given several varied opinions on where to install it.
The two critical questions were:
Which corner of the roof to put the heater tank and heater panel?
According to Vastu experts, any overhead tank should be in the South west corner of the house. Unfortunately, the current overhead tank is in the center (almost North East Corner) of our house. To make up for it, the decision was to put another new tank in the south west corner of the house. But then, the biggest faux pas was that the plan for our house had the North-East line itself wrong because of which we almost ended up screwing up the Vastu of our house even more. That's where I come in. I had a compass in one of the key-chains I'd picked up as a memento of my Chicago Trip. When I took it to the roof of the house and placed it at the center of the building, the truth dawned upon us. :-)
Which direction should the solar heater plates face?
This didn't involve Vastu. It was just a question of getting the most of the sunlight. The sun doesn't rise in the pure east direction. Neither does it go right above you at Noon except at the equator. Nor does it set in the pure west. Because of which the heater plates need to face the south direction. Finally the decision was made and since this morning, haven't been able to enjoy my morning siesta and my afternoon siesta with all the plumbing work going on.
But since the Solar Heater is supposed to save about five to ten grand a year, I don't feel so bad losing a day's sleep over it. Atleast the right decision (on location and direction) was made. After all, this has some contribution from me too. If it wasn't for the trip to the terrace with my compass, we very well might have installed the Solar in the wrong location. It feels good to contribute to the team at home despite being a junior member of the TEAM. :-)
PS: An FAQ from the Government of India's Ministry of Non-Conventional Energy sources for those planning to get one installed.