Solar power from a heating cost reduction perspective can still offer a sound payback. Cheaper well engineered systems seem the best from my experience. A lot is just having the proper location for maximum exposure.

We have had a fairly powerful modest size system for over thirty years now. I think because of the increased costs of materials today. An air system should be looked at if any signifigant area of collectors is going to be involved. Keeping it out of the sight of street traffic is perhaps best and if not possible perhaps a distance from the dwelling.