Solar water heating is reasonably efficient and many people have gotten good results from a few hundred dollars worth of materials and their own fabrication skills.

However, it may cost $80 per week to heat a large house in the Winter and only $80 per year to heat water by natural gas for that same house.

We need to start with new solar house construction and make Federal loans very attractive.

It could start as early in the process as orienting towns, districts and streets so the the long side of the house will face the correct SW Sun exposure (US).