What are the advantages and disadvantages of solar heating?

Question

What are the advantages and disadvantages of solar heating?

Answer 1

solar heating is free (minus the cost of proper insulation, equipment, etc), environmentally friendly

However, it isn't all effective or efficient (depending on where you live).  We use too much heating normally and solar won't give us that amount.  What we really need is a better source of insulation to prevent energy loss (which we have to replace, therego using more energy).  

Plus, some of the equipment is very expensive.