Dozens of different types of systems that use solar energy to
supplement your hot water heater are available, but only a few
have stood the test of time. Sticking with proven entities is
always a good idea, despite the extravagant claims you may hear
regarding new technologies. In the real world, Murphy has a
voracious appetite, and until something is tested thoroughly,
the jury is still out.    • The integral collector system (ICS):
ICS is the simplest and cheapest system, and it's ideal for mild
climates. But it also has the most potential for freezing damage
because the collector holds the water being heated. Big batch
collectors, however, can withstand longer freezing conditions
than smaller systems.      These systems are passive and are
normally plumbed directly between the cold water supply and the
water heater, making the plumbing job easy and straightforward.
Whenever someone opens a tap in the house, water flows from the
collector into the water heater. If the water in the collector
is hot enough, t