Using exsisting house wiring

 Hi all, I just inherited 60w of solar panels, I already own some deep
cycle batterys.
I've ordered some 12V cfl lights to use in the front of the house.  1
on ea side of the garage door and 1 for over the front door.

My question is this , I plan on disconecting the lights from the
switch in the house (all 3 wires) so its totally disconected from the
grid.  Can I just hook into the excisting 120v 14/2 wires, or should I
rewire?  The lights will be 13W each @ 12V, the total length using the
house wires will be no more than 22 ft.  If theres good reason not to
use this wireing I will just do the 2 at the garage door as I can get
at the wires.

13w X 3 9w  X 5 hrs = 195w
60w solar 5hrs per day = 300w

I cant see why not, but you know how the wife can get when one of
these little projects catches fire in the walls...........Thanks
                                             Rob

  Highly unlikely that the three outside lights are on their own circuit,
probably mixed with other lights and/or outlets. You will need to feed new
cables and separate your power sources (don't have 12v and 120v in the same
boxes.

 
O, there on thier own circut, turn off the switch and only the three
lights go out. Planing on disconecting at the switch -to- lights,
Switch still w/power, but feeding nothing, when I move I hoped to
change the bulbs back to 120v, disconn the 12v power and reconn the
120V.

Any hazzard just putting 12v at last light and have it feed the
others?
.......Rob

 How do you plan to use the switch, it probably is in the beginning of the
circuit and you want to feed from the end. If everything is isolated, I
wouldn't have any problem using the existing wiring.

 Also, rather than the complications of feeding cables to your existing
lights, why not install separate light fixtures. If your fixtures are wall
hung ones, add some under soffit or different type of fixtures for your 12v
system, work with a design and to enhance the lighting. This way your old
fixtures will always be available if your PV system is temporarily down.