No takers huh.
That's a tough call - especially without an aether (or 12
) to play with.
I would say you probably need at least 3 or 4. If you put them far enough from the house to make a 18' circle (yes a lot will miss the house in the verticle plane) and then have them overlap about 4' of that, you could cover the wall with 3. If you want more brightness and don't want as much light hitting the ground and roof/overshoot, you could drop to 10' circles of light with ~ 2 foot overlap, which would require 5.
I don't know the light pattern for these particular LEDs, but most lights follow a gausian output pattern so that some overlap of the beams will create a fairly even light output over a larger area. If there is a lens that will spread the light more in the horizontal plane than the verticle, that would give you better results for what you are trying to do.
As always YMMV.
Robert