The best replacement for skylight is uv filter.

The best alternatives to skylight are rated as following:
★★★★★  uv filter
★★★★  uv
★★  solar tube
★★  sun tunnel
★★  dormer
★  solatube
★  roof window
★  new moon
★  light tube
★  skytube
  solar tubes
  deck mount skylight
  uv filters
  sunlight
  borrowed light
  deck mounted

Your alternative for skylight is not listed? Suggest!
Speaking about skylight, one probably shouldn't forget about metal roof.

Other search terms related to skylight and their ratings are:
★★★★★ metal roof
You have in mind a companion for skylight and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of skylight in all years. Click on graph for more.
skylight
uv filter
uv