I started a new map and got a desert biome for a starting area, but my solar panels are receiving no benefit from this mod. I suspect there may be a conflict with the Alien Biomes mod which is preventing this mod from identifying deserts correctly.

Terrain generation involves two primary factors: temperature and humidity. Each (natural vanilla) tile type has a range listed in its autoplace (mapgen) information that specify where it appears. This mod identifies "desert" tiles as any tile that can't appear in any area above humidity 0.3.

I took a brief look at the Alien Biomes mod and it seems that only the "sand" tile and its "dull," "gold," "grey," "orange," and "red" variants qualify. Notably, the "red-desert" tiles and "dark" variants of "sand" and its colors do not.

So, this patch I am in is probably sand-gold-dark, which is probably why this isn't working. If only there was a way to see humidity to help find the sweet spots in this place.

Well the mod works based on the tile type, not the actual humidity (the functionality to query temperature/humidity was bugged and so removed, but it will be added back in 0.16), so your best bet is to identify areas visually anyway.

If you aren't averse to using Lua commands (which will disable achievements for that save), you can use
"/c local p=game.player;p.print(p.surface.get_tile(p.position.x,p.position.y).name)" to find the name of the tile type your character is standing on.

In the meantime, I may have to drop the Alien Biomes mod considering how long I have trudged across this desert and not one grain of it has the appropriate amount of humidity.