I'm pretty sure that's how it's supposed to be. Are they working even with snow on them?
They keep working with snow on them 
Snow its Technically speaking an opaque block, in other words, a block that doesn't affect light too much (Kinda like glass). Thats what the "Clear View to the Sky" condition its still fulfilled with it, ergo making solar panels works with snow on top still.
:O That's why I was against turning the SolarPanel checks from iteration to skylight...
Guess we'll have to add a check for the block above Solar Panels.
Anybody want's to add other blocks which do not affect light but should affect Solars?
pistons don't block skylight but probably should stop solars
Checking of one block above solar wouldn't help. Players can place glass block on any height above solar panel to keep it clear.
Also all RP2 microblocks don't block solars.
Anybody want's to add other blocks which do not affect light but should affect Solars?
I did some testing and found several blocks in vanilla and IC2 that solars should probably be affected by
Fence
Trap doors
Iron bars
Enchanting tables
Chests
Iron and wooden scaffolds
Rubber trampolines
Floor (and all other) luminators
Unhardened construction foam
Signs
All doors
Cauldrons
Brewing stands
Redstone repeaters
Beds
Cakes 
Things that don't affect solars and probably shouldn't
Levers
All minecarts
Vines
Boats
Paintings
And that's the extent of what I found during my testing
Minecarts and paintings are entities. CrafterOfMines' blacklist is a nice one, we may make one that is API-able too.
Quoted from "Alblaka"
Anybody want's to add other blocks which do not affect light but should affect Solars?
I did some testing and found several blocks in vanilla and IC2 that solars should probably be affected by
Display MoreSpoiler
Fence
Trap doors
Iron bars
Enchanting tables
Chests
Iron and wooden scaffolds
Rubber trampolines
Floor (and all other) luminators
Unhardened construction foam
Signs
All doors
Cauldrons
Brewing stands
Redstone repeaters
Beds
Cakes
Things that don't affect solars and probably shouldn't
Spoiler
Levers
All minecarts
Vines
Boats
Paintings
And that's the extent of what I found during my testing
Display MoreI did some testing and found several blocks in vanilla and IC2 that solars should probably be affected by
Display Spoiler
Fence
Trap doors
Iron bars
Enchanting tables
Chests
Iron and wooden scaffolds
Rubber trampolines
Floor (and all other) luminators
Unhardened construction foam
Signs
All doors
Cauldrons
Brewing stands
Redstone repeaters
Beds
Cakes
Things that don't affect solars and probably shouldn'tDisplay Spoiler
Levers
All minecarts
Vines
Boats
Paintings
And that's the extent of what I found during my testing
Hmm, you forgot
Have you tried slabs & glowstone? They are transparent in vanilla redstone engineering. Also try stairs.
Hmm, you forgot
Display Spoiler
- Torches
- Glass
- Reinforced Glass
Have you tried slabs & glowstone? They are transparent in vanilla redstone engineering. Also try stairs.
Glass and Reinforced glass are intentionally blocks that don't affect solar panels, however I did not attempt slabs or glowstone
