try using a detector cable attached to a solar panel
glad I could help 
Use a solar panel + detector cable as a light detector (during day sends Redstone signal, during night it stops)
seems like a pretty useful gadget for SMP, city gates close at night to prevent intrusion from mobs, opens during day for the players to walk around
just keep in mind even with doors that are only open during the day, creepers do not despawn until noon with no one around. so i would set up an iron golem and snow man turrents for defenses with a Cat Ring around your doors so creeper and spiders don't try to rush in at dawn.
I usualy go outside at night and farm the mobs 
I usualy go outside at night and farm the mobs
I usually don't go outside. 
I usually don't go outside.
i don't move.... ever. lol, jk
yeah yeah rick i usually do the same thing, i make iron armor and then rush a nano saber and harvest everything i can find for exp and gunpowder for fuel. i'm currently level 48 on my new server, which reminds me.... what's max level anyways? . i just had a great idea though! in regards to your "Night Door" have the "idiot trap" method of catching enemies that try to sneak in, this is basically a pressureplate connected to 4 pistons, once stepped on raises all the adjacent blocks around it. this would catch and trap anyone or anything at night. then have a glas viewing window. if there is ANYTHING trapped in there then have a level you can flip, this would active pistons above the and cause the room that is 2 blocks high to drop down by one, crushing and killing anything in there. you could have this set up the be activted day or night or whenever you need it online. i think i may invnet and engineer this "Trap and Execusion Blast Tunnel" and toss it up on youtube for you. if i have time i'll make it tonight or tomorrow.
I see a problem with using the detector cable/solar panel idea.
Once the Eu storage is full then the doors will stay permaclosed.
That is unless you hook it up to a mass fab (Which people will probably build long after building this.)
So ya...
hook it to your main power system of the base (if u dont use solar spamming)
my base wil have around 80% EU stored (80% out of 100% max)
this is around 800 mil atm, but stil. hook it up to several induction furnaces or an tesla coil. just something that continuesly uses power..
Display MoreI see a problem with using the detector cable/solar panel idea.
Once the Eu storage is full then the doors will stay permaclosed.
That is unless you hook it up to a mass fab (Which people will probably build long after building this.)
So ya...
solution. hook it to a luminator or an Induction Furnace that is constantly being kept warm. this will force it to stay flowing.
or you could make a HUGE power system and simply tap it into that so that 1 solar panel would never fill it.
