I may have missed something, but why are you not just using a battery?

Long and short of that, is batteries will need to be eventually replaced and even with one of the "coin" cells it's that much more that I have to attempt to hide in the diorama. Yes I could run it that way, and yes it would make life much simpler (for wiring and circuits)... but the idea is to not have to touch it once it goes on display until one of the LED's die. The scale that I usually operate in (1:25 and smaller) makes the whole thing extremely delicate, so the less the piece has to get touched the better.

 

my question now is if I were to add the Zener as you had suggested earlier, do I skip the resistors all together?

Yes. The zener will only start conducting when you over-power your LEDs, and I don't think that's very likely. The resistors would always be reducing brightness, whether you like it or not. Most of the time, it'll be "not".

And will I need one for each of the LEDs or just one that series into the set of LEDs?

Just one, from solar panel positive to ground, to shunt excess current if that were to ever happen. You'll need a zener that can handle the panel's max current, less the 10-20mA or so that the LEDs will be taking under those conditions. You may, thru testing, decide you don't need to protect the LEDs. They're quite cheap anyway, and your panel might not put them at much risk under your real conditions.

 

Thanks again for all the help, I think that I'll have to bread board this and fart around with it a bit to find the configuration that I like/want for the brightness.

 

A "very bright" LED is one with a lot of current or an ordinary one with a focussed very narrow angle that is useless for most things.

I also tested with a white LED but it has a wide beam angle. I used a new pretty big 80mm x 80mm solar panel from a higher power solar flood light. In ordinary room light the LED did not glow. In a room with sunlight coming in the window but not shining on the solar panel the LED was glowing. The LED might burn out if the sun shines directly on the solar panel because I did not use a current-limiting resistor but in bright sunlight an LED at its max allowed current will not be as bright as anything else lighted by the sunlight.

 

an LED at its max allowed current will not be as bright as anything else lighted by the sunlight.

No quibbles there. A good solar panel is ~10% efficient converting light to electrical energy. An LED does well to convert 30% of that electrical energy back into light. That means "state-of-the-art" conversion of sunlight to LED light is no better than ~3%. Throw in battery losses and you can see why the garden lights don't do better.

You know, a fiber optic bundle from the source lighting to the effects lighting might be worth considering.