It sat on my southern windowsill propped up by a rock for months, unfortunately it was always dim. It just wasn't at it's optimum angle to receive the sun's rays. After some thought and simple calculations I came up with an simple solution and the best summer and winter angles for my area (Austin, Texas).
For the summer it was 30 degrees (simply my latitude).
For the Winter it was 56.2 degrees (latitude X 0.9 + 29 = 56.2)
I wanted to have two bases, one for each angle or season.
Once I had the angles I drew it all up on a piece of graph paper with a protractor (old school, its Xmas break so no school computer with CAD and I have a Mac) see attached picture of said sheet. Sorry about the quality, you get the idea, besides you will have to do your own calculations depending on where you live.
Once I had the measurements I cut the the supports out of bamboo skewers and hot glued them together. You simply prop it up according to the season and face it south. Pretty fun craft and my little night light it glowing strong (really strong).