This article was featured in CaliforniaLandscapeDesign.org Fall 2022 issue.
Although this app is popular with the photographers to estimate where the sun is going to be for events at a later date, it is a boon for horticulturalists and designers as well.
The app is available for Android and for iOS. It has various widgets, but we use the sun trajectory application in the 3D view the most to see how much sun each area of the garden is getting on a given day. Before we start our designs, we note the hours of sun for each relevant location on the summer solstice for the hottest sun. However, you can also note any other dates, especially winter solstice and equinox days easily as these trajectories are shown in different lines in the same view.
This app can also be useful to look at how much your solar panels are going to get exposed or blocked by your neighbor’s house or your tree, etc. See the screen shots taken on an iPhone below.
Follow the red line as you move your phone around to follow the sun’s summer arc. The spring equinox is the green line and the blue show the winter solstice. The yellow line will be the current day trajectory. Look at the hours that you get unfiltered, unobstructed blue skies. Note when you get filtered light through the tree canopy. If you have deciduous trees, but are using the app while the tree has leaves, you will have to imagine in your mind’s eyes where the leaves would start and end if you are interested in guessing the winter exposure. Or if a tree is going to be removed and you know that, you will have to do the imagination in your head and add those sun hours to your notes. It might be beneficial to come back and re-measure if there are going to be a lot of tree canopies that will be removed.
One important note: Make sure to calibrate the app before using it for best accuracy. After calibrating, make sure what you see makes sense as in where the north arrow is or where the sun is currently on the yellow line and the time you are looking at it are a perfect overlap. If not, re-calibrate.
Below are some screen shots using the app to check some specific cases. First example, I am standing in front of a fruit tree and looking at the morning sun situation and the second capture shows the afternoon sun to see why this tree is having such trouble fruiting. In the middle of the day there is a big, dense tree canopy with no direct sunlight. What do you think? Is it a sun exposure issue?
The second example is taken from the second floor window of the house to see if solar panels installed over the first floor roof will get enough sun. This one is specifically checking for the afternoon. Is the nextdoor house going to block the sunlight for the solar panels? This screen capture shows that we have excellent summer sun in the afternoon. The yellow line shows the current day (in this case April 10, 2021). In the spring the sun will set at 5pm over the panels.
Have you used this app? What do you think?