My roof under the sun

This is a model of my roof that you can turn.
It shows the four faces of the hip roof, the 36 panels on them, and the neighbor's tree to the west.
Drag it to look around. Then pick a day and a time to see where the sun is and what the tree shades.
It is a schematic.
The faces, their compass directions, their 23° tilt and the panel count on each face are real.
The size of the house and where the tree stands come from an overhead photo.
Where each panel sits on its face, the heights and the shape of the tree are approximate.

Time

Date

the sun and its path that day a face the sun is behind a panel in the tree's shade the tree, approximate

Reading the model

Drag to turn the model. The arrow keys turn it too.
To zoom, pinch on a screen or a trackpad. Or use the + and − buttons on the model, or its + and − keys once it is selected.
A two-finger scroll scrolls the page, except on the whole screen, where it zooms.
A darker face gets no direct sun at that moment.
A panel outlined in red is in the tree's shade.
The amber disc is the sun. The dashed amber line is its path across the chosen day.
The page opens at the moment of the past year when the tree shades the most panels.
At that moment the tree is in leaf, and the sun is more than 10° up.

Imagine the sky over my house as a glass dome, seen from above like a map: north at the top, east on the right, the horizon at the rim.
Under the real sky, with your head to the north, east is on your left. This chart is the same dome seen from outside.

The amber lines are the sun's path on three days of —. On the June solstice it rises in the northeast and passes high, just south of overhead.
On the December solstice it stays low, near the bottom rim. At the equinoxes it runs from due east to due west.
The dots are New York clock hours. On daylight saving time, in June and at the equinoxes, noon sits east of due south; in December it sits close to it.
Shading is the average power the array made while the sun sat in that patch. A patch fainter than its neighbors at that height marks a tree or chimney.
Over the record, —, the sun used only the band between the solstice paths. It climbs to —° at midsummer, computed from latitude.
The arrows show which way the — roof faces point, from the installer's design. Each is as long as its share of the — panels.
The chart groups — readings into — patches. It leaves out patches with fewer than eight readings: one reading cannot tell shadow from cloud.

nonepeak sun's path, computed ↗ roof face, by panel count distance from center is the sun's height

Some things are measured. An overhead photo, north up and scaled by the length of a car, puts the crown's center about 67 feet from the middle of my house.
That center is toward 290°, and the crown is about 40 feet across.
I take every angle from the middle of my west-facing panels, which the tree shades. From there the crown's center is about 60 feet away, toward 294°.
The sky mask I fitted from my production data puts the shade's top edge at 35 to 40°, around 255°. The model places the tree from the photo.
Its height is not measured. I assume my eaves are 16 feet up and the crown is 46 feet tall.
Then a top edge anywhere in the mask's band means a tree 57 to 64 feet tall. The model draws the middle of the band, 37.5°.
It is a deciduous tree, so the model draws it bare from December through March. Those months are my rough guess.
The shade count treats the crown as solid all year. So in those months it overstates the shade.

For each 10-minute window with the sun up, the readout gives what my array made, from Home Assistant's record of my Powerwall gateway.
Python reads the power gauge as a straight line between readings at most 30 minutes apart, and weights the mean by time: Home Assistant writes only on change.
Across a longer silence the last reading holds while the recorder runs. Otherwise the window is not recorded, which is never the same as zero.
A window's energy is the gauge's mean times the window. My daily energy counter is read only about every 5 minutes, too seldom to split a window.
The day so far follows the Every Day page's rule to the window's end: the counter's level where it gives the total, the gauge's energy before.
So it never passes the total; it falls short only by what the array made after the last window, at most 0.03 kWh on days with every window recorded.
Before the counter, a window that is not recorded leaves the rest of that day's running total not recorded too.

Python computed every sun position on this page before publishing, with NOAA's solar position algorithm, at each 10-minute step of 2026 on New York's clock.
Each day of my record reuses the 2026 row for its date, because the sun repeats from year to year.
Compared at every step, no day of the record differs from its 2026 date by more than 0.11° in azimuth or 0.14° in elevation.
For two days, 8 March 2025 and 1 November 2025, daylight saving started or ended on a different date than in 2026, so Python computed their own rows.
The location is mine, rounded to the nearest 0.5°. Every sun figure on this page, the flat chart's included, comes from that point and never from the house.
So none of them leads back to the house more closely than that. Across that rounding the sun moves by under a degree.
At each step Python also tested a line from every panel's center toward the sun against the tree's crown, and marked each face the sun was behind.