What this shows
The Earth's axis stays pointed in nearly the same direction while the planet orbits the Sun. Seasons happen because each hemisphere alternately leans toward or away from incoming sunlight.
Conceptual model, not to scale
Earth, Sun, Tilt
A deliberately distorted 3D scene for understanding why the sun gets higher in summer, lower in winter, and moves differently through the sky by latitude.
- Day
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- Solar declination
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- Subsolar latitude
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Why scale is fake
If Earth size, Sun size, and orbital distance were all drawn honestly, the useful geometry would disappear. This scene preserves angles, not distances.
PV connection
Panel production follows the angle between sunlight and the panel normal. This orbit view explains the seasonal part before adding local roof tilt and azimuth.
Local tangent plane
Ray incidence at your latitude
Same date, same hour, same latitude. Here Earth is reduced to the patch of ground under your feet: the vertical normal, the horizon plane, and the incoming sunlight.
- Solar altitude
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- Zenith angle
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- Horizontal cosine
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- Panel incidence
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- Panel cosine
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- Instant optimum
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- Annual fixed optimum
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ERA5 example JSON
Beam + diffuse + reflected
Real hourly GHI/DNI/DHI samples from the previous `go-solar` work. Pick a weather moment and see how the same panel geometry converts it into plane-of-array irradiance.
Loading examples...
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- GHI
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- DNI
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- DHI
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Plane-of-array split
- Total POA
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- DHI share of GHI
- Beam incidence cosine
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