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Getting Started



Usually the start of a project is accompanied by wild enthusiasm for exotic solutions. In this case I gradually settled in on a more practical implementation.


Here is a concept drawing of my idea for a single-axis solar tracker that is manually adjustable for declination. The inspiration for this concept occurred at Home Depot as we looked at mini-blinds.

The design is a polar tracker, meaning that its rotation is about an axis that is parallel to the earth's rotational axis. The tracker's axle must be oriented true north/south and tilted to the location's latitude angle. Declination is accommodated by an independent adjustment. In this way the tracker will optimally follow both azimuth and elevation angles with only a single tracking axis.

Tracking - Summer Solstice


Polar tracking is a common technique for tracking celestial objects. When applied to photovoltaic arrays, however, the axle tilt is often compromised from a latitude match or is seasonally adjusted for declination. The penalty for this is non-optimal tracking of the solar path.

Actually this concept has two axes of movement, but the elevation axis needn't change much from day to day and nearly perfect tracking is obtained with four adjustments per year.

Tracking - Winter Solstice


I decided against tracking due to its mechanical complexity and the amount of spacing needed between arrays to avoid shading. Still hoping to capture as much solar energy as possible and practical I extended the declination adjustment feature of my tracker design to a fixed array. Here's a concept drawing showing one bay with panels adjusted for normal incidence at summer-solstice noon.

The individual panels must be spaced along the frame length to avoid mutual shading near the solstice periods. This spacing is minimized if the frame is tilted at the latitude angle, however it can be set to any angle if greater spacing can be tolerated.

Finally, after going through these exercises, another concept came to mind. It became the final design.

Fixed - Summer Solstice