What is the difference between the horizontal and vertical (“south-facing” for the northern hemisphere) diagrams?
A. The horizontal diagrams are intended for tilts of 0-20 degrees. The vertical (“south-facing” for northern hemisphere) are for tilts of 20-90 degrees. Because the Solar Pathfinder always takes its reading when true south and level, the sun paths for each month and the solar hours on both the horizontal and vertical diagrams are exactly the same for any given latitude. The only difference between the horizontal and vertical diagrams is the tiny numbers written in the half-hour increments. These numbers represent the percentage of solar radiation in each half-hour. The percentages differ slightly based on the tilt angle. The Solar Pathfinder Assistant software automatically calculates for these differences whether you happen to have the correct diagram in the unit when the picture is taken or not. If you are using the Solar Pathfinder Assistant software, the software will make correct calculations for differences in tilt (and azimuth) no matter what diagram you happen to have in the So
