## Horizontal ns axis with ew tracking

For a plane rotated about a horizontal north-south axis with continuous adjustment to minimize the angle of incidence, 9 can be obtained from (Kreith and Kreider, 1978; Duffie and Beckman, 1991)

or from this equation (Meinel and Meinel, 1976):

The basic geometry of this configuration is shown in Figure 2.10d. The greatest advantage of this arrangement is that very small shadowing effects are encountered when more than one collector is used. These are present only at the first and last hours of the day. In this case the curve of the solar energy collected during the day is closer to a cosine curve function (see Figure 2.16).

Time (hours)

FiGuRE 2.16 Daily variation of solar flux: horizontal N-S axis and E-w tracking.

Time (hours)

FiGuRE 2.16 Daily variation of solar flux: horizontal N-S axis and E-w tracking.

The slope of this surface is given by tan(|3) = tan(\$)|cos(Zs - z)\ (2.29a)

The surface azimuth angle (Zs) is 90° or -90°, depending on the solar azimuth angle:

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### Responses

• aloisio
How to average ew ns slopes?
7 years ago