High accuracy diffuse horizontal irradiance measurements without a shadowband
The standard method for measuring diffuse horizontal irradiance uses a fixed shadowband to block direct solar radiation. This method requires a correction for the excess skylight blocked by the band, and this correction varies with sky conditions. Alternately, diffuse horizontal irradiance may be calculated from total horizontal and direct normal irradiance. This method is in error because of angular (cosine) response of the total horizontal pyranometer to direct beam irradiance. This paper describes an improved calculation of diffuse horizontal irradiance from total horizontal and direct normal irradiance using a predetermination of the angular response of the total horizontal pyranometer. We compare these diffuse horizontal irradiance calculations with measurements made with a shading-disk pyranometer that shields direct irradiance using a tracking disk. Results indicate significant improvement in most cases. Remaining disagreement most likely arises from undetected tracking errors and instrument leveling.
- Research Organization:
- State Univ. of New York (SUNY), Albany, NY (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-90ER61072
- OSTI ID:
- 237264
- Report Number(s):
- DOE/ER/61072-02; CONF-950725-3; ON: DE96010315
- Resource Relation:
- Conference: SOLAR `95: national solar energy conference: 10,000 solutions - paths to a renewable future, Minneapolis, MN (United States), 15-20 Jul 1995; Other Information: PBD: [1995]
- Country of Publication:
- United States
- Language:
- English
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