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4.1 Solar transmittance is an important factor in the admission of energy through fenestration, collector glazing, and protective envelopes. This test method provides a means of measuring this factor under fixed conditions. While the data may be of assistance to designers in the selection and specification of glazing materials, the solar transmittance is not sufficient to define the rate of net heat transfer without information on other important factors.4.2 This test method has been found practical for both transparent and translucent materials, as well as for those with transmittance reduced by highly reflective coatings. This test method is particularly applicable to the measurement of transmittance of inhomogeneous, fiber reinforced, patterned, or corrugated materials since the transmittance is averaged over a large area.4.3 This test method may be used to measure transmittance of glazing materials at angles up to 60° off normal incidence.NOTE 1: A technique similar to the one described but using a pyrheliometer has been used for the measurement of specular solar reflectance; however, there is insufficient experience with this technique for standardization at present.1.1 This test method covers the measurement of solar transmittance (terrestrial) of materials in sheet form by using a pyranometer, an enclosure, and the sun as the energy source.1.2 This test method also allows measurement of solar transmittance at angles other than normal incidence.1.3 This test method is applicable to sheet materials that are transparent, translucent, textured, or patterned.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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The rain spray test described in 8.1 as Method A is based upon Test Method E 331 which is intended for use in the evaluation of exterior windows, curtain walls, and doors. This test method is intended to supplement the water spray test in Practice E 823 that does not include the effects of wind-driven rain. This method includes the use of a pressure differential to enhance the penetration of water into the assembly being tested. This type of pressure differential can occur with many types of solar collector mounting configurations. In the case of solar collectors that form a building element, for example, a roof, this pressure differential will be caused by differences of pressure inside and outside the building. In the case of solar collectors mounted on standoffs or racks, this pressure differential will be caused by positive and negative wind forces acting simultaneously on faces of the collector.Water leakage due to joint expansion can be influenced by several factors, including: the specific collector design and materials used, the test specimen temperature, and the water spray temperature (Note 1), in addition to the pressure differential. The temperature conditions will vary in outdoor exposure. The test temperatures should be selected to be representative of outdoor conditions where the collectors will be used.Note 1—Water spray temperatures are likely to range from 4.5°C to 29.4°C (40 to 85°F).1.1 This test method covers the determination of the resistance of flat plate solar collectors to water penetration when water is applied to their outer surfaces with a static air pressure at the outer surface higher than the pressure at the interior of the collector.1.2 This test method is applicable to any flat plate solar collector.1.3 The proper use of this test method requires a knowledge of the principles of pressure and deflection measurement.1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary information is contained in Section 6.

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