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c/o FSEC, 1679 Clearlake Road
Cocoa, Ft_ 32922-5703
(321) 638-1537 Fax(321)638-1010
DOCUMENT RM -1
Methodology
for Determining the
Thermal Performance Rating
for Solar Collectors
Reaffirmed November 1992
Updated April 1994
METHODOLOGY FOR DETERMINING THE
THERMAL PERFORMANCE RATING FOR SOLAR COLLECTORS
This is the methodology to be used in order to comparatively rate solar
collectors based on thermal performance derived from ASHRAE 93-77: or=ASHRAE
9.6 198.0''Tes.t >Methods. The rating itself is an analytically derived set of
numbers representing the characteristic all -day energy output of the solar
collector under prescribed rating conditions. This methodology does not
address characteristics of durability, reliability, and safety.
I. SCOPE:
This methodology covers the development of a thermal_performance rating for
solar collector panels at specified rating conditions in a specified rating
environment.
The rating methodology is applicable to all non -tracking collector panels
whose instantaneous thermal performance can be adequately established by the
ASHRAE Standard 93-77 or 96-1980.
The rating described herein applies only to the solar collector panel and not
to individual collector constituents or other solar system components or to
the entity known as the solar system. The values stated in English Units
(Btu, F, Lb. °F) are to be regarded as the standard.
It is recognized that this rating methodology may apply to certain innovative
collector designs riot currently identified within the context of this
document. Consideration of variances from these procedures by the Solar
Rating and Certification Corporation can be arranged.
II. SIGNIFICANCE AND USE:
The thermal performance rating derived form the use of this methodology
provides both the manufacturer and the consumer with a tool for making
comparisons between collectors and collector concepts over a broad range of
appliance temperatures.
The rating number is derived from analysis of the ASHRAE 93-77 and 96-1980
test data and is valid only when either of these two ASHRAE standards
sufficiently characterizes the thermal performance of the collector panel.
The following considerations are pertinent to the application and use of this
rating.
A. The rating is based on average irradiation, as derived from the
methods of Liu and Jordan as modified by Rabl. Both direct and
diffuse components of irradiation are specified for the rating
days.
B. Most testing experience has shown that environmental parameters
such as ambient temperature, wind and irradiation interact in
such a manner that the theoretical extremes in measured
efficiency, possible under test restrictions of ASHRAE 93-77, are
very unlikely to occur.
1
C. The scatter of data attributed to environmental parameters is
relatively small and should not significantly influence the
rating number.
The present rating method does not account for the irradiation
transformations necessary for tracking collectors. It does account for
diffuse irradiation, which is assumed to be distributed isotropically
throughout the field of view of the collector. Thus, in the case of
collectors tilted with respect to the horizontal, equal brightness is assumed
for the ground and sky dome.
Intermediate rating numbers may be determined by interpolation.
Extrapolation from a rating number may produce misleading results and should
not be done.
The rating number is valid only for the fluid and flow rate used to generate
the ASHRAE 93-77 or 96-1980 data.
Rating numbers are expressed in thousands of Btu's per day per panel, and are
rounded to the nearest 100 Btu.
Conditioning procedures are intended to be performed with the fluid used to
generate the ASHRAE 93-77 or 96-1980 data.
III. DEFINITIONS:
A. ANGLE OF INCIDENCE: The angle of incidence is the angle between the
direct solar irradiation and the normal to the aperture plane.
B. EFFECTIVE ANGLE OF INCIDENCE: An angle related to the angle of
incidence as shown in Figure 1.
C. ALL -DAY ENERGY OUTPUT: The all -day energy output of a solar
collector panel is the amount of energy removed by the transfer
fluid, per panel, during a specific day.
D. RATING DAY: A rating day is defined by specifying, on an hourly
basis, the average irradiation rate from sunrise to sunset.
E. COLLECTOR AREA: The area used in ASHRAE 93-17 or 96-1980 (generally
gross area) to determine collector efficiencies_
F. ISOTROPIC COLLECTOR: A collector whose optical properties are
independent of direction in the aperture plane, and which has an
incidence angle modifier that depends only on the angle of
incidence.
G. ANISOTROPIC COLLECTOR. A collector whose optical properties depend
on direction in the aperture plane, and whose incidence angle
modifier depends both on this direction and the angle of incidence.
2
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www.solar-rating.org
Solar Rating and Certification Corporation
c/o FSEC, 1679 Clearlake Road
Cocoa, FL 32922-5703
(321) 638-1537 Fax(321)638-1010
SRCC DOCUMENT
OG -100-06
OPERATING GUIDELINES
FOR CERTIFYING
SOLAR COLLECTORS
September 2006
TABLE OF CONTENTS
1.0 Purpose
2.0 Scope
3.0 Definitions
4.0 Referenced Standards and Organizations
5.0 Certification Process
5.1 Standard Solar Equipment
5.2 Innovative Solar Equipment
5.3 Certifying Similar Models
5.3.1 Design Changes
5.4 Collectors Manufactured by Licensee/Private Labeler
6.0 Initiating the Process
7.0 Procedure for Obtaining Performance Ratings
8.0 Protecting Proprietary Information
9.0 Periodic Verification of SRCC Certified Collector Models
9.1 Collector Inspection
9.2 Procedure for the Challenge of Existing SRCC Certification
10.0 Denying Certification
11.0 Suspending, Revoking, or Terminating Certification and/or Program Agreement
11.1 Manufacturer Initiated
11.2 SRCC Initiated
12.0 Certification Labeling
13.0 Agreement for Certifying and Labeling Solar Collectors
13.1. Solar Collector Program Agreement
13.2 Solar Collector Certification and License
14.0 Solar Collector Certification Program Fees
OG -100-06 Page 1 of32
OPERATING GUIDELINES FOR CERTIFYING SOLAR
COLLECTORS
1.0 PURPOSE
This document sets forth the procedures for the operation of the Solar Rating & Certification
Corporation's solar collector certification program. Solar collectors that meet the minimum
standards set by the SRCC will be approved to bear a certification label. A companion
document, SRCC Standards 100-05, "Test Methods and Minimum Standards for Certifying
Solar Collectors," describes the test methods and criteria used for evaluating collector
durability and thermal performance. In addition, the SRCC document, SRCC RM -1-05,
"Methodology for Determining the Thermal Performance Rating for Solar Collectors"
describes the means by which the SRCC computes the characteristic all -day energy output of
a solar collector under prescribed rating conditions.
The thermal performance test procedures are based on:
ISO 9806-1:1994,Test methods for solar collectors — Part 1: Thermal performance of
glazed liquid heating collectors including pressure drop, International Organization for
Standardization, Geneva, Switzerland.
ISO 9806-2:1995, Test Methods for solar collectors — Part 2: Qualification test
procedure, International Organization for Standardization, Geneva, Switzerland.
ISO 9806-3:1995, Test methods for solar collectors — Part 3: Thermal performance of
unglazed liquid heating collectors (sensible heat transfer only) including pressure drop,
International Organization for Standardization, Geneva, Switzerland.
ANSI/ASHRAE Standard 93-1986, "Methods of Testing to Determine the Thermal
Performance of Solar Collectors," The American Society of Heating, Refrigerating, and
Air -Conditioning Engineers, Inc., Atlanta, GA.
OG -100-06 Page 2 of 32