What is the main purpose of this test method?

To determine the thermal performance characteristics of a solar water heater under standardized, quasi-steady state conditions (Clause 1.1).

What is the minimum solar radiation required for a valid test point?

The global solar radiation on the collector plane must be above 700 W/m² during the test period (Clause 6.1.1).

Does this standard apply to evacuated tube collectors (ETC)?

Yes, the standard is applicable to solar water heating systems using various collector types, including flat plate and evacuated tube collectors.

What is the primary output of this test?

A thermal performance curve plotting collector efficiency against the parameter (Tfi - Ta)/G, as described in Clause 7.

IS 12933 Part 2

: 2003

Solar water heating systems - Part 2: Method of test for thermal performance

CurrentSpecializedTesting MethodBIMMEP · Solar and Renewable Energy Installations

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This standard specifies the method for testing the thermal performance of both thermosyphon and forced circulation solar water heating systems. It details the test setup, environmental conditions, measurement procedures, and calculations required to determine the system's instantaneous efficiency and overall performance characteristics.

Specifies methods for testing the thermal performance of solar water heating systems.

Quick Reference Values

Minimum quasi-steady solar radiation700 W/m²

Maximum mean wind speed during test3 m/s

Maximum incidence angle for test points40 degrees

Test fluid flow rate variation± 1 percent

Test fluid inlet temperature variation± 0.1 °C

Key Formulas

ηi = [ṁ * Cpf * (Tfe - Tfi)] / (Ac * G) — Instantaneous collector efficiency

Practical Notes

Test results are highly sensitive to weather conditions; ensure stable (quasi-steady) solar radiation and low wind for reliable and repeatable data.

Accurate calibration of all instruments, especially the pyranometer, flow meter, and temperature sensors, is critical for test validity and minimizing measurement uncertainty.

The standard helps generate a performance curve, which is more valuable than a single efficiency value, as it shows how the collector performs under different operating temperatures.