Cultivating Technologies and Markets for Affordable Low-Carbon Off-Grid Lighting in the Developing World

Test Conditions and Equipment

Goal: To conduct field research and demonstrations involving off-grid LED systems.

Mills, E. and A. Jacobson. 2007. "The Need for Independent Quality and Performance Testing for Emerging Off-grid White-LED Illumination Systems for Developing Countries." Lumina Project Technical Report #1. [PDF]

LEDs in 4" Photodyne integrating sphere
LED voltage measured with HP 3456A DMM current with Fluke A90 shunts and HP 3455A DMM (+/- 0.25%)
Light measured with Tektronix J16 photometer and Licor Photometer (210S)
Sphere / J16 calibrated with a Sylvania 796 quartz halogen lamp calibrated by Labsphere

light mounted 1 meter from measurement surface
illuminance measurements made every 10 cm on a 1 square meter grid
illuminance: Extech Datalogging Light Meter (model 401036), (precision 0.01 Lux; accuracy +/-3% of reading)

light mounted in a "dark box" at a distance of 1 meter from illuminated surface
light begins test with a full battery; it is discharged completely during test
illuminance, current from the battery to the light, battery voltage at 1 minute intervals during discharge
illuminance at center of beam measured with an Extech Datalogging Light Meter
(model 401036; see above for specifications)
current measured with a CR Magnetics DC Current Transducer (model 5210-2)
(accuracy +/-1.0%; output signal 0.5 VDC)
voltage and output signal from current transducer measured with a Hobo H08-006-04 Datalogger (8 bit resolution, accuracy +/-3% of reading)

measurement made by discharging the battery at a constant current
discharge curves are collected using a Cadex C7200 series battery analyzer
(programmable analyzer; records voltage and current information at 1-minute intervals; 100 - 4,000 mA current range; 1.2 - 16 volts voltage range; NiCd, NiMH, SLA, and Li chemistries supported; +/-1% accuracy)

outdoor performance measurement of module output made on a clear, sunny day
PV module oriented so that it is normal to sun's beam during test
peak power estimated from a current-voltage (IV) curve normalized to std. test conditions:1000 W/m² and 25°C
IV measurement collected over 30-40 seconds using a custom data collection system (accuracy +/- 0.5% for current; +/- 0.5% for voltage)
module temperature measured with Type-K thermocouple (accuracy +/-2%)
solar insolation measurement made with Licor LI200-SA pyranometer (accuracy +/-5%; LI200-SA calibrated annually with Eppley PSP pyranometer)
overall accuracy of peak power estimate: +/-10%

Granderson, J., J Galvin, D. Bolotov, R. Clear, A. Jacobson, and E. Mills. 2008. "Measured Off-Grid LED Lighting System Performance." Lumina Project Technical Report #4. [PDF]

Description	Name	Accuracy	Notes
Power supply	TENMA 72-2075		Used in place of batteries
Power analyzer	Voltech PM3000A	+/-0.05% rdg, +/- 0.05% range	Off spec: 0.1% low on voltage, 0.75% high on current
Digital multimeter	Datron 1281	+/- 3 ppm, 150 ppm, voltage, current	Used to calibrate power analyzer
Oscilloscope	Tektronix 7623A	+/- 5%
Integrating sphere		—	2 m
Integrating sphere	—	+/-3.1%	1m
Standard lamp	NBS calibrated 175W incandescent	—	Used w/ 2m sphere
Standard lamp	Labsphere calibrated quartz halogen	+/- 5% reflectance	Used w/ 1, sphere
Photometer	Tektronix J16, J6511 probe	+/-5%	Used with both spheres
Spot luminance meter	Minolta LS-110	+/- 2%	For luminance
lluminance meter	Minolta xy-1 chroma meter	+/- 2%	For x-y
Rotary table	India	+/- ~0.5 degrees
Illuminance meter	Minolta T-1	+/-2%	For candlepower
Spectrometer analysis software	NIST CQS_Simulation_7.1.xls		For quantifying correlated color temperature and color rendering index
Spectrometer	Ocean Optics SD2000, w/ OOIBase 32 software	+/- 0.01 for x & y coordinate values	For quantifying correlated color temperature and color rendering index
99% reflectance standard	Labsphere	+/- 1%	For manual x-y
Spot meter close-up lens	Minolta		For luminance
Neutral density filter	Tiffen ND1.0		For luminance