Change search
ReferencesLink to record
Permanent link

Direct link
Illumination properties and energy savings of a solar fiber optic lighting system balanced by artificial lights
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
2013 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

A solar fiber optic lighting system, SP3 from the Swedish company Parans Solar Lighting AB, has been installed in a study area/corridor test site. A collector is tracking the sun during daytime, focusing the direct sun irradiance via Fresnel lenses into optical fibers, which guide the solar light into the building. The illumination properties of the system have been characterized. The energy saving due to reduced need of artificial lighting have been calculated and methods for balancing the artificial lights in the test site have been evaluated.

The illumination at the test site using solar light was at least as high as when using the artificial lights and even higher at very clear days. The luminous flux output (500 lm) was somewhat lower than specified by the manufacturer (550 lm) at 100 000 lx direct sun illuminance. The output at 130 000 lx was high 767±33 lm the sunlight coupling efficiency 23 %. However, for a 20 m SP3 system the luminous flux output (400 lm) at 100 000 lx was higher than specified (350 lm).

The SP3 system of Parans provides high quality solar light. It has a fuller spectrum close to the spectrum of the sun compared to the fluorescent lights at the test site. The correlated color temperature of the system was 5800±300 K and the color rendering index 84.9±0.5.

The lighting energy saved due to decreased need for artificial light was estimated to 19 % in Uppsala which has 1790 annual sun hours. The savings in Italy, which has 3400 sun hours, is 46 %. Additional saving, especially in warmer countries can be obtained due to decreased need for cooling in the building as the solar luminaires provide negligible heat to the indoor air. Economical saving could also be realized by improved well-being of the occupants spending time under the solar luminaires.

Three ways of balancing the artificial light due to sunshine fluctuations have been investigated. The global horizontal irradiance could not be used as a control signal for balancing the artificial lights but a pyranometer attached to the SP3 sun tracking collector was usable. Also the signal from an indoor luxmeter sensor could be used for balancing the light. However the signal from the light sensor which makes the SP3 collector to track the sun is probably the most cost effective method as it would serve two purposes; tracking the sun and balancing the artificial lights.

Place, publisher, year, edition, pages
2013. , 47 p.
UPTEC ES, ISSN 1650-8300 ; 12032
Keyword [en]
daylight, optical fibers, solar light, energy saving, illuminance, luminous flux, correlated color temperature, color rendering index, luminous efficacy
National Category
Energy Systems
URN: urn:nbn:se:uu:diva-204664OAI: diva2:639649
Educational program
Master Programme in Energy Systems Engineering
Available from: 2013-08-09 Created: 2013-08-08 Last updated: 2013-08-09Bibliographically approved

Open Access in DiVA

fulltext(4053 kB)2421 downloads
File information
File name FULLTEXT03.pdfFile size 4053 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Lingfors, David
By organisation
Solid State Physics
Energy Systems

Search outside of DiVA

GoogleGoogle Scholar
Total: 2421 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 615 hits
ReferencesLink to record
Permanent link

Direct link