Hybrid solar lighting (HSL) isn’t anything like solar power that converts sunlight into electricity. Through the use of optical fibers, HSL captures sunlight, channeling it and piping sunlight into a building. When there is little or no sunlight, these fixtures use electricity so that constant lighting is achieved.
Collector units, positioned on the top floor of a home or building, can provide as much as 50 percent of sunlight for indoor lighting. This is far superior to photovoltaic cells, which convert only 15 percent of sunlight into electricity, which then has to be changed back into light. An incandescent bulb uses only about 2 percent of this conversion and, yes, there is a lot of heat and energy wasted in this traditional lighting technology.
The use of incandescent light, a wonderful innovation of the past, served us well for decades, but has brought us to a crucial threshold. Research for alternative energy sources grows more important every day as we see our utility bills rise and our environment heat up because of our dependence on fossil fuels.
This type of Lighting employs a direct and efficient use of sunlight. HSL fixtures generate much less heat than regular incandescent fixtures, and, compared to fluorescents, the fixtures emit a full spectrum light, rather than the limited frequency spectrums of fluorescents. There are many advantages to using full spectrum light. The human eye and brain responds positively to full spectrum light because it replicates sunlight.
In retailing, colors of products are enhanced by full spectrum illumination. Shoppers, it is proven by retail research, feel good about buying in a full spectrum environment. Presently, HSL can save the most financially in commercial applications, and residential uses are being researched for the near future.
Hybrid Solar Lighting is employed by four foot wide mirrored dishes on rooftops equipped with GPS chips. Track the sun and focus the sunlight down into a single cord of 127 optical fibers. This light-conducting, flexible cord is a “pipeline” to HSL fixtures equipped with diffusers, which spread the light into room. One mirror collector can power eight HSL fixtures, which can illuminate an area of 10,000 square feet. The collector removes infrared rays and this makes HSL light fixtures cool enough to touch. The advantage of this cool operating temperature would be to reduce use of air-conditioning.
The fixture uses photo sensors to switch to electricity when sunlight illumination is weak, so that the fixture is always emitting a steady illumination. On a sunny day, a fixture can offset as much as 80 percent of artificial light. On a dark day, the illumination from sunlight might reduce to as much as 5 percent of required illumination for a given area. Light traveling along optical fibers grows weaker the longer the fiber cord is. Roof top collectors with shorter “pipelines” to fixtures located directly below would be the most powerful and efficient. Cost research for HSL’s aims at an expenditure of $3,000 per 10,000 square feet. This means that payback for the purchase of technology, for example, in Hawaii, would be approximately 3 years. For northern areas, the cost for HSL applications would have to be reduced further to make HSL’s a viable illumination technology for colder regions.
In field tests, interestingly, the solar fixtures emit a reddish light at sunrise and sunset. Test subjects responded positively to this change in color. This response can be attributed to the changes of natural light in sync with our circadian clocks (natural body rhythms.) This could explain why skylights in retail spaces have proven to increase sales. And because Seasonal Acquired Depression Syndrome is directly related to light (actually the lack of it, especially during winter months,) exposure to extended periods of natural light during the winter months could prove to be a welcome aid to those that suffer from this syndrome. Where skylights in commercial spaces have proven to positively effect sales and retailing ambiance, HSL technology has an advantage of providing constant natural light and increasing that positive trend.