There are several bonuses to this concept, especially in sunnier and warmer (southern especially) climates:
On a sunnier day, this concept can provide nearly all the light needed (multiple units, designed properly, etc)... a sunnier day is typically a HOTTER day as well (ambient outdoor temp)... so by using the sunlight, you can power off the bulbs, reducing their heat output and power consumption, reducing the cooling and power load required for climate controlling a building, thus helping tremendously with cooling bills.
More overcast days, the temp effects (ambient, and directly radiated onto the building heating) are not quite as severe, so when the artificial lights are turned on to supplement, it's not as big a deal... basically your overall average power consumption drops.
Regarding UV, glass, especially quartz or UV coated, easily blocks UV rays (the HID sodium vapor bulbs in most "school gymnasium" lights are HIGHLY dangerous UV emitters, but the UV is mostly blocked by the cover glass, down to humanly safe levels.
Between multiple reflections in the tube, and glass outer covers, and probably glass or plastic fiber-optic distribution, UV will be absorbed well before visible light reaches the interior.
IR (the most efficient heating of your building by directly-radiated heat from the sun) will also be nearly lost to ambient by the transmission systems before entry into the climate controlled/insulated spaces. The tubing involved will be absorbing it along the way and radiating it outwards, as well as the glass and transmission tubes, so most will be lost in "exterior" (uninsulated) space before it reaches the interior insulated space.
Looking strictly at the numbers...
The solar energy reaching earth in the "visible light" spectrum is roughly 400 watts per square meter at the equator at noon. If we look at southern US latitudes and average it over a sunny summer day from say 8AM to 8PM (DST), maybe 200 watt/hours per meter average is usable by this type of system (based on size, the reflector looks like maybe 1 to 2m^2).
An incandescent / halogen bulb is roughly 17-20% electrically efficient. So a 60-watt bulb is producing at best 12 watts of "usable" light. So in a room that has 4x60-watt bulbs, you'd need 48 watts of actual "light" equivalent.
This also means that 240-48=192 watts of heat are being produced in the living space as waste, an at a 1:1 ratio (it's not, but that's simple), it means another 192 watts worth of cooling capacity are required to maintain the initial non-lit state (not counting the heat generated by the usable light, which is a constant for comparison's sake). So 48 watts of usable light, and 384 (192+192) watts of power "wasted" as heat (in summer anyhow, in winter you might want to use these little "room heaters).
A fluorescent or modern LED is roughly 20-28% efficient, and HID are typically also around 28-30% efficient bulb output. A typical 4-bulb fluorescent office fixture is 4x40-watt tubes, for a total of 160 watts electrical, however the fixture itself limits the efficiency, so for all these, let's say 25% efficiency of electrical input as light actually leaving the fixture (that's being generous). This gives us 160*.25=40 watts of useful light output.
As above, this means 120 watts of heat generated, and another 120 watts of "cooling" energy required, so 240 watts of "waste" heat.
So using these numbers, the solar light collector could replace on an average sunny day, roughly 4-5 bedrooms worth of incandescent, or roughly 5 overhead office fluorescent "fixtures" (enough for about 2 typical offices, or 6 cubicles worth of area lighting, based on our office). And it would save 480*4=1200 watts of electrical energy for (5*4*6) incandescent bulbs, plus the cooling equivalent of another 192*5=960 watts electrical.
If your utility charges a premium for daytime hours (many are now in power-constrained areas), this could save substantial money... 8 hours a day, this could save (1200+960)*8=17280 w/h or 17.28kwh each sunny day. At $0.20/kwh, you'd save $3.50/day (and since cooling isn't 1:1, but more like 80% efficient,, it'd save more... ).
From the picture, it looks like their is a built-in solar (photovoltaic) cell on the receiving mirror pedestal (perfect placement) so it's self-powered for tracking (no utility power usage, no utility cost).
Nearly all the numbers I used here are conservative (useful efficiencies are all going to be lower on current bulb tech), so $4-5/day savings per light collector are reasonable.
Keep in mind this is based on a 1 meter collection area (the collector mirror, not the concentrated 2ft diameter mirror), if it's actually 2m in collector area, then double those savings to roughly $10/day.
So if we say say only 150 days per year these numbers are solid for, that's $1500/year in potential utility savings (and lower grid usage so better for the environment as well). that's PER UNIT... It is also a more pleasing (natural) light, and another neglected factor, less bulb usage = less replacement costs over time (less harmful mercury used and lost in fluorescent bulbs especially).
Realistically, in areas that need this most, you might save $2000/year/unit plus all the peripheral benefits. The article didn't mention cost, so it's hard to say how long it would take to pay for itself, but it's effectively "free" forever after installation (until it wears out). When it isn't useful (too overcast, winter), then turn on the lights as usual. So long as initial cost isn't too prohibitive, and durability is significant (5+ years minimum, more realistically I'd hope for 10+ years before "major maintenance" is required), there isn't much to NOT like about this solution
Back up lighting is required on cloudy days or at night time. If you want to turn the daylight off, you can do this by taking the system off axis, this feature is available today with wall mounted switches for classrooms or office areas where dimming for Audio Visual would be needed.
The ROI is dependent on solar map, building lighting and what benefit streams from daylight are included - energy, carbon, health and wellness, productivity, etc.
The system can also be directly tied to utility power. The draw is small, typically less than 1 amp for less than an hour a day. The off-utility power zero carbon lighting option is a great way to approach new or existing buildings to power tracking system.
The product is available now.
Did you know that lighting the interiors of our homes and offices consumes nearly 40% of all energy generated in the country? Other than installing compact fluorescent bulbs and diligently turning off appliances, what can you do to cut your monthly electric bill? Have your heard about about hybrid solar lights?
Hybrid solar lights (aka HSL) are not your typical solar power product. Instead of using solar panels to capture energy and convert it into electricity, hybrid solar lights work by literally bringing the sunshine into a room through the use of optical fibers.
The future looks bright for hybrid solar lights. For starters, the efficiency rate is considerably higher than for conventional solar panels. As much as 50% of sunlight collected by a hybrid solar light system can be used to illuminate building interiors. This is in comparison to 15-25% efficiency rate of PV panels.
Equally impressive is the fact that hybrid solar lights will not put off heat as does conventional lighting. This means that you’ll have to pay much less in A/C costs during warm times of the year. Why is this? The light collectors filter out inferred light, which is the biggest heat emitter on the spectrum.
Do you suffer from depression or the winter blues? Hybrid solar lights may be an effective form of treatment. Just as if you were out in the sunshine, the lights emit a full spectrum of light. Ordinary fluorescent bulbs have limited lighting spectra.
The hybrid solar light technology is fairly straight forward. Rooftop collectors are first installed, equipped with tracking devices to maximize sunlight exposure. When sunshine strikes the collectors, the natural light is focused onto a bundle of more than 100 optical fibers, which literally act as “pipes” for the sunlight.
The optical fibers are connected to specialized hybrid solar light fixtures on the interior of the building. A single collector can power about eight HSL fixtures.
But what if its not sunny? No worries! You will still have light in your home or office. As part of the hybrid solar light system, photosensors will automatically adjust the amount of electric current required to keep the room light. One drawback of HSL is that the length of the optical fibers affect their efficiency. Longer fibers do not illuminate as effectively as short ones. For this reason, some people are only installing hybrid solar lights on the top floors of their buildings.
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