Light at Night Using Electronic Light Bulbs on Inverters Richard Perez copyright1990 by Richard A. Perez With Winter's short days upon us, now is the time to consider how we are making our light at night. Shorter days mean not only more hours of lighting use daily, but also reduced power production from PV modules. Here is information about applying a type of high efficiency light. These compact fluorescent lights, called "electronic light bulbs" are screw in replacements for regular incandescent lamps. They not only save power, but they are silent, have near daylight correct color rendition, and run without a trace of flicker. And here's the best part- they operate very well on inverters. Lights at night... The use of artificial lighting at night goes back to the campfire, through candles & oil/gas lamps and into the age of electricity. More than one historian claims that the development of civilization was in no small part attributed to lights at night. Lighting provides the opportunity to work, learn and play when the sun's down. All factors contributing to the development of language, art and culture. Our need for light at night hasn't diminished over the ages. It has increased. And our ability to make the light we need has also grown. Technology has reached the point where we need not use extravagant amounts of power to have lights at night. What we need is to realize the options that technology has offered us. The first major advance in electrical lighting was the incandescent lamp. The lamp (invented by Thomas A. Edison in the dim mists of history when General Electric's major product was light bulbs not progress) heats a filament into incandescence. The major physical effect of the incandescent lamp is not light, but heat. Over 94% of the electricity pumped into an incandescent lamp goes into heat, the remaining >6% of the power is converted into light. Enter the fluorescent lamp. The fluorescent lamp uses a glass tube that is internally coated with phosphors. Phosphors are chemical compounds that emit visible light when in the presence of electric fields. A special electronic circuit, called a ballast, was used to convert the 120 vac power to excite the fluorescent tube (see George Patterson's article in this issue for techie details on ballasts). Fluorescent light is four to seven times more efficient at converting electricity to light than are incandescent lights. Well, great! Except that early fluorescents had several major warts. One, they gave off a bluish light that made everyone look pale and corpse-like. Two, they gave off a flickering light because they were powered at 60 cycles per second (the human eye can perceive a flicker at about 30 Hz directly and over 70 Hz. subliminally). And three, they buzzed like banshees when fed inverter produced power. Well, some bright engineers have come up with solutions to all three of these problems. The OSRAM Dulux EL Lamps These lamps are a significant advance in the use of phosphors to make light. One, the EL lamps use a particular phosphor coating which produces light that is color correct and virtually indistinguishable from daylight. Two, they use a switching type electronic ballast that operates at 35,000 cycles per second instead of 60 cycles per second. This high frequency ballast eliminates all traces of flicker in light output. And three, they love running on inverters. They operate silently on inverters. They will boot most inverters from standby mode into operating mode. The EL lamps have standard light bulb bases and will screw into any standard light bulb socket. And that includes Aunt Millie's 1920 ceramic table lamp with the bronze gilt fruit on the base. What follows below is a table describing the various OSRAM EL lamps. The EL-R11 and EL-R15 are equipped with a reflector and function as spot or task lights. INSERT OSRAM TABLE In this table, there is derived data about the EL lamps savings of electricity and money. That's right, not only do they work well, but they also save money by saving electricity. And that not only saves us money, but also the environmental pollution associated with making that electricity. The column headed "Equivalent Incandescent Lamp Wattage" is just that- for example, consider the EL-15 lamp. In order to get the same amount of light provided by the 15 watt EL-15, you will need to use a 60 watt incandescent light bulb. The next column to the right computes the amount of electrical power (in kilowatt-hours) that the EL lamp saves over its 10,000 hour lifetime. Next follows the dollars saved columns. This is computed on the basis of 10,000 hours of operation (for example a single EL-15 will outlast 10 regular incandescent bulbs). Note that grid users save money with these lamps at a dirt cheap electricity cost of 12› per kilowatt-hour (actually it costs all of us much more, but the grid is not yet charging for environmental consequences). Renewable energy users pay more (about 85› per kilowatt-hour) for their electricity, and thereby they save much more by using efficient lighting. Let's examine the scenario of replacing the 60 watt incandescent bulb in Aunt Millie's table lamp with a EL-15. The EL-15 will save 450 kilowatt- hours of electricity during its 10,000 hour life. Assuming that the EL runs four hours daily, this amounts to 6.8 years of operation. During that time, the EL-15 will save the grid connected user about $34. It will save the renewable energy powered user about $362. It saves our atmosphere tons of carbon dioxide and pounds of sulphur dioxide. All this from intelligence applied to Aunt Millie's table lamp. INSERT AUNT MILLIE'S LAMP What about 12 Volt DC fluorescent lighting you may ask. At Home Power, we have tested virtually every type of DC fluorescent made. They have the following problems. One, they are 12 Volt and require the special wiring treatment used in low voltage circuits. Heavy wire is expensive and difficult to retrofit. Two, they may use hard to find fluorescent tubes that are mostly not even close to color correct. And third, they cost about TWICE as much per light as the EL types. This is because each low voltage fluorescent contains its own micro inverter. And this point is the death- nell of low voltage fluorescents. It is far cheaper to buy a small power inverter (120 Watts) and power six EL lamps than it is to purchase and install six comparable 12 VDC fluorescents. With more and more systems going to a large inverter supplying power for all use, these electronic light bulbs fit into the wiring and constant inverter operation scenario. This price difference is built into the use of phosphors for lighting. Phosphors require high voltage ac excitation to operate. So whether you buy a 12 VDC or a 120 vac fluorescent, you are buying and using an inverter. It is simply more cost effective to use one larger inverter than it is to use a small inverter built into each and every fluorescent light. A last factor is longevity. In our experience, low voltage fluorescents have had short lifetimes (<2,000 hours). The quality of the construction, and thereby reliability, in the low voltage fluorescents has not approached that of the Dulux EL units. Inverter testing of the OSRAM Dulux EL Lamps and others Basically, we took all the EL series lamps mentioned in the table and plugged them into as many different types of inverters as we could get our hands on. Actually, we also had compact fluorescents by five other manufacturers to test at the same time. I'm not going to waste your time and our paper with those that didn't work, so I am writing about the best of the lot, the OSRAM EL units. We measured the lamp's power consumption on the inverter and compared it to operation on sine wave power input. We installed the ELs in every place possible in two homes, one where Karen and I produce Home Power, and the other where Bob-O and Kathleen run Electron Connection. Bob-O and Kathleen's home is a very good test because all of their lighting is powered by 120 vac via the Trace 2012 inverter. We lived with the lamps. INSERT PERFORMANCE DATA TABLE We use two Fluke 87 DMMs to make these measurements. We tested the EL series on the following inverters: the Trace 2012, the Heliotrope 2.3 kW. WF Series, the PowerStar 200, the Statpower 100, the Statpower PROwatt 600 and the Heart 1200. In all cases, the smallest 7 watt EL was able to boot the inverter and hold it on for operation. The EL series lamps started instantly on all these inverters. Several other types we tested went into a 20 second flashing indecision period before starting, while others never did start without first booting the inverter. The EL series operated absolutely silently on all these inverters, except the Heart inverter, where the ELs emitted a loud buzz. We tried the exact same lamps on the other inverters and they were dead quiet. Good Places to use ELs TIME: In any light that spends more than two hours per day operating. Period. IN EXISTING FIXTURES: Their small size make them naturals for existing incandescent lamp fixtures. The only places we had trouble putting the EL lamps was in some recessed ceiling fixtures. I have included the lamp physical dimensions in the table so you can figure if it will fit or not. In most cases we tried here, they fit. The EL lamps will screw easily into most desk and table lamps. WHERE YOU NEED BRIGHT LIGHT: I installed one of the 15 watt reflector models in a clip-on fixture above Karen's work area. This EL-R 15 spends about eight hours a day operating. Karen does a lot of paperwork and her eyes appreciate the bright, natural, silent and flicker-free light. The design and execution of the reflector alone is precise and amazing. We have started and ran this particular EL- R15 when it was at temperatures as low as 36øF. All of us have noticed that it takes all EL lamps about two minutes to warm up and produce their maximum light output when they are cold. Bad Places to use ELs Any lamp that is repeatedly turned on and off (like the light in the pantry). The lifetime of the EL is primarily determined by its starting circuit. OSRAM rates the 10,000 hour lifetime of the EL series on the basis of three hours of continuous operation per turn on. If you switch the light on and off many times daily, then the EL's lifetime will be shorter. ELs are not suited for low temperature environments, like unheated spaces in cold climes. At sustained low temperatures, the higher efficiency of the EL is not realized. Techie Details I am going to refer you to George Patterson's article which follows this one. George showed up here one weekend with several large cardboard boxes full of every different type of compact fluorescent available. We then proceeded to test each one on every inverter. It took all weekend and we learned more than I can cram in here. Bottom Line Time If you are making your own power, you can save very big bucks by using efficient lighting. Every Watt you save is a Watt you don't have to produce, store or convert. This adds to fewer batteries, fewer PV panels, and smaller, more cost-effective, systems. If you rent your power from the grid, you can save small time bucks by using efficient lighting. What you can save big time is our world. In almost all cases, the kilowatt-hours of electric power going down the throat of your light bulbs have expensive consequences. Conservation is the most potent tool we have to combat the environmental, financial and political effects of our energy dependency. And after all, it's not like we have to give anything up to use efficient lighting anymore. In our estimation, the quality of the light that these efficient lamps produce is the best ever. Only thing better is sunlight. Access Author: Richard Perez, C/O Home Power, POB 130, Hornbrook, CA 96044 ù 916-475-3179. I wish to make it clear that: 1) I don't sell these lights, 2) I'm not paid by OSRAM, or anybody else, to say nice things about these lights, and 3) All I get out of this is a warm feeling that you are not wasting your power and thereby our planet. Makers of the ELs: OSRAM, 110 Bracken Road, Montgomery, NY 12549- 9700 ù 800-431-9980 ù 914-457-4040.