No Meter, It's Sweeter Thank you! You know, living off the grid isn't too common here in the Pacific Northwest and it was a moment to relish when Puget Power came up the road (nobody else lives on it), stepped out of the car and scanned the house for the meter. My housemate shut off the belt sander, greeted them, and replied that "Oh, sorry, we don't have one of those." She pointed vaguely at the sky and said that's where we got our power. Jaws agape, they backed into their vehicle, completely unable to reconcile the fact that there was no power line, no generator, no extension cord, just a woman with a beltsander in her hands. I would have loved to listen in when they finally spoke! Janet Welch, 330 Protection Ridge, Port Townsend, WA 98368 I love stories like this. Its amazing that a lot of people who work for utilities are still in the dark about RE home systems. Sometimes their enlightenment comes as a profound shock. - Kathleen Panel Puzzle Dear Richard; Being a faithful reader since your 1st issue of Home Power way back when, I've certainly enjoyed reading almost every printed word. And what an education I've gotten. What I haven't seen is how a 36 cell panel relates to a panel with 33 cells. Let's compare the Solarex with the M-75. As quoted by Steve Willey, "M-75 saves money, but voltage is a little lower. The 33 cell ones CAN BE HARMED if they are put in with the 36 cell panels where the 36 cell panels outnumber them. No problem while charging, because the battery sets all the panels voltage to its own voltage. But when the controller disconnects the whole group, the 36 cell panel forces their higher 22 volts open circuit rating backwards through the 33 cell ones that are only 19 volts open circuit. That causes the 33 cell panels to heat up hotter than just being in the sun, and could melt the encapsulating glue. If the 33 and 36 cell panels are separated and each with their own charge control, no problem." This statement is certainly something to consider by your many readers who have been mixing brands and cell count. Karim Wingedheart, POB 530, Haiku, Maui, HI 96708 Yes, Steve is absolutely right. A solar cell is really a big forward-biased diode. Current through a forward biased diode increases exponentially with increasing voltage. If the 33 cell panel's voltage rises much above its open circuit voltage, it will absorb all of the current produced by the 36 cell modules. This current shows up as heat in the 33 cell module(s). The situation gets worse as 36 cell modules outnumber 33 cell modules. As Steve says, the solution is to give all 33 cell modules their own charge controller. Or better, stay away from 33 cell modules entirely. Ä Chris A River Runs Through It Your magazine is very informative, I enjoy it very much. It is very hard to get much information on alternative energy supplies up here in Canada, so I hope you can get more advertisements from suppliers in Canada. I have a river flowing approximately 100 feet from my house. The problem is, it is a slow moving river, and I have no drop or head available to use the turbine generators I have seen. I would like to know if it would be a good idea to build a water wheel and use the force of the moving water to generate electricity, by stepping up the rpm of the wheel, through a gear train or pulleys. Have you had any articles on this type of situation. If so, I sure would like to hear about it. Eric Dickinson, RR#4, Marmora, Ont., Canada K0K 2M0 Hiya Eric. I've heard tales of a submersible propeller-driven generator which is towed behind a sailboat that might work in your situation, but I've never seen one or know who makes it. Could be baloney for all I know. The only other option would be an undershot wheel, basically a device which sits on pontoons and is guyed in place so that the current running past it spins the wheel. A runner like that would probably have to be designed specifically for a given site, inefficient, a mechanical carnival, expensive, and a real liability during high water runoff. That being said, I'd love to see one. How 'bout it, fellow hydromaniacs? - Bob-O Y-H, Y not PV Direct? A firm believer in using PV power when the power is produced, I can hardly see (except for possible portability) the advantage of storing energy in the form of hydrogen produced at 50% efficiency when an old battery returns 70% of your energy input. With regards to cooking with hydrogen: during the last three years more than 80% of my coffee has been perked and better than 90% of my hot meals have been cooked with PV energy. Over that same period I sold my never used back-up generator and a seldom used microwave oven. I acquired instead a 650 W percolator, a 500 W cooking pot, a small 600 W frying pan and four crockpots of 47, 150, 150 and 250 Watts respectively. Here in the Sierra foothills with good to excellent solar radiation, I do most of my cooking between 8 am and 3 pm. This is when the power output of my 16 Hoxans usually exceed the power ratings of all but my perker, which I seldom use for more than 8-10 minutes at a time. You may say I cook with PV electricity direct. A typical daily energy use for hot coffee, breakfast or lunch and supper cooked from scratch falls between 760 and 940 Watt- hrs with some additional 100-175 W-hrs for dishwater. Reheating a refrigerated supper may reduce that amount by about 450 W-hrs. In order to shorten cooking time and maximize energy utilization, I cover my percolator, frying pan, and crockpot with towels during cooking. For example a 3 1/2 quart of chili takes me a mere 5 1/2 hrs and 585 Watt-hrs. Crockpots with non-removable crocks are by far the most efficient. Also, replace the Lexan lid with available glass or steel lids and do not cover the High-Low adjustment knob! I have melted two Lexan lids, one adjustment knob and a plastic leg baking potatoes or boiling laundry water. So as for cooking with hydrogen, give me instead eight Hoxans (about 1.61 kW-hrs per day at my place), and I'll feed your gang of seven two meals a day, six days a week on equally clean PV power alone. Toast and steaks for seven does present a problem, but if you're partial to the latter, lend me a barbecue for the occasion and I'll throw in soup, baked potatoes and chilled, cooked rice with crushed pineapples for dessert. In general, covering the crockpots lowers the power requirement 30%. For boiling water or baking potatoes the "High" setting is more efficient than the "Low" setting. Also, you may cook soup, bake potatoes, heat dishwater and preheat beans for overnight soaking in the same crockpot in one day. Thus you take full advantage of the crock's residual heat. But so much for cooking. My final purchase of a 12 VDC heating pad for my feet at night and a 12 VDC space heater for my bathroom (I use a large crockpot with crock removed for that purpose at present), will turn my little house into an "All Electric Home" about eight months of the year. Sincerely, Dag (CB handle "Crockpot") Heiestad, POB 788, Soulsbyville, CA 95372 Hey Dag, with your ingenuity, daily amount of sunshine and drive to find efficient answers to cooking power conservation you should be setting your sights on the Home Power Solar Cooking Contest! However, I do heartily congratulate you on the unique way you have made your home fit your energy lifestyle. - Kathleen What, no roast turkey? Baked Lasagna? Pies 'n Cakes? Pizza? Ya gotta be tough...-Bob-O On the Natch I have every issue since #1. Me and my partner live in the Cascades, 3,000 ft. elevation on a South facing ridge, one and a half miles from nearest utility line. We laugh when the town four miles away has blackouts. We have eight PV panels and we do occasionally have brownouts after watching three or four movies on our VCR but like that Motel 6 ad, we can always keep a light on if we want to. P.S. What, no Muddy Roads anymore? We live on a rutted road. Sincerely yours, Greg Conlin, Box 1825, Chelan, WA 98816 I'll tell you what Greg, we have had some of the muddiest roads this winter and it'll be till they dry out before we can look back with humor on them. Bob-O did get a picture of the garbage bag outfits everyone is sporting this season for chic outerwear at Agate Flat, that fashion capitol of RE trends. Ä Kathleen Yes, we had the truck parked 2 miles away from HP Central for about 4 weeks. We backpacked for 2 weeks until we got the buggy running again. Mud for sale, any takers? We could write up our story, but would love to hear others! Ä Therese Sell Wholesale, Buy Retail Dear Home Power; Look forward to each issue, keep up the good work. Some comments on Utility Interface Systems: Part 2 in Issue #33. I once worked for an electric utility and developed their interconnection and metering requirements for small power producers. What we settled on was two ratcheted kWh meters connected back to back as shown below. In this way the customer used his own power as available and used utility power for any short fall. If the small power producer made more power than he could use at the time the utility would take the excess and pay the customer for it. It is not reasonable to expect the utility to buy power back for the same price the utility sells power since generating cost is only about one third of the total cost of delivering electricity to its customers. Transmission, distribution, billing, losses and overhead make up the rest of the costs. You wouldn't expect to borrow money from the bank and pay exactly the same amount back without any interest so why would you expect to borrow electricity from the utility and pay it back without interest? I no longer work for the utility. My present employer is considering installing a co-gen system. We will be pleased to have the same sort of metering arrangement I described earlier. If interconnect is to be accepted by utilities it must be safe and fair to both the small power producer and the utility's other customers and the owners of the utility. I support the work of Home Power and Mike Sagrillo. Sincerely, David Morrison, 649 Hawthorne St. NE, Grand Rapids, MI 49503 Diagram with hard copy Hi David. Good to see that utility and former utility folks read Home Power., too. Your metering diagram is electrically the same as my figure in HP #33. However, I disagree with the prevailing utility perspective concerning net billing. PURPA specified that the cogenerators be paid "full avoided cost", as I stated in HP #32. This includes not only fuel costs but capital expenditures for that capacity, transmission, operation and maintenance, and even the interest owed on the utility debt for construction costs of the power plant and equipment depreciation. The intent of PURPA was to reward cogenerators for the cost of displaced capacity, not just the cost of displaced fuel. A pile of coal doesn't generate any electricity! When I generate my own electricity, the utility doesn't have any costs due to transmission, distribution, billing, losses or overhead. Eight progressive states and a variety of utilities apparently consider this arrangement fair. Ä Mick Open Letter To The Friends Of SEER (Solar Energy Expo & Rally) Dear Friends of SEER.; We are happy to report to you that the rumors of our demise have been greatly exaggerated! In fact SEER is alive and growing. However we are planning something a little different for 1993. This year brings for us at SEER the opportunity for a permanent home. REDI? For those of you who have been with SEER from the beginnings at SEER '90 you'll remember the "desert storm"-like location and have a real appreciation for how important a site can be Ä like the park location of SEER '91 and '92. Well you won't believe the new site that has been offered to us Ä over 100 acres of gorgeous ridgetop land just outside of Willits with 360 degree views of mountains, forests and ocean! What's more exciting is that not only will this site serve as a home for future SEER events but will also be the site for our next step Ä the Renewable Energy Development Institute (or REDI for short Ä who comes up with this stuff anyway?) The plans for REDI are ambitious and far-reaching. For us, the founders of SEER it means on-going staff and office functions, a long-term R&D facility, continuing education programs and an evolution into a permanent and sustainable effort toward the development of renewable energy and transportation technologies. This effort is demanding almost all of our limited time and resources to pursue. Because we need to get our foundation firmly placed, it also means that there won't be a SEER '93 Ä at least as you've come to know it. We've heard much feedback of disappointment that there won't be a SEER '93 - in fact some people have gotten downright hostile and have demanded that we forge ahead. On the other hand most of you recognize the need to establish a sustainable base in order to survive in the long run and have been supportive of our plans to take this next step. SEER has been only one of the many who responded to Home Power's call for "people's energy fairs" and we support each and every one of those groups that is working hard to find better ways for our energy future. We do plan to hold a SEER '94 and if all goes well we will be meeting at the new site! Perhaps just as important as the securing of the site and forming REDI is the current "window of opportunity" which has opened with the new Clinton/Gore Administration. Not since the policies of the Carter years has there been the kind of possibilities of pushing forward with clean energy and transportation systems which we have all worked so hard to keep alive. Because of this shift in the power structure there is an even greater need for our industry to pull together to become more effective in influencing the growth of these industries and the policies that will secure this growth. Announcing The Solar Summit After brainstorming how SEER could be most effective in helping with this effort we have decided to call together our most valuable assets Ä You Ä to meet with government and public sector representatives in convening this first SOLAR SUMMIT. Participation will be limited to 300 participants so we are contacting you first in hopes that you will join us. By all of us working together we can continue to create the solutions for tomorrow's energy problems today. SEER Directors, no address on hard copy Lyric Al Am I blue, My subscription ends with #32, Here is your fee, Hope I see 33. Al McVetty, POB 26, Guildhall, VT 05905-0026 Himalayan Home Systems Have been growing with you since issue #1. Just returned from Asia. You might be interested to hear that the Govt. of India is subsidizing individual solar systems in remote areas of the Himalayas. A happy interface of ancient and modern. Very progressive action from a "backward" country. We love you here and all the good work you are doing. Aloha, Stan Skurow & Prema Dasara, POB 504, Kula, HI 96790 Yep, "backwards" is a relative thing. I met some people from Auroville, a small community in India, who were building their own inverters and controller circuity. It was impressive. Slowly but surely, solar is arriving. ÄMark Let There Be... Home Power, I thought you might be interested in the price of this 18 watt compact fluorescent light bulb: regular price is $6.87, minus manufacturer's rebate of $3.00 = $3.87! It consists of a Q'lite ballast rated at 60,000 hours and a replaceable Lights of America triphosphor bulb rated at 10,000 hours. Larry Thompson, POB 79, Booneville, CA 95415 Wow! That is the cheapest price I've ever seen for a compact fluorescent light! When you get one, let us know how you like it. All compact fluorescent lights are not made the same! My $8 Panasonic is still holding up after two years. It may not have as warm a color as the Osram compact fluorescents, but it works for me! Ä Therese No Soap Dear Home Power; your excellent magazine has been an education for me. Though I'm still constantly learning, I am now working in Industrial PV sales. Without your technical articles I wouldn't have found enough information locally to make this happen. I think you all are doing a great job. I've even started seeing Home Power for sale at my local Walden's bookstore. On a more serious subject: If the oil tanker wreck in the North Sea doesn't prove the stupidity of our world's oil dependence, I don't know what it will take. And here in Texas, TU Electric is about to petition the NRC to allow them to turn on the second phase of the Comanche Peak nuclear power plant. By this summer, some of us lucky Texans will be using that (cheap) nuke power. Oh yes, TU Electric also is asking for a 10% rate increase to help the pay for this new cheap electricity. Well, keep up the good work. I'm off the soapbox for now. Sincerely, Mike Kilgore, KE5F, 2046 Ash Hill Rd., Carrollton, TX 75007 Teach a Man to Fish... First things first: Home Power is good stuff Ä hats off to the crew who makes it happen. (I know you're putting in some long days, and it shows.) What do I like? Count me in as a fan of the Wizard; my psyche can always use a yoga session. Things That Work! works for me. I appreciate the thorough technical testing, complimented by practical and personal evaluations. I'd like to see more reviews on energy efficient appliances and other products which enhance living in an off-the-grid environment. (What is the scoop on the Low-Keep reefers? How do they stack up against the Sun Frost?) A big hug for Richard and Karen and the rest of the Colombian crew for your exceptional work in Tierradentro. I spent nine weeks this Fall in Papua New Guinea, working as a rock climbing specialist for a geologist who was collecting stones in hard to reach places. My side job was keeping our photovoltaic powered barometer and recorder charged and running. Our work took us deep into the jungle to villages accessible only by foot, often places where the level of technology has yet to rise above the machete. In some of the larger villages I was shown microhydro systems and, less often, photovoltaic systems which had been installed in the village health center by the PNG Institute of Technology. To further document a point made by Ken Olson regarding the repair and maintenance of energy systems installed in remote "Third World " locations (see Renewable Energies for the Paez Indians, HP #32), not a single hydroelectric system I was shown was working. In most instances the villagers were "waiting for someone to come and fix it." Judging from the accumulation of rust on many of the hydroelectric generators, I'd guess some have been down for years. The photovoltaic systems were at best funky. In one health clinic the battery, a crusty 100 Amp-hr lead acid, was kept in the foot space under the desk. Yikes! By using the best possible equipment, training a local villager in system operation and maintenance, and arranging for scheduled inspection by professionals (Aprotech), I feel you have overcome perhaps the biggest problem faced by remote, Third World electrical systems: unwitting neglect. Your work in Mosoco reflects much foresight and planning Ä truly a model of excellence. Bien hecho. Well done. Finally, a belated thanks to Richard Perez, Allen Sindelar and STI for the all the hard work, integrity and energy you put into last Summer's Advanced PV. The course was well organized, highly informative and inspirational. Jeremy Werlin, PO Box 816, Hotchkiss, CO 81419 Hi Jeremy, glad to hear that things went well in PNG. Your eye witness report re-enforces the importance of a complete system installation including local education and periodic maintenance need. It is be a big commitment.ÄMark Mountain Bike PV Gentlemen and Ladies: My special interests include EVs and Home brew, such as the digital Amp-hour meter. Pedal powered grinder was good, but need access information. During a two month mountain bike tour of the Ozark Mountains last spring I carried a Solarex MSX-5L (4.5 watt "light") PV panel modified with a switch to achieve 6 Volt operation. (To limit current when charging small nicads, just switch back to 12 V operation!) I charged batteries for bike lights and horns, and lights and radio for camping. I carried that panel up and down hills clear across Arkansas and Missouri and it rained almost every day. Still, when the sun did pop out, the panel was strong enough to quickly give a stiff charge to the 6 V 3.4 A-h sealed lead acid bike battery and four 1.8 A-h nicad C cells. Lawton C. Bates, POB 802, Tustin, CA 92681-0802 Well, Lawton, the grinder cycle was home assembled using an old bike and a purchased grinder. - Kathleen Lawton, it is pretty admirable to pedal that panel for so many miles. It's also is a fitting way to spread the solar word! For more information on the bike grinder you should check out Pedal Power by James C McCullagh, Rodale Press, 1977 Sewing Saved Dear Home Power; Have been re reading your HP#16 issue. Was most interested in letter about copiers and inverters. I am a quilter and we have solar and a generator. I own a "New Home Memorycraft 6000" computer sewing machine. Runs fine on the generator, but who can afford to run it 8-12 hours a day? So we bought a 250 Watt Statpower inverter. The light came on but the computer would not. We took it back and tried it on a Trace 600 Watt inverter and also a PowerStar 200 watt inverter. All the same. Then our supplier received a copy of an ad for the Exeltech SI-250 power inverter. When it came in the electronic engineer checked it out and was most impressed. Now I'm a very happy quilter. The cost was high per watt but well worth it. This inverter has many other features: off/on switch, fuse on outside, and 2 outlet plug. My inverter is serial # 0011. We live in the San Luis valley of Colorado, elevation 7540 feet in Alamosa and higher. The air is clean and mostly clear, ideal for PV. Many of our friends and neighbors have PV. We would never go back on grid even if it were an option. We are three miles from power and have a cellular phone. I would be interested in info about 12 VDC refrigerators. Helen Bowers, POB 814, Alamosa, CO 81101-0814 I'm glad that you were able to find an inverter for your computerized sewing machine that works Ä without destroying it. Often when it doesn't start it is because the inverter just fried the insides of your test subject. Hi-tech electronics are very susceptible to damage to modified sine wave. Anything that contains a thyristor should only be fed true sine wave power. Anything else and PO$O$F. If you ever have any doubt it is a lot cheaper to check with the manufacturer. Ä mark Resource Defense Dear Home Power; I am writing this letter in order to give another perspective to some of your editorial comments and letters from some other H.P. readers. First of all I am a natural resource producer. I have been working in the mining industry of Nevada since 1954 and am a graduate of Mackey School of Mines, University of Nevada, Reno. I have mined or worked in larger mines that produced ores of the following metals Ä tungsten, copper, lead, zinc, silver, gold and mercury. All of these metals are used by you, your readers and me. In your article "Good Manners," Issue #31, I guess by your definition I am the ogre in caulk boots. I state this irrefutable fact: without the mining, petroleum and timber industries, most of us could not function. Your business could not function. Everything around you that is man-made came from a mine, oil well or the forest. All of the plastics in your house and car came from an oil well or coal mine. Your toothbrush, case on your computer, insulation, medicines, tires, fan belts, clothes on your back (except cotton and wool), toys and many other items about us start from an oil well. Your computer and TV sets have fifteen to twenty different metals in them including gold, silver, platinum group metals and rare earth minerals (to give picture tubes color). The same is true with your car, truck, boat, airplane, bicycle or whatever your conveyance might be. They are composed of metals, minerals and wood products that come from the earth. I worked at a copper mine in Eastern Nevada in 1957. To get copper started, it goes to a fabricator who in turn makes it into the products that we use. First the ores that contain the copper minerals such as chalcopyrite or cuprite must be found by exploration crews. At the mine I worked at the ore contained about 0.75% to 1.0% copper per ton of ore. That is 15 to 20 pounds of copper in one ton of ore. The stripping ratio at this mine was about 3 to 1, so 3 tons of waste had to be removed to get to the one ton of ore. The ore went to the concentrator-smelter complex where it was crushed, ground in ball mills and fed to flotation machines which produce a sulfide concentration which contains the copper along with iron, sulfur and other impurities. The concentrates go to the smelter where fluxes are added (limestone, silica) and fed to coal-fired reverbatory furnaces and the charge is melted. This copper is about 90% pure, is drawn out of the bottom of the furnace. This blister copper was then shipped to a refinery in New Jersey where the metal is dissolved in acids and electrolytically deposited on sheets of pure copper. This is finally the product that goes to a fabricator to make the products we use. In other words, it just doesn't appear in a hardware store. Now, if copper had to be produced without making a hole in the ground, only the very rich could afford it. Waste heat from the furnaces above is used to generate electricity. It is the same story with all the other metals we use. The aluminum foil you use in your solar cookers or solar mounts probably started its journey to you from a Bauxite mine in Jamaica, transported to the Northwest where there is cheap hydro-power and melted in large electric-arc furnaces and processed into "pigs" of aluminum metal. Each year, each citizen of the United States requires 40,000 pounds or 20 tons of newly-mined minerals and metals. This includes sand and gravel products, metallic and non-metallic minerals. At this rate of consumption, the average child in America will need a lifetime supply of 800 pounds of lead, 750 pounds of zinc, 1500 pounds of copper, 3593 pounds of aluminum, 32,700 pounds of iron, 26,550 pounds of clays, 28,213 pounds of salt and 1,238,101 pounds of stone, sand, gravel and cement. These figures are from the U.S. Bureau of Mines. To mine, process, transport, fabricate and get to market the products we use takes huge amounts of energy. To melt silica for your solar panels takes temperatures of 1100ø C. What is the total energy flow in the United States to make the system work? For 1991 the total energy consumption was 81.51 Quadrillion BTUs. I wonder how many hundreds or possibly thousands of square miles of solar panels it would take to provide this sort of energy. A "Quadrillion" is beyond me. I can relate to metals though. Take lead, for example. If there were 50,000,000 households in the United States (250,000,000 divided by 5) and 10% of these had a home-power system with 2000 pounds of lead-acid batteries in each system, that would require 10,000,000,000 pounds of lead. It sure would keep the lead miners busy. Lead is mostly obtained from the mineral galena (Pbs) and has to go through processes similar to the copper ores to obtain lead. It seems to me that with present technology, only a few of us can have these home power systems. I read an article in a mining publication about twenty years ago and it stated that there was not enough iron ore on the whole planet to provide each family on earth with a car, refrigerator, stove, etc. By 2050 the U.S. population will be 350,000,000 so we must use our resources wisely and recycle all we can Ä lead, copper, aluminum, iron, paper, and tires. What of the future? Better energy systems, whether it be solar conversion, hot or cold fusion or things that we have not even dreamed of yet. To get there will require tremendous expenditures of time, resources and energy. Maybe someday we will have "free" power. Hopefully, we can get more of our young people interested in science and technology to help us get there. Best regards, Don Jung, POB 69, Austin, NV 89310 Don -thank you for this letter, I really learned a lot here. Your points are very true and well taken. It is always good to get a reality check. We do face some serious problems. Chris figured out that it would take 151,166 km2 or 58,365 miles2 if we use 300 days of sun a year, 7 hours of sun per day, and assume that we can convert 8% of the suns energy (1kW per m2) falling of the earth. Currently we are told that it takes between a year and a half and four years for a panel to make back the energy that it took to produce it, depending on it manufacturing process. And then there is the wiring and storage and... Nothing is free. Tough questions and even tougher answers. Ä Mark Rule of Thumb Renewables Dear Sir: A sign of maturity in any industry is spec standardization. The solar industry should do some effort to get to that stage. With more and more people and manufacturers getting into PVs, it will be a blessing if the manufacturers could get together and agree on a meaningful set of tests that a particular product should conform to. The results of these tests will go into a common format that will constitute the specification for that product. Standardization helps both the industry and the consumers. The "apples to apples" comparison will be easier, and the good products will be recognized, because all will be measured with the "same stick." Right now we have too many specs that are a page or two pages of plain literature, instead of two columns of hard data on pre- established test runs, common to everybody. For example, there are manufactures that will give mechanical, electrical and reliability (MTBF) data for some models of their product line, but not for all of them. Why? Operating temperature range seems to be unimportant or a secret only to be disclosed to those who ask for it. Have you seen de-rating data for output power vs. operating temperature for converters? And how about de-rating of output power vs. operating temperature for PV panels? Either the coefficient is too low to be practical, or you get a set of high temperature curves that, in some cases, only goes to 47ø or 48ø Celsius. Do they want us to play with tiny little graphs to come up with a meaningless de-rating factor? By the way, have any of them heard about the desert areas in Northern Mexico, the American Southwest or some areas in Latin America? They have the tendency to be rather hot places, 48ø C could be the temperature the panel gets to in the shade. The best way to complement the standardized format is to have notes in the spec sheet and to offer Technical or Application Notes on request. That is where the good literature should be! We are not so dumb. We can read, ask questions, and get educated. That's all folks! Hector L. Gasquet El Paso, TX Hector, we agree with you that there should be easy to read and understand yardsticks for consumers. Not that it can't be better, but in reality, those manufacturers who cater to the AE industry are better than most in that regard. All PV manufacturers give output curves at the industry STC (Standard Test Condition) of 25ø C and most (but not all) give them at 50ø C and 75ø C as well. Temperature deration curves or continuous duty ratings for inverters and controls on the other hand, would be welcome. MTBF (Mean Time Before Failure) data is meaningless on products operated over a vast range of varying input voltages and currents, output wattage, and temperature swings. That pretty much covers most of the usual AE machinery. Ever seen the kind of industry standards you suggest for refrigerators?, toasters?, blenders? Me neither. - Bob-O