PV Maintenance Manual Needed We are looking for a simple illustrated manual on the maintenance and operation of a small PV system. Our organization, Terrasol, assists the installation of small one and two panel PV systems in Central America, mostly in Nicaragua. The systems use one panel, one deep cycle 12 Volt battery, a charge controller, and typically are used to run 12 Volt fluorescent lamps in a community room. We instruct two members of the village in maintenance and have hired and trained a Nicaraguan to periodically visit each system. Still, we could use a two or three page instruction manual to leave with new installations. Because the literacy levels are often quite low, it needs to be heavily illustrated. If you have one in Spanish, that is even better, though we can translate it, even if it is in French, Tagalog or anything else. Please send to Cal Broomhead, 204 Ellsworth St, San Francisco, CA 94110 ù fax 415-864-6919, evenings ù 415-550-0151 Hello Cal: To the best of my knowledge, there is now manual such as you request. I know that are there are bilingual organizations that could produce such a much need manual. Contact Sustainable Technologies International at 303-963- 0715, they often do educational work in Latin America and are wizards at small-scale PV. Also try some of the major PV manufacturers, I know that both Kyocera and Siemens are active in Latin America and certainly have the expertise to produce this much need "comic book" manual. ÄRichard Hi Cal; Just wanted to add that Terrasol is a non profit organization run by volunteers doing great work Ä hope someone can help you out. Ä Amanda On The Lam Dear Home Power; I recently found HP#31 on the shelf of a local magazine shop. I was surprised and delighted to find a magazine covering subjects so dear to my heart. I have read the magazine from cover to cover several times and am now writing to several of your advertisers. I am considering buying some solar panels. The best price I have been quoted is $806 (US$435 approx.) each for new MSX60s, (comparable to US prices with freight and NZ sales tax added), so the used panels advertised in your magazine caught my attention. The panels I am considering are the M52L Mud from Kansas Wind Power (pg 67) and the 83W Quadlam from Abraham Solar Equipment (pg 76), both choices based purely on price. The Quadlams cost US$2.40 per watt and the M52s $2.64 per watt. Your opinion on used panels in general and these in particular would be greatly appreciated. My budget will stretch to about US$900 including freight. I am interested in finding a source of Sterling cycle engines up to a couple of hp which could be solar powered but have been unable to find information. Anything on this subject would be greatly appreciated. As you can imagine we are not in the mainstream of AE down here and finding information can be difficult. I plan to subscribe to several of the magazines and newsletters advertised in your magazine. I am also hoping to build an electric vehicle in the next year and I'm part way through building a wind generator. Thanks for a fascinating magazine, and (I hope) for answering my questions. Justin Southam, 17a Pimlico Pl., Newlands, Wellington 6004, New Zealand Justin, a "quadlam" is four ARCO M52 panels in series. Each M52 puts out about 6 Amperes at 4 Volts. Quadlams are grouped into "Golds", "Bronzes", and "Muds" depending on how abused they were during their life in a commercial solar plant in Carrizo Plains, California. Many of the panels were used with concentrating mirrors, and the "Muds" especially suffered from the heat, with surfaces turning brown from the heat and light. I've been told that Ethylene Vinyl Acetate used to seal the modules formed small amounts of acetic acid, which erodes the metalization (traces and contacts) and darkens the cells' anti-reflective coating. We've noticed a bit of degradation of the cells' contacts on our set of "Golds". Muds will be more degraded. We've only tested bronzes and golds. Electrically, they perform very well. We found our golds to be about 20% underrated in power output, whereas new modules tend to be overrated. If you plan to buy muds, understand that they don't come with frames. This makes installing them a little more difficult. Also, if you're short on space, I wouldn't recommend 'lams. They use about twice the area per watt as, say, a Siemens M55. But as far as dollars per watt, they're the best show in town. Sterling engines: Detroit Diesel Corp, Peter L Perdue, 13400 W Outer Dr., Detroit, MI 48239 ù 313-592-5441, and Cummings Power Generation, Jerome Davis Box 3005 - Mail Code 60125, Columbus, IN 47202 ù 812-377-3743 both do sterling engines, but I think they're into big ones (20 or 30 kW). On the Home Power size scale, contact Reliable Steam Engine Co. P.O. Box 671, Waldport, OR 97394 ù 503-563-2535. Also contact Phil Manke, RR2 Box 320, Valley Road, Markesan, WI 53946 ù 414- 394-3431 ÄChris Foreign Exchange ATTENTION DOWN UNDER! We have great interest in finding out more about NEW ZEALAND. We have been living with PVs for over nine years and are willing to correspond about our experiences in exchange for your local knowledge. Ultimate goal would be "face to face" exchange in either or both places! Katcha & Bill Sanderson, 20295 Panoche Rd.,Paicines, Ca. USA. How about it, renewable energy New Zealanders? Katcha & Bill: the Alternative Technology Association, 247 Flinders Lane, Melbourne, VIC. 3000, Australia ù 03-650-7883 publish a RE magazine called Soft Technology. They might be able to put you in touch with some RE Kiwis Ä Chris Cool Reflection Dear Folks; I have thought about writing this letter every time I see articles referencing solar panel output vs. temperature and/or the use of reflectors to amplify light gain. Having used reflectors in installations for both hot water collectors and photovoltaics, I have made some observations. To wit: metallic surfaces reflect heat and (to the degree that they are polished) light. This is very helpful in heat gathering and hot water panels. The metal surface does not have to be exposed for the heat fraction to be reflected (painted metal will reflect heat about the same as bare). Porous, non-metallic materials (masonite, cardboard, etc.) which have been painted white will reflect almost as much light but very little heat. Oddly enough, I discovered these facts while designing and building greenhouses. In a greenhouse it is critical to gather and bounce as much light around as possible, but the accumulation of heat presents a serious problem. While there is a net loss of light to have glass on the north wall of a greenhouse, if you are north of 30 degrees latitude, you should not use foil-faced insulation in that wall. The foil, behind the wall surface will raise the internal temperature of the greenhouse significantly. When I first discovered these facts, I was dubious. I set up the following simple test to confirm my theory. I took a white styrofoam sheet used to separate photovoltaic panels in their shipping boxes (a 1 foot by 4 foot piece of cardboard, painted white, will do as well) and covered one half of the sheet with aluminum foil. I faced this panel toward the sun and, with a light meter, measured the reflected light from the foil covered end and again from the white end. The reflected light was almost the same (<10% difference). I did not have equipment to accurately measure the difference in reflected heat, but just a hand in front of the respective ends gave the answer. The white end felt no different than ambient air while the foil end was distinctly warm. I have since read technical documents which support this empirical finding. My conclusion is that if you wish to reflect light onto a photovoltaic, use a non-metallic reflector. If you want a heat gain, use a metallic reflector. I have found masonite to be a good base for the non- metallic reflector, with at least two coats of good, flat white paint. I'd appreciate anyone else's observations on this. Bill Sechler, Solarwind, POB 780, Bandon, OR 97411 ù 503-347- 3316 This sounds like a great idea. But be aware that adding reflectors of any kind invalidates the PV module's warranty. Also, I'd still recommend not doing this in hot climates Ä even if no heat is reflected, the panels will still get hotter, from the increased light levels and decreased air circulation.Ä Chris Seasonal Hybrid I'm interested in whatever back issues you have dealing with small hydro/solar crossover systems. We have enough water in winter and spring, enough sun in summer and fall, probably not enough of either out of season. Have a moderate water source (will be measuring flow this year, since it varies) with approximately 175 foot drop over a long (maybe 1/2 mile) run. Have two cabins approximately 1/4 mile apart. Is it possible to set up a hydro half way in between and run both ways? Or is it too far? Thanks for your info, Jennie Elford, Whitefeather Farm, POB 29, Tiller, OR 97484-0029 Jennie; Issue 15 has an article on a small hydro/solar system. Your best option (according to Richard and Bob-O) is to locate a few batteries at the point of power generation, to serve as a flywheel to supply power surges your loads require. Then, at that point, invert the power to 120 volts ac to minimize voltage loss during transmission. Assuming the round trip wire lengths to each cabin are 1/4 mile (1320 feet) and that you have a 2400 watt inverter (20 Amps at 120 vac), you can use #3 copper (or #1 aluminum) wire with a voltage loss less than 5%. If you have a smaller inverter, you can reduce your wire size accordingly. You might also consider a pair of 2.4 kVA 120/240 vac transformers to save on wiring costs by transporting the power at 240 vac.See Therese's Back to Basics article in issue 33, page 86 for more on wire sizing. The cost of this wire may seem expensive but assuming you're producing 240 watts (20 gal/min, 150 foot head), 24 hours/day, you've got 6 kw-hrs a day. You'd need 24 PV modules to produce that much power (assuming you have 50 Watt modules and 5 hours of sun a day). The hydro system will be well worth it! Ä Amanda Getting Dowsed Dear Home Power; I read with interest, and not just a little dismay, your article on obtaining water for a remote home site. First let me congratulate you on an ever improving magazine! The following information is meant to fill in where your last article was lacking... on dowsing. There are some areas of the country where the water saturates a sand bed that makes locating water a simple matter of choosing a convenient spot for the well. In most areas, however, the underground strata is a complex combination of saturated layers, fractures, solution channels and the classic small water vein. In this situation, dowsing is the only way to determine where the water is flowing. Since 1975 I have been locating underground water for clients by dowsing, the modern term for locating water with a divining rod. My track record over this period is a good well in 19 out of 20 locations.First, there is nothing particularly special about the dowsing rod. It simply amplifies the slight, subconscious muscular reaction in the dowser. Anything can be used as a dowsing device, the most common being the forked stick, now called a "y" rod, and made of nylon rod. Other instruments include the pendulum, bent wire rods, bobbers, and rotating devices like the Russian Loop. Much has been learned in the last twenty years about the mind and the validity of the dowsing reaction. Electro- encephalographic studies have shown that the rod moves from a subconscious muscle reaction triggered by the mind, not some aqua-tropism pulling on the stick! We have also learned that dowsing is part physical detection of changing energy anomalies and part psychic perception of information. Among experienced dowsers, it is common to hear of accuracy rates between 90-95%. I would caution the new home owner to find a dowser with references and some record of his performance. This is a skill, like anything else. Generally the more experienced the dowser in a given geographic area, the less time and effort required to locate a well site. I first visit the property with the client. Hopefully the client has not already started the house or put in the septic. Put the well in first! It's very disheartening to find the only good location to intercept an underground stream is in the middle of the septic field! I'll ask the client what water needs there are and estimate minimum acceptable quantities to look for. Often a well site is a compromise of water quality, quantity and location. Several sites are often located and the client can then decide for themselves what priorities to follow. During this first outing the client is allowed to follow along, ask questions when I'm not dowsing (to limit distraction) and provide background information on the property if needed. I may look for water moving in fractures or simply set parameters for water that will meet the minimum needs of the client, letting the dowsing process lead me to a suitable well site. With some preliminary sites selected, I'll go home and re- dowse the area remotely over a map of the property (yes this can be done!). This is not as accurate, but gives me a general overview picture of major fractures and water flows crossing the property. The field dowsing will be redone the next weekend or as soon as possible to check old findings and further explore new information turned up in map dowsing. This will usually be done without the client, preferably alone. I find this much less stressful and I can concentrate more fully on my dowsing. It also gives me additional time and flexibility to carefully sort out various flows, levels of strata, faults and geologic structures that may impact the well. Generally, I will look for the largest high quality flow of water obtainable. I essentially develop an image of the underground situation. When the driller sets up the rig, it may be important that the rig is maintained plumb. Often a dowsed underground water vein or small stream is flowing in a fracture or small solution channel and may require fairly accurate drilling to intercept it. The tools used can provide a nice plumb hole, but the high air pressures used to clean the hole of rock dust and cuttings often also clog the small water veins that are encountered. If the hole is drilled in this way and water is not found, a thorough scouring with dry ice and water often will pull the cuttings out of the impacted water veins and produce a usable well. Also, the driller may want to drill just ten feet deeper after hitting the water source to help prevent the aquifer from silting up. I would encourage anyone planning on drilling a well to get in touch with a local chapter of the American Society of Dowsers. They will be able to teach you the basics and refer you to an experienced dowser in your area. Write to American Society of Dowsers, Danville, VT, 05828-0024 for a list of local chapters and a book list for further study. Everyone has the capacity to learn dowsing to some degree. Practice is the key. Prove up your initial dowsing, gain confidence and increase your limits. After gaining experience with water, you may want to try dowsing for minerals, lost items, pipelines, buried cable, fluid and electrical breaks, etc. This list is as long as your imagination and as useful as anything else in your life. May your search be fruitful! Stephen Bosbach, 16304 Westview Trail, Austin, TX 78737 Pres. Armadillo Chapter, ASD Thanks for the info on dowsing, Stephen. Actually both the dowsers that sited our well were right, we hit water. It was deeper than they expected, but then we drilled in the summer and they dowsed during the spring. ÄRichard Golly Stephen, and I thought it was just magic! Bob-O Sensitive Environment Dear Home Power Folks; I'm still hoping to someday live off the grid, but I have two big concerns: First, my family does not seem to appreciate the importance of energy conservation Ä they leave lights on all the time when they're not needed, use the clothes dryer instead of the,clothes line, etc. We live in area where electric power is relatively inexpensive, and so have all electric appliances, and electric water and HVAC (heat pump). I've talked to my wife and 5 year old son about conservation a few times, but they always seem to forget. Do you or any of your other readers have any suggestions that might help? I can see that if we ever do manage to make it off the grid, that we'll have difficulties keeping the batteries charged... My second concern is that my family has severe allergies and Multiple Chemical Sensitivities (MCS). The only way that AE is practical is to reduce your electrical loads as much as possible, which usually means propane or natural gas appliances and hot water heating. Unfortunately, my family gets sick when they're around propane or natural gas appliances. I don't know if improved ventilation, exhaust fans, etc. would make it possible for them to tolerate living with propane or natural gas appliances, but since they're so sensitive, it doesn't seem likely. I'd like to try hydrogen as an alternative, since when it burns, it only produces water as a by-product; but it seems like a big undertaking to generate and store the quantity necessary to power a household year-round. By the way, can you tell me if it is possible (and practical) to convert natural gas or propane appliances to hydrogen fuel? I intend-to buy and read the book Fuel From Water: Energy Independence From Hydrogen, by Michael Peavey, but I haven't done.so yet... Again, do you or any of your other readers have any suggestions that might help? Finally, I have a suggestion for a Homebrew article: How to build a pyranometer for under $100. Off-the-gridders (or wannabees) interested in passive solar heating could design their system better if they had some way of measuring the solar radiation at their site. Commercially built pyranometers are too expensive for most people to consider buying. The homebrew pyranometer should be calibrated in Langleys, which is the unit that the literature uses for solar irradiance data. A digital display is preferred and an RS-232 output for unattended computer monitoring would be a bonus. Keep up the good work! Bruce L. Broweleit, 21312 Wanapum Village Loop SW, Beverly, WA 99321 Bruce, sometimes it's difficult for people to see the incentives for conserving energy when it doesn't affect their pocketbooks and they can't see the pollution caused by the central power plant. Living on a stand alone system is a different story though. It doesn't take many low energy days to learn to do without the appliances you don't really need! Hydrogen's an alternative to natural gas and propane worth looking into (if you'd like an interesting hobby) but again reducing your demand is the first step Äsolar water heating and a solar oven can go a long way to this end. HP33 and HP34 have hands-on articles on converting a natural gas/propane stove and catalytic heater respectively to run on hydrogen. Electrolyzers for producing hydrogen can be bought from Hydrogen Wind, Rt 2, Box 262, Lineville, IA 50147 ù 515-876- 5665. Walt Pyle of Richmond, CA is just about to replace his propane use with hydrogen Ä we're hoping to write it up soon.Ä Amanda We use the LI-COR LI-200SB pyranometer. It measurers solar radiation from the whole hemisphere (global sun & sky radiation) and puts out a 10 mV signal at 1000 Wm-2. We plug it into a Fluke 87 multimeter or a data logger. The company will calibrate it to within ñ5% (max) ñ3% typical. The LICOR costs $200 plus shipping: LI-COR, Box 4425 Lincoln, NE 68504 ù 402-467-3576. Typically, you don't need to know the solar radiation of your site with great precision, since it will vary day to day anyway. You do, however, need to find where the sun shines the most on your land. The best tool we've found for this is the Solar Pathfinder (see ad on page 114). You can also build a cheap & dirty model. See the Homebrew article in HP 28, page 61 Ä Chris Tanstaafl Dear HP; I have seen a video tape put out by Dennis Lee, of Conserve Inc. He contends that he has the technology to produce a flat plate condenser, super heat pump with a C.O.P. of up to 12. With a heat box storage unit, 33% efficient electrical generator, and a heat engine. He has made some incredible claims about rethinking energy production. Are you aware of his work? Is it credible? Do you have any desire to explore heat pump technology as a viable sustainable/renewable energy? If not could you refer me to someone who can critique his claims? Aside, I am building my first house. I could find only two articles to help me on architecture (HP#19 pp. 40-41; HP #26 p. 77) in my back issues, which are incomplete. Are there more? Aside, aside, the amount of energy it takes to make a PV panel exceeds the energy it can deliver over its lifespan - true or false? I terminated my solar engineering B.S. at New mexico State University in 1982 when I found the answer was true. I have rekindled enthusiasm with the heat pump issue. Any response is appreciated. You are doing noble work. I hear about you at HPV (Human Powered Vehicle) meetings in Massachusetts, to part time homebuilders while fishing in Bristol Bay, Alaska. A sincere "Thank you", John Fleming, 734 N Baker St., Port Angeles, WA 98362 Hi Jeff; so we've been skeptical of everything we've seen or heard about Dennis Lee's heat pump. We saw their video tape, and it just didn't make sense. As an engineering student you should recall that any heat engine cycle, can, in theory, be made from Carnot cycle engines, and that a Carnot engine's efficiency is: 1-Tc/Th where Tc is the temperature of the cold heat well (the ambient temperature, radiator water temperature, etc.). and Th is the temperature of the hot temperature well (the burning gases in your car's cylinder). If you were to "run" a heat pump off the ambient air temperature, then Tc =Th = ambient air temperature, so efficiency equals zero. We've talked to a couple of these heat pump guys on the phone and offered to test their product the way we test PVs, inverters, etc. We never received anything. Otherwise heat pumps are a great idea. Look into ground coupled heat pumps for low cost home heating. PVs used to use more electricity in their manufacture than they ever produced, but this is no longer the case. Now energy payback time is less Ä down to a year or less. Some manufacturers say six months. Single crystalline cells are most energy intensive, followed by polycrystalline, and then amorphous. We usually run an article every couple of issues (lately more) on solar architecture. See the interview with Stephen Heckeroth's article #32, Passive solar HP#32, glass & glazing HP#30, Earth Berm Homes HP#29, architecture software review HP#29, Radiant Barriers HP#28...Ä Chris Overshot Option Dear HP; I just read the letters in #33, including Bob-O's advice to Ed LaChapelle of Olympia, Washington on page 103. Very low head hydro is a difficult proposition because of the high cost, low speed, and limited availability of equipment. If Francis turbines don't work out for Ed, he might look into building or buying an overshot wheel, which will be about 80% efficient if properly designed. The primary drawbacks are the low speed, vulnerability to high tailwater, and a need to be housed for operation in subfreezing temperatures. I am familiar with Francis turbines in the 100 to 500 kw range. I have neither experience with or specific information about overshot wheels. For advice or design information Ed might try the Society for the Preservation of Old Mills or one of the millwrights advertising in its publication, the Old Mill News. The Society is rather decentralized. The magazine is published by Michael LaForest, 604 Ensley Dr., Rt 29, Knoxville, TN 37920, while its Technical Editor is Steve Kindig, RD2, Lobachsville Mill, Oley, Pa. 19547. The Mill Bookstore has, among other items, reprints of literature published by the Fitz Waterwheel Company, the nation's last waterwheel manufacturer, and is run by Frank Kehner, 2265 Fallen Oak Cir. NE, Massillon OH 44646 Good luck. Matt Foley, Riverat Glass & Electric, Box 593 Church St, Wadhams, NY 12990 ù 518-962- 4514 Cheap & Easy Greenhouse Here's a great design for a greenhouse that we learned from some friends of ours that built one. It's clean and quick to build. Cattle panels are the main structure. Cattle panels can be bought at any local feed store.$14.00 Bend the metal 16 foot by 52 inch cattle panel into an arch. Put as many next to each other as you like depending on how long you want it. Attach the bottom of the panels to a wood frame which is on the ground. Put a vertical support beam on each end with a horizontal beam between them the length of the ceiling to help stabilize the structure. Cover with plastic, add a door on one end, and you're done. For a more efficient greenhouse place thin strips of wood on the outside arched over the plastic then add a second layer of plastic. John & Deb DuMont, Rt 2 Box 337, Salem, MO 65560 Grid Bottom Line Greetings All; I just finished reading yet another letter from someone who's already hooked up to utility-power and and can't quite justify to him-(in this case) self the expense of purchasing and installing an AE system. Electrickians here in our area have stated "authoritatively," quite recently, that PV watts still cost much more than utility watts. Does anyone ever figure in access fees? Here, for instance, just for the privilege of being hooked into the local REA, one will pay somewhere around $10-15/month. That's if you use no electricity. That works out to at least the price of a panel or storage battery per year. What originally pushed me over the edge, so to speak, was when I was quoted $4,000 just to bring poles and service across the creek to our house. Total, our system has cost us $1,182, to date. That's collection, storage, regulation, wires, solder, ring-terminals, I2V motors for Maytag wringer/washer, outlets, fixtures, cover plates, everything! We used to do the washing in town, and we feel that the washer alone has just about paid for the system in savings. (It used to be that the nearest laundromat was a two-hour round trip away.) We're completely 12V and intend to stay that way. I feel that EMF radiation very well could be more deleterious to our health than anyone knows for sure. Yet, driving down a highway with the radio on and passing under a power line often causes noise through the speakers. What is happening to the micro-circuitry in my brain? That brings to mind a friend recalling riding on his bicycle in the cooling fog of a DDT- spraying truck of a warm summer's eve back in the fifties. Taking everything for granted - or as touted by the powers that be - can be a dangerous undertaking. Gee Whiz, am I glad you folks exist! Thank you. OOPS! The point of this was to ask if you have current cost comparisons of (particularly) PV-to-utility? And is there a formula whereby one could figure in their access fees? Maybe a graph with an x-y break-even line? Thank you folks, David T. Bearman, POB 356, Guadalupita, NM 87722 David, in your case it's clear that you saved money by going with RE. Let's say you put your $1,182 into the bank earning 3% interest instead of buying a system. You hooked up (for free, say), and used the bank account to pay $20 a month to the power company. In five years, three months your bank account would be dry, and you'd have no renewable energy system. But goodness, so many variables! If the initial sum was $8000 instead of your $1,182 then the interest off the money would exactly cover your power bill. It's a good application for a spreadsheet or a small program...Also, do you want to count in the value of your labor building and designing the system? How much of your system was scrounged? Your point is a good one Ä small AE systems are very cost effective. Ä Chris Step by Step Greetings! We are soon to move (May) into our log cabin with 100% solar, wood heat & cookstove, small propane stove and, oh joy, a Sun Frost refrigerator. We were able to locate almost everything recycled, except the Sun Frost, alas. We hope to run a word processing business and medical transcription, so we still need a fax and answering machine. We invested in a FM radio telephone that will handle a modem, etc. Now we just need the work. Your magazine has proved to be an invaluable resource throughout our five learning and building years. We're still learning and building. But we were able to make some major decisions with your help. We are two women building an upright (palisade) log cabin with a full basement (unintentional!). While continuing to work in the city, we managed to acquire a Trace 2012, eight Kyocera panels on a Zomeworks tracker, and two sets of 1340 Amp-hr batteries, along with a Backwoods charge controller and power distribution box. The plumbing is still in progress. But we got a Sears low flush toilet for $100 based on a Consumer Report study, and a Real pump, so far. We'll have a 1,000 gallon holding tank and our 50 gallon pressurized tank. The rest is still pending. We are also hoping to design a good gray water system, as many folks have. We would love to have visitors, advice and questions. All for now, Jan Revell, Highland Enterprises, Beaver Canyon Rd., Wauconda, WA 98859 ù 509- 486-1006 Wow, you're doing it all and doing it right. The move to the country is shock and work enough for most folks. Add to it renewable energy, building one's own home, and earning a living from a home business and you have a deed indeed. I salute you and your energies! ÄRichard Good Wood Hello Folks, In regards to the question of what materials make good containers for lead-acid batteries, I am a strong advocate for good ol' renewable wood. About ten years ago I repaired the rusted out, acid worn battery tray in my VW bus and cut a piece of 3/4" pine for a temporary piece to fit under the battery. The wood is still holding strong... no paint or polyurethane or poly anything! My wife, two daughters and I are now living under construction in our off the grid house here in Bridgewater, Connecticut. Despite the status quo skepticism, the sun has provided us with all the power we need to build and live in our home. Four PV panels (Solarex MSX56) mounted on the roof of my bus charge Exide 6C 5 batteries which are regulated by a Buss controller. A Trace 2012 inverter powers the 120 volt loads. I have never had any problems with that set up in the four years it has been in operation. In the last month we wired the house and installed the PV system. It consists of 20 Siemens M75 panels, charging a 24 Volt Trojan T 105 battery bank (20 batteries). We are using two Trace C 30 controllers and the Trace 2524 inverter. The battery shelves are made of, you guessed it, pine! Thanks for your energy, Ed Witkin, 74, Tappen Rd, Bridgewater, CT 06752 Thanks for the tip, Ed. As it turns out, the shelves holding the cells in our battery room are also made of woodÄfir. They show no degradation as yet (less than tow years. I had a lead- acid cell explode and disgorge three quarts of sulfuric acid onto the plywood floor. Cleanup was less and graceful and a substantial amout of acid soaked in the floor. After neutralizing the spill and washing the floor, no damage was in evidence except a deep brown stain. The floor still gets walked on daily. While high-tech plastics seem best for the cell cases housing the reative innards, wood is just fine for battery shelves and containments. ÄRichard