Solar Power Is Happening Here Richard Perez Main Street in downtown Carbondale, Colorado isn't much different from any other in America, except for the photovoltaic-powered home of the Solar Technology Institute (STI). STI uses solar energy to electrify their educational extravaganza, right under the nose of the local coal-burning utility. Location Carbondale Colorado is located on the west slope of the Rocky Mountains not far from Aspen. At six thousand feet altitude, STI's home gets its share of snow and low temperatures. The Solar Technology Institute is centrally located downtown, right in the middle of Carbondale's business district. It is impossible to drive by without seeing the pole-mounted photovoltaic (PV) arrays. People Solar Technology Institute is a very impressive sounding name. Names are a matter of imagination. What really counts are the people behind the name. In the case of STI, the people are Ken Olson and Johnny Weiss. Ken and Johnny have been teaching hands-on solar technologies for the last ten years. They are active in the Cold Chain Project bringing PV-powered vaccine refrigeration to developing nations. After installing hundreds of PV systems for others, Ken and Johnny will finally have solar power for themselves. Purpose I participated in STI's two week intensive course in photovoltaics for remote homes. The participants came from Columbia, Dominican Republic, Mexico, Alaska, Hawaii, California, VermontÐ from all over. The first week of the course consisted of seminar sessions in the mornings followed by lab and workshop sessions in the afternoons. The subjects covered in the first week included: basic electricity, instrumentation, batteries, controls, inverters, wiring, efficient appliances, NEC requirements and more. The second week of the course consisted of installing PV systems at STI's downtown site. It was the second week that had me worried. I'd done many seminars and labs, but I had never before installed systems with a group of twenty-five people. I wondered about the complexities of the wiring. As it turned out, the STI students installed everything with no problems. Loads Usually a photovoltaic power system's design starts with estimating the energy consumption of the loads. Well, STI's situation was backwards. The loads powered by the system were determined by how much power the system could produce. Solar Technology Institute is a non-profit educational organization. Almost all the equipment we used was donated by manufacturers and distributors. These farseeing makers realized the advantages of having STI students using their hardware. Fortunately, the STI stockpile contained first rate hardware. Ken and Johnny had a long list of equipment including copiers, computers, overhead projectors, lighting, and electronics to power from the system. To further complicate things, the leased building uses a large furnace fan for winter heating. We decided early on to leave the building's heating system on the grid and concentrate on powering the office and educational loads with PVs. The System's Design Actually we designed and installed three distinct PV arrays. One large (six modules on a Zomeworks tracker) and two smaller, each with two modules. All these modules power STI via the main battery and inverter. Part of the course was a presentation and discussion with John Wiles (author of Code Corner in HP) of the Southwest Technology Development Institute. The topic was National Electric Code (NEC) approved PV systems. The entire class decided that the STI system would contain all the code required equipment and would be wired according to NEC specs. All wiring would be in conduit. All power sources would have NEC-approved fused disconnects. In short, a Skookum system right down to the color coding on the wiresÐ black for positive, white for negative, and green for ground. Energy Sources The source of the power is sunshine directly converted into electricity by photovoltaic modules. The main system at STI uses ten PV modules made by Spire. Each 45 Watt module has an output of about 3 Amperes at 15 Volts DC. The ten modules were wired in parallel to make an array producing 30 Amperes at 15 VDC. On an average day, these arrays will produce 2,900 Watt-hours. Eight of the modules are mounted on two Zomeworks Track Racks (one holds six and the other two modules) that follow the sun's path. The remaining two modules are mounted on a Zomeworks stationary pole mount. Each module was parallel interconnected with 10 gauge wire with sunlight resistance USE insulation. All current handling connections on the arrays were soldered. Each module had its own 10 gauge grounding wire attached to the module's framework with a self- tapping sheet metal screw. The large tracker's framework and the five inch diameter steel pipe supporting the tracker were grounded using 6 gauge bare copper wire. A waterproof enclosure was mounted on the tracker's pole. This enclosure housed the connections between the individual wires from each module and the larger #2 aluminum cables carrying the power to the system. The mechanical connections made inside this enclosure were made with 250 MCM Al/Cu lugs and with antioxidizing grease. The PVs rise above the roof of STI's home like a solar phoenix. The constantly moving trackers attract the attention of all who see them. The message is clearÐ solar power is happening here. Energy Storage Storage is primarily in alkaline nickel-cadmium batteries. The STI system used thirty Edison ED-160 nicad cells to make a battery of 480 Ampere-hours at 12 VDC nominal. This battery was generously donated to STI by John D'Angelo of Utility Free in Basalt, Colorado. These cells were reconditioned by Utility Free from previous railroad service. John was also kind enough to open his battery reconditioning shop to the entire class for a visit. The batteries are housed outside the office in a wooden enclosure beautifully built by one of the STI students, Allan Sindelar. This enclosure not only contains STI's nicads, but also an assortment of lead-acid batteries. All the nicad cells are housed on stair-step racks that allow easy viewing of their electrolyte levels. A large four inch conduit pokes through the common wall shared by the battery compartment and the inside wall housing all the energy processing equipment. The inside of the battery enclosure is equipped with a four inch square steel raceway housing wires and cables. Battery parallel interconnect cables and inverter cables were made by the STI students from 0 and 00 gauge copper welding cable. The students used the soldered copper tubing connector technique described in HP#7. Energy Processing A small room off the main office houses the energy processing equipment. Here an entire wall is covered with fused disconnects, controls, instruments, and inverters. Ropes of conduit connect everything together. There is not an exposed wire anywhere; everything is enclosed in either the raceway on the wall, in metallic conduit, or within a NEC-approved box. The result is an impressive array of electric stuff that rivals the bridge of either the Starship Enterprise or the Yellow Submarine. The power flowing from the PV arrays first must pass through a two pole, single throw, 60 Amp DC-rated Square D disconnect equipped with 30 Amp DC-rated RK5 fuses made by Littlefuse. The input PV power is then moves to the Heliotrope CC60C PV charge control. This same switch also disconnects the battery from the charge control. If this disconnect is operated, then the charge control is disconnected from both the PV array and the battery, as per NEC specifications. The Heliotrope CC60C PV control keeps system voltage under control. The CC60C uses Pulse Width Modulation (PWM) to maintain a user set voltage. This user set voltage limit can be set high enough (Å16.5 VDC in 12 Volt systems and 33 VDC in 24 Volt systems) to function well with alkaline batteries. The CC60C accepted the conduit fittings with no problems. This CC60C contains the factory installed LCD digital Ammeter/Voltmeter combo which is large in size and easy to read. The inverter is the Trace 2012 with digital instrumentation and the new-model built-in programmable battery charger. This inverter supplies all the 120 vac loads connected to the system. This inverter allows the low voltage, direct current power made by PV modules to be consumed as standard 120 vac, 60 Hz. house power. And consuming it was on Ken and Johnny's minds. I took a look at the photocopy machines, overhead projectors, slide projectors, light tables, not to mention almost a kilowatt of fluorescents, and I knew that this Trace wasn't going to have an easy time of it. The output of the Trace inverter is fed into a second Service Entrance panel (or mains panel) that supplies all of STI's wall outlets and lights. This Trace is equipped with the super sophisticated new battery charger we reviewed in "Things that Work!" HP25, page 58. If STI has to use grid power to recharge their batteries, then at least there is an excellent charger around to do the job. There is a single grid connect outlet next to the inverter just for battery recharging. After much discussion the STI crew decided not to hook up the battery charger, but instead to live with the PV power made on site. The Trace 2012 is connected to the battery using 00 gauge copper welding cable and with hand-made, soldered copper tubing connectors. In series with the inverter/battery circuit is a Heinemann DC circuit breaker rated at 250 Amperes. This circuit breaker protects the inverter and its cables from over-current and also functions as a switch disconnecting the inverter from the battery. This highly specialized breaker is hard to find, expensive (Å$150), and required by the NEC. Many thanks to John Mottl of Rainshadow Solar for providing the one installed in STI's system. The main instrument used to fly STI's system is a Cruising Equipment Ampere-hour meter. This instrument uses a shunt to sense and record all current flow both into and out of the battery. Ampere-hour meter serves the same function in a PV system that a gas gauge serves in a car. Additional instruments used in the STI system are the built-in digital Ammeter/Voltmeter in the Heliotrope charge controller, and the extensive instrument package built into the Trace inverter (battery voltage and battery charger functions). The Installation The installation began with a seminar on the system to be installed. We took a large greaseboard and drew the whole thing out. Every wire in the system was included in the diagram. I have attempted to reproduce this system diagram here. INSERT SYS DIAGRAM Installation was complicated because the building was off the grid and powerless for two days. Separating the 120 vac circuits within the building took two commercial electricians two days to complete. During this grid-less period the STI crew set up three sets of batteries feeding four different inverters. This swamp of temporary systems provided the power to run all the construction tools. This temporary lashup gave everyone the opportunity to try a wide variety of power tools on four different inverters (Trace, Heart, Vanner, and PowerStar). Amazement was universal when the five pound PowerStar UPG1300 ran a worm drive Skilª Saw. Installing the trackers and the poles supporting the PV racks took two days. The main array (six modules on the big Zomeworks tracker) was placed on a fifteen foot length of five inch diameter steel pipe. This pipe was set into a five foot deep hole that was then filled with cement. The result was a secure mounting place for the Zomeworks Track Rack high in the air and away from people and cars. Several of the students took the task of fabricating the inverter/control/instrument panel. Here a sheet of plywood served as a back plane for mounting the various components. Another crew ran the conduit and wiring necessary to hook everything together. A third crew took charge of wiring the individual modules into arrays. Juan Livingstone of STI gets extra credit for swimming through the attic's insulation with conduit gripped between his teeth. System Performance It worked the first time the switch was thrown. The first evening that the system operated at STI was a fiesta. Sixty local solar supporters and the STI crew gathered for barbeque and enchiladas cooked in a Sun Oven donated by its maker, Burns-Milwaukee. We had the lights and the stereo going until midnight. The Cruising Equip. Amp-hour meter said we used 148 Ampere-hours from the batteries in a six hour period. A highly electric time was had by all. On a daily basis, STI lives within its energy budget of about 2.5 kiloWatt-hours daily. They have broken new ground by feeding business and audio/visual tools with inverters. Photocopiers have been known to fry and die when fed the modified sine wave power produced by inverters. At STI, Ken and Johnny have successfully used long list of business and education gear. INSERT LOAD TABLE The Toshiba 2510 photocopying machine runs flawlessly on the Trace inverter. This copier is a high output, full-featured office model that sorts, enlarge, reduces, duplexes, and collates. Ken and Johnny said that the Toshiba engineers were very helpful and interested in the performance of their machine on inverter power. Another full scale copier that functions perfectly on the Trace inverter was the Minolta EP5400. It has roughly the same features as the above Toshiba model and the test model even did color. The only copier Ken and Johnny tried that didn't work was the Ricoh 5540. The Ricoh 5540 didn't fry and die when powered by the inverter, but it made copies that were very poorly and inconsistently toned. Standard audio/visual aids like the overhead projectors and slide projectors have little problem making the transition to inverter produced power. And since the business of STI is education, the system contains two coffee makers and a microwave. Everyone knows that the best education happens over a cup of coffee and a hot danish. STI is still working on their lighting. The front room uses about one kilowatt of standard fluorescents driven by coil/capacitor ballasts. While the Trace 2012 powers this deeply reactive load, it really discharges the battery rapidly. Ken and Johnny are working on increasing the efficiency of their lighting with the help of Sardo Sardinsky from Rising Sun Enterprises in Basalt, Colorado. The lighting specs given on the table are for the stock, unmodified fluorescents. The remainder of the loads are real lightweights and are easily powered by the system. Items like laptop computers and answering machines really consume very little energy in comparison with a large photocopying machine. System Cost Well, since the entire show was donated, the system cost STI virtually nothing. Even the labor was donated by the willing and eager crew. To give you an idea of the real costs involved, I have worked up the following cost list based on the retail price of the donated gear. INSERT COST SPREAD The Solar Tech Experience There is a lot more going on at STI than listening to an instructor drone on and on for hours at a time. Sessions are closer to visits over the dinner table than conventional classroom scenes. Education at STI is more of a discussion than a lecture. Every morning's classroom session is followed by an afternoon lab session demonstrating the principles learned that morning. After a week of intensive (we worked hard) learning, then comes the second week of actually applying what is learned. This is critical. Not only does actually installing a real-life system cement the concepts firmly in mind, but also makes everyone one aware that nothing is as cut and dried as it appears in the classroom. Every real world installation is filled with unique compromises and glitches. In a large part, becoming adept at renewable energy systems means being able to deal with each system as an individual entity. Each system has its own requirements and problems. STI realizes this and teaches how to solve these problems. And there is still more. For one example of many, during the class we converted a Maytag washer using one of Wattevr Works' Guzzle Buster Kits. We measured the power consumption of the unmodified washer on four different inverters. Then we converted the washer to a super efficient 120 vac setup and ran it again on the same four inverters. In fact, Jim Forgette at Wattevr Works is telling the truth about his washer conversion kits. The Maytag used one-third as much power after conversion. The STI students did the conversion and made the measurements. They said that Wattevr Works' conversion documentation and instructions were the best they have ever used. The STI students not only learned the innards of a washer, but also the importance of reducing power consumption, and maybe most importantly the ability to use and understand instrumentation. And the washer conversion was only one ring of a multi-ringed circus. Over in the back room another group lead by Kent DeVilibiss converted a Marvel vaccine refrigerator with a super-efficient Danfoss compressor transplant. And in the center ringÉ The part I enjoyed the most happened in the evening when the whole group invaded a local restaurant and discussed renewable energy over beers and dinner. You can always tell those with the Spark because they are still talking shop after hours. The discussions were far-reaching and comprehensive. Often they would slop over into the next morning's classroom sessions. One discussion in particular, on working with renewable energy as a profession, was so fruitful that I have assembled the material into an article in this issue (Careers in Renewable Energy on page XXXXXX). Paul Wilkins was on-hand and video taped the entire proceedings. At last count I think that he had recorded over 22 cassettes. Paul is going to edit these down and there are plans to make them available to whomever is interested. Ken and Johnny are now offering Solar Technology Institute memberships. A membership supports STI, a nonprofit educational venture, and the members get the STI newsletter. All STI memberships, except the low income model, come with a free one year subscription to Home Power Magazine. This is our way of helping Ken and Johnny with the essential work they are doing. Conclusions I'm having trouble writing a conclusion here. Things at STI don't concludeÐ the beat goes on. After I left, Don Harris from Harris Hydroelectric showed up for a week long course on microhydro. I wanted to stay for that course as well as the following courses on solar home design & construction, solar remodeling, passive solar design, heating, and solar building skills. A short course in low-tech hydrogen production and use is being scheduled. And I hear that Mick Sagrillo may be teaching a wind course in the SpringÉ Access Author: Richard Perez, C/O Home Power, POB 130 Hornbrook, CA 96044 ¥ 916-475-3179. STI: Ken Olson and Johnny Weiss, Solar Technology Institute, POB 1115, 358 Main Street, Carbondale, CO 81623 ¥ 303-963-0715. Companies who donated equipment to STI: I usually don't include free plugs for companies that can and do afford to advertise within these pages. I am making an exception of companies who donated gear for STI system. In my opinion, these companies deserve recognition for their donations. So here's a list of the companies that care enough to support the Solar Technology Institute: Bobier Electronics Burns-Milwaukee Cruising Equipment Gates Battery Harris Hydro Heart Interface Heliotrope Hoxan Independent Energy Kyocera Lil Otto Hydroworks Midway Labs Photocomm Photron PowerStar Products PVI (Mark Fitzgerald) Rainshadow Solar Real Goods Rising Sun Enterprises SCI Siemens Solarex Sovonics Synchronous Design Sunnyside Solar Trace Engineering Trojan Battery Utility Free Vanner Wattevr Works Zomeworks