120 VDC Wind and Photovoltaic Hybrid Arthur K. and Maxine Cook c.1992 Arthur K. and Maxine Cook We have been experimenting with wind and solar power since 1978 when we installed our first energy producing systems. We became "Earth Conscious" in the late 1960's and early 1970's as did many other people worldwide. We realized that Mother Earth and her resources were being rapidly depleted. We felt powerless to do anything about the world's environmental problems, but decided we could and would take our own personal measures to live environmentally friendly lives in harmony with the Earth and our fellow man. Awakenings On December 29, 1974 an electrical snow storm hit with devastating effects. Over forty inches of wet snow fell overnight. The storm was windless, so the snow lay where it fell. Our utility lines were stretched to the ground. Most of the large transmission towers feeding our county were crushed. No more electricity. We slept in a 29¡ F house with no heat or light. We had no water for our cattle which were trapped in the barn. There were no backup generators to be had Ð they were all immediately bought up. Five days later we got our power restored and I pledged that this would never happen to us again. Beginnings Maxine and I, our two Tennessee Walking horses (Go-Boy and Prince), two German Shepherd dogs (Tuffy and Velvet), and three macaw parrots (Ruby, Scarlet, and Sparky) live on a 70 acre solar-powered farm in Somerset County, Pennsylvania. Somerset, Pennsylvania is located about 60 miles southwest of Pittsburgh in the beautiful Laurel Highland Mountains. After 14 years we are now comfortable with a fine working system that uses the utility grid as a backup if we don't choose to use our backup generator. Maxine and I were married in 1969; she was 22 and I was 25. Like most young couples we were anxious to start our life together. I was working in a family business which I was to take over. While it was quite lucrative, it was simply not for me. We were both drawn to the land, country living, and a simpler lifestyle. On May 5, 1973 we made the move to our cattle farm in the country. In 1987 we sold our cattle and became vegetarians. Raising beef cattle will do that to you! We have been building our system since 1978. In those years we were all pioneers. Nobody was an expert. Electronic controls, inverters, and so on were "iffie" and some were outright junk. Man has always thrived on challenges. My wife, Maxine and I were no exception. We have learned through failures, ours as well as others. Wind System Our first wind generator was a 115 VDC rebuilt Jacobs. It was destroyed in a terrible blizzard in January 1980. The wind that day gusted to 82 mph and the temperature was -27¡ F. The Jacob's governor failed due to the cold; the springs lost their tensile strength, the rotor overspun, and the machine flew apart. We replaced our "Jake" with our present Northern Power Systems' HR3, an 825 pound, direct drive 120 VDC alternator with a five meter (16.4 foot) diameter three-bladed rotor. We mounted her atop a 60 foot Rohn self supporting tower. This magnificent machine will produce 3,500 watts at 25 mph and requires only one hour of maintenance per year. It hasn't missed a beat in 11 years. The HR3 is 270 feet from our house and is fed with two runs of #00 gauge copper cable and one run of #6 copper cable. We experience virtually no voltage loss at 120 Volts. I always overdo everything Ð it's my nature. Maxine calls me, "Mr. All or Nothing At All." INSERT WIND MACHINE PHOTO The Photovoltaic System Photovoltaic (PV) systems complement wind systems because there is often wind without sun and sun without wind. We installed forty, 63 Watt, 20 Volt, Kyocera K63 panels. These Kyocera PV modules contain 44 series PV cells instead of the usual 36 cells found in most 12 Volt modules. Eight panels are wired in a series string producing 160 VDC at 3+ Amperes. With five of these strings in parallel, our PV array produces 16+ Amperes at 160 VDC, or 2,500 Watts. On very bright days we have gone over 3,000 Watts. Energy production from this array amounts to about 10 kiloWatt-hours daily. One clear and cold day this spring, our PV array produced 3,600 Watts (22.5 Amperes at 160 VDC). We routinely get 20 Amperes from this Kyocera array even on hot summer days. This power production is about 25% greater than Kyocera's ratings for these K63 modules. One reason for this is that our array is operates at 145 VDC or less, which is below its maximum power point. See page 34 of this issue for more info on maximum power point. We built our own PV racks out of 1 1/2 inch by 5/16 inch angle aluminum stock. All hardware used on the racks is stainless steel. Each rack holds four panels and is adjustable from 30 to 50 degrees. At $50 per rack, we saved some money over commercially available racks. Number 10 gauge wire was used to series connect the PV modules. Number 8 gauge wire was used to connect the array to our batteries, a 70 foot run with no measurable voltage loss. INSERT PV ARRAY PHOTO Power Production During the year from March 1991 to February 1992, the wind generator produced an average of 239 kWh per month and the PV array produced 196 kWh per month. Our total power production from both RE sources was 5,220 kWh for that year. INSERT POWER PRODUCTION CHART PV Regulation Bobier Electronics designed and built a 6 kiloWatt voltage regulator for us. I had them make a load diversion circuit (shunt regulator) so when we reach top voltage of 145 VDC, PV current is diverted into heating our domestic hot water supply. Battery Storage Battery storage is via two 120 Volt lead-acid batteries each consisting of twenty Surrette 6 Volt, 200 Ampere-hour batteries wired in series. Both banks are then wired in parallel giving us a total of 400 Ampere-hours of storage (48 kiloWatt-hours). One bank is 12 years old with 85% capacity. We added EDTA to the older battery last year and EDTA does work well. See page 45 in this issue for info on EDTA treatment of sulfated lead-acid batteries. Inverter Chad Lampkin of Michigan Energy Works built a 3,000 Watt, 120 VDC to 120 vac inverter for us. I can't say enough about Chad. His custom-made inverters are of the highest quality. Our inverter runs at room temperature Ð no heat means high efficiency. Chad hand delivered the inverter and helped us install it. 120 Volt DC I feel the high voltage systems are far superior in performance and efficiency. There are many reasons for choosing 120 VDC over 12 or 24 Volts DC. Some of the advantages are: small wire sizing, very low conductor losses, higher efficiency in DC motors, cool running inverters, very low off-gassing of batteries and longer battery life due to gentler charging and discharging currents, inexpensive switches and fuses, and greater compatibility with appliances such as vacuum cleaners, and electric hand tools. We operate several loads directly on 120 VDC. These loads are a 20 cubic foot refrigerator, a 20 cubic foot freezer, and the resistance water heating elements for our domestic hot water. Backups Backup power is supplied by two sources. I don't believe in keeping all my eggs in one basket. One backup power source is a 1,500 Watt, 120 VDC Onan gasoline-powered, engine/generator with blocking diode in the circuit. We installed this generator before we had any photovoltaics. In addition, we maintained utility power to run a 1,300 Watt battery charger with automatic controls. This battery charger automatically starts working when the battery voltage falls to 105 VDC. It then regulates the battery voltage at 125 VDC when they are full. Utility and generator transfer controls were built by Natural Power Company. Utility power only runs our electric range, electric clothes dryer, and arc welder. The range and dryer can be fueled by LP gas if we so choose, but at only $0.08 per kilowatt-hour for gird-supplied electricity, it's not practical at this time. We use about 200 to 300 kWh of utility power monthly and our power bill averages about $22 per month. 120 vac Inverter-supplied loads We power the following appliances with inverter processed electricity: 30 compact fluorescent light bulbs, two 40 watt fluorescent light fixtures, one 80 watt fluorescent light fixture, my amateur radio station (NB3E), three televisions, stereo, three ceiling fans, several outside spotlights, microwave, blender, vacuum cleaner, dishwasher, washing machine, sump pump, timers, ultraviolet water sterilizer bulb, forced air furnace, humidifier, and a juice extractor. Refrigeration We built our own freezer and refrigerator in 1980. Each unit is 20 cubic feet and runs on 120 VDC. we used Baldor motors (1/3 hp for the frig and 1/2 hp for the freezer), Fricke model 16436 compressors, and homemade controls. We started out with stainless steel boxes made by the Howard Co. For the freezer's evaporator, we zig-zagged 200 feet of 1/4 inch copper tubing under the freezer's shelves. In the refrigerator we used an old fashioned evaporator setup and added a 120 VDC fan motor (10 watts) inside the box. Both boxes only have 2.5 inches of insulation, so efficiency is limited. Each unit consumes 3 Amperes at 120 VDC. Our collective refrigeration load is about 2.5 to 3 kiloWatt-hours a day. I have calculated if we had the amount of insulation that the Sun Frost units have, we could equal their spectacular performance. The Water Pumper All of our water is pumped from a 170 foot well by an 8 foot Aeromotor windmill installed in 1978. She is perched atop a 40 foot tower. A 2,000 gallon concrete storage tank sits beside the mill just below ground level. The mill is on a hill about 60 feet above our buildings. Water flows by gravity to home, barn, and shop. We have enough pressure (38 psi) without having to add an additional pump. Isn't gravity wonderful?! Controls and Hot Water Both wind and PV controls are designed to divert excess power to heating domestic hot water. Two 4,000 watt resistance heating elements immersed in a 140 gallon insulated tank absorb this excess energy. When the battery voltage reaches 140 VDC, the wind generator's output is diverted into heating water until the voltage drops to 130 VDC. The PV diversion regulator works in the same fashion on the second water heating element. PV diversion starts when the battery voltage reaches 143 Volts and stops when the battery voltage falls to 133 VDC. Fifty-five square feet of solar thermal collectors also add to heating our domestic hot water tank. We installed these Israeli collectors in 1978 at a total cost of $800. This closed loop system circulates a non-toxic, silicon- based oil instead of water. This offers protection from freezing and rust. These collectors have been working since 1978 without failure; we are delighted. Heating We heat our 3,000 square foot farmhouse with a wood-fired furnace with oil backup. Heat delivery is via twin blowers which can be driven by 120 vac from the inverter or 120 VDC directly from the battery. Concluding thoughts We were not forced to use alternative energy because we already had utility power. A backup generator would have been sufficient for emergency power. We chose the alternative energy lifestyle because God has already given us all we need to live comfortably and once we started building we just couldn't stop, it was so much fun! I applaud Home Power Magazine and its contributors for helping raise the consciousness of us all. Keep up the good work. Access Author: Arthur K. and Maxine Cook, R.D. #3, Box 295, Somerset, PA 15501 ¥ 814-445-4520 HR3 Wind Generator: Northern Power Systems, One North Wind Rd, Moretown, VT 05660 ¥ 802-496-2955 Inverters and Kyocera PVs: Michigan Energy Works, Chad Lampkin, 9605 Potters Rd, Saranac, MI 48881 ¥ 616-897-5161 Custom PV Controls: Bobier Electronics, 512 37th St., POB 1545, Parkersburg, WV 26101 ¥ 800-222-3988 Dynamic Load Switches: Natural Power Inc., Francestown Turnpike, New Boston, NH 03070 ¥ 603-487-5512 Refrigeration Compressors: Fricke Co., 345 West Main St., Waynesboro, PA 17268 ¥ 717-762-2121 ¥ 717-762-8624 Fax Misc. Refrigeration Parts: Johnstone Supply, Exton, PA 19341 ¥ 800-262- 8400