Info Exd
Grand Total
$22,465
years and has survived numerous hard freezes and inch sized hail stones. These evacuated tubes have the insulation value of a vacuum bottle. Inside each two and a half inch diameter glass tube there is a finned heat pipe partially filled with an alcohol/water mixture. Sunshine causes this mixture to boil and heat is transmitted to a glycol mixture which in turn transfers the heat to the home's 80 gallon Rheem SolarAid hot water tank. This DHW system is rather complex with two stages of heat exchange and a single Laing pump
(driven by 0.25 Amperes at 12 VDC). The reasons to undergo this degree of complexity are absolute freeze proofing and the incredible cold/cloudy weather performance of the Thermomax collectors. On sunny winter days when the ambient temperature is well below freezing and the wind is blowing, the Thermomax still delivers 180°F to the hot water tank. Bob-O also has a Myson on demand, propane-fired water heater on line. This Myson has the happy ability to moderate its heat output in relation to the incoming
- Above: from left to right, Kathleen Jarschke-Schultze, Amelia Airedale, Allen Schultze, and Bob-O Schultze.
water's temperature. If the weather has been sunny and the solar hot water heater has been producing, then the water passes straight through the Myson without any additional heating. Using the on demand heater as a last resort ensures that the house will always have plenty of hot water regardless of the weather or the amount of hot water needed. This hot water system supports two bathrooms, a kitchen sink, and a washing machine. Between the months of May and October the pilot light on the Myson is shut off and the hot water needs are met by the Thermomax alone. Kathleen has a sign above the sink for visitors that reads, "Caution - Solar Heated Water - HOT!"
System Performance
Well, there is never a power outage at Bob-O and Kathleen's place. The photovoltaic array produces about 4,000 Watt-hours of power daily. The wind generator is a new comer to the system and we don't yet have years of data on its performance. If the wind is blowing, then Bob-O reports that the Whisper makes about 2,000 Watt-hours of energy daily. The small
The Utility versus Renewable Energy
Energy Consumption = 6 kiloWatt-hours daily Distance from Utility Lines = 1.7 miles
Utility Power Cost Renewable Energy Cost hydroelectric turbine produces about 1,200 Watt-hours of energy daily. Bob-O figures that he puts about 25 hours of operating time on the Miller engine/generator yearly. This system is about two-thirds powered by photovoltaics, with the remaining one-third divided between wind and microhydro.
The battery in Bob-O's system contains enough energy to power their homestead for about three days with no RE power input whatsoever. And since every day contains at least some renewable energy, the battery is virtually never fully discharged.
System Cost
The tables here detail the costs of all the renewable energy equipment. Bob-O and Kathleen have invested just about $20,000 in their electric renewable energy systems. While this sounds like a lot of money for power, let's examine the alternative.
Bob-O and Kathleen's property is located 1.7 miles from the end of the utility's power lines. The local utility, Pacific Power, charges $10.35 per foot for new line extensions. The going local rate for electric power is $0.095 per kiloWatt-hour. Bob-O and Kathleen consume an average of about six kiloWatt-hours daily. The table here compares the cost of running in the utility lines versus using renewable energy. This table does make some assumptions. One is that the renewable energy system lasts ten years, which is far more certain than the second assumption, that the utility will not raise its power cost in the next ten years. I figure that Bob-O and Kathleen saved more than $70,000 by using renewable energy for electricity.
If you consider that a new truck costs about twenty thousand dollars, it's easier to understand Bob-O and Kathleen's investment in self-sufficient and clean energy. In terms of performance for money spent, I pick an RE system over a gas guzzler any day.
Being here now
Bob-O and Kathleen live on an energy self-sufficient homestead. Their dedication to a sustainable future that all can share makes them friends of all living on this planet. I salute them!
Utility Power Cost Renewable Energy Cost
|
Line Extension Cost |
$88,762 |
RE Systems Cost |
$19,207 |
|
10 Year Power Bill |
$2,081 |
10 Year Power Bill |
$0 |
|
Maintenance |
$0 |
Maintenance |
$875 |
|
10 Year Cost |
$90,842 |
10 Year Cost |
$20,082 |
|
$/kWh over 10 Years |
$4.15 |
$/kWh over 10 Years |
$0.92 |
|
RE saves Bob-O and Kathleen $70,760 | |||
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Author: Richard Perez, c/o Home Power, PO Box 520, Ashland, OR 97520 • 916-475-3179
System Owners: Bob-O Schultze and Kathleen Jarschke-Schultze, Electron Connection, PO Box 203, Hornbrook, CA 96044 • 916-475-3402 Voice, 916475-3401 FAX Ä
Solec full page black and white this is page 15
Converting a 12 Volt System into a 24 Volt System
Bob-O Schultze KG6MM
©1994 Bob-O Schultze n the beginning it was a 12 Volt battery and a radio. And the radio begot the tape deck and rock 'n roll and it was good. And the tape deck begot taillight bulb lighting and the CB radio, which begot ham radios and electronics projects, which begot the 12 Volt soldering iron, flashlight battery rechargers, and 12 Volt water pumps for killer showers and it was getting really good. But not great.
Then came the small inverter which begot computers, TVs, bigger stereos, better lighting, small electric tools, motors, and blenders for making Margaritas. Then the need arose for more powerful inverters to run businesses, microwaves, toaster ovens, well pumps, and larger power tools to build bigger houses to shelter all this good stuff and the children begotten as a result of the Margaritas. And wisdom dictated that the universe be reconfigured to 24 Volts to run more powerful inverters while still providing 12 Volt for the many wonderful (and spendy) 12 Volt goodies. And it was great, but now we had a few problems.
The Reasons
Kathleen and I finally decided that we needed a sine wave inverter to run a laser printer and other goodies we'd been drooling over. I wanted a big inverter to run my air compressor and other power tools. The new Trace SW4024 seemed perfect. Sine wave and lots of "snort". But it required a 24 VDC input. At the same time, the Whisper 1000 was about to go in the air and the long wire run to the house called for either a higher voltage on the line or a spendy high power LCB. The handwriting was on the wall for a 24 Volt system.
The Problems
Over the years, you tend to accumulate quite a few 12 Volt goodies. Not only do these represent a fairly large investment, but most of the gear is high quality stuff and is more efficient to operate using DC than any available ac replacements. However, it's a good idea to re-evaluate each DC appliance in terms of value, life expectancy, overall system impact, and replacement cost of a comparable ac unit. In our case, the cost of buying a high power voltage regulator far outweighed the cost of replacing our 12 Volt RF-16 SunFrost and buying 117 vac power supplies for the ham gear. In different circumstances, where the major DC usage is lighting, for example, it may pay to replace older DC incandescent and fluorescent lamps and fixtures with some of the newer compact and circleline fluorescent lamps. If you make the switch, make sure that your wiring is up to snuff. Two conductor circuits without a separate ground work fine for low voltage DC loads, but won't be safe in a 117 vac circuit.
Additionally, all our RE sources had to be reconfigured to 24 Volt. The DC fusing and circuit breakers had to be sized down to reflect the drop in amperage.
Solutions
We bought a 20 Amp Vanner Voltmaster to power our 12 Volt loads from the 24 Volt battery bank. It has three inputs: -, +24, and +12. You tap half of your 24 Volt battery at +12 in addition to the major positive and negative 24 Volt connections. The Vanner monitors the voltage in both halves of the battery pack and electronically switches the load from one side to the other when a voltage imbalance occurs.
Rewiring the PV modules was easy and it actually eliminated a number of conductors, but it took some thought and different wire lengths to get the best configuration. Since the Wattsun tracker mounts the modules in two rows, it was possible to wire modules as pairs and parallel them as 24 Volt units. Running all the parallel connections at 24 Volts halves the currents on the wire and reduces line loss. The tracker to battery conductors were sized to carry twice the current at half the voltage than we had now, so the wire resistance and voltage drop went down significantly and we experienced a net gain in wattage delivered to the batteries. The conductors are 1/0 Cu wires with a one-way distance of 75 feet. Figuring an output of 36 Amps at 16 Volts at the modules, I calculated a 3.8% voltage loss from the tracker to the batts. Using 18 Amps at 32 Volts, the voltage loss drops to 0.9%. Under full sun conditions with the PV temperatures hovering at about 50°C, it roughly measures out to an extra 12 Watts. Free! Since my PV charge controller is a Heliotrope CC-60, all that was required was a flick of the DIP switch instead of control replacement.
With all the PV junction boxes opened anyway, it's a good time to inspect, clean, and tighten all the wire terminal ends in the array. How do those spiders and tiny buggers get into a sealed J box anyway?
The hydroplant alternator needed to be upgraded with a rewound stator to maximize output at the higher
voltage. While the alternator was disassembled, we replaced the brushes, bearings, and polished the slip rings. Since the hydro lives at the creek and off the beaten path, none of this routine maintenance had been done in years. Finally, a "round tuit"! Yes, I know I'm supposed to be a professional, but did you ever see a mechanic's pick-up? Ugh.
The wind jenny was always set up for 24 Volt due to a long wire run. Converting to a 24 Volt system happened just before the tower went up and we were saved from buying an expensive linear current booster.
One of the most important things to do when making the change to 24 Volt is replacing the fuses and circuit breakers in the system with the proper values. In theory, that should be one-half the amperage rating of the old ones, but you know how that goes.... I found it was easier (and safer) to recompute the current flow of each circuit. Figure the maximum current flow (the short circuit current with PVs), add 25%, and round up to the next standard value. While you're in the fuse or breaker boxes, check for corrosion and retighten all the connections and lugs. Only takes a minute and who knows when you'll be in there again?
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Author: Bob-O Schultze, Electron Connection, PO Box 203, Hornbrook, CA 96044 • 916-475-3402 «w storing solar energy..........
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