have a THD between 3 and 5%. The Exeltech sine wave inverters use 416 steps and have a THD of 1.5 or less. We have done long-term measurement of grid power, and found THDs from 5 to 17% at the outlet.

Grid power is a very pure sine wave when it is generated at the power plant. But, after it leaves the plant, goes through the high voltage lines, is stepped down by your local substation, is distributed to the local neighborhoods, and is stepped down by the transformer feeding your home, the THD will vary widely. When it comes to grid power, the whole neighborhood shares the power. If your neighbor is welding, or has a refrigerator with a marginal motor/compressor, then it effects the quality of your power. When you have an inverter, then you have a power plant making electricity just for you.

How much THD is too much? Well, it depends on the appliance. Incandescent light bulbs don't care at all about THD, and neither do electric heaters. In general, this is true for all resistive appliances. Other devices do care—running cooler, better, and more efficiently on low THD sine wave power. Such devices include most electronics, TVs, stereos, computers, fluorescent lighting, microwave ovens, most induction motors (found in everything from refrigerators to table saws), and many others. The reason is simple and straightforward—that's what the appliance was designed to operate on. In general, if your 117 vac power source has a THD of less than 10°%, then all appliances will run well and efficiently.

Total Harmonic Distortion (THD) is not the only criteria for choosing an inverter. You should also consider such things as rms voltage regulation (should be 117 vac rms ±no more than 5%), peak ac voltage (should be 164 vac peak ±no more than 10%), and frequency stability (60 Hz ±0.5 Hz or less). For people using 240 volts at 50 Hz the ±% tolerances are the same. Richard Perez

How Many Amps?

What is the maximum number of Amps you can charge a 6 Volt, 220 Amp-hour golf cart battery when it is discharged fully, to bring it two-thirds of the way back? I know the last part of the charge must be slow. Howard Clunn, Auburn, CA

Hello, Howard. The maximum recharge rate for a lead-acid battery is C/5 if you want it to last. This C/5 rate should only be used when the battery is between 20 and 80% State Of Charge (SOC). For your battery of 220 Ampere-hours, this rate works out to 44 Amperes.

You mentioned that your battery is fully discharged. This is an SOC below 20%. When a lead-acid battery is fully discharged, its electrolyte becomes water. All of the sulfate ions are in chemical combination on the plates and the electrolyte is depleted of sulfuric acid. At this point, the electrolyte has much higher resistance than at 20% SOC.Use a C/20 rate of recharge (that's 11 Amperes for your battery) until the battery reaches 20% SOC. At this point, you can move to the faster C/5 rate.

Using the C/5 rate on a fully discharged battery, or on an almost fully recharged battery (over 80% SOC), will reduce the life of the battery. Most of the energy will be converted to heat instead of breaking the chemical bonds. This heat expands the plates in the battery (thermal cycling) which will lead to early battery demise. In general, I'd recommend using rates no faster than C/10. It's a matter of efficiency— the faster you recharge, the more energy is lost to heat and water electrolysis. Richard Perez


October / November 1998

Introducing a new Power Center Solpan 30B

Cover with window

Cover with window

Cover removed

• PWM (Pulse Width Modulation) charging strategy

• 30 amps, expandable to 60 Amps

• Suitable for outdoor environments

• Use with DC loads and/or inverters

• Modular scheme with addition of Heinemann breakers, 10-250 amps

• SOC set by DIP switches for all battery types

• Automatic battery equalization

• Temperature compensation standard

• Meter reads voltage and amperage charge and load

• Load shunt option

• Pricing starts at $615.00 Heliotrope General is the originator of PWM PV charge controllers.

Call for new data sheet.

The name means reliability.

Heliotrope General

3733 Kenora Dr. Spring Valley, CA 91977

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PURE CASTILE & VEGETARIAN SOAPS. Handmade in an AE environment. We also have hard to find natural bath & body care products. FREE catalog: SIMMONS HANDCRAFTS 42295 AE, Hwy 36, Bridgeville, CA 95526

HYDROELECTRIC SYSTEMS: Pelton and Crossflow designs, either complete turbines or complete systems. Assistance in site evaluation and equipment selection. Sizes from 100 watts to 5 megawatts. Manufacturing home and commercial size turbines since 1976. Send for a free brochure. Canyon Industries Inc., P.O. Box 574 HP, Deming, WA 98244, 360-592-5552._

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INTERESTED IN INTENTIONAL COMMUNITY? Communities magazine offers complete, updated listings of intentional communities not found in the Communities Directory. Practical information about forming/joining community — alternative buildings & structures; getting off the grid, legal, financial & land options. Plus Eco-villages, Cohousing, decisionmaking, conflict resolution, successful communities, children in community, research findings on community living. Quarterly. $18/yr, $5/sample. 138-HP Twin Oaks Rd, Louisa, VA 23093. (540) 894-5798._

COGENERATION CENTRALAir conditioner for independent power homes. Do it yourself installation parts, plans, send $10.00 for info packet to: Petit Electronics, P.O. Box 996, Luling, LA 70070

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The big-box Solar Mart may talk a good game from behind the order desk, but are they actually out there doin' it? VERMONT SOLAR ENGINEERING takes pride in being a reality-based dealer/designer/installer. We know the products because we work with them every day— PV, hydro, wind & domestic hot water. From components to complete systems, our new DO IT! SOLAR™ catalog contains the industry's best and is available for $2(refundable with purchase). So reject the romantic salesspeak offered by the volume dealers and give us a call. Thanks! 800-286-1252, 802-8631202, 863-7908(fax). PO Box 697, Burlington, VT 05402. Our Website contains our installation portfolio and attractive sale pricing—

CEILING FANS:The largest selection of DC Powered (12 & 24VDC) ceiling fans anywhere in the U.S. From traditional to modern, classical to custom design. For brochure and list of dealers send SASE to R.C.H., 2173 Rocky Crk Rd, Colville, WA 99114. Dealer inquiries welcome FAX 509-685-0535

EARTH-SHELTERED HOMES This definitive manual by noted authority Loren Impson features detailed building instructions for the amazingly affordable and practical Ferro-Cement Dome Home. Only $15 from Sun Life 71 Holistic Hollow, Mount Ida AR 71957

YOUR ALASKAN SOLAR EXPERTS! Complete source for Alaskan alternative power. ABS Alaskan, 2130 Van Horn Road. Fairbanks, AK 99701 907/452-2002, AK 800/478-7145_

I AM A SOLAR WHOLESALER looking for retailers to carry my solar electronic and hobby goods. Phone # (916) 486-4373. Please leave message.

NEMO SUBMERSIBLE WELL Pumps feature Flojet pumps enclosed in rubber gasketed all metal cases. Complete Units low as $155. Case Kits just $50. Free Info Packet— Call 508-627-1319_

TRACE POWER PANEL, Model SW4024 8kw 24 volt—120/240 60 amp. Never installed! $4,900.00. Frostek 8 cubic foot propane freezer, used 3 months $1,000.00. Sunfrost 19 cubic foot refrigerator 24 volt, oak veneer, 1 year old $1,500. So. Cal. 760-408-0213

WIND/SOLAR/HYDRO ELECTRIC SYSTEMS. Propane refrigerators, ranges, lights & heaters. Diesel battery charger, Best buys on Inverters & Sun Frost refrigerators. DC Compact Lights, Pumps, Low cost DC motors, Grain mills, Tankless water heaters, Composting & Low flush toilets, Fence chargers, Solar cookers, Books, Shortwave radios & much more in $4 Catalog. Windmill Water & Hand pump Catalog $5. Food Catalog $3. KANSAS WIND POWER, Dept. HP98, 13569 214th Road, Holton, KS 66436"Since 1975" 785-364-4407 Discount Prices!

PHOENIX COMPOSTING Toilets Odorless, waterless, low maintenance, solar powered. Greywater systems. Cabin, home or Public Facility. 888/862-3854

OVER 23 YEARS IN SOLAR Business. Talmage Solar Engineering, Inc. has served customers from the islands off the coast of Maine to Honduras. We take time to figure out the exact needs of each customer, design and engineer systems that will work and give the best possible price on equipment. Give us a chance to show that our experience will help you build a solar power system that will work. We are always here to give back up support. 18 Stone Rd Kennebunkport, ME 04046 207-967-5945 E-mail [email protected] website

RADIO/TELEPHONES FOR Remote Home or Business: Commercial quality, up to 20+ mi, Best Prices. (208-263-9755 PST) Send $1 cash: KRES, Box 215-HP, Kootenai, ID 83840._

FOR SALE: Photocopied reprints of Home Power issues 1-10 available. All proceeds will be donated to IRENEW. Call 815-469-5334 or e-mail [email protected]. Sold only in sets of 1 thru 10 for $30 which includes shipping in most cases.

DIRECT TO YOU SALE!!!! (no pickups on these items) Servel by Dometic 7.7 cu. ft. propane fridge $1,029; Trojan L-16, $155; T-105, $65; all items freight extra. New Bogart Tri-metric meter $169 delivered. VT Solar 1-800-286-1252_

VERY LOW PRICES Solar Electric & Thermal Equip. Panels-Inverters, Charge regulators, wind generators-pumps-controls Please Call (888) 817-1737 or write to 6 Cresta Cir. #7, San Rafael, CA 94903

EDTA RESTORES SULFATED Batteries. EDTA tetrasodium salt, info, catalog, $12/lb plus $3.50 ship & handle. Trailhead Supply 325 E. 1165 N. Orem, UT 84057 email: [email protected]

ALTERNATIVE ENERGY Power for Alaska Kenai Penn.& Anchorage Specialists in Bush systems. Northern Alternate Energy Systems P.O.Box 973, Sterling, AK 99672, 907-223-9156_

LOW PRICES, QUALITY Merchandise and Friendly, Experienced Design Service all come together at Taos Green Solar. We've been helping people with their solar energy needs since 1992. Can we help you? (505) 751-5946. Trace inverters 25% off in October & November.

NEW SURVIVAL COMMUNICATIONS Book How to build communications systems. Covers all needs — shortwave radio, amateur radio, citizens band, scanners, federal weather, alternate news, satellite radio, equipment sources. How to build and use alternate emergency power sources, solar, generators, backup batteries. 200 pages. $24.00 Fast Delivery Priority Mail. MC or Visa. Call Universal Electronics 800-241-8171

VERMONT PV DEALER. David Palumbo/Independent Power & Light has been installing off-grid systems, and helping do-it-yourselfers (who buy their equipment from him) with free professional design advice for over 10 yrs. David offers free educational workshops (see Happenings). Trojan and Surrette batteries. FREE with battery purchase IP&L deep cycle battery instructions. Trace, Solarex, Siemens, and BP at fair prices. Large supply of wire and cable. Beware of "fast buck artist", slick talking, "lowest price anywhere" mail order companies who don't take the time to find out what you really need and can't spend the time on personal support and service. Buy from an honest dealer who knows the products and cares about your success in using them. David's installations are innovative, simple to live with, and successful. And our long following of do-it-yourself customers always come back for more because they can rely on getting straight talk, no BS, and the best service possible. "David is one of the original RE pioneers... he knows how to really squeeze all the energy out of a kWh!" Richard Perez HP#60). I P & L, 462 Solar Way Drive, Hyde Park, Vermont 05655 Call David Palumbo 802-888-7194. E-mail: [email protected]. Web site: INDEPENDENT-POWER.COM. No catalog requests please. Please call for appointment before visiting.

FREE PROPERTY LIST for mountain land, some with creek or river frontage in beautiful Scott Valley, Northern California just 15 minutes west of Yreka off I-5. 5 to 320 acre parcels, perfect area for retirement or country lifestyle. Call Scott Valley Real Estate (530) 468-2252,

Y2K CONCERNS? Prepare for power and communication interruptions predicted for year 2000. Keep critical lighting and appliances operating in home or business. Install non-generator based power system and prepare for outages. Book includes photos, diagrams, and design information. $29.95 + $4.00 S&H, packaged systems available. Phone (804)457-2500, Dunimis Technology Inc., P.O. Box 10, Gum Spring, VA 23065

TECHNICIAN IN RE is interested in buying used Photovoltaic Panels, Charge regulators and Track Racks in small quantities, but regularly. Shipment should be made to Florida. Payment terms to be agreed. Interested persons please write indicating models and prices to: Nieves Garcia, c/ Corregidor Diego de Valderrabano, 1 — 28030 Madrid — Spain.

TOTAL SELF-SUFFICIENCY & Serenity—Surround this immaculate 3 bd., 2 bath home on 11.50 private acres with incredible views. Skylights, family room, new carpet, vinyl, deck and State of the Art Solar and Generator systems—$159,000/ Please contact: Patricia R. Gay, Associate Broker, Patricia Sprague Real Estate, Ashland, Or., (541) 482-2905 or (541) 482-1011 Eve

FOUR ONLY: 20KW Jacobs (23 kva) Stub tower assembly from California wind farm, should be redone but running when laid down, but are as is. The units have Onan Alternators, 26' Laminated wood blades, 13/4" Governors, and I have had all 4 Master Mind Inverters Remanufactured (6 mo. Warranty) and this package includes a dbl choke. $4850.00 pls shipping. One Onan 25 KW wind turbine alternator $3500.00 as is. I have some towers and lots of parts for Jacobs Wind Turbines. Lets talk and see what I have, I can have these units remanufactured by former Jacobs employees. Palouse Wind & Water, 1015 Rothwell Rd Viola ID 83872 1-208-883-3676_

GRASS VALLEY, CA 960 sq ft solar-off grid 2 yr old home 2 bd-1bth 5 acres 7gal/min well Historic gold mine rights $109,500 or offer 530-272-8841 [email protected]

UNDERGROUND PV & WIND Home Beautiful remote 18 acres in S. Oregon's high desert. 800 sqft living space w/600sqft greenhouse + attached cabin & 2 wells, off grid. $55,000. For photos or ?'s call Brian (415)362-8707_

STEAM ENGINE KIT, all materials and machine drawings. Power small boat, generator or machinery. Information; 550 stamp to Pearl Engine Co, RR1 Box 45 Sutton VT 05867 (802) 467-3205_

FOR SALE BY OWNER: Wind Powered Custom Home in South Park, CO 45 min. to Breckenridge 90 min. to Denver. 2 acres, 1200 sq ft passive solar, 3 bedroom 1.5 bath $97,000. Great views. 1-800-994-7336.

10 ACRES 10 MI. from Reno, Nevada: $35,000 surrounded by undevelopable land. Perfect for independent living and seclusion. Minoff, Box 5, Mapleton, OR 97453

EQUAL SHARES OF OUR Herb Farm in exchange for work on our energy projects. Opportunity to get your own business started, using our site and equipment. Adirondack Herbs, 822 State Hwy 10, Caroga Lake, NY 12032. 518-835-3211 [email protected]_

IS YOUR HOME AN Eco-Home? It can be. Eco-Home International can make your home environmentally safe. Air and water filtration, non-toxic cleaning products, and more. Call Dr. Cohn at (800)-618-7536, 3200 Bristol St. #695, Costa Mesa, CA 92626._

1983 WHISPER 1000 never used in box $1700 Tip down tower 64 ft. 4-305ah deep cyc. never cycled. 8' x 12' energy shed meets MN Energy code. After 6pm 320-240-8421_

EROS 12V BIKE DRIVE Complete with cable lift-off. Generates energy when going downhill. Cost when new $220. 15 months old. $95 Precious Mountain 1221 Niestrath Rd, Cazadero CA 95421 707-847-3638

GENERATOR, KOHLER 6.5 RMY LPGas 2 years old $2800. Trace SW 4024 Inverter $2500. Gibson POBox 1115 Yellville AR 72687 870-449-5297 day or 870-4494005 evenings

FOR SALE: ADOBE HOME featured in HP#61 (pgs 12-17). On 40 acres, Silicon Valley commutable. $419K 1-800-777-7921, (408) 628-3362 or see web page <> for details.

ENJOY LIFE! Complete Solar-Wind Home Privacy Galore Elk in your backyard Beautiful sunsets and sunrises 1200 sq ft artistic home wood, tile, spiral staircase Ridge top view, 5.9 acres Two bedroom, 1.5 bath, 12 miles from Olympia, WA 360-264-5391 185,000 Firm

INVERTER-Manufactured by Vanner, model#24-3000TPF, 24 volts, 3000 watts, $500 OBO PO Box 720787, Pinon Hills, CA 92372, 760-868-8830._

ONE ONLY: 10 KW to 17.5 KW Jacobs Smooth Case wind turbine. 1 3/4" Governor, gear head, and Fidelity Alt, 26' Laminated blades with springs these are As Is the Master Mind Inverter has been remanufactured (6 mo. Warranty) and includes a choke. $3200 Pls shipping Joseph Singleton, 1015 Rothwell Rd, Viola, ID 83872 1-208-883-3676_

USED RADIO/TELEPHONES:Skycell briefcase SAT-phone, works all N. Amer $2695 ($4700 new). Two Ritron UHF R/T pkgs $1995 & $1895. One modified 49MHz cordless, 1 mile $600. 208-263-9755 PST

SUN ELECTRONICS is a wholesale/exporter located in Miami, FLA. We're looking for distributors + dealers in the U.S., the Caribbean and Latin America. Like everybody else, "We can beat everyone's prices." I've been in the business of solar energy for 25 years. We've never advertised in Home Power before. Now we're looking to expand into the U.S. Just call us or fax. We carry close to $1,000,000 in inventory, ready to ship at a moment's notice. We carry all the regular stuff from all the typical manufacturers. (It keeps them a little more honest that way) I'd advertise our prices, but we're already disliked enough. Just call us, you'll see why. And don't worry, we actually know how to design as well as sell. Contact: John Kimball (305) 381-6166 Fax (305) 371-2353. E-Mail [email protected] One Exception: VLX 53 Watt Modules $228 ($4.30/Watt). We've got over 600 of them and they've got to go! We're specialists at shipping to Latin America and the Caribbean.

Index to Advertisers

Abraham Solar — 80

ACR Solar International — 103

Advanced Composting Systems — 107

Alternative Energy Engineering — 7 Alternative Solar Products — 33 Astropower — 41 BackHome Magazine — 105

Backwoods Solar Electric Systems

Bogart Engineering — 82 BP Solar — 2 & 3 Brand Electronics — 87 BZ Products — 92 BZ Products — 103 C. Crane Company — 105 China Diesel — 63 Clean Energy — 32 Communities Magazine — 99 Cruising Equipment — 1 Dankoff Solar Products — 24 Delivered Solutions — IBC Electro Automotive — 85 & 99 Electron Connection — 75 Energy Conservation Services — 99 Energy Outfitters — 97 Energy Systems & Design — 32 Environmental Marketing — 83 EPower — 86 ETA Engineering Inc — 87 Exeltech — 50

Feather River Solar Electric — 66 & 105

Golden Genesis Global Distribution

Green Mountain Energy Resources

H-Ion Solar — 91 Harris Hydroelectric — 103 Heaven's Flame — 73 Heliotrope General — 91 & 124 Hitney Solar Products — 82

Home Power Back Issues — 112 Home Power Biz Page — 81 Home Power CD-ROM — 62 Home Power Sub Form — 80 Home Power T-shirts — 80 Horizon Industries — 105 HOTPRO — 85 Hydrocap — 87

Intermountain Solar Technologies — 105

Jack Rabbit Energy Systems — 79 Kansas Wind Power — 85 KTA— 91

Lake Superior Renewable Energy — 104

Lil Otto Hydroworks — 120 Maple State Battery — 90 Midway Labs — 104 Millennium Power Systems — 39 Morningstar — 24 MREA Workshops — 111 Murdock University — 49 Natural Energy Systems — 92 NESEA— 97

New Electric Vehicles — 79

New England Solar Electric, Inc. — 99

New England Solar Homes — 38 New Frontier — 104 Newinli Corp. — 82 Northwest Energy Storage — 51 Oasis — 98 Offline — 98 Pacific Solar — 93 Planetary Systems — 66 Platypus Power — 80 Pulse Energy Systems — 70 Quick Start REading Special — 122 RAE Storage Batteries — 92 Read Your Mailing Label! — 74 Ready Reserve Foods — 90 Real Goods — 62 Redwood Alliance — 74

Renewable Energy Videos — 111

Rolls Battery Engineering — 15

Siemens Solar Industries — 55

Simmons Handcrafts — 120

Small Power Systems — 86

Snorkel Stove Company — 99

Soda Mountain Company — 74

Solar Electric Inc. — 103

Solar Energy International — 71

Solar Pathfinder — 93

Solar Villiage Institute — 60

Southwest PV Systems — 38

SunAmp Power Company — 83

Trace Engineering — 23

Universal Electronics — 90

University of California Press — 92

Vanner Power Systems — 40

Vermont Solar Engineering — 86

Wilde Evolutions — 93

Windstream Power Systems Inc — 85

World Power Technologies — 22 Zomeworks — 90 **>

Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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