Using Solar Power In Joshua Tree National Monument Michael Johnsen c. 1993 Michael Johnsen Over the Thanksgiving holiday I attended an annual gathering of climbers, naturalists, and environmentalists in Joshua Tree National Monument in southern California. A friend offered me a cheap round trip ticket (non-stop to boot!) and I couldn't refuse. A week in the desert sounded like the perfect break from Washington DC's city life. I only had a few weeks to get things together. In addition to climbing, hiking and relaxing, I planned on testing some simple solar equipment I had compiled from my meager salary. Not wanting to bring the city with me, I kept the gear simple and functional Ä just a few small panels. The main photovoltaic panel, a 10 Watt Solarex MSX-10 Lite, measures about 10.5 inches by 17.5 inches. I could plug this panel into a 12 Volt AA battery recharger, laptop computer, or tape player. In addition I had a few smaller panels for AA battery recharging packed away. I unified my battery needs to all AA type. I tossed my four nickel metal hydrides (NiH) AA cells from Harding Energy Systems and four Golden Power AA Nickel Cadmium (nicad) cells into my carry-on luggage along with a diverse collection of jazz, industrial dance, and classic rock cassettes. The jazz played on... Over the few days I was there I used the the equipment and learned a few things. First of all, I was completely satisfied with the nickel metal hydride batteries. I could get well over 5 hours of continuous cassette play on my Walkman with two AAs, even with the phantom load LCD clock. I used a Petzl headlamp for light, which requires 2 AAs, and could count on powering the halogen bulb for over four continuous hours. The tape player boom box ran on six AAs (four NiH cells and two nicad cells) and ran for about 2 hours. The small battery chargers worked OK, but I didn't like to take the chance of not getting the full charging time. I usually slapped the dead batteries into the 12 Volt charger, powered by the 10 Watt panel, which recharged 4 AAs in a day's worth of sun. I wanted to make sure that the nicads were fully charged before sundown to prevent memory effect. Sintered-plate nicads, such as flashlight batteries, must be fully charged and discharged to retain their full capacity. Nickel metal hydride batteries don't suffer from these memory problems. The panel also had no problem powering the nine Volt tape player boom box. I used a cheap DC voltage regulator which allowed me to plug the 12 Volt panel into 3-12 Volt DC appliances. With the panel putting out over 15 Volts, even in the waning afternoons with decreased sun intensity, the jazz played on. Future Designs To improve my setup, I'll develop a small, lightweight battery bank, something like the "power station" Real Goods is carrying. I think I could design and build a better one tailored to my needs, using the nickel-metal hydride batteries. I could probably get rid of the smaller chargers, although I did use one that I modified. I added a small Solarex panel (2 inches by 4 inches) in parallel to shorten the charging time. I might need to streamline the 12 Volt battery charger Ä it was bulky and didn't need to be. A flexible, zippered, fold-out amorphous panel like those made by Sovonics would be nice, but to get the same kick it would need to be larger. In this situation my applications were not complex or difficult. The main objective was to shape the power generation around my current energy use, not create a larger load just because I could generate more power. I probably could have used a smaller panel, but I have a tendency to "over-power" systems to make sure that I am charging at full force even on partially cloudy days. Take the sun with you! As we enter "cyberspace", a future littered with portable technology, information, virtual reality and nano-technology, the need for portable power systems will increase. Solar power can make a strong stand in the portable energy field as many people find themselves working with computers and instruments in the outdoors and other unusual situations away from the plugs of everyday life. My trip to Joshua Tree not only reaffirmed my connections with nature, but also reassured me that technology can help us lead lower impact lifestyles. It is also nice to know as I type this in overcast Washington DC, that my walkman, playing Dee-Lite's latest CD, is running on sunlight gathered in the California desert. Access Mike Johnsen, c/o Greenpeace, 1436 U Street, N.W., Washington DC 20009 ù 202-319-2412