Portable Solar Power Plant By N. Bleecker Green Caption: N. Bleecker Green with his portable solar power plant. The self contained unit wheels around homestead with 12 volt power for emergency lights, plus tools and appliances. Home Power Magazine urges readers to try easing off the grid. Richard Perez talks of basicsÄone person, one module. Think big. Start small. Here is my hands-on account of how I built a portable solar power plant. Not big stuff like a whole house system costing big bucks, but one man's approach to easing off the grid, while working with limited knowledge and funds. Cooking and charging I have been cooking my evening meal in a solar oven for several years. Over a year ago I switched all my small batteries to rechargable nickel-cadmium batteries (nicads). Solar charged. Last year I bought a 5 Watt Solarex photovoltaic module. I built a small cart on wheels with a combination back/handle angled at 45 degrees toward the sun. I solar charged a small lawnmower battery for use around the shop. But something was lacking. I wanted more. Then I came across a 10 Watt Chronar photovoltaic (PV) module in a catalog at a good price. I ordered it and started to work. I wanted a self-contained unit, a wheeled cart carrying PV module, battery, controls and meters, plus a 12 Volt outlet and a good radio, in-line fuses and soldered connections. PV Module Starting Point Since the module was 1 x 3 feet, it was my starting point. I built a box of 1/2 inch plywood, four feet long and about 20 inches square. I mounted the box on 15 inch lawnmower wheels, plus a sturdy handle for easy movement. Partitions divided the box into three sections. Keeping Cool in Texas My first concern was the PV module. I did not want a stationary ground mount being plugged and unplugged as the cart was moved around the homestead. I wanted the module riding atop the cart, hooked up and constantly charging the battery. So I cut a piece of plywood slightly larger than the module. It has five cutouts or openings to allow air to circulate around the back during the hot Texas weather. I then mounted the module (3/8 inches thick) flat on this frame, held in place by plastic mirror holders. The frame was then fastened to the top of the box with three hinges. This allows the module to be pivoted to face squarely into the sun whether facing straight up in the early morning or late evening or laying almost flat when the sun is overhead. I had learned a lot about facing and tilting with the 5 watt Solarex module and the shop battery. A short 2 by 4 block helps align pivoting panel to sun. Just swing the panel up or down until shadow disappears. Tinkering was paying off. Manual trackingÄerector set look To hold the module at its proper angle, I fastened two perforated metal strips (1 3/8 inch x 1/16 inch) to the top of the box and bolted them to two small angle irons. I then fastened two sliding door latches to the frame. The bolts on these fit snugly into the perforations, holding the pivoting module securely. Battery in Center for Balance. The 115 Amp-hour RV/marine battery is located in the middle compartment. It's heavy, so placing it near the center of the cart makes for better balance and easier wheeling. It is blocked to prevent any tipping or movement as the cart is moved around. I drilled holes for plastic conduit wherever wiring penetrated the plywood partitions. Simple Control Panel One of my goals was to use some of the basic concepts of large, house-sized solar setups. The polarized plug supplied with the Chronar module serves as an array disconnect. A Sun Selector M8 controller, along with an in-line fuse, is wired between the module and the battery, and prevents the PVs from overcharging the batteries. The fuse protects against overcurrent surges. Another in-line fuse is used on the other side of the battery along with two DC meters for Volts and Amps. Next is a cigarette style double 12 Volt outlet, and finally the Pioneer AM/FM cassette radio from "Old Blue", my retired VW bus. With some paint, the Portable Solar Power Plant was finished and ready for duty. Does it Work? Yes, it certainly does work. It is heavy. Probably more moveable than portable. And the radio gets used the most. The 12 Volt soldering iron has been a help when I could not take work into the house. And the 12 Volt compressor keeps the tires of the van aired for country travel. Other items that work from 12 Volt outlets: an emergency fluorescent light, vacuum cleaner, clip-on and plug-in extensions, nicad battery charger, and dustbuster. The biggest thrill was the test use of emergency lighting. I placed a 12 Volt 15 Watt Thin Lite fluorescent light above one window in my trailer. I then wheeled the Portable Solar Portable Plant under this window and plugged an extension into the double outlet, then snaked it through the open window and into the male plug wired to the light. I Saw the Light I turned this light on. Turned the other lights off. And stepped outside into the dark night. Light streamed from the small fluorescent, making a pool of light on the grass outside. I walked to the right. Then to the left. Down the drive a bit. And then back. I was mesmorized by the glow. Real homemade power. Useful, productive and working power. No connections to the power line. No utility bills here. I was hooked right then and there on home produced electricity. What did it Cost? When I told a friend what the Portable Solar Power Plant cost, he just shook his head. Said to put a battery in a wheelbarrow and that a transistor radio with throw-away batteries would be cheaper. And just put the 12 Volt battery on a 110 volt charger. If you take a short range look as he does, well.... It may cost me more right now, but down the road I'm way ahead. COST CHART Another Small Step Designing and building the Portable Solar Power Plant has given me both the experience and the encouragement to take another step in alternative energy. Lights, radio and a fan in my trailer. The same for the small toolshed/shop I am building. And I'll expand my PV systems: larger module, disconnect switches, load center, and perhaps a small plug-in inverter. It's been a great learning experience. Sort of a miniature PV system: module, battery, controls, meters, fuses, and outlets. Big and small. Practical and theoretical. Watching the amp meter, I learned that a higher volume on the radio does use more current, andI learned which plug-in units draw the most. I learned that the PV module can push up to 14 Volts in the middle of the day. I watched the LEDs on the controller switch from charging to analyzing and back to charging. Almost as if the unit could think. Boosted by all this, I am eager to get started on the next home power project. Just ordered a larger, full sized module. When UPS delivers it to my front gate, I'll be off and charging. Access Author: N. Bleecker Green, PO Box 304, Royse City, Texas 75189 ù (214) 635-2848 Photo sidebar: When I switched to rechargeable nickel-cadmium (nicad) batteries, I tried a variety of solar units. I learned that Radio Shack batteries had low capacity. To get more capacity, it costs more. You get what you pay for. My high capacity (4400 mAh) D cell nicad batteries are used in a Panasonic electronic typewriter. I ended up with a variety of chargers and put them to work for various uses. Battery adapters help pocket-sized solar chargers handle AA, C and D cells. A DC motor is used with various sized battery holders to discharge nicads down to zero and prevent memory effect. SEE Captions for all photos.