The following is an article published in 1989 in Home Power Magazine and posted here with their permission. Some of the info is a little dated but the concept is still quite valid. -DCK http://www.homepower.com

Emergency MicroPower Systems

By Richard Perez

Earthquakes, hurricanes & tornadoes happen. And when they happen big-time, the power goes out. And when the power goes out so do lights and radios/TVs. When Nature goes nuts, an emergency micropower system (EMPS) provides electricity for essential services like lighting & communications. It can make the difference between sitting in the dark and wondering what will become of us, to sitting under a light and listening to what is actually happening.

Why me? An often heard phrase in disasters is, "Why me?". The recent San Francisco earthquake left many people without power for days. Some of the folks surviving the recent hurricane in South Carolina are still without electricity. The earthquake edition (published on generators) of the San Francisco Chronicle mentioned our humble publication, Home Power, and suddenly we were overrun by folks in the Bay Area wanting information on site-produced electricity. While I have no answer for "Why me?", I do offer information that will allow you to contemplate this question in the light while listening to the latest disaster news on the radio or TV. The time to get an emergency micropower system (EMPS) is now, before you need it. As you may have noticed, Post Office and UPS deliveries are slow in the middle of natural disasters

The EMPS An emergency micropower system is designed to supply essential services. We are not talking about running the freezer or the 27" color TV here, we are talking powering up a small light and a radio/TV receiver indefinitely. Emergency power systems come in all sizes to meet all needs. The one we are suggesting here is designed from a minimalist approach. It is small (fits within a 4"X12"X16" box), light in weight (less than 10 pounds) and totally powered by sunlight. The EMPS consists of three basic components. One, the PV panel which converts sunlight directly into electricity. Two, the battery which stores the electricity. And three, the appliance. A diagram of the system is shown on the next page.

The PV Panel The photovoltaic (PV) panel sources the energy for this system. It doesn't matter if the electrical grid has failed, all we need to do is to place the PV panel in the sunshine. The PV panel used in the EMPS should be portable, making it easy to move around to catch the sun. The Sovonics flexible PV panels are ideal for this purpose since they are small and light in weight. The panel we used as an example is a SunPal Model 105 that is 13.5 inches by 9.9 inches and 3/8 of an inch thick when folded and weighs only 2 pounds. It produces 0.35 Amperes at 15 VDC under full sunlight. Now, this is not a lot of power, but it is enough to source a small light and radio indefinitely. Larger Sovonics flexible modules are available should your EMPS plans include higher powered appliances.

The Battery The type and capacity battery depends on the amount of electricity you wish to consume and the length of time you wish to run without recharging. In the photo we have shown three types of 12 Volt batteries- a lead acid gel cell, the new Ovonics nickel-hydride battery and a nickel-cadmium battery pack. Twelve volts DC is the best choice of system voltage for EMPSs because all the gear will interface directly with automotive and portable equipment.

The Lead-Acid Gel Cells The major advantage to the gel cells is capacity. The one pictured in the photo stores 6.5 Ampere-hours at 12 VDC. This gel cell battery (a Panasonic #LCR12V6.5P) weighs 4.85 pounds. Gel cells are available from 1 to over 40 Ampere-hours. They are totally portable and sealed. They will run just fine upside down (don't try this with your car battery).

The Ovonics Nickel Hydride Cells This is a new battery technology developed by the innovative folks at Sovonics. It is a variation of the nickel-cadmium cell that uses no toxic cadmium. These cells also have about 75% greater electrical capacity than the same sized nicad cell and NONE of the memory effect associated with the small nicads. This pack was composed of ten nickel hydride "C" sized cells in series. The pack shown in the photo stores 3.4 Ampere-hours at a nominal 12 VDC. The battery pack is 1.5 inches by 3.25 inches by 6.5 inches and weighs 2.5 pounds. This pack comes in a plastic box with a female auto cigar lighter receptacle.

Nickel-Cadmium Cells The nicad battery pack shown in the photo is a shrink wrapped collection of 10 @ series connected "D" sized nicads. The electrical capacity is 4 Ampere-hours at 12 VDC. This pack weighs about 3.5 pounds.

Lighting, Radios and TVs The effectiveness of your EMPS will greatly depend on the appliances you use. The design criteria here are essential services- a small light and radio/TV receiver. The smallest system uses the Ovonic 3.4 Ampere-hour battery sourced by the small 5 Watt Sovonics flexible PV panel. This system will supply enough power to run a car dash lightbulb (about 0.22 Amperes consumption) and a transistor radio (about 0.10 Amperes consumption) virtually indefinitely. Choose the light for your EMPS carefully. Power consumption should be low, on the order of 3 Watts or less. The same goes for the communications device-either radio or TV. Efficient 12 Volt communications gear is commonly available. For example, here on Agate Flat we use a Panasonic 5 inch, B&W TV that uses 12 VDC directly and consumes only 4 Watts (*0.3 Amperes at 12 VDC). If you choose your light and comm gear carefully, then this system will power everything as long as you keep the PV panel in the sunshine.

To Invert or not to Invert? If your EMPS plans include 120 vac appliances, then include a micropower inverter to convert the battery stored 12 VDC into 120 vac. Shown in the photo is the Statpower 100 Watt inverter and the PowerStar 200 Watt inverter. Both work well on small batteries and will provide 120 vac wherever necessary. We've powered all sorts of 120 vac appliances form these microinverters. Don't let their paperback book size fool you, these units will power 120 vac lights, computers, printers, tools, radios, VCRs, and other emergency essentials like the coffee grinder.

Using the EMPS All the EMPS gear can be stored in a small box in a closet, ready for when it's needed. The battery can be floated on the grid via a battery charger (supplied with the Sovonics setup). This means that the battery is always full and ready for action. The EMPS should have modular plugs to interface with automotive stuff. This is the reason all the gear pictured is equipped with car cigar lighter plugs. One of the nice features of the EMPS is that you don't need to wait for a disaster to use it. Karen and I use the panel and batteries in the photo to power a light and ham radio gear when we go backpacking or camping. There is nothing like a light in the tent at night and talking to our friends on the 2 meter ham radio transceivers. Just lash the panel to the top of the pack frame during the day, hook it up to the battery within the pack, and have a light and radio at night!

EMPS Cost & Access An EMPS will cost between $250 to $500 depending on PV panel size and battery capacity/type and whether you use a microinverter or not. This is cheaper, lighter, more portable and infinitely quieter than a generator. And it keeps going when gasoline is a memory. Emergency MicroPower System equipment is available from just about any Home Power advertiser. I urge you to support your local installing renewable energy dealer!

-- Don Kulha (dkulha@vom.com), August 02, 1999