The Evans earthship in Colorado is powered by renewable energy and built with recycled and earth-friendly materials.

n iving with renewable energy puts a smile on my face every time I think about it—even more today than it did in 1995 when we first built the Lb PV system for our earthship (see HP59, page 6). We've gone through some adjustments in six years of living off-grid, and we are now sailing comfortably on the high solar desert of the Colorado Plateau.

South-facing windows facilitate passive solar heating.

South-facing windows facilitate passive solar heating.

The newly discovered "energy crisis" masks the real crisis that motivated us to live on solar and wind in the first place—pollution. Moving off coal-fired, nuclear, and centralized hydro power is about ending massive contamination of our air, water, and soils. Conservation is easy once you understand the real issue. As legendary British bluesman John Mayall says, "Nature's disappearing. It's goin' down—do you care?"

The Earthship

An earthship is an independent home built on principles of

It is a beautiful, comfortable, energy efficient, and low impact home.

sustainability. It is made of materials readily available anywhere in the world. It functions as a passive solar house, with sunlight heating thermal mass walls made of rammed earth, tires, and adobe. It supplies its own power from the sun and wind, and collects its own water from the sky with a rooftop rainwater collection system. The design represents an effort to change our methods of living, our ways of thinking, and our understanding of the environment.

While enthusiasm is critical, practical knowledge of how to design and build a home and an energy system to meet your specific needs is not so common. We have, through a combination of diligence, necessity, and trial and error, finally reached solid ground with our renewable energy (RE) system.

We started out with a 1,500 square foot (140 m2) structure and a very modest power system. Over the years we increased the size of the house to 3,000 square feet (280 m2), and gradually rebuilt and upgraded many of our solar-electric system components. Expanding the size of the earthship was in the original plan. The additional size really didn't impact our solar needs, because we continued to follow a "lights on in the space you're in" conservation policy. We have more lights and outlets, but our consumption hasn't changed much.

Water is collected from the Colorado sky by roof catchment.

Home Power #84 • August / September 2001

Recycled tires with rammed earth fill make cheap and energy efficient walls.

Earthen stucco creates energy-storing thermal mass. How We Started

Our original system was of modest proportions: eight Kyocera 51 watt panels, an Air 303 wind genny, and a Trace 2,500 watt modified square-wave U-series inverter in a 12 volt nominal system.

The first big problem from our original installation came with the batteries. The first set, ten T-105s, were used not only in the construction phase to run tools, but during our learning phase, when we made most of our mistakes. I didn't know what "equalization" meant until several years of system use had passed, and we didn't have an engine-generator.

Equalization is a periodic, controlled overcharge to bring all the battery cells to the same level of charge or voltage. This reduces sulfation, mixes the electrolyte, and extends battery life. Equalization of flooded lead-acid batteries requires overcharging the battery until the individual cells reach 2.6 volts per cell. That means 15.6 volts for a 12 VDC nominal system.

Check with the manufacturer for equalizing specifics for your particular batteries. And never attempt to equalize sealed batteries. Overcharging sealed batteries will seriously damage them! In our system, when the batteries began to perform poorly, we added a Generac 4000 engine-generator to the system, and started to maintain the batteries properly.

A Closer Look

The next concern, which then became my primary target, was the charging system itself. The original system was built with an on/off switching device that broke the panel charge off at about 14.2 volts. This meant that we could never equalize with the panels alone, no matter how much sunlight was available.

After numerous discussions with installers, dealers, and various experts in the field, I found an installer (Leif Jewel of Ridgway, Colorado really knows his stuff) who could remove the switch system and replace it with a Trace C40 charge controller. This little wonder brought my PV system back to life. One fully automated, solidstate, pulse-width modulated charge controller allowed me, for the first time, to manage my system with the sun. And my batteries were so happy.

A solar hallway along the south wall connects all rooms.

A solar hallway along the south wall connects all rooms.

Every room receives solar gain.

More Problems

While the system was given new life after this, our loads continued to make their demands, and take their toll on our batteries. One of the culprits an RE system will encounter is the conventional 1/2 HP AC pressurizing water pump. This energy bandit has a significant motor surge.

I literally ran to the voltage meter every time this monster kicked on, like a frightened deer bolting from oncoming headlights. The voltage would get as low as 11.5 V, and under load in the best of times would be 12.2 V. With each passing month, the meter would dip farther into the white zone as the pump began its sluggish mantra.

Natural building materials lend themselves to artistic creativity.

I was desperate for an alternative. One day I discovered Backwoods Solar. The good folks there told me that this was not such a difficult problem to solve after all. With great trepidation and after intense discussions, I

ordered a Shurflo AC pressurizing pump (model #2088594-154, 115 VAC; 0.94 amps maximum. Actual running amps will depend on gpm flow rate). I was so freaked out that I bought two. (One is still in the box.)

Earthship Loads


Total Watts

Hours per Day

Watt-hours per Day

Days per Week

Watt-hours per Week

Avg. WH per Day

Percent of Total

Sun Frost RF-12

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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