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Independent Power - How Big a Power System?

This is an area where you need to set goals that fit your circumstances. It's easy to waste money and time either trying to do too much, or get by with too little. If you're like most people you just want to know what to do, and what it will cost. However in order to answer that we need simple answers to a few questions.

The first question is:

How much power do you need?

This is one of those questions that most of us have no clue how to answer. I can get an idea on maximum power consumption by adding up the power requirements of all my appliances, but how often are they on all at the same time. Almost never.

To use our own circumstances as a place to start we have a small home, and we use Empire propane heaters for heat. We also have a wood stove which we use once in a while, but a we use a full size propane stove for cooking, and a propane hot water heater. I am a work-at-home programmer so I have a lot of computer gear running all day. My wife uses a vacuum many times, we have a 4 place toaster, an electric refrigerator and freezer. We also have a 3/4 electric pump for our well, and an electric washer.

Our entire home runs nicely on a single 3600 watt Xantrex inverter!

In your case you may need more power than we do, but the point is that these appliances all run at different times, and that the 24 hour average power consumption is not as large as you might think.

Conservation is Always a Great Idea

We use energy saving light bulbs, and we try to conserve. Our electric appliances are energy efficient. I would advise everyone who wants to be independent to conserve. Independence is much easier to achieve when you minimize your needs. But don't take that too far. We need a good quality of life or life isn't too much fun! Usually you can conserve and still have what you want.

Want a big screen TV? I do. But you can bet that mine will consume as little power as possible while delivering me that high quality picture and sound!

Most homes that use gas for heating use about 15KWhrs per day. That is higher than you should need, but at least this will give a clear starting point. That works out to be an average of about 600 watts/hr average over a 24 hour period. At times you might need much higher power, so you need to figure higher than this, but I'm preparing you for some other ideas to be presented later...

A pair of 3600 watt inverters like what I have, would run nearly any home. They can be stacked to provide 240v single phase power, and are unbelievably reliable. My only failure in 11 years was due to a lightning strike to my solar panels! (I've added lightning protection since then..)

There's a really nice device called a "Kill-A-Watt" that retails for about $35 that you can plug your appliances into, that will track power consumption over time. This can be a real eye-opener. Many appliances have a rating on them that is nearly twice that of their real consumption. When averaged over a day many appliances use much less power than you might think. When planning an independent power system, you can use this information to decide how much power you actually need.

Newer 'energy star' compliant appliances can offer significant savings on electricity. I spent quite a bit for our refrigerator to get better energy efficiency. However, now you can better efficiency and larger refrigerator for a much lower price than I paid a few years ago. Look for a yellow tag on the appliance you're interested in and compare power consumption. It varies a lot!

If you want a good washer that uses less electricity, be sure to look into a tumble washer. Once again compare yellow tags and you'll see that the difference in energy use is substantial. Tumble washers also do a better job of cleaning clothes and clothes last longer because they are take less of a beating during the wash cycle.

What are your Goals?

If you're trying to protect yourself from power outages, then the size of your system is going to be much less than if you intend to supply your own power completely. Let's take a look at a couple different approaches, based on real life situations.

A. You have no power currently, and are starting from scratch.

In this case you might want to start with a 12-20KW water cooled diesel generator so that you have reliable power large enough to run your home completely right away. Such generators vary widely in price, but are currently costing about $5,000 for new and reliable equipment. A good diesel generator can provide many years of reliable service!
Then you might want to purchase good batteries and a good inverter so you can increase the generator's life and keep everything quiet, but still running all night.
After that, you can start adding solar and wind power supplements that gradually reduce your dependence on the generator.

B. You have public power, but you want to have emergency power available..

In this case a smaller gasoline or propane/natural gas generator would do the job. Air cooled is fine, since run time is limited.
In this case the price can be less than $1,000, including a transfer switch and a little help in installing the switch to your power system by a professional. This is something I think every one should consider.

C. You want to go completely to solar and wind power..

This has the highest entry costs, but if you properly size the system from the beginning it is very attractive. You need to do a careful power need assessment, plan on at least 4 days of continuous bad weather when buying batteries, and be sure you have adequate sunshine and wind where you live. You should still have a small emergency generator 'just in case'. We'll talk about this option more later, when we talk about panels, inverters, etc.

Costs for solar panels have been dropping over the years, and quality has been steadily improving. And it's sooo nice to have a totally silent system that has no moving parts, requires no fuel, and extremely low maintenance!

Plan for Growth

Always consider the need for more than you thought in the beginning. I know when we started out we had no freezer and a very poor propane refrigerator. We used a lot less power. However, the power for these things is worth it, and we save money by having these appliances. Always weigh total costs, not just power. Cost and benefit are both needed to arrive at a solid decision.

Set a Minimum Size You Can Live With!

The whole philosophy of being independent requires that you set a minimum threshold that can sustain if all else fails. In our case we have solar panels, and a large wind machine that could sustain us without any other input with some degree of sacrifice. We might not like to do with less, but we can get by. That is an important threshold that can add a lot of peace of mind. I highly advise that you map your strategy to get to that point as quickly as you ca