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Powering Your Home

One area of home design, that I don’t believe I have covered adequately, is the necessity of services, and how they can be provided under different circumstances.

For your house to be livable, with most modern amenities, electricity is quite important as most other services depend on it to some extent.

Electricity can come directly from the electrical grid, provided to North American homes as 120/240 volt alternating current, at a frequency of 60 hertz. The utility company may want to know if you expect to use an unusually large amount. You need to know the point from where your hookup will be sourced. You may have choices such as an underground service, overhead, or a combination of the two. A direct overhead connection will likely be the most inexpensive. But your homes service entrance will have to be placed so this is possible. Allow for that in your planning. Check with the utility company before committing. The utility may, or may not, have an original connection charge. If your site is outside of an urban area you may be faced with a substantial capital cost for a grid hookup.

If you are too far from the grid for an affordable hookup, or simply want to be independent of increasing grid and electricity rates, the calculations are more complicated. Whether or not it makes economic sense, to provide some or all of your own electricity needs, depends on many factors. I have little direct experience with these systems, but have done a lot of research and feasibility studies so the following should be of some value to you. I am providing multiple links to give you added help.

The first thing you will need to determine is what your power needs are expected to be, for now and the foreseeable future. The simplest calculation is simple to add the usage from your current electrical bills and adjust for any changes. Usage will usually be calculated in kilowatt hours (1000 watts for one hour). Watts or kilowatts will be the units describing load or supply. If calculating the load represented by each appliance, you may have to convert from amperage draw. Watts are amperage multiplied by voltage (usually 120 volts in North America, but may be different in other areas). A joule is a measurement of energy equal to one watt for one second if you need that conversion. 3600 KJ would be a KWH.

For comparison you will also need to know your current and future expected electrical costs and rates. This will be comprised of two parts, often separated on your utility bills. One is the fixed or grid delivery costs, charged whether you use electricity or not. This cost will probably rise with inflation and could have increases related to grid upgrading, government regulation and taxes. The other is actual usage multiplied by the electrical rate. Usage is somewhat in your control but rates can be subject to wide swings, sometimes weekly. They are influenced by spot price markets, the utilities contracts, government regulation. Recently, government regulation is having a greater and greater effect. Check some of the most regulated markets as a guide to what is possible.

Location is an important consideration. You should first determine if incentives such as grants, tax credits, or rebates are available from any of the government sources. The type of incentive is important. Tax credits may not be worth anything to you. Rebates require an upfront investment. Grants usually have special qualifying rules. Some Alberta, Canadian, U.S. and Australian sources. Do not neglect any level of government. Some areas may have a mandated feed-in tariff that will pay for some of your surplus generation, if you choose to remain connected to the grid as backup.

It is also important to determine what alternate sources of energy are practical for your location. Options include solar, wind, small hydro, and a few other less common sources. Solar depends on year round sunlight being dependably available. Wind is an option in many areas, if you have enough land area for siting without undue impact on your neighbors. Hydro, of course, requires a reliable source of running water within reasonable distance.

Calculating the suns position at different times, dates at your locations is needed to estimate panel efficiencies on the days of least sun and calculating the angle of your mountings. Most important in high northern or southern latitudes. Since batteries are expensive, it is probably best to plan generation and backup generation sufficient for your needs on the lowest output days. Batteries used to even out daily use and variations in cloud or wind. Storage for seasonal variation is likely not practical.

All types of generation will require storage or backup, usually batteries, a grid connection or both. Without a grid connection, enough storage is needed to cover your peak loads and also to cover periods of low generation. Batteries will likely be needed if you expect the system to work during grid outages. Backup generators, or a grid hookup, can reduce the amount of battery storage needed and the size of the generation method. Fuel for backup can be a major factor. For lower cost and less maintenance, natural gas fuel may be the best option, if it is available. There is the possibility that an electric car could change the economics and perhaps even provide extra battery storage in some instances. To lower overall cost, the efficiency of your appliances, lighting and other draws are extremely important. Powering some high draw appliances with an alternative to electricity is possible. Examples would be, a gas range, gas clothes dryer and gas hot water heater. Even propane refrigerators are possible. If you are in a sunny area where frost is rare, a solar hot water heater may be an option.

It is obvious that alternatives to conventional electrical hookups is comparatively costly. It will take careful accounting to determine if payback times are reasonable. Do not neglect maintenance and replacement costs, capital cost, or the monthly grid costs if you choose to remain connected. With your own system, your electrical costs should remain more or less fixed, while grid costs are subject to fluctuations. There are non monetary considerations. You may be replacing some high carbon, high pollution source. There are a lot of ROI (return on investment) or payback calculators available on line but many are from organizations with a bias. To avoid being misled, it is probably better to develop your own spreadsheet. Make sure to save it so you can update as things change.

Probably the hardest calculation is the effectiveness of any system. Clouds or fog can reduce solar generation for several days at a time. Wind speeds can fall below needed levels for long periods. The suns inclination, and a shortened day, is a larger effect the farther you get from the equator, and can severely reduce the effectiveness of solar panels in northern areas during winter months just when you need it most. A tracking system can increase efficiencies considerably, but increases costs. There are tables available to help you with these calculations.

If you are in an urban environment, rooftop solar panels may be your only alternative option. You will need to determine if you have enough unshaded southerly facing roof area. This may determine whether you need a grid hookup or not.

I have run the numbers for my own situation. Low usage, low electrical rates, a northern location, shade, and the absence of reasonable feed in tariffs or incentives made it uneconomical to install my own system. Things are changing rapidly, however. Incentives are coming. Rate increases are inevitable due to the retirement of coal fired power plants, carbon taxes and other government regulation. An electric car might change the figures, if it can be charged during the day. Costs of solar installations are falling. I will have to do my calculations again, soon.

If alternate systems cannot be made to make sense, addressing the electrical efficiencies of your home is another way to lower costs. It may even make alternatives work.

In my next post I will discuss some of the other required services.

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