House plans, home builders & dreams

Issue No 3:
9 July 2008

Welcome to our third Building Chit Chat.

Here is our news:

• We have decided to only send this newletter every 6 months and to make it longer when we do write it.

• We would like to hear your stories about the planning, construction and completion of your new or remodelled house. Please email us via [email protected]. Prizes will be awarded for the best stories and for the best photos. See Competition for further details.
• We would like to hear your suggestions for Building Chit Chat and for the website in general. Please email us via [email protected].

In this issue, we have an article about:

• Sustainable living.

Sustainable living

The following is an extract from the book called "Getting Started In The Country" written by Stephanie Chambers and published by Earth Garden Books in Australia. Please note that since this book was written, some of the solar equipment available on the market has improved. We are thinking of adding a chapter like this to our e-book House plans, home builders and dreams (also written by Stephanie Chambers). If you think this would be a good addition to the e-book, please email us via [email protected]. Then we will do the necessary research to update it.

Solar-powered electricity

In this section I will explore one of the ways to obtain sustainable power on your property, namely using solar power and a backup generator. There are also other alternatives such as wind power or micro-hydro turbines or a combination of these approaches which you may like to research for yourself.

In some areas in Australia, you can set up a system called a "Green Grid" where you use electricity from the grid when you need it, and where you generate your own alternative power at other times. You can give back to the grid any excess power you have generated. Generally the net result is that you still have very low (or no) power bills to pay. Although the initial set up costs are high, this works well in the longer term and it means you don't need to use a backup generator or have any batteries as part of your alternative energy system.

Assessing your power needs?

A quick way to assess your power needs is to look at your last electricity bill and divide it by the number of days to obtain your daily power consumption. If you want to use power hungry devices such as a deep freeze, then your energy use will probably be very. However, most other electrical devices can be powered by alternative power sources.

You can dramatically reduce your power needs in various ways. For example, most of our energy requirements are made up by cooking, hot water and heating devices. You can cancel these requirements by installing a combustion stove which not only allows you to cook but heats your home and your hot water as well. Another alternative is to install a solar hot water system and a gas stove and gas heater.

Electricity use for refrigeration can be markedly reduced by the use of a special low voltage refrigerator or by the use of a gas fridge.

So if you are seriously considering your options, you should turn off your stove and hot water service and heater and check your electricity meter. Check it again in a few hours and work out your average energy requirements per hour. This will give you an idea of your real electricity needs.

Another way is to look at the electricity consumption details (ie volts and load) marked on your devices and/or their documentation or to ask your electricity supplier or a consultant (eg a solar electricity supplier) to help you calculate your power needs.

Solar power

Solar power is a practical option if you prefer a more environmentally friendly solution to your power needs.

You have to determine your power needs and then work out a solar system to meet these needs.

Using solar power does require more attention than just using standard electricity. You have to regularly check your batteries to make sure that you haven't reached their usage threshold. Usually you do this by checking the voltage is over 12.1 volts DC with lead acid batteries.

If you are using a small inverter, you have to make sure you don't turn on too many appliances at one time or use an appliance with a load greater than the capacity of your inverter.

By investing in control panels and in a generator which automatically switches itself on when your batteries have reached a specific level, you can reduce the need for regular monitoring of your system. However, you still need to check the water level in the batteries occasionally.

The main items you need to purchase are solar panels, an inverter (if you want to use 240 V power), batteries, a battery charger, a regulator and a back-up generator.

Solar panels

Solar panels range in size from 2 Watts to 83 Watts per panel.

If you are only wanting to run two 20 watt 12 V lights, you would need one 40 W panel and an 100 amp hour x 12 V deep cycle battery.

Most people buy a number of modules and arrange them in an array. You can reduce the number of modules you need by using energy efficient devices such as compact fluorescent lights.

You should always pick a spot where no shadows fall on the panels. Generally energy is generated by the panels for an average of 6 peak hours a day in summer.

Trackers or manual adjustment of the panels can allow your panels to follow the sun so that they receive the most sun.

Inverters

The solar modules produce DC electricity with a voltage usually around 17 volts DC. This is high enough to correctly charge a 12 volt battery. You can run 12 volt appliances such as 12 V lights, car radios and cassette players, televisions, 12 V notebook computers etc or you can run 240 volt appliances using an inverter drawing energy from this solar-charged battery. The inverter turns the 12 volt DC electricity into 240 volt AC electricity. Inverters range in size from 200 W to 3000 W (48 V DC).

Some people run a combination of 12 volt and 240 volt appliances. Twelve volt wiring costs more than 240 volt wiring because the wire has to be a lot thicker. That is why a lot of 12 volt power users have reverted back to the old system of only having the wiring to the lights and not back to the switch. In this case, you have to pull a dangling cord to turn on the lights.

The size of the inverter you require depends on the maximum combined load of the appliances you intend to run at the same time. For example, a washing machine has a start up load of 900 watts and a run load of 300 watts. An iron has a maximum load of 1000 watts. To run these sorts of appliances you require a 1200 watt continuous inverter (1500 watts intermittent).

Some people choose to run some appliances (eg television and lights and 12 volt refrigerator) with a small inverter (eg 200 W) and then run the high load appliances such as their washing machine with their generator.

There are a number of types of inverters - sine, square wave or stepped square wave. Sine wave inverters are the most modern wave and provide energy of a similar quality to the standard electricity grid. The older types of inverters can create a background hum with some appliances or other interference problems. All though the modern sine wave is a little dearer, it is the preferred option for most households.

Batteries

You can't simply use the solar power generated by your panels directly unless you are pumping water. However, you can store the power so that you can use it later in batteries (eg so you can run your lights at night).

To determine the batteries you need, you must consider your energy use, the number of days of storage required, energy losses in the system and the depth to which the battery can be discharged.

You cannot use your normal car battery to store the power from your solar unit. You need deep cycle lead acid batteries. You should only discharge deep cycle batteries by 50% of their capacity.

A typical small solar system battery set consists of 2 batteries (each 150 amp hours). A system sufficient to run a normal household generally has 12 or 24 batteries.

What to look for when purchasing solar equipment

The solar panels are fairly hardy and even if purchased second-hand they are generally useable. You have to be very careful when purchasing batteries second-hand as they can be useless if they have been misused.

Your solar power supplier will be able to help you calculate the number of solar panels you require and the best size of inverter for your needs.

Conclusion

Solar power is an option as long as you don't want to use incredibly power hungry devices such as air-conditioners or clothes dryers. For these, it may not be economic to use solar power. As long as you don't mind not using these appliances, the rest of your energy efficient household appliances can easily be run by a proper solar setup.

All the best

Stephanie
Director Merri Mysteries Inc. - New House Building
www.newhousebuilding.com