Entries Tagged 'Performance' ↓

Most Tasmanian homes are suitable for solar energy.

All you require is an unshaded roof facing roughly north (any aspect between north west and north east will give good results). Even an Easterly facing roof can work without too much loss of efficiency.

The solar collector should be mostly unshaded by large trees and buildings, especially between the hours of 9 am to 3 pm.

If your roof aspect is very limited, there are always solutions. An offset frame can be installed, or in some cases, it is possible to face part of the system in one direction, part in another.

(Some houses do get too much shade for adequate solar gain. If your house has limited solar access for some reason, then consider installing a hot water system driven by a heat pump technology. These are extremely efficient and will reduce your hot water bills by a similar amount.)

This largely depends on the size of the solar system you install. You can roughly work on the basis of 10 litres of water storage for each solar tube that you install.

For Tasmanian conditions, we recommend a minimum cylinder size of 250 litres if you install a smaller (20-tube) solar system and 315 litres if you install a 30 or 40-tube system.

If you fit a smaller cylinder, you may have hotter water, but less of it, and you will lose some system efficiency.

If retrofitting to an existing smaller cylinder (say 170 litres) you can expect some loss of efficiency. However, this is not advisable if you install a larger solar system because you will waste much of your solar gain.

A larger cylinder will enable you to store more heat during periods of inclement weather and will enable you to maxi mise the efficiency and solar gain from your system.

In Summer months you can expect most of your hot water supply to come from the sun (about half the year).

But the technology works well in cooler climates too, and you will get significant heat even on cooler days that have light cloud cover, so expect solar gain throughout the year.

While evacuated tube technology works efficiently even on very cold sunny days, keep in mind that the solar intensity is 5 times less in Winter than in Summer.

For this reason, it is best to optimise your system for Winter conditions by tilting the solar tubes to a slope of 45 degrees. By doing this you will get maximum efficiency in Winter whilst avoiding excessive heat wastage in Summer.

Low cost stainless steel frames are available if your roof is not steep enough.

(In Summer, you can expect to get 25kWh of heat per day from a 30tube array, whereas in July you can expect 5kWh per day on average. Even in the winter, it is possible to preheat the water to 40C or more if the sun comes out. The booster will then take it up to your desired temperature.)

By way of example — a 270litre cylinder of water heated to 65°C will hold around 14.3 kwh of energy storage. (This is equivalent to running a 1 kilowatt heater for 14.3 hours.)

The Apricus system will boost the cylinder temperature to 80°C, so a fully charged hot water cylinder will give you ample heat capacity for a typical home.

Yes.

You can markedly reduce electric boosting by installing a timer or by manually switching it off in fine weather. This way you can prevent the electric booster kicking in at times when it is not appropriate (such as just before sunrise).

There are many other ways you can improve the perfomance of any hot water system, by building an insulated box around the cylinder, dropping the booster thermostat to 60 degrees (so that it does not cut in unnecessarily), by making sure your hot water pipes are insulated.

Go to Sustainable Living Tasmania’s website ( ) to see the many and varied ways you can save energy in your home.