E-News Issue #14
New ProductsThere are a few new products which may be of interest. A larger version of the SE10 Sine Wave inverter has been released. It is called the SE12. The 12V version is rated at 600W continuous and 1500W surge while the 24V unit does 700W continuous and 2000W surge.
We've also released a PIR Motion Detector capable of switching 100W. Both 12 and 24V versions are available. It only draws 6mA on standby and the Time On can be adjusted between 5 seconds and 12 minutes. These are very handy for switching on verandah and driveway lights etc.
The Air 303 Wind generator is being upgraded with a new model and the price has gone up by about $50.
Please let me know if you would like any more details about these new products.
DC or AC LightingI've been asked to discuss the pros and cons of 12/24V and 230V type lighting. The advantages of 230V type lighting are mainly that they are cheap, readily available with a large variety of shapes, sizes and types. A further advantage is that they use conventional wiring which is understood by electrical contractors. Some may see this as a disadvantage if you want to do your own wiring. The disadvantages are that you have no lights should the inverter fail; you have to buy a larger and more expensive inverter than you otherwise would need if you had 12/24V lights; and a loss of efficiency.
The loss of efficiency relates to two issues. With incandescent globes, the higher voltage ones need a longer and thinner filament. Consequently low voltage light bulbs are more robust and can be run at a higher temperature because they aren't so fragile (e.g. halogen lights are 20 - 30% more efficient). The other issue relates to the efficiency of the inverter. On average, you might expect a 15% loss through the inverter. However, this could vary considerably depending on the inverter model and how well (or badly) it is loaded in relation to its efficiency curve.
The advantages of 12/24V lights are their better efficiency and they aren't reliant on an inverter. One can argue that the lower voltage is safer, however they should still be adequately fused as even a 12V fault can cause a fire! However, the wire needs to be heavier and arguably this can become uneconomic in large houses, schools etc. Another disadvantage is that they tend to be more costly and the range and availability is smaller than conventional 230V type lights.
To conclude, we usually recommend 12/24V lighting unless it is a large building and system. In these 'larger' situations, the cost of 12/24V wiring would get too high and the inverter would tend to be running all/most of the time anyhow due to all the other 230V loads.
Lastly, for 'medium' sized installations, remember that the wire size for 24V is quarter that for 12V!
That's all for this month folks! Don't forget to send us your comments and questions.
Cheers from Dave and all the RPC crew.
Dave Lambert (Director)
- Issue #92 - 06/12/2005
- Issue #91 - 15/11/2005
- Issue #90 - 20/10/2005
- Issue #89 - 29/09/2005
- Issue #88 - 01/09/2005
- Issue #87 - 29/07/2005
- Issue #86 - 04/07/2005
- Issue #85 - 03/06/2005
- Issue #84 - 05/05/2005
- Issue #83 - 01/04/2005
- Issue #82 - 03/03/2005
- Issue #81 - 23/02/2005
- Issue #80 - 02/02/2005
- Issue #79 - 05/01/2005