Newsletter Archive

E-News Issue #31

May 2, 2000

SE42 Inverter

This new Selectronic inverter is now available. The retail price is AUD$3800 or $4095 if you want the energy management module. A leaflet is available on request.

Large Trojan Battery

We've added a larger traction battery to our range. It is rated @ 438Ah at the 100 hour rate. Weight for a 12V set is 120kg. They come with handles.

Computers

This is our longer article for this month.

Computers are very much a part of our modern society even for many people living in the bush. Consequently, we are often asked to design systems for people wishing to use renewable energy. For the home or small office there are two main choices - a conventional desktop or a laptop. We have measured the power consumption on the AC side of a number of desktop computers (without the monitor).

The results were:

PC only
286 vintage 27W
386 DX 43W
486 and 2 drives 40W
Pentium 51W

We also tested several monitors:

Screen only
14" monochrome 19W
14" colour 60W
15" colour 80W

The wattages of the following systems (with monitor on) were recently measured on the DC side of the inverter (Selectronic sine wave):

Full systems
Pentium 100 & 15" monitor 120W
K6-2/450 & 15" monitor 112W
Pentium 200 & 15" monitor 117W

So, to conclude, a desktop computer will draw around 120W. Depending on where you live, a rough guide is that you'd need an 80W panel to run such a computer for about 2 hours per day.

The K6-2/450 uses about 40W when in standby (with monitor, hard drive & CPU fan off), and around 60W when operating, but with monitor on standby.

The other option is to consider a laptop. In general, we have found that these draw about 1.8A @ 12V (about 24W) on the DC side. One problem is that most laptops run on something like 18V. We've found the easiest solution is to run the laptop off our micro inverter which retails for AUD$100.

So a laptop is in the order of 8 times more efficient than a standard desktop. This means that one 60 - 80W panel could run your laptop for 8 hours per day. Unfortunately, laptops have some limitations and are more expensive to buy and repair than desktop units.

It is not cost effective to convert computers to run directly off 12/24V DC. The other problem is that such a conversion would usually void the warranty. The good news is that we've generally found computers to run okay off modified square wave inverters.

Cheers from Dave and all the RPC crew.

Dave Lambert (Director)

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We install solar systems in Northern NSW and Southern QLD.


QLD:
Gold Coast (from Coolangatta to Southport), Nerang and Hinterland (Beaudesert) and out West (Warwick, Stanthorpe, Killarney)


NSW:
Northern NSW (Tweed Heads to Yamba, including Evans Head, Byron Bay and Ballina); the Far North Coast Hinterland (Grafton via Lismore to Murwillumbah) and out West (Casino to Tenterfield, including Drake and Tabulam, as well as Woodenbong and Bonalbo)

For larger system we also go up to Brisbane or down to Coffs Harbour and even Glen Innes. Other places by arrangement.