Newsletter Archive

Computers

We have received several inquiries about the power consumption of LCD type monitors. I recently bought one, so I have updated our information about computers.

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 computers (without the monitor). The results were:

286 vintage 27W
386 DX 43
486 and 2 drives 40
Pentium 51
Pentium II 56

We also tested several monitors.

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

In April 2001 we measured three Pentium III computers in a shop with 15, 17 and 19” monitors. They all used about 125W measured on the AC side.

The wattage of the following systems (with monitor on) was recently measured on the DC side of the inverter. (Selectronic sine wave).

Pentium 100 & monitor 120W
AMD K6-2/450 & 15” monitor 112W
Pentium 200 & 15” monitor 117W

I recently purchased an AMD 1300 MHz computer with 20GB hard drive, CD writer, modem and 15” LCD monitor. While running as the only load on a 1600W Selectronic SE22 inverter the computer without the monitor used 120 Watts but only an additional 80W if used while the TV was on. The 15” LCD monitor used an additional 12W.

Apple computers used similar amounts of power. Without the monitors, we have been given the following figures:

Apple Power Mac 7600/132 - 75 watts
Apple Power Mac 9600/232 - 95 watts
Apple Power Centre 120 - 65 watts

So to conclude, we would suggest a desktop computer will use 50 – 70W plus 60 – 80W for a monitor (12W for LCD) plus inverter losses of 10-30% (depending on the size and efficiency of the inverter and whether or not other loads are on at the same time).

The other option is to consider a lap top. In general, we have found that these draw about 1.8A @ 12V (about 24W) on the DC side. One problem is that most lap tops run on something like 18V. We've found the easiest solution is to run the lap top off our micro inverter which retails for AUD$121. So a lap top is in the order of 8 times more efficient than a standard desktop. This means that one 60 - 80W panel could run your lap top for 8 hours per day. Unfortunately, lap tops have some limitations and are more expensive to buy and repair than desktop units.

Your comments and questions are most welcome; however there is no need to send our newsletter back to us when you reply! If you would like a price or product information, please tell us which country you are from if is not evident from your e-mail address. This allows us to assess if local GST (tax) is applicable or whether 230 volt 50HZ products will work in your country etc.