Powering a small office [closed]
Currently I am aiding the MoH [Ministry of Health] here in Liberia in potential ICT Solutions for linking up the Districts to the central MoH. The issue is that there is no internet back-bone in the country and currently very little information is being passed to the central MoH; because of a lack of resources and information. The idea is to install a VSat in every county (15). However; all electricity is provided through generators. Is it possible to run a VSat using alternative power (such as solar)? The VSat system will be hooked up to a maximum of 4 desktops and maybe even a server. Ignoring maintenance and training issues; how much power can a solar solution provide for the system? Would 4 computers, server plus peripheral technological equipment be too much for a solar unit?
Potential VSat: C-Band VSat with dedicated bandwidth 1.8 m dish 5 watt transmitter Indoor modem
Closed for the following reason
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close date 2014-02-03 05:17:30.641227
I have successfully powered the VSat itself from heavy duty truck batteries, 1 or 2 dependant upon the actual VSat. This allowed charging the batteries separately from the generator, when it is running. This could also be done with solar on trickle charge to the batteries. As for running servers and PC’s from solar. This is possible, but the size (& cost) of the solar panels may make this not viable. It may be cheaper to run the generator, but protect the computers and servers with a voltage regulator (AGVC) and power them all through a UPS. This would give an element of protection from voltage and frequency variations in the generator. Whatever you do care should be taken to protect the computers from mains powered spikes. In locations where there are huge variations in power (voltage) supply, a better option is to use laptop computers on battery only and have spare batteries. The Batteries can then be charged separately, when not in the laptops. So if there is a problem with the power supply only the batteries on charge will be damaged, not the laptops. Even the server can be run on a laptop. Another couple of general housekeeping points: 1. If the servers are not needed outside of office hours, it is a good idea to shut the servers down and disconnect them from the power supply overnight. It goes without saying that the regular computers should be unplugged from the electricity supply when not in use. 2. If using truck batteries, then the batteries should be topped up with distilled water, NOT battery acid. This will prolong the battery life. Battery Acid should only be used if the hydrometer reading indicates low acidity. (fairly rare in warm climates).
It is perfectly possible to power your VSat and/or your office with solar panels. You just design your setup depending on your consumption. It all depends on how long you are going to use your computers and VSat. It is sad to know that the offices are powered through generators and even more that desktops are used. Generators should only be used to supplement not to power offices.
What you have to do first is make sure that you eliminate wastage from your system. So absolutely no inverters if possible. Also don’t forget: on a 70W panel, you can power 4 laptops where you need up to 4 panels to power a desktop. You can have a laptop for the price of a desktop now. The main advantage is that they come with an integrated UPS (their battery) and you can power them without using an inverter (you have targus power supplies directly feeding from 12V batteries) and you don’t need regulators when they are on mains power (the supply can handle fluctuations of 110V up to 240V). You can bolt them into desk with special locks so theft is not an issue. To be short: by not using laptops you end up spending a lot more money than needed and doesn’t make sense form a technical point of view.
When you buy new computers, make sure you don’t buy the basic version of vista as it only has limited networking capacity.
When you mention the use of a server you probably mean that you want to share the internet system and printers. This can be achieved through one of the laptops and/or by a wireless router. So you don’t need a separate computer to achieve this.
I couldn’t find exact figures for the consumption on the VSat (I read somewhere 2 amps), but it works on 24V. This can be done directly from a 24V solar system setup, ideally separated from your computers. The advantage is that your VSat can then be treated as a priority. The size will then depend on how long you are going to run your system for/ day.
It all depends on the speed and reliability of the VSat. If the VSat is quick, but at some point further down the route out of country goes through a slow trunk route then he will not get a fast reliable link, then Skype will be stuffed, he will need to get advice on the country backbone system, unless his is a direct to sat link.,
The short answer is that it is quite viable to run a solar system to power his office set-up as described, however the best way to do this is to choose equipment that is low power when procuring and to choose equipment that can by design or accident be run from the low voltage output from the solar system (see below).
I did make a solar system to run field offices a few years ago in Sierra Leone, and ran various office equipment. How to do this depends on the budget, I used available solar panels and batteries to produce a 12 volt power system in the offices. I also used lap top computers, printers and other office equipment which used external power supplies which had out put voltages of 12 volts to run the laptops etc and by dispensing with the power supplies and running the equipment direct from the low voltage (12 volt) circuit I had installed in the offices.
Actually I did not get the choice with most of the office equipment and made do with what was provided, however this worked quite well, even though the Toshiba laptops nominally should have had a 16 volt input they ran without difficulty at 12 volts however would not charge the internal batteries while running in this mode.
What Mohammed requires is a larger as a system, and he will need to look at the power requirements of each unit. The VSAT output power is not reflective of the power consumed by the unit, he would need to see the power requirement spec for the particular model. Likewise desktop computers, a traditional server (and probably old style monitors) generally waste a lot of power which becomes a factor when building PV system. If Mohammed has a free hand I would urge a hold on office equipment procurement so that all can be bought to be compatible with a low voltage low power drain system, otherwise he would need to build a large solar array, plus inverter to take it up to 220v AC which itself wastes power, to then run a series of chunky desktop machines which will in turn waste a lot more power and put the price of the solar system up a lot.
Buying equipment that is compatible with a low power (12 volt) system does not have to be expensive, it just means being clever about the device power requirements, ensuring that they will run from a direct 12 volt source. This stuff is not in the manuals, you would source this information by checking the model in question ... (more)
What about using mobile phone technology instead of VSat terminals? They have issues in Chad with internet connectivity but have a reasonable mobile phone network.
Given the ubiquity of mobile phones and the costs associated with VSats I feel confident this would be worth investigating. This link may be a good start.
Would be good to now how you get on solving this.
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