easytim

I'm wanting to build my own solar system that will keep a battery charged to to run a desktop,router and cable modem so I can operate 24/7 on its own. Can someone point me in the right direction where to get batteries, power invertor and solar panels. I'm willing to do what ever it takes. I like the DIY stuff.

THANKS,
easytim

Torben

Canadian Tire sells everything you need. Of course if you don't live in Canada that's useless information. If you filled in your location information in your profile you'd maybe get some more replies. Nobody likes to guess.


Torben

ericgibbs

hi,
Have you measured the current required for theses devices.?

As Torben says, if we knew your location we could give more info.

eg: if you live in England you will need big panels and batteries, not much sun these days, especially for 24/7 operation.

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Nigel's: www.winpicprog.co.uk/
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

easytim

I live in the Midwest

ericgibbs

I hope you get more Sun out there than we do...

I would recommend that you measure the current drawn by each piece of equipment you are using. Let us know the values.

This will give an indication of the size of the panels and the batteries required.

You should also consider the losses in an dc to ac mains output invertor.

Remember some of the equipment probably operates from an external dc psu or could be modified to work from a low voltage dc source, this will reduce the size of the invertor required.

If it must be 24/7 for the full year, calculate the solar panels to suit the reduced sunshine during the winter months.

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Nigel's: www.winpicprog.co.uk/
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

easytim

O.K. cable modem, 8 port netgear hub, D-link wireless router, axis video sever, computer without LCD uses a total watts 252 watts.

blueroomelectronics

That 252W is at 120VAC, solar panels are usually 12V and peak current rated. So you'll need at least 3000W worth of 12V panels. $$$$$
Again that 3000W rating is ideal and not practical unless it's noon on a clear day on the equator.

Here's a 195W panel $1,323 at least it's 55.3V
http://www.outsidesupply.com/browsep...lar-Panel.html

__________________
Bill
Smart Kits build Smart People
http://www.blueroomelectronics.com

easytim

yes, 252 watts at 120 volts

ericgibbs

Using 12V panels/batteries and just for explanation assuming 100% overall.

Thats 252w/12v = 21Amps

At a rough calculation for a 24hr worst case period thats a 24hr * 21A =504AHr battery.!

Allowing for a invertor conversion efficiency of say, 75% gives 504/0.75 =672AHr Battery.

Allowing for a battery recharge efficiency of 60% at a charge rate 21Amps,
just to keep the batteries topped up, 21/0.6 = 36Amps

Allowing for 12hrs of sunshine per day,,, 36A * 2 =72A

Although these calculations are very rough, it would suggest to me that the project is going to be VERY expensive.

You have explained that you need to keep the system running 24/7, can I ask why.?

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Nigel's: www.winpicprog.co.uk/
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

mvs sarma

The attempt of Easytim is really appreciable. I have few suggestions for Easytim.

While on one side the trial for Solar based power kit can be continued, He/she can perhaps support it by thinking around power conservation--
1. Attempt to convert the PC to a Laptop where the power demand falls,
2. Look around for possibility of direct feeding of Dc power to other devices where ever applicable, in order to help reduce conversion losses from Dc to 120V and back to Dc. It will be one time investment and later on help reduce power demand on the solar based power unit.
3. Generally such power plants are designed around a triangular system. like solar, diesel Genset, and public mains. As pointed by other members, during cloudy days etc the genset and public main will support the system.

__________________
Regards,
Sarma.

easytim

Thanks for the help, I need to look at all my devices and see how many are powered by 12vdc. And also think about docking a laptop to use as a desktop.

What part of India are you at? mvs sarma

easytim

Thanks for the help, I need to rethink somethings, 24/7 I think is the best way to run a computer, just for that reason alone. It may not be the best way with solar

mvs sarma

Thanks for indicating need to modify Location data. I have now given a general mod.

I live at Hyderabad (17°21′58″N : 78°28′34″E), Andhra Pradesh, India.

__________________
Regards,
Sarma.

HS3

Running a standard desktop would be wasteful because of the many conversions involved: solar to DC battery to inverter AC to PSU and back to low voltage. Every conversion wastes energy. The best way is to use a laptop which will be fed at about 18 V so you can use a car-air adapter from a 12V battery. This is more efficient and laptops tend to use much less energy to begin with so you will need to generate much less energy in the first place.

I suppose you could find desktop PSU which starts out from 12 VDC but that is rare and will not be cheap.

The Mad Professor

Low power computing is possibble.

Wander over to http://linitx.com/ for some inspiration

they specialise in small form factor computers for automotive use
low power motherboards and PSU's designed for a 12vDC input.

Price wise.. the motherboards are not dirt cheap but you do get bang 4 your buck performance..

Changing over to a Linux operating system such as "Puppy"
also has power saving benefits. I use it on a bootable re-writeable DVD and don't need a hard drive to run, will also operate from a USB flash drive if motherboard supports this as a boot option.

Calculate how much power the HDD alone requires, it may surpise you.

Students of recent history may also recall Win98 from microsoft..
a little heavier than Puppy linux (Puppy is 90Mb / Win98 is around 240Mb)

Well Win98 will install to a USB flash drive and run quite happily even though a tad slower than Puppy Linux. The point is why have the hard drive spinning and using power if it's not actually doing anything?

Puppy by the way is a free download, and Win98.. well there are lots of old copies & product keys about.

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It may seem like a good idea at the time , but never stir your cold coffee with a soldering iron.