Solar Server Question

[cyberblitz]

Ok.. I have a server running 24 hours.. It currently pulls around 150Wh which works out to be around to be 3.6kWh/day..

I had hoped to run it off a set of batteries. But If my calculations are correct, I would need a 1.5kW solar system (allowing for loss) to charge the batteries and I would need 4 x 12volt batteries ... I have no idea if i have these correct. I'd thought the Server would require very little to run...

Please Help...

[cyberblitz]

Really!! No one wants to help!!!

I have been using different calculations but come up with different answers..

Say to find Watts of a 12v 150Ah battery      12x150 = 1800 Watts

That means it could run my server for 12 hours (total depletion of battery) I know there a variances/losses somewhere so this would not be totally accurate, particularly due to load placed upon the battery and it would be really bad to totally drain the battery...

To find Ah of the server presently is 150Watts / 240v = .625 Amperes = .625Ah 

To find the Amps drawn from the Battery = 150 watts / 12v = 12.5 Amperes = 12.5 Ah which again allowing the battery to run the server for 12 hours.... But i know the more drainage of the battery = variances in voltage...

So the setup i thought would be best would serialise 4 x 12 Volt batteries = 48Volts .. this would place a great deal less stress on the batteries..

48v x 150Ah = 7200Watts
7200Watts / 150 watts = 48Hours approx of constant usage...

150 watts / 48v = 3.125 amperes = 48 hours again..

150Ah / 3.125 = 48 Hours again

But is not best to only drain the batteries to approx 80% capacity.. So this would reduce the total constanct usage.. Which only gives me approx 30Ah, allowing for 9.6 Hours of constant usage.. Which would be ok for my needs...


Now what about recharging the Batteries using Solar..... Any ideas!!!!

[cyberblitz]

Well, this forum is not very good is it...... No one is remotely interested in helping you.... After 5 days no one has replied at all!!!!!

[warlock]

Hey dude,

Recharging by Solar is easy enough, you need to make sure that you put more ah into the battery in the sunlight hours than what you pull from the battery over 24hours, depleting the battery to 80% is not a good idea it will drastically reduce it's life span.
Once you know this, then you'll want to have enough battery to sustain your server for the number of zero sun days. this way when the sun does return you batteries won't be completely dead and the server would not have gone ffline.

[MJLorton]

Cyberblitz, read this thread and try the spreadsheet. It should help with what you are trying to achieve.

http://mjlorton.com/forum/index.php?topic=239.0

[zoneblue]

Mate solar isnt magic. The first place to start is demand management. In this case it means looking how you can reduce the power used by the server. 150W is a lot for even a beefy server. My home NAS/web development/mysql/monitering box draws 25W. The latest dual core atom mini-itx boards use about 10W, plus drives.

[cyberblitz]

Hey..

I don't want to deplete the battery by 80% only to 80% capacity, taking only 20% at a time. Any less than this would be useless any more can be damaging...

I admit the server is pulling a lot of power, but this is not ONLY the main server (the main server has 8 x hard drives and 1 x SSD, by the way).. I also have a NAS drive for backup (4x Hard Drives), a UPS, and Network Switch.. All this pulls 150 Watts.... I can't reduce this any more, I've tried...

 I have tried the Spreadsheet and my figures have been correlated.... Thanks...

Just seems a lot doesn't it...

[cyberblitz]

Ok.. After a lot of research, i'm convinced a return on the massive investment would be a long time coming, maybe 5-10 years...

4 x 12v 150Ah batteries would cost approx. - $900-$1000AUD
A decent Charge controller (for future expansion) would cost - $800AUD
Solar Panels (approx. 1.5kW) - Approx. $2000AUD

Then there's the inverter on top, maybe another $1500 - $4000AUD...

That's approx. $5000 - 8000.. Just to run a server... I appreciate expansion would be cheaper thereafter but WOW....

[SeanB]

It probably would be better to use the battery investment in a UPS then, and not use solar unless you want to charge the batteries a little, or use the panels to drive a grid tie inverter to reduce the power bill overall.

[cyberblitz]

I had thought of supplementing the UPS but it would render its main function useless, i.e. as a Back-Up when things go really wrong... The Server will shut itself off gracefully after a certain time if the Mains power is not restored. So, this is not an option. Besides, they are not really designed to run off battery continuously anyway.

[SeanB]

That is why I suggest a grid tie inverter, as then you are using the grid as a battery to store charge for night use essentially. You will need a UPS for when the grid fails, and buying bigger batteries for the UPS ( of course the UPS must support using extra battery banks, look on Ebay for an APC one with a dead battery and buy new ones to place in the unit) will give a longer run time and allow the batteries to run cooler outside the hot box.