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High Wattage Off-Grid System Design - 12V System Possible?

High Wattage Off-Grid System Design - 12V System Possible?

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  #1  
Old 01-10-21, 07:34 AM
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High Wattage Off-Grid System Design - 12V System Possible?

Hello, I'm wondering if anyone would be willing to help shed some light on my current project/problem. I am interested in moving a piece of electronics equipment up to my land and setting it up on a small off-grid system(Solar/Wind Hybrid System).

I've attached the specs for the factory power supply, which states that it supplies 12V @ 133A Max(240V). I've ran through some calculations, but only seem to cause myself more confusion by doing so haha. Which is why I find myself here!

My original plan was to use an inverter to get up to 240V, but now I'm wondering if this is necessary. Would it be possible to skip the PSU/Conversion and run this system strictly off 12V(which is what's provided directly to the board)or would I run into issues trying to accommodate that type of amperage at 12V?

Hopefully I have provided all of the necessary information, but feel free to let me know if there's anything missing.

Any and all help is greatly appreciated!
 
  #2  
Old 01-10-21, 09:14 AM
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Curious what load is being driven. But, 133A can be supplied by a couple of 8D wet L/A batteries. For a little while. What kind of time are you needing?
 
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Old 01-10-21, 10:36 AM
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The device is a processor board(Hashboard) out of an old crypto currency miner. The PSU specs that I included above are for powering the entire Miner, which consists of 3x Hashboards and a control board. The board is powered by 3x 6pin PCIe terminals and the control board has a single 6pin PCIe, so 4x total power inputs. My plan/hope is to run a single board and the control board off a pole mounted solar/wind system.
 
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Old 01-10-21, 10:45 AM
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Forgot to mention that I'm not looking for this system to be fully autonomous until down the road. Planning to start with a single battery and only run it when there's ample sun and/or wind. I will then add batteries on over time to increase the Ah's.
 
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Old 01-10-21, 12:29 PM
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What is the distances between:

the solar/wind and the charge controller,
the controller and battery, and
the battery and the load?

With 12V, you'll need HUGE wires to minimize voltage drop and not melt them if you are running 133A. 2/0 wiring is like $3/ft. You'll need bigger conduit and terminal lugs, fuses, etc. So unless everything is within a short distance you probably should use higher voltages.

I think you'd be better off around 48V or higher (or whatever voltage you can series your panels to) and then buck ing the voltage to your load or battery if necessary. Wind turbines are 3 phase AC, so you'd have to rectify that to DC.
 
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Old 01-10-21, 12:46 PM
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Plan was to pole mount all of this(if possible) or an enclosure at the base of the wind turbine mast, so the distances would roughly be as follows:

Solar/Wind->Charge Controller: 10' Max
Controller->Battery: 3-8"
Battery->Load: 3-8"

Starting to think I might be making this more difficult than it needs to be haha. My thinking was "Why go from DC to AC with and inverter, only to have the device PSU convert back down to 12V". Seemed like an unnecessary step.
 
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Old 01-10-21, 02:06 PM
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There's no way around getting around rectifying the wind turbine power. With PV, you can stay all DC. There are MPPT controllers that can take higher voltages and output 12V, so that 10' run from the panels to the charge controller can be done at 60V.

However, I don't know how you can get exactly 12.15V +/- 2% from a battery. The voltage is going to drop with capacity, so you'll need to boost/buck to stay in that range. Even then, I wouldn't trust my DC system over the AC to DC power supply your equipment comes with.
 
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Old 01-10-21, 04:11 PM
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Thanks for the responses and advice. Exactly what I needed to help my brain get moving. Looks like I'll be going with my original plan and grab an inverter. While the 12V system would be possible for one of these, it leaves no room for future expansion. Thanks Again!
 
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Old 01-11-21, 09:54 AM
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For wind turbines that output AC, you can put the batteries very close to the load.

The AC can be stepped up to a higher voltage if needed to get to the load with less voltage drop. Then it can be stepped down to the desired voltage and then rectified (converted to DC) possibly and hopefully once and for all.

For solar panels,, inverting to AC at the solar farm and rectifying at the load is not necessarily wasteful. It is much more efficient to step up to higher voltage to transmit the power any significant distance, and transformers do not work with DC.

Power companies use the same idea. Using New York as an example, power is generated at Niagara Falls at probably a few thousand volts. It is stepped up to probably a few hundered thousand volts to go the distance to Manhattan. Then it is stepped down to the 120 and 240 volts we use. (Detail: there are intermediate step downs, say to around 50000 volts approaching populated areas and to usually around 13000 volts to go under/over the streets to the various buildings.)
 

Last edited by AllanJ; 01-11-21 at 10:14 AM.
  #10  
Old 01-11-21, 10:33 AM
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You touched on it but you need to come up with how much "uptime" you need.
That means you'll need to establish system operating current draw.
You won't get much with one battery.
 
 

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