Off Grid Crypto Mining with 48V, system design

**Mike90250** · 06-30-2021, 10:59 PM

Look into used forklift battery packs. They are made up of +1000ah 2v cells

just to give you a heads up, doing this with solar & batteries will cost several times more than grid powered.

**Fullblast** · 07-24-2021, 10:51 PM

Thank you for the input about the forklift battery. I'm looking into it.

I know it's easier to run miners off of the grid, however I will be moving to an area without power and want to do this for some extra income.

I would like to build a 10,000 watt 48v system to run this. I've been thinking it may be more efficient to run them from sun up to sun down, then scale back to low power mining at night. Theoretically I would not need a massive amp hour battery bank if I ran it only during the day.

I'm trying to understand about wiring solar panels to a 48v system.

Was looking at getting 30 used Canadian solar 335 watt panels (CS6U_33M)

The voc is 46.1, vmp 37.8, imp 9.87

Can I run these panels parallel to achieve 48 volts, or will they need to be in series.

The wattage on the 30 panels is 10,005. Would it be better to run two 5000 watt systems or one, 10000 watt?

If I ran these panels in series, the voltage goes up, but does it decrease the total wattage of the panels?

I understand 12v parallel, still trying to understand 48v.

**Mike90250** · 07-25-2021, 12:50 AM

The voc is 46.1, vmp 37.8, imp 9.87
Can I run these panels parallel to achieve 48 volts, or will they need to be in series.

37V will not charge a 48V bank, so you have to run 2 panels in series. Most large MPPT controllers accept up to 150Voc at their input.

**peakbagger** · 07-25-2021, 06:28 AM

You are about a year too late. Look up a DC Solar trailer. Add some panels and you have all the pieces and parts you need. If you do not need the AC, sell off the inverters.

**Fullblast** · 07-25-2021, 12:03 PM

What am I a year too late for?

If I were to run 2) 37 volt panels in series, wouldn't it make the system 74 volts, then the mppt will regulate it to 48v?

You say most large Mppt controllers accept up to 150 voc on the input.

These particular panels have a 46.1 voc. Does that mean with a 150 voc input Mppt will only accept 3 of these panels?

I'm considering buying 30 of these 335 watt panels.

If I am correct, 30 panels will equal 10,050 watts at 48v. Would this mean I need 10, 150 volt mppt charge controllers?

**SunEagle** · 07-25-2021, 10:06 PM

Originally posted by Fullblast

What am I a year too late for?

If I were to run 2) 37 volt panels in series, wouldn't it make the system 74 volts, then the mppt will regulate it to 48v?

You say most large Mppt controllers accept up to 150 voc on the input.

These particular panels have a 46.1 voc. Does that mean with a 150 voc input Mppt will only accept 3 of these panels?

I'm considering buying 30 of these 335 watt panels.

If I am correct, 30 panels will equal 10,050 watts at 48v. Would this mean I need 10, 150 volt mppt charge controllers?

Uh with 30 335 watt panels you will have a system over 10kw. So to charge a 48V battery bank you will need over 200 amps of CC's to properly charge it. That would probably require 3 80amp MPPT CC's.

**Fullblast** · 07-26-2021, 12:20 AM

Okay thank you. I figured for a 10kw system, the total amps would be 266.1, if they are 8.87 amps per panel. The voc is 46.1, Vmp is 37.8

(For example) I'm looking at the midnight classic 150 controllers. They are rated at 150 volt, 96 amps.

Does the 150 max voltage mean I can string 3) 46.1 voc panels at a time to a combiner box, as long as I don't go over 96 amps?

3 strings of 3 panels, 113.4 Vmp and 138.3 voc for each string. 26.61 amps per string. Total amps 79.83

Is my math correct on this?

Since I'm basically starting from scratch on a higher voltage system, would it be better to go with 72 volts instead of 48?

**robbyg** · 07-26-2021, 01:49 AM

Originally posted by Fullblast

Okay thank you. I figured for a 10kw system, the total amps would be 266.1, if they are 8.87 amps per panel. The voc is 46.1, Vmp is 37.8

(For example) I'm looking at the midnight classic 150 controllers. They are rated at 150 volt, 96 amps.

Does the 150 max voltage mean I can string 3) 46.1 voc panels at a time to a combiner box, as long as I don't go over 96 amps?

3 strings of 3 panels, 113.4 Vmp and 138.3 voc for each string. 26.61 amps per string. Total amps 79.83

Is my math correct on this?

Since I'm basically starting from scratch on a higher voltage system, would it be better to go with 72 volts instead of 48?

There is another well known Solar Guy on YouTube who is trying the same thing and he has basically said he is giving up on it.
I get the feeling that your going to spend a whole lot more money on this system than what you will ever recoup from it.
And yes I know a single BT can generate 50K but I get the feeling from his post he has been running his a long time and had zero return.

**Mike90250** · 07-26-2021, 02:44 AM

> These particular panels have a 46.1 voc. Does that mean with a 150 voc input Mppt will only accept 3 of these panels?

On a warm 75F morning, 3 panels in series gives you138.3v When it's 50F, you might get 149V, but at 35F, you get 157V - which cooks the controller rated for 150. Unless you are i the tropics, and will never get much below 60F, you are limited to 2 panels in series, or move to a 600V, 80A controller .

As tempature goes down, the Voc goes higher. Your panels will have the exact spec on their label, I just typed in some educated guesses

**peakbagger** · 07-26-2021, 11:08 AM

The DC Solar reference is that the DC Solar trailers that got dumped on the market last year had large batteries (two 540 Amp Lead acids) , charge controllers and PV panels and in some cases diesel generators to equalize the batteries all assembled and in one piece for far below the selling cost of the components. Unbolt the arrays and convert to fixed mount, move the batteries, unbolt the electronics enclosure and sell the inverters and the trailer and your net cost is lot less than assembling from scratch. Go on YouTube and search for DC Solar and you will folks that are building large systems out of multiples of these trailers for the same reasons stated.

**Fullblast** · 07-27-2021, 12:23 AM

Originally posted by robbyg

There is another well known Solar Guy on YouTube who is trying the same thing and he has basically said he is giving up on it.
I get the feeling that your going to spend a whole lot more money on this system than what you will ever recoup from it.
And yes I know a single BT can generate 50K but I get the feeling from his post he has been running his a long time and had zero return.

Do you know who this solar guy on YouTube is? There are several solar Mining farms on there.

My thing is, I want to be completely self sufficient with a huge off grid solar system to power a window unit ac, fridge, computer, power tool charging, electric water heater etc.

Whatever power I have left over (should) go to profit, on an otherwise unprofitable solar system, except for saving on an electric bill. So why not use a solar system to generate additional income and help pay back an investment that I wanted anyway. If it doesn't all pan out, I still have a solar system.

**robbyg** · 07-27-2021, 02:13 AM

Originally posted by Fullblast

Do you know who this solar guy on YouTube is? There are several solar Mining farms on there.

My thing is, I want to be completely self sufficient with a huge off grid solar system to power a window unit ac, fridge, computer, power tool charging, electric water heater etc.

Whatever power I have left over (should) go to profit, on an otherwise unprofitable solar system, except for saving on an electric bill. So why not use a solar system to generate additional income and help pay back an investment that I wanted anyway. If it doesn't all pan out, I still have a solar system.

Yes but he runs a competing forum so mentioning the name or place would probably not go over well.
In any case he only mentioned it briefly in one of his videos on another topic as he was panning the camera over his property and pointed out a bunch of panels that he is using for that setup. He then stated that he is thinking of giving it up and using the gear for something else. I don't think he would be giving it up if he had mined even a single coin.

**azdave** · 07-27-2021, 07:57 AM

Originally posted by Fullblast

Whatever power I have left over (should) go to profit, on an otherwise unprofitable solar system, except for saving on an electric bill.

You say you need 3250 watts continuous power 24 hours a day for mining. Even with a large off-grid system in place you will not have that kind of "excess" power sitting around unused on most days. That is a major design parameter that must be factored fully, just like the A/C unit, refrigerator and the electric water heater you mention in your recent post. You would be far more likely to strike it rich by playing the lottery each week but as I always say, "You can't lose if you don't play".

I don't get your comment about "except for saving on an electric bill". An off-grid system is not going to save you money compared to being on the grid.

**robbyg** · 07-30-2021, 01:37 AM

Originally posted by azdave

I don't get your comment about "except for saving on an electric bill". An off-grid system is not going to save you money compared to being on the grid.

Well that does kind of depend on what your power company charges per KWH of usage. Another factor is how much DIY effort your willing to do.
If you are making your own packs from EV batteries you can get a pretty big bank of batteries for a fairly low cost but it's going to be a lot of work form start to finish.

Off Grid Crypto Mining with 48V, system design

Off Grid Crypto Mining with 48V, system design

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