144 kWh per day off grid system

AntronX

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Ok, GPU cards and host PCs need 12V dc. This already removes the need for DC-AC inverter and saves you about 20% on your battery and solar size required due to removing inverter and PSU losses. I guess you have multiple GPU rigs. Try converting one to DC supply and solar. You can get away without battery by feeding output of solar charge controller directly to 12V dc bus together with grid powered power supply in parallel. This way it becomes effectively grid supported but partially solar powered mining rig. But you can only offset <50% of energy usage that way. Going with battery will not save you much money and requires large up front investment. Your best bet is to try going DIY permited AC grid-tie solar with interconnect agreement if you can get 1:1 net metering. Storing and discharging 1kWh of energy in cheapest DIY LFP battery will require $200+ investment and will provide 1 - 3k equivalent cycles depending how lucky you get with your battery supplier. That comes out to 6.7 - 20 cents per kWh battery stored energy cost. If you have full net metering then you get "free" battery from the grid.
 
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sunshine_eggo

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It seems most things I’ve read recommend to think with my end goal system in mind.

I usually preach that.

I keep getting stuck with how can I further add on to scale the system, if I did start small, without increasing the overall cost of the total project. Like having to swap out inverters and batteries and do-overs. It would be good and wise if I could just scale up as long as the sum of the scales equals the sum of the end goal system. Is it possible to start smaller with lets say a quarter of capacity on solar for my system specs?

Get the big inverter and add batteries/panels/MPPT as you can. You can always fall back to AC input if you need to, but you may want to make provisions for any issues on the switchover - about 20ms.
 

Supervstech

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You could also look into grid feedback solar, instead of buying 50K in batteries, have the 30+ solar directly feed the grid reducing your grid usage, and back feeding your power.
It may not eleminate your bill, but it may drop the daytime draw, and lower the overall bill.
 

sunny1972

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144kWh is the anti-thesis of an entry level DIY project.
Must say, I looked at this and thought, cricket - I need to up my game as a beginner! My system produces 2Kwh / day if I am lucky :-D

Fair play though, there are levels to the solar game, as I am finding out. Shame no-one could help me with my simple question though about fuse sizing :-(
 

Alace

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Ok, GPU cards and host PCs need 12V dc. This already removes the need for DC-AC inverter and saves you about 20% on your battery and solar size required due to removing inverter and PSU losses. I guess you have multiple GPU rigs. Try converting one to DC supply and solar. You can get away without battery by feeding output of solar charge controller directly to 12V dc bus together with grid powered power supply in parallel. This way it becomes effectively grid supported but partially solar powered mining rig. But you can only offset <50% of energy usage that way. Going with battery will not save you much money and requires large up front investment. Your best bet is to try going DIY permited AC grid-tie solar with interconnect agreement if you can get 1:1 net metering. Storing and discharging 1kWh of energy in cheapest DIY LFP battery will require $200+ investment and will provide 1 - 3k equivalent cycles depending how lucky you get with your battery supplier. That comes out to 6.7 - 20 cents per kWh battery stored energy cost. If you have full net metering then you get "free" battery from the grid.
Thanks for the response and learning lots.

I’ve always run them at 120v. Is this what you mean?https://www.parallelminer.com/produ...num-94-delta-2400-watt-power-supply-200-240v/

Do you recommend a MPPT or PWM for a DC system?

Also if I was fully off-grid and required battery, do you still recommend going 12v DC in terms of savings?
 

Alace

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You could also look into grid feedback solar, instead of buying 50K in batteries, have the 30+ solar directly feed the grid reducing your grid usage, and back feeding your power.
It may not eleminate your bill, but it may drop the daytime draw, and lower the overall bill.
Not really possible where my rented warehouse is. I guess I ask myself how long this system could last? If I’ll save money over the long term. Based on the system demand I described do you think it could last 15-20 years?
 

AntronX

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How much do you pay per kWh right now? Is your goal to save money or to use solar power? How long do you expect this GPU mining operation to last?
 

AntronX

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Thanks for the response and learning lots.

I’ve always run them at 120v. Is this what you mean?https://www.parallelminer.com/produ...num-94-delta-2400-watt-power-supply-200-240v/

Do you recommend a MPPT or PWM for a DC system?

Also if I was fully off-grid and required battery, do you still recommend going 12v DC in terms of savings?

No, I meant to skip AC power supplies and go 12V dc from battery direct to your mining rig. But as a beginner that may not be right for you. Definitely go with MPPT. If fully off-grid I would recommend 48V system with one of those rackmount turnkey LFP batteries, a Victron MPPT 150/60 Tr or similar and 90V solar PV strings. You can avoid DC>AC>DC inverter and PSU loss by going with 48V DC ATX power supply like these: https://www.powerstream.com/DC-PC-48V.htm
I would find most efficient 48V > 12V + 5V step down buck converters and make my own but for you plug and play ATX solution may be easier. By going DC to DC you are saving the cost of AC inverter and corresponding conversion loss of about 10%. And with 48V system you need smaller wires and can easily add inverter later for house loads.
But going offgrid will probably not save you money long term sue to cost of LFP battery per cycle.
 

kromc5

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You can look at my system for comparrison, it's a long tread but I have posted lots of data.
 

circus

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Can someone explain this mining thing. Looks to me like a sort of currency that consumes valuable resources but produces nothing. Is scarcity, even if it exists only in a ledger, the measure of value?
 

upnorthandpersonal

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Take what I write as a simplified and somewhat (ha!) idealized introduction to where value in crypto comes from. The main computer science problem that crypto solves is the Byzantine generals problem: that is, how can you be sure that if you send a message from a to b across an insecure network that it arrives intact and not tampered with. In the case of crypto, this message is an amount of coins sent from a to b, a currency if you will. It does this with a proof of work mechanism. The more people participate in the network, the more distributed it is, and the more fault tolerant. Because this proof of work takes a lot of computing time (it's essentially brute forcing hashes until it matches a certain pattern, again simplified) people need an incentive to do this. This is where coins come in: you get coins as a reward for calculating the proof of work challenges that secure the network - this is mining.

Now, what determines the value of the coin in question is related to its maximum supply (scarcity), how difficult it is to mine them, popularity of the project/coin, and a (un)healthy amount of speculation and gambling.

Again, all simplified. In principle, it's an interesting solution to a real problem, but the practical implementation (proof of work is wasteful, and many other drawbacks) leaves a lot to be desired. Other versions exist that use proof of stake instead of proof of work, and there are other aspects that sit on top the blockchain (which is essentially just a long list of hashes) such as smart contracts, etc. but I digress...
 

Alace

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No, I meant to skip AC power supplies and go 12V dc from battery direct to your mining rig. But as a beginner that may not be right for you. Definitely go with MPPT. If fully off-grid I would recommend 48V system with one of those rackmount turnkey LFP batteries, a Victron MPPT 150/60 Tr or similar and 90V solar PV strings. You can avoid DC>AC>DC inverter and PSU loss by going with 48V DC ATX power supply like these: https://www.powerstream.com/DC-PC-48V.htm
I would find most efficient 48V > 12V + 5V step down buck converters and make my own but for you plug and play ATX solution may be easier. By going DC to DC you are saving the cost of AC inverter and corresponding conversion loss of about 10%. And with 48V system you need smaller wires and can easily add inverter later for house loads.
But going offgrid will probably not save you money long term sue to cost of LFP battery per cycle.
It seems like batteries are getting more efficient and may be cheaper in 5 - 10 years?
 

AntronX

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It seems like batteries are getting more efficient and may be cheaper in 5 - 10 years?
It could be so with upcoming sodium-ion batteries. But in near future LFP batteries will get more expensive due to raw materials shortage from high demand for Li batteries. You could invest into batteries now, use them for few years and then sell them for probably similar cost in couple years. But I could be wrong. This is speculative and you need to do your homework as with any investment.
 

Alace

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How much do you pay per kWh right now? Is your goal to save money or to use solar power? How long do you expect this GPU mining operation to last?
Around 0.10/kwh. Both. At least another 5 years.
 

AntronX

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So looking at https://signaturesolar.com/eg4-ll-lithium-battery-48v-100ahd/ for $1850 with shipping you get 7000 cycles or 25804 kWH cycled which comes out to 7.17 cents per kWh. Already cheaper than the grid, that's good. But solar panels will power your rig directly 30% of the time on average so assuming your panels are used and cheap they will likely cost 1 cent per kWh. Another thing you can do is to switch to TOU plan with cheap off-peak rate and use your battery to carry the load through expensive on-peak time of 4 - 9 pm. And if there is no sun you can shut down your rig to avoid paying expensive on-peak rates. This could be easier and cheaper than permit grid tie but you got to do detailed cost study of both.
 

AntronX

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If you want off-grid I would do it with TOU grid supported setup. I would go with 48V system, cheapest used solar panels i could find that have decent efficiency at least 15% and up. I would use 98% efficient 500W I7A4W033A033V-0C1-R 48V to 12V DC-DC converters to power the rig. For feeding grid power into the system I would also use 96% efficient 240Vac to 48Vdc PFC corrected power supply like Meanwell UHP-1500-48. Combined 240Vac to 12Vdc efficiency would be 94% which rivals many PC power supplies. Edit: DC converter would be more like 95% efficient at 4:1 conversion ratio. Maybe another topology can be used like an isolated one. At 24V battery voltage 750W converter version can do 40A 12V out at only 12.5W loss for 97.5% eff.
 
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Nickatnyt

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Can someone explain this mining thing. Looks to me like a sort of currency that consumes valuable resources but produces nothing. Is scarcity, even if it exists only in a ledger, the measure of value?

There's tons of websites that explain crypto mining. After all the research I have done, you are either all in, or all out, when it comes to crypto. You also better have a pretty good exit plan with at least part of the crypto holdings. FWIW, I have warned people to stay away from it unless they have an amazing capability to deal with massive volatility. I personally do not have that capability. My deep seeded opinion is that it is a twist on a Ponzi scheme.
 

AKvalleyguy

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Never go for Chinese solar chargers.
Good advice, I think. I've been running all USA equipment since 2005 so I'm no expert on a lot of made in China equipment.

That said, I plan to get some of the fun, new stuff to play around with in the outbuildings. And, I laugh at myself, the LiFePO4 cells and BMS's are all from China. Sorta forget that one detail.
 
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