Current Difficulty
Bitcoin's current difficulty is 19,729,645,941

That became true when the final block of round 156 (block number 314,496) was mined 3.74 hours ago.

Predicted Difficulty
The longest block chain on the Bitcoin network is currently predicting a new difficulty of 21,970,933,720 to take hold in approximately 12 days, 9 hours, 56 minutes and 41 seconds. This statement is said with 1.24% accuracy.

The difficulty prediction is 1.24% accurate because 1.24% of the 2,016 blocks required in this round before the network difficulty is re-calculated have been mined.

The longest block chain is currently 314,520 blocks in length. So we have mined 24 blocks thus far and we have 1,992 blocks remaining before the next difficulty change.

Taken from: https://cryptanalys.is/difficulty/bitcoin_btc.php

Slightly off topic but:

http://blogs.dallasobserver.com/unfairpark/2014/07/bitcoin_atm_startup_hoping_to_plant_its_flag_in_dallas.php

and

http://www.coindesk.com/bitcoin-atm-map/

What I suspected and expected to hear, thanks for the clarification and sanity check.

I have the S1's locked into 128 difficulty and the S3's @ 512. If left in "automatic" the pool places the difficulty at much higher values for both. 128-512 for the S1's and 1024 for the S3's.

I got used to the small variances of the S1's when, for instance, adjusting clock rate. When I started tweaking the clocks on the S3's it appeared in the short term to cause the hash rate to become "unstable". But when averaged or a longer period each unit seemed to find a "sweet spot" and be consistent day to day. Was just throwing that out there so as to relieve some anxiety of new S3 owners. Cuz' it drove me a little crazy for a few days.

Hey all,

What the chart below graphs is 12 S3's (upper band) and 12 S1's (lower band) and indicates that the S3's have a lot more "jitter" or volatility in hashing rate than S1's. I think when tweaking them, taking a longer term running average is more indicative of any improvements/degradations. My opinion is that changes should be evaluated over days versus hours.

And as we all know: "Opinions are like assholes, everybody's got one and they all stink."
And yes we hash at the pool that shall not be named.

The breakeven on the panels currently installed is 24-26 months. Which were purchased 2 years ago year from ML Solar @ $0.76/W. At the time of installation, cost per KWH from Lake Country Power was $0.134/KWH. So these panels are about to hit the breakeven point.

This includes accounting for being @ ~45 degrees latitude which effectively derates a panels output by 30% (70% of rated output, have always found it interesting that the output is roughly the sine of the angle of the latitude, oh shit physics really does work in real world everyday life). Panels are typically rated @ 1000W/meter squared (which is somewhere near the equator). Here in Northern Minnesota that figure drops to ~700W per square meter due to us being higher up on the planet making the photons travel through more atmosphere. Hence less of them reach the surface and energy density is less.

Regarding the Solar charging hours per day issue, this is mitigated by using extremely efficient charge controllers and/or grid tie inverters. Hence my favoritism of enphase microinverters and the Morningstar MPPT charging controller product line.

In conjunction, in battery bank style systems, by designing the battery bank to the lowest feasible voltage. Charging hours are expanded. Because the panels have to overcome a lower voltage to cause battery charging to happen. Thereby expanding the charging hours per day on both ends (morning and evening).

In the current system, which is charges a 12V battery bank, three solar panels are connected in series, which means to cause charging to occur each panel (Voc 37.35V, Vmpp 29.29V) only needs to output 4.4 volts (13.2V combined). This occurs ~8AM and ceases ~6PM. Now is the panel putting out rated current at those times, No. But what it does do is expand the effective hours per day to something closer to 8+.

By changing the battery bank nominal voltage to 48V charging would occur much later in the morning and would cease much earlier in the afternoon. Consequently losing or wasting all the energy the panels were capable of supplying during those early morning and evening hours. The lower nominal battery voltage accounts for a 20%-30% increase in harvested energy (time of year dependent).

To your point, in badly designed systems the effective charging times per day can be as short as 4 hours per day. The devil really is in the details.

Low hours per day charging propaganda is bantered about by fossil fuel dependent energy sources as a means to dissuade consumers from closely examining alternative energy sources.

Yes, absolutely.
The 2 systems need not be tied together. And, in fact, can be geographically distant.
The downside is that the power sold is at a lower $$$/KWH than the power bought.
So it makes monetary sense to use what you generate and sell the excess.
Hence the need/desire to tie the systems together and let it "load balance" itself. Buying some at times and selling some at times.

Current plan is DC to AC to DC using off the shelf tech. That way any excess KWH is sold to power company. The grid becomes our "battery bank".

Am exploring a 600V to 48V Battery Bank system to power the miners.
So it would be 600V DC (solar array) to charge controllers (Morningstar MPPT 600's) to 48V Batteries (probably US Battery 425A/hr L16 HC's in strings of to 48V/12V DC/DC converters to the miners. System would include AC/DC battery charging for those non-sunny days. Backup genny for battery charging when/if the grid goes away (I own a continuous duty rated 35Kw Onan that is just looking for a purpose in life). This is a grid isolated system technically.
Downside of that route is conversion inefficiencies, cost of batteries, cost and complexity of DC/DC conversion(s). Upside is that the miners are effectively UPS'ed and battery backed up.

Am also looking at using Syn-Gas to power a genny. Which is wood gasification, purify and warehouse the gas (methane, CO, and minor amounts of H2 in suspension, Nat Gas effectively), then use the Syn-Gas to power the genny to do battery charges periodically. Logging scrap is plentiful here and currently considered an annoying waste product of the logging industry.

Am also investigating using wood gasification Syn-Gas as a feed stock to a Fisher-Troops processor to make liquid fuels (diesel/gasoline, GTL-Gas to Liquid). http://en.wikipedia.org/wiki/Fischer%E2%80%93Tropsch_process

Another possibility is using wood gasification Syn-Gas in Bloom Energy processors. Like the ones used by eBay, Google, and Walmart. http://en.wikipedia.org/wiki/Bloom_Energy_Server.

We have time to sort all this out and make an informed decision. As we move forward I'll try to remember to post pics.

We would be interested in participating in a group buy.
Volume pricing is a good thing.

Solar powering just makes a good business decision.
Pay for input costs 1 time versus a re-occurring cost.
Isolates input cost fluctuations. Amortization of Capex becomes input cost.
Builds equity in the business.
Federal Tax incentives.
Possibly State Tax incentives.
Possible State rebates (cash).
Installation can be Depreciated.

The list goes on and on.

Oh yeah and it doesn't screw the planet in the process. lol.

Tad off topic, but here goes.

Like Bitcoin mining the solar installation industry is the "Wild Wild West". Caveat Emptor

ML Solar on eBay, from time to time, sells the Sharp 250HAT's SHIPPED @ $0.76-$.087 per watt. But for the best pricing it's best to call and talk to them directly (no eBay selling fees) http://mlsolar.com/.
www.sunelec.com sells a variety of panels that are in the sub $0.50/W range.
We have purchased product in the past from http://www.simpleray.com/, we are listed with them as "Solar Installers".

For grid tie installations we like the enphase microinverters (http://shop.mlsolar.com/Enphase-M215-60-2LL-Solar-Power-Inverter-180917011985.htm), and for battery bank installations we use exclusively the MorningStar MPPT Charge controllers (which by far have the fastest MPPT algorithm in the industry and the best warranty coverage) http://www.morningstarcorp.com/products/tristar-mppt-600v/.

Probably will regret doing this, but, contact me @ admin@planetcrypto.com

Less than .0986/KWH.
We are building/installing a solar farm to supply the energy required.
Payback/breakeven on the solar farm is 24-26 months and is grid tied, so under Minnesota Statutes any excess generation the power company must pay us for.
By the end of the year, the power company (Lake Country Power) will be our backup power source.
And if w ever decide to cease mining operations the solar farm ends up becoming a nice little revenue stream.
It is a fact in America that the cost of electricity NEVER goes down and tends to track with the cost of living.
The secret is to be on the supply side of the equation versus the consumption side of the equation.
And with installed solar at less than $1.00/W this is a reality.

Pics of the "Wall-O-Fans"/Fan Door may be found here:  http://xmpp.planetcrypto.net/images/

Next to Duc Tape, single-component polyurethane foam sealant is the neatest invention since sliced bread.

Exhausts directly to the outside.
There is so much airflow that even in a Thunder Storm there is no water infiltration into the building.
And I don't have to sweep the floor. All the dirt ends up in a pile just below the bottom fans.

Cheapest solution to having the gear survive a Minnesota Summer.

The first rack are S1's, the second rack are S3's.
As of last night, the 12 S1's are hashing @ 2,265 GH/s, and the 12 S3's are Hashing @ 5,228 HG/s for a total of 7,494 GH/s.
After that measurement, I overclocked the S3's to 237.5MHz and am monitoring them to see which ones are capable of this increase.
This morning it seems I have 2 "problem children" that don't like the increased clock rate.
But am hashing around 7.9 TH/s.

They are supplied with / included with the EVGA 1300's.

Thanks Man
Have prettied up the wiring since I took that pic.
"Why Waltz when you can Rock'N'Roll."

Pics of how we dissipate ~24K BTU (what we affectionately call the "Wall-O-Fans") and other pics of our mining rig may be found here:
http://xmpp.planetcrypto.net/images/

Currently pushing a little over 8TH/s

Will post that pic tomorrow.

Other images may be found at:
http://xmpp.planetcrypto.net/images/Mining_Array_1.jpg
http://xmpp.planetcrypto.net/images/Mining_Array_2.jpg

Image 1 includes a glimpse of our baby supercomputer (10x SC809T's ~40 TFp/s).

Have tried a variety of supplys and have settled in on the EVGA 1300's.
They are tanks. Ultra dependable. A little pricey. But worth every penny. Good insurance for expensive BTC mining H/W.

http://www.menards.com/main/shelving-visualizer/garage-basement/wire-shelving-14-x-36-x-54-four-shelf-black/p-2193676-c-13051.htm
$49.97 each

As a footnote, 24K BTU is enough to heat an average sized decently insulated home in Minnesota in Janurary (-30F).
Am planning on moving one or more racks into my house and get paid to heat it this winter.
Kill 2 birds with one stone, so to speak.

Bought the racks @ Menards in Brainerd, MN. They are available online @ Menards.com

What is not pictured are the 8x 20" box fans at the back door (4'x8' door) moving the heat away from the units.

If interested will post image of back door.

Currently, the S3 supply's are running off of 120V.
Will be swapping out the breakers to 240V double poles probably tomorrow.
Using the EVGA 1300's each S3 at a stock clock draws exactly 325W each at the wall or about 975W per PSU (8.125 A @ 120VAC).
So 1 20A Sigle Pole Breaker per 2 PSU's (16.5A draw per 20A breaker).
So @ 240V one should easily be able to run 4 PSU's (12 S3's) per 20A 240V breaker (240V*20 = 4800W).
Am making the swap to 240V cuz' have heard that the EVGA 1300 are slightly more efficient @ 240V than 120V.
And also allows for using thinner gauge wire per circuit.

Think your idea of 2x 30A@240V is overkill.
2x 20A @ 240 would run 24 S3's USING THE EVGA 1300's.
Other PSU's may not be as efficient and hence require a larger current draw.

Hope this helps.