Topic: [Withdrawed Offer] Butterfly labs & solar loan - page 2. (Read 5343 times)

Sorry, lenders look at financials. They don't deal in sentimentalities. You should be happy. D&T has saved you from a poor financial decision.

Agreed, This is way over my head for a loan.

This.

We've got a grid-tied system. Without a feed in tariff, the investment is marginal. But here, the gobbermint pays us more than twice the price to buy off us the excess electricity we produce than what we pay for their coal-fired power, so it's one of the better investments out there. I do think though that the feed in tariff distorts the market and will make electricity more expensive in the long run because it kills off a lot of potential alternative clean energy solutions and creates huge problems for the distribution networks as they now have to cope with power going both ways and still have the capacity to keep the lights on when it's cloudy.

^^ Off grid solar is the most expensive way to make electricity there is AFAIK.  Burning dirt (coal) is the cheapest.  I have a grid tied 7.5 KW system for my house and I love it.  Here in Colorado we get plenty of sunshine year round and the power company pays me dollar for dollar (I simply run the meter backward during the day) for all of my production up to my consumption for the year.  At the end of the year they send me a check for my yearly overproduction but they only pay me their cost of production for my overproduction.  So instead of giving me $0.12 per KWh they only give me about $0.02 per KWh, nice profit margin for them since they burn lots of dirt.

Given this sytem I will break even in about 6 years but only because the power company paid for over half of my system in rebates.  If I had to pay for the system out of my pocked my break even would be more like 12-15 years, depending on how fast the panels and inverters wear out.

You have a nice idea but I fear it will probably be too expensive to implement and run.

DeathandTaxes, ruining dreams just like death and taxes 

Your array and batteries aren't even in the ballpark. A 160W array puts out 160W per hour in PEAK sunlight.  Peak sunlight being 100% mid-day at the equator sunlight.   Depending on where you live your average solar insolation is likely 4-5 hours per day.  So in 24 hour day you only get about 4 to 5 times the nameplate rating of the panel.  A solar insolation of 4.5 means in 24 hours you get the equivelent solar energy as 4.5 hours of peak sunlight at the equator.  A 160W panel only outputs 160W under peak sunlight.  That doesn't mean it only works for 4.5 hours it just means that it isn't always outputting 160W. 

So 160W /1000 * 4.5 = 0.72 kWh daily.
1 Single @ 80W * 24 = 1.92 kWh daily.  
You would run out of juice 1/3 of the way through the day ... every day.
1920W / 4.5 = 430W.  
So your array cost is now ~$1500.

However it gets worse.  Without a charge controller you are looking at losing 20% to 30% of your power due to voltage mismatch between panel output (variable) and the battery optimal charging voltage (also variable).  Given the cost of solar panels the charge controller is cheaper than trying to "brute force" it.  So that adds another $150 or so.

Still we haven't even got to the really bad news.  That 4.5 hours is avg solar insolation, it is roughly 35% less in the winter.  So unless you plan to run your rigs only 9 months out of the year you need to size your array so it is large enough even in winter.  So we are more like looking at 640W array (~$2000).  Yup that also means you will be wasting the excess power it produces in the summer.  No way around that limitation on off-grid system.

Your battery will need at least 1.92 kWh of capacity but you likely will want more.  You may have a rainy day (or 2 or 3) so really you want enough capacity to last 2-3 days to ride out the day to day variance, unless you want your single shutting down a couple times each month due to overcast or rain.  We are talking a dozen of deep cycle batteries.  Maybe $500 in battery capacity.

So excluding mounting, rails, wiring, installation costs you are talking somewhere in the tune of $2000 (640W array), $150 (charge controller), $500 (8 kWh battery bank).  At $2650 in capital cost and $0.10 per kWh average electrical rates.  You will get $0.19 in "free power" per day.  Break even point is in 39.7 years.  Direct DC (offgrid) solar systems are prohibitively expensive, small solar systems are prohibitively expensive.  One that combines both is just foolish.

A gridtie system will still be expensive but is easily half the cost (or less).  It really is your only option.  Still break even is likely in the 10 to 15 year range.  Why is a grid tie system cheaper.  It allows you to exploit the AVERAGE solar insolation.  Once again using 4.5 hours as average annual solar insolation.  A 80W BFL Single will use ~700 kWh annually.  Lets increase than 10% to compensate for system losses.  Say ~770 kWh / 365 / 4.5 = 460W.  Smaller array and no need for batteries = cheaper system.  

just get a grid tie inverter.. all you gotta do is plug it in like any appliance. no wiring no fuss!

if you go the that way.. all you need is panels and a inverter.

It is.

Fair enough.  :p

Im Good with electronics but once it comes to things like house hold wiring i wouldnt have the slightest clue where to start nor would i trust my self with direct power lines to my house dont think any other room mates would appreciate the power outage if i did mess up either. I could imagine my neck being strangled and red becuase they just passed an important part of skyrim and didnt get to save in time.

Why batteries?  Why can't you just contribute the full amount of solar energy to the rest of the household during the day, and assume that it basically covers the electric for the BFL miner?  Is it difficult to tie a solar panel in with the power of the rest of the house or something?

Bounty you say? May be me and my future investors can kill two birds with one stone.!

I think deep cycle is what im looking for thanks, and yes ill need a lot of batteries or a battery that can store alot of amps of power which leads back to your point that ill need a few i scince i havent seen a consumer battey like that.

You need a deep cycle battery.  Actually, you need several.

http://www.ebay.com/itm/12V-35Ah-Deep-Cycle-AGM-SLA-APC-UPS-BackUp-Power-VRLA-Battery-Nut-Bolt-Posts-/330715931760?pt=US_Batteries&hash=item4d0034a470

I presume your rationale is ideological rather than economic?

I think I have a bounty on this type of rig somewhere here on the forums.

btw: 1 12volt battery might not be enough to carry you through the night.

Try looking at 24v Marine Battery for better bang for your buck.

The idea is to have enough batter power for 24 hrs for your BFL and that the solar panel can charge the batteries during daylight hours.

Trickle Charging might or might not be necessary.

(watching)

I see what your asking for now, Let me get back to you on that.

I wasn't talking at all about bitcoin mining costs, but the costs of your solar electricity.

The running cost for solar may be free, but the upfront capital outlay is huge compared to mains power. Most larger mains-connected photovoltaic systems require government subsidies to be viable. A battery system is even more expensive.

The calculation/estimate would go some like this:

Average hours of sun per day (various solar website can give a good indication for this, remembering that early morning and late afternoon won't generate as much power). Units: hours.

Average power generation: Units: Watts/kW.

Length of operability of system. Panels can last 25 years, but inverters generally 10, and batteries probably less. Also, if mining becomes unprofitable sooner, you will need to depreciate your equipment faster. Units: Years. Convert to days by multiplying value in years by 365.

Cost of system. Units: $.

Thus:

Cost estimate per kWh = {cost of system} / {kWh generated over useful life}
                               = {cost of system} / ({Ave hours sun per day} x {Ave power generation} x {operating lifetime in days})
                               = $??/kWh

Good point, i updated the solar panel requirements to 160watt as the inverter i have does not have switching to main power supplies.




Good question! I live in california , usa the electricity costs here are around 13cents/kWh but PG&E runs this teir system(as they like to call it when i was talking to a pg & e representetive on the phone). The way their teir system works is that once you go over a specified limit you pay 14cents/kWh thats called the first tier. The second tier is 15cents/kWh and so on and so forth...
I live in a house full of power hungry people running multiple computers, one big screen tv, multiple smaller lcds, heating/cooling, refigerator, etc

When discussing my options with the representive on the phone they said that this house hold always hits the teir 1 and some of the time(every other month) hits tier 2. Dosent sound too profitable going through home electricity and its almost impossible to promise or guess profits projections from mining in the next ten years.

If projections is what will make you feel more confident i will be willing to take time and do the math but it really all is speculation beyond the next difficulty change so i cant promise my projections would be accurate over a period of ten years.

What is your motivation for going solar? Have you worked out an estimate for the cost per kWh for solar electricity based on depreciating the capital outlay over, say, 10 years? How does it compare with mains pricing?