[amsat-bb] Re: Solar Power (I was wrong)

[k0vty@juno.com]

Afternoon Sir:

I have enjoyed your postings on the BB.
However this time I have to ask a question of you.
The term Grid-Tie for the purpose of Solar efficiencies has me stumped
If you would be so kind I would like an explination.
As the old saying goes , "when one in the class does not understand,  bet
on 5 more in the same conditon"
Additionally if there is data on where such a system is currently
available, that might help.

Best Regards
   
Joseph Murray ( K0VTY)
Amsat # 860
Amsat Coordinator NE.
=========================
On Fri,  2 Oct 2009 09:03:18 -0400 (EDT) "Bob Bruninga "
<bruninga at usna.edu> writes:
> > My simple math says it'll take almost 
> > 16 years to be reimbursed on a $30k system.
> 
> Its more like 5.5 years.. I'll show you my numbers for Maryland:
> 
> > Initial outlay:  $30,000
> > US tax credit:  5%
> 
> No, Federal Credit is 30%
> 
> > US reimbursement:  $1500 (this is not 
> > real money, but a reduction in taxable income)
> 

> at 30% it is $9,000 and it is a *credit*, not a deduction, so that 
> is cash in your pocket off the tax you pay.
> 
> Then most states, give either similar Tax *credits* or grants, in my 
> state it would be about $4,000 check, payable to me when 
> installation is complete.  Then the county makes up the difference 
> to 50% of the cost of the system.
> 
> > Total:  $28,500 
> 
> No, here, my net outlay is reduced to 50% or only $15,000.
> 
> > Savings per year in electricity:  $1800 
> 
> That, plus Solar Energy Renewable credits paid to you by the power 
> company or brokers at about $250 per KW capacity for a 4 Kw system = 
> $1000 per year.  They buy this credit from you so that they dont 
> have to build solar systems.  By paying you this credit, they get to 
> subtract the capacity from the amount they are required to build by 
> the year 2020? or whatever.  So add the two and you get a payback of 
> $2800/year.
> 
> > $30k / 1.8k = 15.83 years
> 
> * My numbers show $15k / 2.8 = 5.3 years (even less if electric 
> rates go up)
> 
> > One of the points of the post, I think, 
> > was to make ourselves less dependent on 
> > foreign oil..
> 
> > Personally, I do not think PV cells are 
> > that efficient.  To get the 12VDC I need 
> > to power my remote... repeaters, I...
> > lose more than 30% in generated heat.
> 
> Yes!  That was my mistake too. Energy Storage in batteries is very 
> inefficient.  About 30% or more losses.  But GRID-TIE systems are 
> 95% efficient PLUS you are selling the power to the grid at PEAK 
> rates in the middle of the day, and buying it back at discout rates 
> at night.  Net effect is not a loss, but a GAIN.  Of course, this 
> does not help at a repeater, but do not carryover these losses to a 
> Grid Tie system where it does not apply...
> 
> > they only last so long.  
> > Twenty years, tops maybe?  
> > Do they really pay for themselves?
> 
> You bet for sure!  Compare that to a $30,000 car, which is junk in 
> 10 years and you have nothing.  The solar system cost $30,000 
> (actually $15K) and you MAKE $15k in the first 5 years, and for the 
> next 15, you make $45,000, and then your array has decayed to maybe 
> only 80% of its original life... but it is still MAKING money at 
> then CURRENT rates...
> 
> The 20 and 30 year life does not mean they die, it is just that 
> their power has dropped by XX%...  Im guessing that the threshold is 
> 80%?
> 
> 
> 
> > in California. .. the power company is 
> > only required to pay you the WHOLESALE 
> > cost of electricity. This amounts to 3 
> > to 4 cents per kw-hr.
> 
> Ah, but if you pay 15 cents per KWH during the day to run your home, 
> and you have enough solar to balance that, then the payback to you 
> is still 15 cents per KwH.  Its only the excess you generate that 
> pays you the low rates.
> 
> The key word is "net metering".  In other states with net-metering, 
> they have to give you the full 15 cents credit for the excess power 
> you generate.  But in most all cases, you cannot beuild up credits 
> beyond a year cycle.  
> 
> > ... bird poop to cut the efficiency.
> > be prepared to get on the roof every 
> > month or so to clean the panels.
> 
> AMEN.   PV cells are in series.  One big splat that covers one CELL, 
> reduces the power of the ENTIRE PANEL.  A single Flag Pole shadow 
> across a roof, can reduce the power of the entire roof array 
> tremendously...
> 
> >> if you sell back over 50,000 watts 
> >> of power you will incur additional taxes, 
> >> ... you are considered a "generator" 
> 
> I assume that is NET.  To build up that much excess capacity would 
> require an array on my house covering 3 times the roof area I have 
> available.  And it would make no sense to build an array that big, 
> since you aleady know that you get paid peanuts for excess net power 
> (wholesale). 
> 
> >>  Lets say you were able to generate 
> >> and sell back 100,000 watts to the 
> >> utility company.
> 
> Yes, that is my annual consumption.  But my array will be sized so 
> that I generate 100,000 in that same year.  SO the NET "sell back" 
> is ZERO.  And I got all my electricity for FREE that year.  You are 
> right, that if I make my array TWICE as big as I need, and spent 
> about $100,000 for it, that then, I would generate twice the 
> electricity I need, and would not get paid but probably HALF the 
> rate for it PLUS the taxes you mentino.  Oh, and that array would 
> coer 8,000 square feet almost an Acre...  So I would not worry about 
> a homeower making the mistake of building too big a system...
> 
> >>> > 1) Solar panels (PV) are 1% of what they cost in 1970
> >>> 2) PV dropped 40% this year due to 2007 Energy Boom and 2009 
> economic bust
> >>> 4) $5,000 to $20,000 tax and cash back incentives for YOU
> >>> 5) Grid-tie systems operate at 95% efficiency compared to 70% of 
> battery systems
> >>> 6) Local electric rates DOUBLED in the last 2 years
> >>> 7) Laws require utilities to pay you the same peak rates they 
> charge you.
> >>> 8) Solar Energy credits can gain an additional $275 per 1Kw 
> system per year
> >>> 9) Payback is at least 10% per year or better
> >>> 10) The same money in the bank gets 1% interest
> 
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