[amsat-bb] Re: Solar Power (I was wrong)
k0vty at juno.com
Fri Oct 2 10:50:07 PDT 2009
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.
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
> > $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
> > 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
> >> 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
> >> 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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