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 " <[email protected]> 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 > > _______________________________________________ > Sent via [email protected]. Opinions expressed are those of the > author. > Not an AMSAT-NA member? 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