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Thread: Solar electric...what's up with that?

  1. #46
    Quote Originally Posted by Steve Rozmiarek View Post
    Mike, you illustrated what I meant. The example you cited of land and a 401K have intrinsic value for an infinite period. Machinery, cars, and solar panels don't. One way to look at it is you are prepaying the electric bill until the system breaks even, then you are in the profit. Using a quick google of some government site http://www.eia.gov/tools/faqs/faq.cfm?id=97&t=3

    my state uses an average of 1029 kWk/month, costing $95. This puts breakeven on a 900 kWh/month system at 17.54 years as calculated on cost. If it runs for another 2.5 years (20 year life) you make $2,850, or if it goes to 30 years, you make $14,250, assuming no breakdowns.

    Now, if you had invested $20,000 at 3% for 20 years, you would get back $33,090, 30 years gets you $42,570. For my simple mind, investing in this scenario nets you $10,240 more, or for a 30 year, $8,320 more.

    At some point, it looks like the solar panels beat the return of the investment, but it would be in year 70 or so I think. Another thought, sure the panels may last 30 years, but what if technology changes between now and then, and in year 15 the "new improved panel" comes out and you want to replace yours. Then you've lost money for the first 15 years.
    Perhaps electricity is a lot less expensive in your area than it is in mine - I can assure you that the breakeven in California for a 1029KWh/month is not 17.5 years. With the cost of electricity in my area, I believe I'll have 20 years of free electricity from the system I installed. And when I said I expect to pay it off in present value terms in 10 years, that takes into account the cost of money (which is pretty cheap right now). Present value is what stream of money, discounted at the present cost of money, will equal your investment.

    While better panels may come out in the future, it will not obsolete my panels. If I decide to replace what I have, it would have to be because I could make more money with the new panels than I could leaving what I have in place. So if I "scrap" my panels, it will be because I can make more money with new panels. But people have been trying to improve the efficiency of solar panels for a long time and the advances have been pretty small - and increase the cost of the panel. I'll welcome a breakthrough but I won't hold my breath waiting for it.

    Solar panels beat the investment (for my installation) in about 10 years. Solar panels for people who use a lot more electricity beat the investment (in California) in a lot less than 10 years, not 70 years. For your area, with your cost of electricity, it may be 70 years. If so, be thankful you have cheap electricity. Only a good financial analysis could answer that question.

    Mike

    [I'm not trying to convince anyone to buy a solar-electric system. I'm only telling people what I did and why.]
    Last edited by Mike Henderson; 03-27-2013 at 11:17 PM.
    Go into the world and do well. But more importantly, go into the world and do good.

  2. #47
    Quote Originally Posted by Steve Rozmiarek View Post
    David, they aren't mine, a neighbors. I don't know the answer to the average, I would guess a bit better than that though. We have the (mis)fourtune of living where the wind always blows. Some day I may make a little money, and move someplace between the mountains with tall trees so that I get a change of pace.

    I'm not sure what the rate that the utility paid initially, but he set them up based on it, and got cut to about a tenth. He is using them when he runs the irrigation now, said it costs money to run them into the power line. I think you are right, turbines are probably a horrible idea in most of the country.
    A lot of the turbines I've seen are rated at some ridiculous windspeed, like 35 miles per hour. If the wind blew constant at half that, they'd only make about 1/4 if their rating. The bigger ones might be a lot more reasonable about their ratings.

    http://www.neo.ne.gov/renew/windreso...0m_0408052.pdf

    I see from this map that there are a lot of places with average wind speeds of 15-17 miles per hour in Neb. That's really good....but not if you don't get paid for the electricity.

  3. #48
    Join Date
    Dec 2009
    Location
    El Dorado Hills, CA
    Posts
    1,311
    As much as I hate big government and big power companies, I think solar is one system that works best on a large scale.

    The present system has 1000 individual homeowners putting up 14 panels each with 1000 separate inverters and 1000 extra meters and 1000 different rooftops with holes in them.

    It would be more efficient to have large installations on the rooftops of Walmart and Home Depot, or out in the parking lot where they can provide shade. The wiring could be optimized. The power inverter could be highly efficient because it would run at a higher voltage. One skilled worker would keep the system at high efficiency. One low skilled worker would keep the panels clean.

    Steve

  4. #49
    Quote Originally Posted by Steve Peterson View Post
    As much as I hate big government and big power companies, I think solar is one system that works best on a large scale.

    The present system has 1000 individual homeowners putting up 14 panels each with 1000 separate inverters and 1000 extra meters and 1000 different rooftops with holes in them.

    It would be more efficient to have large installations on the rooftops of Walmart and Home Depot, or out in the parking lot where they can provide shade. The wiring could be optimized. The power inverter could be highly efficient because it would run at a higher voltage. One skilled worker would keep the system at high efficiency. One low skilled worker would keep the panels clean.

    Steve
    It's interesting that you mention this. Here in southern California, in the area known as the Inland Empire, companies with low flat buildings, such as warehouses, are renting their roofs for a solar installation. A company comes in and installs the solar panels, gets the connection to the grid, and pays the building owner rent.

    And just a few comments on your numbers. Solar installations are now done with mini-inverters, so each panel has an inverter. The old method, where the panels were connected in series and fed to one inverter has a problem - if even one panel gets shaded, or has a problem, the output of the system is decreased quite a bit. So if 1,000 homes each install 14 panels (a very small system - most installations have more panels), there are 14,000 inverters.

    There are not 1,000 extra meters. The old mechanical meters would simply run backwards if power was fed from the system back to the grid. The new electronic meters monitor which direction the power is flowing and record it. So you just keep your existing meter.

    One advantage of distributed generation is that it minimizes the need for transmission lines. Power companies encourage generation close to the point of use (other power users in the neighborhood will not have generation capabilities and will take the power you generate.)

    Mike
    Last edited by Mike Henderson; 03-28-2013 at 11:06 PM.
    Go into the world and do well. But more importantly, go into the world and do good.

  5. #50
    Join Date
    Mar 2003
    Location
    Upland CA
    Posts
    5,548
    An unexpected solar bonus.

    They started installing today, and I noticed this nice looking aluminum extrusion they use to mount the panels. I mentioned to the guys that if there were any scraps left I would be able to use them. The boss said they were finished with that part of the job, and I could have the extrusion they didn't use.

    That was two 14 foot extrusions, about 2 3/4" high and 3/4" thick, anodized aluminum with a couple T slots. I see some new router table fences, etc. in my future. I think I might just make a fence for my Jet Oscilating spindle sander too, I just used a makeshift one today to smooth the inside cuts of a breadboard cutout. Worked great.

    Rick Potter

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