Parabolic Trough size

I'm looking to build a 30 Kw solar trough to generate power for both my house and my home business. I was curious if there was a "best porabola shape" when it comes to designing the trough.

Comments

  • mike95490mike95490 Solar Expert Posts: 8,470 ✭✭✭✭✭
    Re: Parabolic Trough size

    Will this be a fixed East-West trough, or a North-South, that rotates to track the sun ?

    E-W, has 2 possible shapes, highly optimum, if monthly altitude adjustments are planned, or not quite as optimum, if you want the shape to track the seasons.

    Same for N-S, the more accurate the sun tracker, the "tighter" you can have the focus.

    I'd go for an E-W, optimized for winter months.
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  • System2System2 Posts: 6,290 admin
    Re: Parabolic Trough size

    I live in the North-East, pennsylvania to be exact, so i'm well out of the sun belt. Which would be more efficient (cost & energy production) for my location?
  • BB.BB. Super Moderators, Administrators Posts: 29,717 admin
    Re: Parabolic Trough size

    Just out of curiosity, what kind of conversion system will you be using for the 30kW of hot oil (or whatever your heat transfer medium) to electrical energy would you be using? Or is this just for "process" heating?

    This is not a small system--you should be working with an engineering firm (or system designer) on the details.

    This sort of system is generally out of the scope for a "simple/small" home type energy system.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Parabolic Trough size

    from bb,
    "This is not a small system--you should be working with an engineering firm (or system designer) on the details."

    millercj,
    indeed this is big. from the impending solar reaching the ground at 1000w/m^2 you would need 30 square meters if running at 100% efficiency. this is more apt to be far less than 50% efficient just from converting heat to electricity alone so that will more than double the area. do get some engineers to figure this out for you even roughly so you know more of what you are up against.
    it may actually be cheaper to go all fixed pvs if you have the land/roof area to accomodate that many pvs.
    you did not state what you will require over 24hrs in watt-hours or kilowatt-hours. is that 30kw x 24hrs for 72kwh per day? or is it 30kwh needed in 24hrs for a bit over a kwh for every hour of the day?
  • System2System2 Posts: 6,290 admin
    Re: Parabolic Trough size

    Ok, maybe I'm looking at this the wrong way so i'll start from the beginning and ask for advice. I'd like to build this whole thing myself..but we'll see.

    My home and my business are essentially on the same property, through roughly 6 acres apart. I have 300 acres at my disposal, however I only plan to use a fraction of that. Using an estimate from the house I live in now, we use approx 2,300Kw per month (1,800min-3,600max) and my business uses about the same (Total demand 4,600Kw). I'm really clueless as to the size of system i need whether it be PV, Concentrating Solar, or Wind. I'm in the VERY preliminary stages (I will only begin construction in 2 years) of planning but I really like the trough design. It seems cheaper than PV and the wind in my area is only 5mph on average. I also want to carefully consider what to do about power in the evening. I would like a grid-tie in system but I'm not sure if batteries are worth the $$$.

    As for conversion from hot oil transfer fluid into a heat exchanger i was looking at the products offered by infinity turbine simply because I was having a hard time finding small generator solutions.
  • BB.BB. Super Moderators, Administrators Posts: 29,717 admin
    Re: Parabolic Trough size

    OK, some simple numbers:

    2,300 kWhrs per month for your home, 4,6000 kWhrs per month for both (average). 4,600kWhrs per month * 12 months = 55,200 kWhrs per year

    Solar PV array (fixed, set at defaults). Try Wilkes-Barre Pennsylvania:

    1 kW of solar panels, grid tied, produce 1,113 kWhrs per year

    (55,200 kWhrs per year / 1,113 kWhr per yr) * 1kW panels = 49.6 kWatts

    For a Grid Tied system, "easy install", large quantity--call it $7.50 per watt (SWAG).

    49,600 watts * $7.50 = $372,000 for the system.

    Assuming no maintenance expenses, taxes, or interests for 20 years, your power would cost:

    $372,000 / (55,200 kWHpyr * 20 yr)= $0.337 per kWhr...

    Note, in California, any system over ~10kW in size may run the risk of having to pay reservation charges... Basically, 1/2 of our power bill is "generation" costs and the other 1/2 is "distribution and transmission costs". If you do not lower your 15 minute peak usage (per month or per year?)--then you will only be able to reduce your electric bill by approximately 1/2.

    Review this thread (with article) for details.

    If you go with a thermal power conversion system (roughly a 50kW system would be needed to "zero" out your power usage). The installation/maintenance costs may be less--but that would require you to work with Infinity Turbine + installer + engineer to really work out the details--really beyond the scope of most (all) people here.

    If you have Time of Use billing available, you may be able to zero out your dollar costs (sell expensive power during the day, buy power at night when cheaper). Can save you, perhaps 30-50% of your system size and costs... But yo have to be able to shift your power usage to off-peak times (late evening, early morning, weekends)... May not be possible for your business.

    Going with an off-grid system, cost of extra panels/equipment because you have to generate power even in winter when you have less sun plus batteries, your 20 year costs are probably going to be 3x-5x that cost (replacement batteries every 5-15 years, somewhat higher equipment costs, lost opportunity of storage--3 days max).

    Being completely off grid will save you 100% of your electric bill--but in some areas, again California, if you take your home/business off-grid and use your own generators/etc., we have to pay the power company for "stranding costs" of equipment that was financed based on the assumption we would be purchasing power from the utility for 20+ years.

    In the end, yours would be a relatively large system--one that any installer would give their eyeteeth to install (lots of $$$, one site, etc.). They should be able to give you a report/quote with the costs and payback.

    This is something that would be difficult for somebody to do from scratch with no experience... Not because the solar itself is difficult, but because of the regulatory and permit nightmares that you might have great difficultly just trying to get the project off of the ground.

    I would suggest that you contact somebody "local" (utility, turbine supplier, engineering school, local/state "green" agency, etc.) and see if you can partner... You provide the Land and the Load, much of the capital--and they can share in the "free" advertising and perhaps even school field trips and such.

    I recommend that you read the article thread I posted above--even a government school district missed some major issues installing Solar Grid Tied in San Diego--which should have been a no-brainer... A "Green" state, lots of state and federal rebates/tax credits, and lots of sun. And yet, without understanding their electric bill or implementing conservation/load shedding/time shifting--the real electric costs (electric bill plus interest payments) actually went up.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Parabolic Trough size

    I guess I'm just confused. By looking at this
    http://www.technologyreview.com/Energy/17169/

    it seems like all I would need to do is make 40-50 of these and that would be well below the 300,000 mark
  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: Parabolic Trough size

    A complete BS pipe dream ( pun intended ) to think a home brew 1kw steam system is cheaper than PV, they suggest a use power-steering pump for the "turbine" and an automotive alterantor for the generator, a big "whatever"

    Could something like this be built, maybe, would it work for more than a week or two before needing maintaince or repair, not a chance.

    Also, any steam system is the single most dangerious thing one could build, and would require not just approved engineering to build, but a license to run one.

    In any event, you can stop right now in thinking this will provide you the 55 MEGAWATT hours of energy you now consume and nothing, ever, will be cheaper than grid power for that amount of energy
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