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Thread: Need online solar calculator that calculates return on investment, monthly savings, etc.

  1. #1

    Default Need online solar calculator that calculates return on investment, monthly savings, etc.

    http://sharpusa.cleanpowerestimator.com/default.aspx
    The calculator above assumes that the LOWEST a system costs to install is $4 per watt DC.

    If you are installing it yourself the cost is more like $2/watt D.C.

    Is there any solar calculator out there that will allow you to enter in lower cost values and give you all the financial benefits like break even year, savings, per month/year, etc.

    This site below lists a few, but wondering if there is something better as that artical is 4 years old.

    http://www.getwithgreen.com/2008/09/...r-calculators/

    I know I could do the calculations manually, via pvwatts but I'm lazy.

  2. #2
    Join Date
    Feb 2010
    Location
    South of Erie, North of Pittsburgh PA
    Posts
    894

    Default Re: Need online solar calculator that calculates return on investment, monthly savings,

    To me it sounds like a myth that you can self install a solar system for $2 a watt with good quality components. It would be nice if you could explain how to do it! I think it cost me at least that much for everything I needed for the polemount racks. solarvic
    16 KC 158G & 3 KD185GX-LPU panels on Fronius IG PLUS 3.0-1 inverter and 14 SHARP NDU3A & 1 KD185GXU panel on FRONIUS IG-3000 inverter. All mounted on pole top racks. Retired and enjoying it!!

  3. #3
    Join Date
    Apr 2012
    Location
    Van Horn, TX (West TX)
    Posts
    582

    Default Re: Need online solar calculator that calculates return on investment, monthly savings,

    Well lets see what I got so far.

    1- Midnite Classic 150 $543
    6- 145w panels $915
    10 AWG PV wire (100 feet) $45
    6 AWG wire (10 feet) $12
    100 Breaker $13
    250 amp Bluesea fuse and holder $34
    Bluesea Battery Switch $26
    Combiner Box (QO) with 6 breakers.. $54
    MC4 connections $12
    Cheap mounts x6 $54

    Total is $1708

    I have no batteries and no inverter yet.. which I figure will be another $1500

    $3208 if all goes right..

    and my 870 (STC) watts of panels will get me about 452 watts per hour to the AC side.. (about 37.6 amps per hour)..

    I stink at math so maybe someone can figure the cut / % on this.. looks like $3.68/DC watt.. and $7.09/AC watt..
    Al Z.
    1160 watts PV, 30.86 & -104.792, MidNite Classic 150, Xantrex Pro SW 2000

  4. #4
    Join Date
    Mar 2006
    Location
    SF Bay Area (California)
    Posts
    16,831

    Default Re: Need online solar calculator that calculates return on investment, monthly savings,

    I think this is more weighted towards Grid Tied systems (no batteries or charge controllers).

    -Bill
    20x BP 4175B panels (replacement) + Xantrex GT 3.3 inverter for 3kW Grid Tied system + Honda eu2000i Inverter/Generator for emergency backup.

  5. #5

    Default Re: Need online solar calculator that calculates return on investment, monthly savings,

    Once again much depends on where you are at. Up here you couldn't even buy the panels for $2 a Watt (even out of Arizona; once you cross the border the costs mount up). Weigh it against the ten cent electric and you get a payback time of around "never" (the equipment may need replacement before any value is realized).

    But I agree with Rolland that any such calculator ought to allow you to put in your particular costs, not a generic $ number.
    Four 175 Watt panels, OB MX60, 232 Amp hrs, OB 3524, Honda eu2000.

    Ohm's Law: Amps = Volts / Ohms
    Power Formula: Watts = Volts * Amps

  6. #6

    Default Re: Need online solar calculator that calculates return on investment, monthly savings,

    Yes $2 a watt is for grid tie only doing a self install.
    $1/watt for panels
    $0.50 a watt for inverters
    $0.25 for racking
    $0.25 BOS, wiring, combiner boxes, cut off switches, conduit, etc.

    Just priced up a 10K system and it was $2.20 a watt before any rebates. Easily less than that after rebates.

  7. Default Re: Need online solar calculator that calculates return on investment, monthly savings,

    Quote Originally Posted by rollandelliott View Post
    Is there any solar calculator out there that will allow you to enter in lower cost values and give you all the financial benefits like break even year, savings, per month/year, etc.
    This PV ROI calculator does what you want, I think: http://pvcalc.org/pvcalc

  8. #8

    Default Re: Need online solar calculator that calculates return on investment, monthly savings,

    thanks i'll check it out.

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