Interesting example of practical PV usage

Steven LakeSteven Lake Solar Expert Posts: 402 ✭✭
http://www.motherearthnews.com/natural-home-living/historic-home-produces-more-energy-than-it-consumes.aspx

You guys have probably already seen lots of setups like this before, but this one was done to a 110 year old house. Given that about half the project involves a new PV system, I thought you'd find it interesting none the less. :) I just kinda wish they'd given more details on the PV system they used.

Comments

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Interesting example of practical PV usage

    from the pic it looks like they have some shading issues with trees.
  • Solar GuppySolar Guppy Solar Expert Posts: 1,972 ✭✭✭
    Re: Interesting example of practical PV usage

    Based on the shadows in the porch, the sun is just about perpendicular to the panels. They literally have tree branches hanging over the PV panels if you look to the middle right

    On of my neighbors has a PV system installed when the house was built in 1998 as part of some Fsec grant, they planted palm trees right in from the array that now shades the panels 100% of the day, the owners could care less, they paid nothing for the PV and like the palm trees:confused:
  • solarixsolarix Solar Expert Posts: 713 ✭✭
    Re: Interesting example of practical PV usage

    My hat is off to them but as for being an example for the rest of society, but they are probably in the small minority of people (in Michigan especially) that have the wherewithall to do this. Despite the shading, their house is better situated than most. How many people in Michigan right now are going to invest big bucks in a depressed housing market? They better be planning on staying there a long time or they will never get the investment back. Still, they are taking the right approach for their home and I wish everybody could follow their lead, but the article makes it sound like a good investment especially the part about making money from the utility. Credits maybe, but I get people all the time wanting to make money from producing power. Wrong.
  • solar_davesolar_dave Solar Expert Posts: 2,382 ✭✭✭✭
    Re: Interesting example of practical PV usage

    Makes me wonder how much of the renovation cost were considered a business expense in the effort to support of Greenovation.tv . Most I would suspect, All done with pretax dollars would be a big advantage, even if they handled it as a S corp.
  • Peter_VPeter_V Solar Expert Posts: 226 ✭✭✭
    Re: Interesting example of practical PV usage
    Based on the shadows in the porch, the sun is just about perpendicular to the panels. They literally have tree branches hanging over the PV panels if you look to the middle right

    On of my neighbors has a PV system installed when the house was built in 1998 as part of some Fsec grant, they planted palm trees right in from the array that now shades the panels 100% of the day, the owners could care less, they paid nothing for the PV and like the palm trees:confused:

    I'll bet this is a seasonal issue. It looks like it's mid-late fall in the photos, so perhaps during the summer the shading isn't an issue.
  • Peter_VPeter_V Solar Expert Posts: 226 ✭✭✭
    Re: Interesting example of practical PV usage

    Hmm, this whole article doesn't add up.

    They have an 8 kw array that is shaded at least part of the year and their latitude and location isn't great for PV (it's ok, but not great)

    They claim to power the whole house, AND charge an EV for 10,000 hours of operation AND sell back $1,400 worth of power per year.

    Assuming the EV averages 30 mph and gets about 250 watts per mile, that works out to 75 MW per year just for the EV.

    Then again driving an EV for 10,000 hours per year works out to driving it 27.4 hours per day. :roll:

    I'm thinking whoever wrote this article didn't pay a lot of attention to the details.
  • BB.BB. Super Moderators, Administrators Posts: 31,884 admin
    Re: Interesting example of practical PV usage

    They were saying they would generate 10,000 kWH per year... from PV Watts and Flint Mi:
    "Station Identification"
    "City:","Flint"
    "State:","Michigan"
    "Lat (deg N):", 42.97
    "Long (deg W):", 83.73
    "Elev (m): ", 233
    "PV System Specifications"
    "DC Rating:"," 8.1 kW"
    "DC to AC Derate Factor:"," 0.770"
    "AC Rating:"," 6.2 kW"
    "Array Type: Fixed Tilt"
    "Array Tilt:"," 43.0"
    "Array Azimuth:","180.0"

    "Energy Specifications"
    "Cost of Electricity:"," 8.3 cents/kWh"

    "Results"
    "Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
    1, 2.69, 544, 45.15
    2, 3.79, 690, 57.27
    3, 4.30, 835, 69.31
    4, 4.99, 905, 75.12
    5, 5.42, 986, 81.84
    6, 5.56, 952, 79.02
    7, 5.43, 932, 77.36
    8, 5.34, 936, 77.69
    9, 4.77, 829, 68.81
    10, 3.83, 700, 58.10
    11, 2.41, 437, 36.27
    12, 1.79, 342, 28.39
    "Year", 4.19, 9086, 754.14

    It looks like that the husband is a host here:
    Matt is host of www.Greenovation.TV.

    Their power production estimate looks high--especially with the trees in the way (pictures):
    Estimated Energy Production:

    12,474 kWh (12.5 megawatts)



    Energy Consumption:

    Less than 10,000 kWh

    And using energy credits:
    *Annual DTE Renewable Energy Credit (REC) Payment $1,372 = 20yrs / $27,400.

    Annual DTE credit $1,372 (eliminates our entire energy bill which is $77,400 over 20 years adjusted for 3% annual inflation).

    You can go to their photo album and see the tree coverage for October 18th (date of photos). Only ~4 weeks past fall equinox.

    Lots of trees around... But short days during "winter"--so perhaps they will not loose that much power due to winter shading if it does not cover the whole array.

    Installed October of last year--Wonder how well the panels actually produced now that it is April.

    They have done a lot of earlier work to reduce energy usage (geothermal heat pump, lots of foam insulation, etc.)... All for the better.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • jagecjagec Solar Expert Posts: 157 ✭✭
    Re: Interesting example of practical PV usage

    Oldest net-zero restoration in the country...REALLY?

    Because my >100-year-old house is getting solar panels within the next couple of months, and based on my calculations it will be net-zero...heck, I'm in a "historical district", too, for that matter. I doubt that solar panels on older houses are THAT rare. I wonder how much research went into that claim...

    As far as the numbers go, I also get only 9.35 MWh/year production for that array (8.1 kW in Detroit, MI, at 34-degree angle). There is a DTE REC program of sorts, but the numbers don't jive with what's in the article.

    When I run the numbers, I get a 20-year "income" of $43k. That differs pretty sharply from the $106k that they claim, although my figures don't include inflation, and they may pay a higher rate for electricity.

    (Assumptions: the PV-watts production figure is correct, they pay 12 c/kWh for electricity, they consume the exact amount that they produce every year, and DTE pays them $0.11/kWh of production based on their SolarCurrents program.)

    We can back-calculate their installation costs as well, based on the federal 30% credit and DTE's $2.40/watt rebate (I'm jealous).

    At $19k after incentives, I get $46.5k if the utility incentive is untaxed, and $54.9 if the utility incentive is taxed, for an installed cost of $5.7 or $6.8/watt. Not too bad for a professional installation, especially with those generous rebates floating around.

    Payback period after incentives is 8.8 years.

    Based on the pictures, it's an enphase installation, so that shading shouldn't matter *too* much.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Interesting example of practical PV usage

    "Based on the pictures, it's an enphase installation, so that shading shouldn't matter *too* much. "

    shading always matters in solar as it affects power production. the pvs shaded at the bottom with the microinverters are a waste if shaded as they won't produce power and they threw away their money on them. winter might even look worse as it may affect more of the pvs. by the pic they are about at equinox give or take. from the shadows i see it may just be the one tree, but in the winter its hard to say as that pic isn't depicting very far out to show if any other trees will possibly shade.
  • SolarLurkerSolarLurker Solar Expert Posts: 122 ✭✭
    Re: Interesting example of practical PV usage

    It does appear that there is some shading, who knows what the plan is. Maybe that tree is going to be taken down.

    Or it's is possible they knew off the shading and decided to go ahead anyway.

    Unless I missed something I do not believe sunpower allows the use of any inverter with their panels, then their sunpower rebranded sma inverters.

    If they got the real sunpower panels for less than 6 buck Per watt installed I would be shocked.

    The math seems a little fuzzy, but I commend them on doing something.

    With all of the state and federal incentives, we have gotten to the point where solar can be seen as an investment.
  • russruss Solar Expert Posts: 593 ✭✭
    Re: Interesting example of practical PV usage

    I'm sure they will get invited to all the PC parties by their little green friends with all the fuss they are raising.

    That is probably their point.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Interesting example of practical PV usage
    russ wrote: »
    I'm sure they will get invited to all the PC parties by their little green friends with all the fuss they are raising.

    That is probably their point.

    and they didn't invite any of us.:grr:roll::p
  • jagecjagec Solar Expert Posts: 157 ✭✭
    Re: Interesting example of practical PV usage
    niel wrote: »
    and they didn't invite any of us.:grr:roll::p

    You guys are too fond of saying things like "Most people tend to overestimate how much power they'll get from solar, and underestimate how much power they use" and "A Honda eu1000 generator can supply reasonable amounts of power for very little fuel, and costs much less than a full off-grid solar system." BORING and DEPRESSING.

    Try saying "Solar is the best thing ever, you can eliminate your power bill with panels that you can build yourself for pennies and an ebay grid-tied inverter (don't bother calling the utility first, they'll just deny you because they're GREEDY), and if you add a couple more panels on your Prius you'll never need to buy gas again!"

    Then watch the invitations roll in...
  • russruss Solar Expert Posts: 593 ✭✭
    Re: Interesting example of practical PV usage

    I'm designed a trailer to be towed behind the Prius for all those panels required to support it.

    Unfortunately it causes the consumption to skyrocket therefore the design had to be made larger. Right now it is starting to look like an eighteen wheeler.:cry:

    Russ
  • XRingerXRinger Solar Expert Posts: 529 ✭✭✭
    Re: Interesting example of practical PV usage
    russ wrote: »
    I'm designed a trailer to be towed behind the Prius for all those panels required to support it.

    Unfortunately it causes the consumption to skyrocket therefore the design had to be made larger. Right now it is starting to look like an eighteen wheeler.:cry:

    Russ


    I guess you can build a PV powered vehicle, but you will need a dog to drive it.
    Humans are too heavy.. :p

    renewable-energy-rv.jpg
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Interesting example of practical PV usage
    jagec wrote: »
    You guys are too fond of saying things like "Most people tend to overestimate how much power they'll get from solar, and underestimate how much power they use" and "A Honda eu1000 generator can supply reasonable amounts of power for very little fuel, and costs much less than a full off-grid solar system." BORING and DEPRESSING.

    Try saying "Solar is the best thing ever, you can eliminate your power bill with panels that you can build yourself for pennies and an ebay grid-tied inverter (don't bother calling the utility first, they'll just deny you because they're GREEDY), and if you add a couple more panels on your Prius you'll never need to buy gas again!"

    Then watch the invitations roll in...

    sorry, but i'm not always saying that and i do say more realistic things when they apply. i have no doubt solar is a great thing or i wouldn't be here let alone have it. only a fool would look at it as a panacea for every circumstance and a cure-all for all of our energy needs and problems. it is what it is, though.

    for the record, i was poking fun at not being invited for an invite from them doesn't all of a sudden make me any different than i already am. also, being in a click doesn't change solar and doesn't make an individual any better.
  • Steven LakeSteven Lake Solar Expert Posts: 402 ✭✭
    Re: Interesting example of practical PV usage

    Well said, Niel. One of the things I've learned in all my wind and PV research (and subsequent work) is that no one system fits every need, and people who want Wind/PV for their home need to first go as literally "green" as possible.

    I think that was the first thing someone said to me around here. "Don't size the PV for the house. Size the house for the PV." Well, ok, that's a paraphrase, but still it gets the point across. In short, make your footprint as small as absolutely possible, then build your Solar/PV/whatever off grid system around that.

    I mean, if I learned nothing else here, I at least learned that, and it's actually one of the smartest, and most logical things. lol.
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