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PV Panels $1.98/Watt?

Discussion in 'Home Power and Microgeneration' started by vaughn, Sep 20, 2009.

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  1. vaughn

    vaughn Guest

    Pull in your spam antennas. I have no connection to this company except I
    bought an EU-2000 from them once, and I may buy a new PV panel from them
    tomorrow if those prices are real. At that price, they have the SUN-130 and
    SUN-150. The minimum number of panels they will ship is two. I hope to
    drive down there tomorrow and pick up one.

    Two years ago we were talking about a silicon & carbon shortage and
    impossibly growing PV prices. Is the PV industry facing over production
    now? How quickly things change.

  2. Hey Vaughn, If you can confirm those prices, I might just be interested
    in getting a few up here...

  3. vaughn

    vaughn Guest

    Wow! "...could drop below $1 a watt next year, and to 50 cents a watt in
    2011. If that happens, he says, up to half the more than 200 solar
    manufacturers won't survive."

    The next year or two could be a real "sweet spot" for those who are
    considering a new PV system. After that, a combination of rising prices
    from the expected recovery and lost production from the dropped-out
    producers will swing the pendulum the other way.

    Even with drastically lower prices, the economics of my little system are
    simple. My PV system's calculated payback time is...NEVER. I consider my
    system a hobby and also part of my hurricane preparations. If the power
    goes out, there are a few lights in my house & yard that will stay lit as if
    nothing had happened. Come back a week later, and they would *still* be
    lit. No generator, no noise, no fuel, no "nuthing"; they just work.

  4. vaughn

    vaughn Guest

    Sorry, no clue. They have an AZ warehouse as well as their FL location,
    which may help some folks. The shipping weight of the SUN-130 is 35#.

  5. vaughn

    vaughn Guest

    I just got back from Miami. Picked up one Sun-130 panel for exactly the
    advertised price. It seems to be well made. It will take me a day or three
    to get it installed & tested.

    The place is right downtown & near the Port of Miami. Just like when I was
    there before, it was cramped, crowded & busy. They have been in that
    business for several years that I know of. Would not be surprised to find
    out that their main market is in South America & the Caribbean. I purchased
    my EU-2000 from them perhaps 5 years ago.

  6. Thomas

    Thomas Guest

    since I'm local in Ft Lauderdale, would you care to describe a little of the
    components that you currently use?
    perhaps I can start up a similar system using some of the learnings you might care to
  7. vaughn

    vaughn Guest

    My system started out as simply a way to keep my generator's battery
    charged. For that, I was lucky enough to find 2 used, mismatched PV panels
    that total about 100 watts in rating. To keep from overcharging my battery,
    I added a new C12 solar controller. From there, I noticed that the C12
    controller is designed to also control outside lighting, so I added 12 volt
    compact fluorescent bulbs (1 amp of current draw each; 40 watts of equiv
    light) in porch light fixtures in our front and back yards.

    That was about 7 years ago. Over the years, I have upgraded the batteries,
    but little else. Those outside lamps last forever! In the dark days
    following our S. Florida hurricanes, My yard was the only one in the
    neighborhood lit up at night, greatly confusing the neighbors, who were sure
    that I somehow still had grid power.

    Just lately, I have been gradually figuring out ways to pipe 12 volt
    circuits inside the house. (I have an old Florida CBS house with no attic
    access so running new circuits ain't easy. The first one was right between
    our easy chairs in the family room, a lamp fixture with 2 of those 12-volt
    CFL bulbs. It serves as our everyday lamp and is powered only from the PV

    As I add loads to the system and as my ancient PV panels age, I have been
    noticing that my battery "fills up" later and later in the day. For that
    reason, I am adding that new 130-watt rating panel to the mix.

  8. Thomas

    Thomas Guest

    As I add loads to the system and as my ancient PV panels age, I have been noticing
    what's your take on the off-grid "complete systems"

    for example, they have a 2000 watt system and that would cover all my airconditioning
    use 24/7 as all my systems are inverter controlled heatpumps (read: both compressors
    and air handlers are inverters, running ac to dc conversion and use very little power
    at start, slowly ramping up according to demand)

    at the cost or about $8000, do you have any idea what they mean by "complete" or is
    this an implied installation by sunelec or does it just mean that everything I would
    need, is included but it's up to me to figure out how to install and where to install
  9. vaughn

    vaughn Guest

    First, I would call the price "nearly $9,000", not "about $8,000".
    Second, I really doubt that system would run your home's AC 24/7 for the
    simple reason that the sun does not shine 24/7. Their "complete system"
    does not seem to include installation labor, nor incidentals like the panel
    mounting system.

    (I am not saying that the system is a bad deal as PV system go, just trying
    to fill you in on the "real world".)

    A good conservative guess is that system would make about 10 kWh/day if
    properly installed in South Florida (2 KW x 5 hours equiv full sunlight).
    Check your power bill to see what you pay per kWh, but that will come to
    less than $2.00/day worth of power. To the installed price of your system,
    be sure to include an allowance for the use of about $10,000 and an
    allowance to replace $1,080 worth of batteries every few years plus
    allowance for whatever incidental maintenance the system may need..

    I don't know what condition your roof is in, but are you ready to have a
    crew drill a few dozen holes in it to mount the panel frames? Remember that
    the installation job will need to be repeated if you need any roof work over
    the life of the PV. system. That won't be free! Since you live in
    hurricane country, you will want the very best panel rack system possible.
    Further you will want to be sure that it is installed properly and
    structurally tied to your roof beams so that everything does not take flight
    in the next hurricane, leaving you with no power, a torn up roof, and
    pissed-off neighbors who got their homes and cars torn up by the expensive
    hardware flying off your roof.

    Still sounding like a good idea?

    I love PV, but you need to go into a project like that with your eyes wide

  10. Thomas

    Thomas Guest

    ok. just to make you aware, I run a 1 ton 12,000 BTU all-inverter system at 72 F year
    heatpump, thus same coil produces both heat and cool, despite outside temps.
    when it runs at full speed, max throttle, it consumes just 685 watts of power.

    it would appear to be easy to meet the demand of this smart unit at such a low max
    both the compressor and air handler are full inverters, capable or running at any

    my other inverter heatpumps are running on more conservative settings for the rest of
    the house but
    indoor temps never exceed 76 F in any part of the house

    my entire house FPL powerbill is below $120 even during hotter months and this
    includes pool pumps,
    sprinkler pumps, water heater, stove, electronics, etc.
  11. vaughn

    vaughn Guest

    That's pretty impressive. We do about the same in the Palm Beach area, (no
    pool pump, gas hot water) but we do it by only using our whole-house AC a
    few hours per day. At night we run a little mini-split in the bedroom, and
    during the heat of the day we run a single high-efficiency window unit to
    cool only the den.

    Some day we will replace our central unit with inverter technology, but
    probably not until the system we have dies a natural death. (At 4 hours per
    day, 5-6 months per year, that may be a while) The mini-split is brand new.
    It has efficiency that trumps any present window unit, but is not inverter
    technology since I didn't get to choose. (It was a nearly-free
    "brother-in-law" deal, so it has its own type of cost effectiveness)

  12. Bob F

    Bob F Guest

    It may be that the efficiencies of the AC motor make up for the losses in the
    inverter. Reading about electric car conversions, the AC seems to win
    significantly over DC for miles per charge.
  13. Guest

    Not that I've heard of, and it would seem to be a niche too small.
    It's the same with welding at my place - 24VDC gets converted to
    230VAC, and then the welders turn it mostly back into 20 some volts

  14. daestrom

    daestrom Guest

    I think you'll find it's a bit more complicated than that.

    Most variable speed drives are actually VVVF (variable-voltage,
    variable-frequency) drives.

    A standard motor for a compressor or blower can be run on variable
    frequency *if* the volts/hertz ratio is kept nearly constant. If the
    voltage is kept constant while the frequency is varied over a wide
    range, you burn out the motor.

    Of course if the inverter section was a pulse-width modulated type of
    unit, you could get something similar to VVVF, but it would still be
    hard on the motor (high harmonics in PWM). AFAIK, most hi-power VVVF
    use a simple H-bridge for the inverter section and vary the voltage
    output of the converter section.

    So the AC-DC converter section is a variable DC voltage. If you have a
    homepower system with DC, you'd have to find a way to vary the voltage
    by a wide range. One common way to do that is with an
    inverter-converter arrangement, but now you're right back where you
    would be if you ran the VSD off of a typical inverter.

  15. Bob F

    Bob F Guest

    My misunderstanding.
  16. daestrom

    daestrom Guest

    From what I've seen, modified-sine wave inverters and PWM all require
    FET's of one form or another. If you're just using FET's or such, you
    can turn them off whenever you want in the cycle to reduce the pulse
    width. But highly inductive loads that can act as induction generators
    will have a current that is out of phase with the applied voltage. This
    requires some snubbers (filters) to absorb this reactive current.

    In large VVVF drives, those suitable for several horsepower and up, the
    reactive load can be more than what simple caps and resistors can handle
    in any realistic way.

    The large units I've worked on (50 to 500 hp) opt for SCR's in an
    H-bridge circuit instead (well, the three-phase equivalent of an 'H').
    To turn off an SCR in one leg of the bridge, the corresponding SCR
    above/below it is turned on. This would be a direct short if not for a
    center-tapped inductor placed between the SCRs that commutate the SCR
    that was previously conducting current through the inductor when the
    non-conducting SCR is turned on.

    Using SCRs like this doesn't allow for any sort of PWM, so the supply
    voltage to the bridge has to be controlled. Typically this is done with
    a three-phase rectifier with the diodes replaced with more SCRs and
    these are phase-controlled to control the average output of the converter.

    I suppose the small motors in a furnace (fractional hp) could use PWM
    and power FET's, didn't think about that much. I'm used to thinking in
    larger numbers :)

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