are transformers and solar a possiblity?

ok this is just food for thought. i have been reading some article on homepower. And one of the things i noticed is that utility companies boost the volts on a high power line. cause there is voltage drops over distance and since you the consumer are only paying for the energy they use, so instead of having say 6kwh, they boost it to 60,000kwh the drop is costing the power companies money but with the increased boost it is not costing as much, so they use transformers to boost the voltage and then transform it back down near your house to usage voltage. is that a basic enough explaination?

well my question is why cant you transform your own energy or boost it up in voltage, like a power company does? is the technology not there, is it too expensive, why cant i just put 200 panels out in the desert boost it up and support 5-10 houses? so i dont understand the science behind it so if someone knows or can explain it to me i would appreciate it.

Jake

Comments

  • System2System2 Posts: 6,290 admin
    Re: are transformers and solar a possiblity?

    Hey Jake
    The reason behind the utilities boosting the voltage, is that for any given POWER IN WATTS to be transmitted, the higher the voltage used, the lower the current in amps and so the farther it can be transmitted before the losses in the transmission conductors become unacceptable.
    The energy required to power homes is WATTS, not volts. The voltage is the force that drives the current through the conductors. Watts is the product of voltage times (X) amps.
    Yes, you can use a transformer to boost the voltage, but except for the losses in the transformer, the power in watts stays the same, because the amps go down.
    The voltage required to transmit power over long distances is extremely high and extremely dangerous, thus the step down transformer outside your house, which drops the voltage down to levels safe for use in your home. In the process, the amps available, go up.
    Again, except for transformer losses, there is no change in watts (power).
    Cheers
    Wayne
  • System2System2 Posts: 6,290 admin
    Re: are transformers and solar a possiblity?

    ok if you can boost volts to send the wattage farther, why cant you boost watts?
  • BB.BB. Super Moderators, Administrators Posts: 29,511 admin
    Re: are transformers and solar a possiblity?

    Yes, as Wayne says, you can do it... The utilities do it to save on the price of copper... the basic equation being:

    Power = Volts * Amps

    Multiply the voltage by 1,000 and the current drops by 1,000 and you keep the same power.

    However, transformers only work on AC... They do not work on DC. To step up or step down DC voltage (efficiently), usually there is a circuit to "chop" the DC and change it into AC. Now, you can use transformers to raise or lower the voltage, efficiently, to your needs.

    Just as an aside, it is actually more efficient to send large amounts of power using DC transmission lines rather than AC (but the conversions stations have got to be horrendously expensive). We have one of those here that connects LA to Oregon. I believe they use something like Klystron Tubes for the voltage conversions (you can see the LA side of it driving down I5 -- it looks like a big screened metal cage).

    http://www.usbr.gov/dataweb/html/pninter.html
    Celilo-Sylmar, 800-kV d-c Transmission Line

    This line runs about 845 miles from the Celilo Converter Station, the northern d-c terminal of the NW-SW Intertie on the Columbia River near The Dalles, Oregon, via Nevada to the Sylmar Station. This bipolar overhead transmission line, with an operating voltage of 800 kV (±400 kV) and a power rating of 1,440 megawatts (MW), was constructed and placed in service in 1970.

    And, by the way, you still pay for the power that is lost in transmission--it just is not directly charged on your bill.

    And, if you have a large facility (like an oil refinery) where lots of huge motors are used, they will charge you for the Power Factor too. Basically, the average power meter charges for the actual (in phase, PF=1) power you use. PF=1 means the voltage and the current used are in phase (AC sine wave). This how a filament light bulb or electric heater consumes power.

    However, large motors will take the current somewhat out of phase with the power. For example the peak current will not be at the peak voltage, and when voltage is zero, there is still current flowing. Remembering physics, if there is current flow with zero voltage, then no work is being down, and the power company will not be charging you for energy... However, there is still current flowing through the transformers and distribution lines and the utility will still have I^2*R heating losses--hence the penalty (or extra charge) for places whose PF is not close to 1 (motors can be PF=0.6). There are things that can be done to correct the PF, but won't bother discussing here--does not matter to most folks.

    -Bill

    PS: Boosting Watts is WORK. For example a bouncing ball does no work. Falls down, giving up potential energy for speed, then hits ground, giving up speed for potential energy for compression, then expands compression back to speed, then slows down as it rises, changing energy back to potential energy (distance above ground over gravity).

    The example above is just forms of energy conversions. Other than the work needed to lift the ball the first time, and the energy loss to heat each time the ball bounces a bit lower, there is no work being added to the system.

    If you want the ball to bounce higher, you will have to add work (burn fuel, cost money). Work is what the utilities sell. Transformers simply convert the energy from say, 120 vac at 100 amps to 12,000 vac at 1 amp (like your local power distribution system outside your home/office). now that wire which can carry say, 100 amps can either carry it to one home at 120 vac or to 100 homes at 12,000 vac.

    There are loses with any conversion, the trick is to balance the costs of the transformer, wire, I^2*R heating losses, the dangers of arcs, etc.... There are many solutions, some just cost less than others or have other advantages.

    As my example above--AC high voltage distribution over large areas is not as efficient ad DC high voltage--but the costs associated with managing high voltage DC in a multi-voltage AC environment limits it usefullness.

    -BB
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: are transformers and solar a possiblity?

    i'll put this simply as watts as was said is volts x amps. you boost the amps the volts go down and even a small loss occurs due to conversion losses. you boost the volts and the current goes down. to boost both volts and amps (ie watts) is impossible as this defies the laws of physics to create power where there is none.
  • System2System2 Posts: 6,290 admin
    Re: are transformers and solar a possiblity?

    You can boost the Watts by burning more oil, to push the generators harder, or, if you're on solar, install more PV's, or if your power is from the wind, get a bigger wind turbine, or make the wind blow harder. To boost watts, you must add extra energy that has to come from somewhere. There is no free ride.
    Cheers
    Wayne
  • System2System2 Posts: 6,290 admin
    Re: are transformers and solar a possiblity?

    Greetings,
    Higher voltage in a DC system comes into play where distances are involved. For instance if I have a wind generator 800 feet down my mountain. The wiring at 12 volts would be very large and very expensive. Best to use a 48 or 24 volt generator. That would down size the wiring needed to make the distance. The previous posts are correct. It all comes down to dollars. In my mind it makes sense to start with the voltage that is being fed to the inverter. Why tolerate the losses of the conversion process? I suppose I could put the inverter and batteries down the mountain with the generator and send the AC back up the mountain. However, even with the 110V AC there would be a large drop over 800ft. requiring larger wire. As previously stated, it is more efficient to transport the DC over distance and the higher voltage will keep the wire size small and less expensive. The transformation is achieved at the inverter.
    Tek
  • RCinFLARCinFLA Solar Expert Posts: 1,280 ✭✭✭
    Re: are transformers and solar a possiblity?

    This is one of the benefits of MPPT charge controller. MPPT controller is a switching power supply that converts higher voltage DC to lower voltage DC to charge the batteries (or push to grid for grid tie inverter). It also attempts to convert as much power as possible by examining the input V-I product.

    The only down side of higher PV voltage stacking is potentially greater opportunity of power generation degradation when a section of the series stacked PV cells are shaded.

    It is possible to build a buck-boost MPPT controller that would allow the PV panel voltage to be higher or lower then batteries. It would be slightly less efficient because it requires four FET switches instead of two for buck only design.
  • BB.BB. Super Moderators, Administrators Posts: 29,511 admin
    Re: are transformers and solar a possiblity?

    For the distances/power levels that any of us would be talking about, DC and AC would have the same losses (at the same voltages) over a few hundred feet...

    For somebody that need to send power some distance... I would expore placing the panels/generator/batteries with an inverter at the source location, then use a step-up transformer to send the power 800' and a step down at the otherside.

    With DC, there is no good and cheap way to get the power a hundred volts or so and use it at the other end with off the self equipment for home power (the MX60 can use up to 125 vdc--a Xantrex Grid-Tie 3.x can use up to 600 VDC)...

    I have never looked into the problem of sending a few kilowatts of AC power 800 feet. Has anyone looked at and/or used "small" step-up/down / regulating transformers? Up to 600 Volts would work with standard Home Depot type wiring. Obviously, it works for distribution by utility companies. Any other suggestions?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Robin GudgelRobin Gudgel Registered Users, Solar Expert Posts: 58 ✭✭✭✭
    Re: are transformers and solar a possiblity?

    Here are a couple more thoughts on this subject.
    1. An MPPT controller could be made to boost and buck, but for most installations, there is little power available if the wind or solar voltage is below the battery voltage. In otherwords, it ain't worth the extra expense, and believe me it would add serious complexity to the product.
    2. You will soon be able to boost at the source and then buck at the battery bank. boB Gudgel is working on the MidNite Classic that will have this capability. There will be a version of the Classic that will go to 200 volts. The down side of this technique is that it will require two controllers. You may be able to achieve acceptable results just by letting the wind turbine fly up to 150 volts or so and then buck it down at the Classic / battery bank. There will be a pretty sophisticated Clipper circuit that works in conjunction with the Classic MPPT controller for use with wind turbines too. Keep looking at the MidNite Solar web site for further details as they become available.
  • BrockBrock Solar Expert Posts: 633 ✭✭✭✭
    Re: are transformers and solar a possiblity?

    Very nice, Looking forward to it!
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
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