solar and wind

ws9876
ws9876 Solar Expert Posts: 448 ✭✭✭
in General Solar Power Topics #1
If you had 2 200 watt panels and 2 micro inverters and ran a small AC battery charger off it
.... how would you incorporate a 500 watt wind turbine into it..?? no grid tie... 2 L16 batts
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: solar and wind
    ws9876 wrote: »
    If you had 2 200 watt panels and 2 micro inverters and ran a small AC battery charger off it
    .... how would you incorporate a 500 watt wind turbine into it..?? no grid tie... 2 L16 batts

    You wouldn't.
    Microinverters are grid-tie only; no grid = no power from the inverters.

    Basically if you have batteries you charge them from the panels through a charge controller.
    You can do the same with a wind turbine -> charge controller -> batteries.

    BTW, 200 Watts of panel won't do much for a set of L16's which run 300 to 400 Amp hours. You might get about 10 Amps from that much panel and about 600 Watt hours of total power. That would work for around 50 to 100 Amp hours of battery.

    Wind is usually a poor investment in terms of power returned for money spent. You must make sure you have a site suitable to wind power before you invest in it.
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  • ws9876
    ws9876 Solar Expert Posts: 448 ✭✭✭
    #3
    Re: solar and wind

    you cant run the AC from a micro to a small sub panel and use it???? what???
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: solar and wind
    ws9876 wrote: »
    you cant run the AC from a micro to a small sub panel and use it???? what???

    Nope. It's called "anti-islanding". No grid power to synch to and GT inverters of all types shut down. This is so they don't energize lines disconnected at the utility side, making them safe to work on.

    Some have tried to use off-grid inverters or generators to provide a "synch signal" to keep grid-tie systems running in the event of a power outage. A lot of trouble, because the equipment isn't designed to function that way (although I understand the latest XW inverters are, as well as the SunnyIsland inverter).

    Remember GT inverters do not have a steady input like battery-based ones. No steady input = no steady output. They take everything they can get from the panels and convert it to Voltage to "push" against the electrical inertia of the grid, thus turning it into current (and Watt hours). Off-grid inverters rely on having a fairly steady Voltage source to produce a steady output Voltage. The current on the input varies in proportion to the demand on the output.

    It's not practical to try to adapt the one technology to the other application (this excludes the battery-based GT inverters from Outback and Xantrex which are designed to function as either/both).
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  • ws9876
    ws9876 Solar Expert Posts: 448 ✭✭✭
    #5
    Re: solar and wind

    i meant not connected to the grid.. just run the micros to a plug or 2. That is a no go??

    btw you might know this other question.... why does a sine wave from an inverter match
    up with the grid exactly and not overlap like a split phase,at least somewhat..??
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
    Re: solar and wind
    ws9876 wrote: »
    i meant not connected to the grid.. just run the micros to a plug or 2. That is a no go??

    No; without the grid the GT inverters shut down. They can not produce power without an AC signal to synchronize to and feed.
    btw you might know this other question.... why does a sine wave from an inverter match
    up with the grid exactly and not overlap like a split phase,at least somewhat..??

    That magic word: synchronize. They literally adjust their frequency so that their output is in synch with the grid they're connected to. They also "test" that frequency to be sure it's there and at the right Hertz and will shut down if it is out of specification. This is one of the reasons that they can't synch with a standard fixed-RPM generator; its speed varies a bit as loads change which causes its frequency to drift as well (since the frequency is dependent on engine speed). The generator's output can drift outside the "acceptable range" and the GT inverter will perceive this as "bad frequency" and turn off.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #7
    Re: solar and wind
    ws9876 wrote: »
    i meant not connected to the grid.. just run the micros to a plug or 2. That is a no go??
    Unfortunately, no. This is one of the first lessons folks newly coming into the world of PV have to learn. You cannot just throw up some modules, connect them to an inverter, and go off-grid. Off-grid systems are challenging to design and install, and they are a lot more expensive than grid tied systems of the same size.
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  • ws9876
    ws9876 Solar Expert Posts: 448 ✭✭✭
    #8
    Re: solar and wind

    you say they sync... physically...how do they do that??

    I was going to say that if a freq is exactly the same then they are mirror images of themselves and it just happens...but split phase freq. are the same and they dont line up...
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
    Re: solar and wind
    ws9876 wrote: »
    you say they sync... physically...how do they do that??

    I was going to say that if a freq is exactly the same then they are mirror images of themselves and it just happens...but split phase freq. are the same and they dont line up...

    Actually split-phase are out of synch by exactly 180 degrees.

    Have you ever heard of a frequency counter? Ever seen a sine wave on an oscilloscope?
    In simple form the GT inverter "looks" at the line frequency, then varies its own output frequency until the peaks and valleys align. There is a tolerance of about +/- 3% for this, and it only takes a moment to achieve.

    If you're not careful, one of the engineers here will give the full, technical explanation. Then you'll have a headache that lasts all day. :p
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #10
    Re: solar and wind
    Cariboocoot wrote: »
    Actually split-phase are out of synch by exactly 180 degrees.

    Have you ever heard of a frequency counter? Ever seen a sine wave on an oscilloscope?
    In simple form the GT inverter "looks" at the line frequency, then varies its own output frequency until the peaks and valleys align. There is a tolerance of about +/- 3% for this, and it only takes a moment to achieve.

    If you're not careful, one of the engineers here will give the full, technical explanation. Then you'll have a headache that lasts all day. :p

    Here's the full, technical explanation: It's magic. ;)

    But seriously, you might as well look at it that way, since it's not something installers have to worry about. GT inverters synch their output to grid voltage, frequency, and phase, and turn themselves off when conditions are such that they cannot do so, such as when the grid goes down.
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  • ws9876
    ws9876 Solar Expert Posts: 448 ✭✭✭
    #11
    Re: solar and wind

    I know all about split and 3 phase.
    and I would like to know,even if its complex, how a sine wave encounters an existing wave of identical waveform and laps on it precisely right without being slightly before or after the grid wave...

    sampling the grid and making a identical wave doesnt seem hard... its just the lapping that
    seems hard......

    if you could explain it would be good..
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #12
    Re: solar and wind

    There is not much to explain, the AC converter just uses the AC grid sine wave as a reference to convert the DC to AC. It also compares the grid signal to be within parameters to create the anti island safety required of all grid tie generation devices.

    Think of it as an amplifier with the AC as the input side and the DC as the power to create the amplification.
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