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  • Module preference?

    Hello SolarPanelTalk -

    Today I'm wondering why I often hear installers say 'voltage is cheap'. If higher voltages are 'easier' to achieve, which of two equal wattage modules would you choose - the one with higher voltage and lower current, or the one with lower voltage and higher current? I suspect the answer will be 'it depends...'

    Thanks
    Walt

  • #2
    Originally posted by Walt_Solartown View Post
    Hello SolarPanelTalk -

    Today I'm wondering why I often hear installers say 'voltage is cheap'.
    With high voltage, you have lower amps, and can use less expensive copper wire. (10 ga instead of 4 ga)
    Smaller wire = smaller condouit, less weight ...
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister

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    • #3
      With two equally powered panels, would the module with a higher amperage have intrinsically better wiring and connections within the panel? Maybe this is splitting hairs as my opinion of a panel comes down to the power it produces.

      Thanks
      Walt

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      • #4
        Power = volts x amps. More amps mean larger more expensive wire.
        MSEE, PE

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        • #5
          apart from the wire size argument.

          The answer will depend on the invereter you'll be using.
          In general: inverters that comprise a transformer should be run a rather low voltages as the maiority of their losses come from magnetizing losses of the transformer which are in relation high if the power is low. If you take a look into e.g. a handbook of a SMA inverters they'll show 3 graphs of effieciency with respect to their input voltage.

          In contrast. Inverters that do not utilize a transfomer should be operated at voltages higher than the peak voltage of your AC grid. If this is not the case case, the inverter uses internally a so called "DC-DC step up converter" to reach this voltage level. And this internal conversion costs ... efficiency.

          Another point - that depends on systems size - is the possible reuirement of a array junction box in case of low voltages. In this case you'll have a lot of parallel strings, that require protection.

          To conclude from my point of view: Use highest voltage that is possible in combination with a transformerless invereter (if this is permitted by your utility).

          Solarc

          Comment


          • #6
            Originally posted by Walt_Solartown View Post
            With two equally powered panels, would the module with a higher amperage have intrinsically better wiring and connections within the panel? Maybe this is splitting hairs as my opinion of a panel comes down to the power it produces.

            Thanks
            Walt
            Higher currents will reveal any flaws in the interconnects / wires faster. Larger systems are using 200W, 60V, 3A panels.
            Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
            || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
            || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

            solar: http://tinyurl.com/LMR-Solar
            gen: http://tinyurl.com/LMR-Lister

            Comment

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