Module preference?

[Walt_Solartown]

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

[Mike90250]

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 ...

[Walt_Solartown]

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

[Sunking]

Power = volts x amps. More amps mean larger more expensive wire.

[solarc]

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

[Mike90250]

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.