Voltage sweetspot?

[Cal Dan]

I was asked this question but was not positive about the answer.

Assuming your MPPT controller can handle it, is higher voltage always better or is there a "voltage sweetspot"?
I know that higher voltage is better for wire sizing at least up to the point that you don't feel safe working with high voltage. But is there any other considerations? Is there a certain place where you should start parallelling your panels or is higher voltage just always better?

I am sure this has been answered but don't see it.

Thanks, Dan

[thastinger]

I built mine to be as high a voltage as possible in all areas. Higher voltage means more efficient transmission.

[inetdog]

I was asked this question but was not positive about the answer.

Assuming your MPPT controller can handle it, is higher voltage always better or is there a "voltage sweetspot"?
I know that higher voltage is better for wire sizing at least up to the point that you don't feel safe working with high voltage. But is there any other considerations? Is there a certain place where you should start parallelling your panels or is higher voltage just always better?

I am sure this has been answered but don't see it.

Thanks, Dan

Some MPPT CCs give an efficiency versus voltage curve, and it seems to favor higher voltages up to a point and then it falls off again. In most cases the MPPT range stops at a lower voltage than the safe range, so definitely stay under max MPPT voltage.
The decision of how high to go will depend on part on how long a wire run you have from the panels to the CC. As long as the wires are not so long that you are spending either too much money or too much energy, I would go for the max efficiency voltage. Keeping in mind that the panel voltage may be higher or lower than nominal depending on temperature.

[Sunking]

I was asked this question but was not positive about the answer.

Assuming your MPPT controller can handle it, is higher voltage always better or is there a "voltage sweetspot"?
I know that higher voltage is better for wire sizing at least up to the point that you don't feel safe working with high voltage. But is there any other considerations? Is there a certain place where you should start parallelling your panels or is higher voltage just always better?

I am sure this has been answered but don't see it.

Thanks, Dan

Yes Dan there are sweet spots, but everything is a trade-off. For example if say you are using a Outback FM80 on a 24 volt battery system with 2000 watt input. If you loo, but the panels are located 75 feet from controller. If you reference the Outback manual you find the highest converter efficiency is a Vmp of 34 volt to achieve 97% efficiency. However you would go broke to limit the wire loss to even 4% with 60 amps flowing on 150 feet loop length of wire to the controller. That would give you a total loss 7% operating at 34 Vmp. However you can run the Vmp at 100 volts and the controller efficiency is 96%, and now you can afford to run wiring loss to 3% with 20 amps over 150 loop length for the same total loss of 7%.

You just have to run the calculations to find the ECONOMIC Sweet Spot.

FWIW the king of efficiency is Midnite Solar Classic 150. They have the highest current conversion ratio of 1:3. The sweet spot for a 24 volt system is 70 volts and can go up to 120 volts Vmp. Quality cost less in solar.

[Cal Dan]

Thanks all,

Some how I knew just to say "more is better" wouldn't quite tell the whole story.