Start feed in voltage 4000TL

[wstevew]

I noticed on the sunny boy 4000tl the start feed in voltage is 150v per string. But it can be adjusted down to start at 125v.

Is there a reason this is not 125v as standard?

Is it that if the start voltage is 125v and stop is 80v then the voltage drop on start could drop below 80v causing hysteresis.

 

[BruceB]

I have not seen an explanation from a manufacturer, but yes, that is roughly how I would explain it.

The time to reduce the start voltage is when you have few panels in series. By the time they reached that start voltage they would be well into the flatter part of their voltage curve and you would not get the drop you postulate on starting to draw power.

Regards
Bruce

 

[matt25]

i asked sma this same question and there email response was
I wouldn’t recommend it though as this might put undue stress on the internal components of the unit. At 125V you could be using more power to make the inverter operate than the panels are producing i.e. net loss for that string

 

[wstevew]

I sort of came to that conclusion. You would be generating little to nothing and wearing out the inverter.

 

[deeyup]

A bit like trying to drive your car with the clutch out at 500 rpm?