question

brian avatar image
brian asked

Can I lower the conversion start voltage from 5 volts to maybe 2 or 3. It usually doesn’t start the conversion until 5 hours after the sun is up.

MPPT Controllers
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

3 Answers
JohnC avatar image
JohnC answered ·

Hi Brian. If you're talking panel Voc vs Vbat, then no you can't. It's perhaps the only disadvantage of mppt over pwm cc's that I'm aware of, and I guess it would come to the fore at your latitude.

Is it possible to rewire your panels to longer strings? Even if you find yourself with an 'orphaned' panel, it may be worth trying that route..


1 comment
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

brian avatar image brian commented ·

Hi John. Thanks for the info. Too bad I can’t lower it. Maybe my old PWM controller might be better at 50 degrees north.


0 Likes 0 ·
Mark avatar image
Mark answered ·

You are cutting it too fine with the panel voltage vs battery voltage.

The system design is the real issue & not the MPPT logic/ability.

The correct way to resolve this is a) if you currently have multiple solar panels, rewire them in series to increase the voltage output, b) buy some more solar panel(s) of the same type & wire them in series to increase the voltage, or c) replace your current panel(s) with units that have a higher voltage output (such as panels used for regular household solar - they typically have a Voc of ~40v each).

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Paul B avatar image
Paul B answered ·

Just as a idea, you could put say 2 x 9 volt dry cell batteries in series and then connect them across the PV input for a few seconds every hr in the morning as this may fool the mppt unit into starting as once its started it only needs 2 volts above battery to hold.



I dont know how ell this would work but its not a expensive try out in you situation

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.