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The manual of the MPPT states that the Vpv start voltage should be 5V above Vbat. That is not problem. After starting Vpv should stay 1V above Vbat to keep charging.
"● PV voltage must exceed Vbat + 5V for the controller to start. Thereafter minimum PV
voltage is Vbat + 1V."
What i see in the VE connect app is that the MPPT always keeps Vpv aprox. 5V above Vbat.
This causes the battery to not charge completely.
"This causes the battery to not charge completely."
How so? Battery voltage? Ah capacity? Load connected?
PV array specs? Panel #/Vmp/Imp?
A MPPT charge controller is designed to work best when the solar voltage is significantly above the battery voltage.
It's a different arrangement to an old PWM charge controller. If you cut this too fine (ie. use a solar array with a Voc/Vmp voltage that's not high enough) then you will have trouble, particularly on overcast days and during winter.
The +5v just refers to the 'wake up' PV voltage each morning. The +1v just refers to the 'shut down' PV voltage in the evening.
Normally during the day (when there is good sun) the the PV voltage should be somewhere around your solar array Vmp during charging and around Voc if the battery is fully charged. Ideally the system should be designed so that the PV voltage is at least 10v to 20v above the max battery voltage.
Thnx for the response.
I understand the principle of mppt.
But what is the use of a shutdown voltage of 1V Vdiff you stop charging at approx. 5V Vdiff anyway?
In my case it would be ideal to keep charging (with low power ofcourse due to pv specs) untill alprox. 2V Vdiff
Performance of my pv is at optimum at nominal bat voltage +10V. Ideal and max efficiency.
I think the premise of the argument is too incorrect to really fully understand? maybe something lost in translation?
Vpv can be way above the Vbat in a properly working system. Right now, for example, in my system, the Vpv is 40.22V and Vbat is 13.57V.
The excess voltage gets converted into a higher current - so the "Ipv" is 0.8A and the "Ibat" is 2.3A
The Vpv being 1V higher than the Vbat is not a target for operational running, it is just a minimum difference that is required to keep the controller from shutting down.
