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fedez asked

Very low charging W with low battery - Mppt 75/15

screenshot-2021-12-13-11-15-21-336-comvictronenerg.jpgImage CaptionHi, having a strange issue with my solar system. 15screenshot-2021-12-13-13-35-50-030-comvictronenerg.jpg5w solar panel with victron smartsolar Mppt 75/15. It is charging only 2 - 3w with a lot of sun. I tried a reset disconnecting the battery cables for few minutes and after connecting again looks like working good, having around 36w. But after a few minutes it dropped down again to 2 -3W. Battery are not fully charged. Attaching some screen.I will appreciate any help, I'm struggling to keep the battery charge without the solar panel working...

MPPT SmartSolarsolar
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2 Answers
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fedez answered ·

The pictures cut my question...issue with 155w solar panel...

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marcmu answered ·

Ciao Fedez

il problema potrebbe essere dato dal voltaggio del pannello fotovoltaico, in quanto gli mppt devono avere un voltaggio superiore al voltaggio della batteria per lavorare in modo corretto. da quel che vedo sul manuale del tuo mppt viene richiesto un voltaggio minimo dei pannelli fotovoltaici di almeno 5v superiori al voltaggio della batteria (Vmppt = Vbatt + 5v).

(https://www.victronenergy.com/upload/documents/Manual_BlueSolar_MPPT_75-10_up_to_100-20/MPPT_solar_charger_manual-it.pdf?_ga=2.95844252.1052849551.1639390948-660297564.1620119093, capitolo 4.3)

Quello che posso consigliarti è di aggiungere un pannello in serie in modo da raddoppiare il voltaggio dei pannelli fotovoltaici mantenendo la stessa corrente.

Attualmente l'mppt si accende e puoi modificare le impostazione perche è alimentato dalla batteria, ma se vedi nell'applicazione ti da che il regolatore di carica è spento, appunto perche il voltaggio in entrata non è sufficientemente alto per attivare la carica "MPPT".

Fammi sapere se riesci a combinare e confermare se il problema del "malfunzionamento" è dovuto da quanto appena detto


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marcmu avatar image marcmu commented ·

English:

the problem could be the PV panel voltage, as mppt's need to have a higher voltage than the battery voltage to work properly. from what i see in your mppt manual, a minimum PV panel voltage of at least 5v higher than the battery voltage is required (Vmppt = Vbatt + 5v).


(https://www.victronenergy.com/upload/documents/Manual_BlueSolar_MPPT_75-10_up_to_100-20/MPPT_solar_charger_manual-it.pdf?_ga=2.95844252.1052849551.1639390948-660297564.1620119093, 4.3)


What I can recommend is to add a panel in series in order to double the voltage of the PV panels while maintaining the same current.


Currently the mppt turns on and you can change the settings because it is powered by the battery, but if you see in the application it tells you that the charge controller is off, precisely because the input voltage is not high enough to activate the "MPPT" charge.


Let me know if you can combine and confirm if the "malfunction" problem is due to the above.

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