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ceciltheram avatar image
ceciltheram asked

MPPT 100-20 - remains on bulk

Hi, was wondering if someone could assist. I have a 48V system with 4 x 12V 120Ah lead acid deep cycle batteries. I have 8 x 185W panels wired in 4 x strings of 2 panels in series (strings in parallel). Each panel is producing 3.9A and 39V on a good day. (So 78V going in which is reflected on the shunts' external display monitor). It has been quite hot and clear here in a Queensland Summer but my batteries are only increasing around 0.5% per day. The system just stays on BULK. Thanks in advance. The system seems to recharge fine when we take 1.5 -2% of the battery capacity but this time after 3 days of rain batteries went down to 89.5% and like a said are charging up at about 0.5% per day.

MPPT Controllersbattery charging
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klim8skeptic avatar image klim8skeptic ♦ commented ·
@ceciltheram on a good day you should be seeing a charge current approaching 14a. Sound right?

Could be you are using too much power for the solar to keep up with demand.

Look at the mppt'sdetailed history to check the pv arrays peak output and array yield.


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ceciltheram answered ·

Thanks @klim8skeptic. I should have said we have switched mains off (so no power going out). The current sits on around 2-4A. I think you are right, we should be getting around 15A when wired in parallel like we have. (add Amps - 3.9 x 4) May be time for new panels.

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