BlueSolar 75/15 -- 12v PV in to 24v bank?

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andersonmiles asked Aug 5, '20

BlueSolar 75/15 -- 12v PV in to 24v bank?

this has been asked before with no satisfactory and definitive answer:

can a 12V PV maintain a 24V bank?

what does one need to do in order to get this to work? connect the battery first, to establish V being 24V, and then attach the 12V PV to show the input current? is there any built-in buck boost in the BlueSolar 75/15?

I have read that a BlueSolar MPPT 75/15 will only start to charge when the PV output V is 0.5V more than the current battery bank V, then stop when it is under 0.1V, but does that mean that it absolutely will not work as 12/24V dependent/congruent system?

will it work from 24V PV to 12V bank? why not versa vica?

thanks.

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Answer 1 · 2022-11-21T14:02:33Z

andersonmiles answered · Nov 21, 2022 at 02:02 PM

I have limited space on an antique working boat for a pv panel, and 12v is a much more common size than anything in 24v.

dimensions required in panel size are 73 x 80 cm, or 28 x 31in.

any suggestions would be most welcome!

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Answer 2 · 2022-11-21T14:22:01Z

kevgermany answered · Nov 21, 2022 at 02:22 PM

Sorry, but this will not work. Charging will only start when panel voltage is 5V higher than battery voltage. Not the 0.5V you quote. And the panel voltage needs to be 1V higher than battery voltage to keep charging. Not 0.1V.

12V PV is rare. What is the Open circuit voltage (VOC)

If you can find space for a second identical panel and connect the two in series to the MPPT, then it will work.

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