It should be from the batteries as neither the panels or controller have a SOC AFAIK. But your test confirms what I suspected, that 200 or more watts of solar would be needed to fully replenish the battery bank. I am now thinking of 200 on the roof using the Solar30 I ordered and the 100w suitcase to supplement. I may still move the suitcase controller to the RV to minimize loss and allow for longer cable from the panels.