Ditto re: battery capacity. Using all 35 Amp-Hours repeatedly will destroy the battery. Anode terminals dissolve during discharging. They are electrolytically plated (thickened) during charging. So repeated full-discharging can reduce their solid volume to such an extent that they cannot be fully restored during charging.
In general, "deep-cycle" lead-acid batteries shouldn't be discharged to less than 50% of their rated capacity to ensure a healthy, long life in an off-grid solar setup like this one.
So more like 17 yrs to repayment - as long as he hasn't already bricked his battery.
In general, "deep-cycle" lead-acid batteries shouldn't be discharged to less than 50% of their rated capacity to ensure a healthy, long life in an off-grid solar setup like this one.
So more like 17 yrs to repayment - as long as he hasn't already bricked his battery.