How To Determine The Amount Of Time It Will Take To Recharge Batteries With Solar Panels

Question:

Good day I have a yeti 3000x connected to 4 expansion tank batteries, I have 2 solar panels charging the yeti from the Anderson port, I have added 2 more panels to the 30 amp controller and plug it to the last battery in the chain , how long will it take for the green bars to indicate a full charge, it took about 3 days to show 2 bars then ped to one overnight, yeti is at 75 percent change, one thing I also noticed is that the yeti panel charge indicator is fluctuating high 400 to 600 watts the down to 85 watts is that normal

asked by: Tim R

Expert Reply:

The charge rate of your batteries is going to depend on a number of factors, some of which include the amount of sunlight and the wattage of the solar panels. Solar panels all have a wattage rating that will tell you their capacity to recharge the battery. The amount of sunlight, including whether or not the Sun is beating down directly onto the panel with no obstructions can vastly change the amount of wattage running from the panel to the batteries. Because of this there's really only speculation on what the full amount of time could be since you'll most likely have varying climates day-to-day.

The bars dropping from 2 to 1 would indicate that the battery ran down a bit over night and the fluctuating wattage on your Goal Zero Yeti External MPPTX Solar Charge Controller # 287-98085 is most likely caused by the intensity of the sunlight on the panels.

To determine what it would take to charge the batteries you would need to convert the wattage being transferred per hour to amp hours and then compare that to the amp hour rating of your battery bank, while also taking into account the weather conditions in your area.

expert reply by: Kevin C