PV Gap

Everett Said:

What time it would take for a 1.8 W (12v) solar panel to charge a 300w (12 v) battery?

We Answered:

If the battery wouldn't self-discharge, it would be:

300W/1.8W = 166 h 40 m

With 12 hours of sunlight per day, it will take about 14 days.

However, since all rechargeable batteries self-discharge over time, it would take much longer, if it could be done at all. Many batteries give a figure of 1% per day loss, so that would be 3 W per day, or 1 h 40 m per day required just to recover to the level of the previous day. So, if there were only a 1% loss per day, you'd only get a net gain of 10 h 20 m per day. That would take a total of 16 days of 12 hours of sunlight.

If you lost 8% per day, you could never fully charge the battery...

Dorothy Said:

10 POINTS IF YOU ANSWER THIS QUESTION!!!!! WILL A 12V SOLAR PANEL CHARGE A SEALED LEAD ACID BATTERY?

We Answered:

To fully charge a lead/acid battery, you would need a bit more than 12 Volt, usually 13.2 Volt.
Many Solar panels which are rated at nominal 12 Volt can deliver up to 14 Volt in direct sunshine, and at perfect angle to the sun.
So, the answer is, under ideal conditions, you can. Under less ideal conditions, the battery will not be charged to its fullest capacity.