Renogy

Time to charge = (Battery Voltage x Battery Ah )/ Solar Panel Watts
Theoretically, if you have a 100 AH battery with the sun shining directly on your panels, it will take (12×100)/100 hrs = 12hrs.
Because the sun is not always directly overhead, and due to other inefficiencies, multiply the result by 2 or 2.5. This means it will take about 24 – 30 hrs of direct sunlight to charge a fully depleted 100Ah battery completely. If we estimate 5 – 6 hours of sunlight in a day, we can expect this solar panel to charge your 100Ah battery in 5 – 6 days. Therefore, you will need 4 of these panels to charge your 100AH battery in one day.

Extension cables, Solar Charge Controller, MC4 Removal Tool, Mounting Hardware – It really depends on how you use your panels, but these are the basics. You may also consider an inverter, battery, etc.

These panels have several uses, and their smaller size and weight make them ideal for tight spaces – Off-grid rooftops, Ground-mounted residential, RVs, Trailers, Boats, etc.

This depends on where you live, but I usually say as needed or when anything is blocking the panels from direct sunlight. I clean mine once a year.