Agree that post by georgesymond121 is rubbish and spam. Yesterday I visited a friend who had professional solar panels put on their house about 6 years ago. I don't rememberer the exact wattage, but over 10,000 watts, and the cost was about $30,000 with inverters. The unit feeds power to the grid during the day and the house draws from the grid at night. They pay less than $500 a year for total electrical power. The plan is to pay off the cost of the installation by 20 years--the expected life span of the panels.
If the panels output is more than 4 amps (or 50 watts in 12 volts) you definitely need a controller. Most trickle charges are 5 to 10 watts, larger boats and RV's use up to 50 watts for large battery banks. I have used a 10 watt solar panels on both an RV and the C Dory 22 and 25 to keep the batteries topped off when in NV or CA. storage.
If the panels output is more than 4 amps (or 50 watts in 12 volts) you definitely need a controller. Most trickle charges are 5 to 10 watts, larger boats and RV's use up to 50 watts for large battery banks. I have used a 10 watt solar panels on both an RV and the C Dory 22 and 25 to keep the batteries topped off when in NV or CA. storage.