Sixty cell solar panels, a.k.a. 20V solar panels, are commonly known as grid-tie solar panels, as they are most often used in grid-tie solar systems without batteries. We compare charging a 24V deep cycle battery bank with a 20V solar panel and a 24V solar panel on a hot summer day with a PWM charge controller. Because silicon solar panels output a lower voltage in the heat, the voltage output of the solar panels is lower than standard test conditions (STC), so we see if the voltage is high enough to charge the 24V battery bank. In a follow-up video, we do the same test with an MPPT charge controller.