Heat could slow down your system's energy production if it is higher than the ideal ambient temperature for your panels.
The best ambient temperature in which solar panels operate is 25 degrees centigrade. Extreme heat can lower the output of solar panels because the flow of electricity in the circuit changes speed due to changes in electron activity.
As with all-electric appliances, your panels are susceptible to overheating. Thus, solar panels are installed a few inches above the roof line to allow passive cooling by letting air flow underneath the system. Inverters also work best when not installed in direct sunlight to reduce the risk of overheating.