A complete note on solar panel installation.
Direct connection to solar panel.
Solar panels when there is at least weak direct sun run a constant vmp and low isun current.
Add a blocking diode on the positive rail between the battery and the panel or as previously suggested and the best solution imho use a small solar charge controller.
It is very possible though that you will need a larger solar panel to start the fan and run it under less than full sun.
Install batteries for the solar panels based on your decision whether to replace your.
Go ahead and connect measure the fan voltage and see if it is ok.
Connect battery to charge controller in the first step you are going to wire the battery to a charge controller.
Direct current motors are the easiest and best motors to power with solar panels.
Alternating current motors can also be powered by solar panels but they require a power inverter to change the direct current of the solar panels to alternating current to feed the motor.
If you keep the panel connected as shown in your diagram it will absorb some power when it is not getting sunlight.
Wiring the loads the following step is to wire the loads.
How to wire solar panel to 12v battery and 12v dc load 12v dc fan light etc dc load only.
Solar panel used to power fan directly probably not the typical brushed motor is pretty voltage tolerant.
These can be an inverter 12 volts dc box or both.
The lcb takes solar panel power at low current and fixed vmp vmp i sun and converts to high current low voltage used to start the pump motor.
How to connect a solar panel to a 12v battery.
How to connect solar panels to my house s electricity.
Series connection of batteries with solar panel or how to wire 24 v solar panel to two 12v batteries with automatic ups system.
Connecting solar panels in series the series connection is done by wiring the positive terminal of each panel to the negative terminal of the next panel a connection similar to the ones of the christmas lights until the final panel is connected to the charge controller or inverter.