Solar Attic Fan - replaced 10w module with 100w module

[SolarfortheOuachitas]

Hello,

I recently replaced a 12 volt 10 watt solar module with a 100 watt module to run my solar attic fan.

It seems that the fan runs faster with the new module and doesn’t require as much sun as the old one.

Am I causing any overheating problems by using the larger panel to run the fan?

Could it overheat?

I can’t find any specs online about the amp draw on the fan. It’s a big fan designed to help ventilate an attic.

 

[Hedges]

Compare the open circuit voltage (rating or measurement) of each panel.

The 10W panel would load down to a bit lower voltage.
But if rated voltage of 100W panel is much higher, then motor is being asked to run faster.
Probably OK if not too much higher. But I would imagine a fan with built-in 10W panel was fairly cheaply made, may not last as long at higher current and faster rotation.


Not all motors are happy to run with gradual voltage & current increase as the sun comes up. I tested a few at a salvage place, using the adjustable power supply they had for customer use. I selected Pabst 24V fans which run fine off "12V" solar panels and a 48V fan meant for a server rack that runs fine off "24V" solar panels. The big one I installed as a gable vent fan.

 

[efficientPV]

Some of the newer 12V panels have a power point over 20V and lightly loaded could easily be 24 or more volts, double what your motor was designed for. If it concerns you there are 24V to 12V converter modules. These will give you even longer daily run times.