Re: Rand Solar Attic Fan/ Controller Question
Welcome to the forum.
In order for a solar powered attic fan to operate at night it needs to be able to store energy in a battery to have it available when there's no sun. This would mean it would probably have a larger capacity solar cell, a battery, and some circuitry to regulate the charging of that battery - as opposed to a motor powered directly by the solar panel.
Whether this would work to power another make's fan depends on its Voltage and current capacity. Your fan is 12 Volt, and the unit from Costco appears to be 38. Right there you have a problem: put 38 Volts to a 12 Volt motor and it will run very fast, and very briefly.
Without more details about each unit (which the manufacturers seem loathe to give - they prefer marketing hype to facts) it would be impossible to say whether it could be adapted or not. Most likely not. If so, you'd end up doing some significant amount of modification which would amount to building your own battery and charge controller and possibly changing the solar panel as well.
Perhaps someone else on the forum has a different idea/perspective.
Four 175 Watt panels, OB MX60, 232 Amp hrs, OB 3524, Honda eu2000.
Ohm's Law: Amps = Volts / Ohms
Power Formula: Watts = Volts * Amps