Inverters need fans to draw in cool air into the inverter component housing and expel the warm air out through the ventilation ports on the device. Three types of fans are typically fitted by inverter manufacturers, namely continuous fans, load-controlled fans, and thermally controlled fans.
Inverter fans can become noisy if the fan motor becomes worn due to overuse or when the load placed on the inverter is too high, or when the temperature in the inverter remains too high despite the fan running at full speed. Dust on the fan blades or air intakes also causes the fans to be noisy.
Inverter maintenance and the correct installation for proper cooling will greatly reduce the potential of developing noisy inverter cooling fan problems. These measures will include:
- Correct installation of the inverter
- Inverter maintenance and care
- Inverter AC loading
- Inverter cooling fan replacement
- Elimination of thermal overloading
Let’s review how you can correctly install and maintain your inverter to minimize the wear on the cooling fans and reduce the impact of fan noise.
Avoiding Inverter Overheating And Noisy Cooling Fans
An inverter is designed for chopping, inverting, and adjusting incoming direct current (DC) into a pure sine wave alternating current (AC). This current manipulation and wave modulation is energy-intensive and causes heat to be generated in the inverter circuitry and components.
The active components of the inverter are located on large aluminum heat sinks fixed to the aluminum inverter cover to help dissipate the heat. Cooling fans draw cool are into the inverter housing to help cool the internal components and circuits.
An inverter must be installed in a space where the heat can easily be dissipated through the heatsink and cooling fans. At least one foot of space must be available on all sides and above the inverter housing to facilitate airflow.
The cable connections from the battery bank must be as short and thick enough to minimize resistance and voltage drop. The cable connections to the battery and inverter terminals must also be very tight and free of corrosion.
Bad Cable Connections
Poor or corroded cable connections can often manifest in a noisy inverter. The battery bank state of charge (SOC) must also be sufficient to power the inverter with enough DC to meet the AC load demand.
The depths of discharge range (DOD) on Li-ion batteries or deep cycle gel batteries can be as low as twenty or thirty percent. Still, on lead-acid batteries, the DOD should not fall below fifty percent to prevent chemical degradation of the battery.
Insufficient battery state of charge can also cause the inverter and cooling fans to run noisily. As the inverter housing can become static and draw in the air via the air intake ducts, dust buildup can act like an insulator preventing the efficient cooling of the inverter.
The air intake vents and the cooling fan blades must occasionally be cleaned of dust buildup to prevent the cooling fans from running excessively to cool the inverter.
Switch the inverter off and disconnect the battery terminals and the AC loads before brushing off the dust and vacuuming out the inverter air intakes.
Check that the cooling fan blades are clean and that there are no insects or small lizards stuck in the fan blade housing.
Open the inverter housing, remove any obstructions, and gently vacuum the interior, taking care not to touch or damage any components.
3 different types of cooling fans in inverters
- Continuous fans
- Load controlled fans
- Thermally controlled fans.
Continuous fans are the cheapest and designed to run whenever the inverter is switched on, even when there is no load demand. They drain the battery bank and become worn out due to continual running much faster than other types of inverter fans.
Load-controlled fans will run when there is an AC load demand on the inverter and will increase their fan speed as the load increases. When the AC load on the inverter is at or above 80% of the maximum output rating of the inverter, the fans will run continuously.
Thermally controlled cooling fans are linked to a thermocouple that measures the temperature inside the inverter housing and accordingly controls fan speed. They are more expensive but will last longer due to their controlled use.
Degradation of Fans
All cooling fans have moving parts that will wear out over time and need to be replaced. Fans wear out and become noisy due to the cooling demand of the inverter.
Quality brushless cooling fans are designed to last 80,000 hours (nine years) in ideal running conditions.
If you have eliminated potential causes of noisy cooling fans on your inverter, consider replacing the cooling fans. An inverter has a typical operational lifespan of ten to fifteen years.
Consider having the inverter replaced or an extensive service to replace other components.
Where To Install Your Inverter To Avoid The Fan Noise?
The point of installation for your battery bank and inverter should be far away from bedrooms or living rooms. The buzzing of the inverter or fan noise can become irritating, but it needs to be in an easily accessed space and often visited.
The installation point should also be well ventilated and dry. The battery bank will require monitoring and servicing and must be close to your power supply system’s inverter and other components.
Ensure that there is enough space to allow good cable management and have all components and cables clearly labeled. Also, label the AC load plug-in connections with the appliance and watt-rating for the appliance.
The total load connected to the inverter should never exceed 80% of the maximum output capacity rating of the inverter. An overburdened inverter will be noisy and have a much-reduced lifespan.
7 Most Common Mistakes When Installing A Power Inverter
If you are planning an off-grid or grid-tied solar power generation system, considers the following steps before designing and purchasing any of the components:
- Don’t confuse daylight hours with productive sun hours (PSH). PSH varies for each area and is the average number of hours your system will generate power each day. PSH is 5 hours on average in the US.
- Don’t underestimate your power consumption for all the electrical appliances and devices in your house. Make a comprehensive list and get the energy usage for each device. Determine how long each device will run each day and calculate the Watt-hours per device.
- Look for ways to eliminate or decrease the power demand of your household first. Replace incandescent light bulbs with energy-efficient LEDs and replace old energy-inefficient appliances with modern low-energy ones.
- Don’t have unreasonable expectations of your solar power system. Installing too little battery capacity, solar power generation, or inverter capacity will frustrate you. Also, have some redundancy built into your system. Augment the solar panels with wind power or a diesel backup generator.
- Poor solar panel installation can also lead to inefficient power generation. Your solar panel array must be south-facing and angled correctly to get the optimal PSH in the US. Allow for sufficient cooling of the solar panels and correct wiring. Solar panels are designed to run best in cold conditions.
- Beware of being talked into a cheap grid-tied system by the solar companies installing such systems for “Free.” If something sounds too good to be true, it is because taken for a ride.
- Don’t buy any hardware before you have defined your household load. You will buy components that are too small and will have to replace them sooner than you expect.
- Plan for the modular expansion of your backup battery capacity and solar power generation.
- Plan for having excess power available and a backup plan for when the sun does not shine for more than a week.