FoxESS 120mm fan mount (KH10 support)

Designed specifically for the Fox ESS KH10, this mount likely fits a wide range of Fox ESS models. If your inverter has heatsink fins approximately 2.7mm thick with a 12mm pitch (center-to-center), this mount will clip directly onto the cooling fins without the need for drilling or permanent modifications.

Performance

In my testing, adding active cooling made a massive difference:

• Without fan: I was seeing 75°C+ peak temperatures under full solar production (10kw)

• With fan: ~50°C peak temperature

 While the inverter can handle high temperatures, I reckon this will be significantly reducing thermal stress on internal components.

Hardware

• Fan: 1-2 x 120mm fan (Standard PC fan, USB fan, or Solar-powered fan)

  • KH10 can just fit two 120mm fans side-by-side. Other inverters may be less. The bracket is 120mm wide exactly so if you have say 145-150mm (to account for fins), you'll probably fit two fans up there. 

• Bolts: 2-4 x M3 or M4 Bolts (30mm–45mm length; take your fan's thickness + 2mm for the bracket + 5mm for the nut)

• Nuts: 2- x M3 or M4 Nuts

  • Nylocs would be good if you have them. Not necessary. Don't use Loctite if you print in PETG as this will eat the PETG. 

• Quantity: This model holds one fan. Print two mounts if you wish to run a dual-fan setup.

This installs on top of the inverter, blowing down. In my case, I tried sucking air up but the fans weren't as effective in this setup. I know this is fighting convection, but there's no arguing with performance!

You may wish to print/procure a fan cover for the exposed side. I used the Noctua fan grille they released here, but a commercial one would obviously be fine too. 

Print settings

• Material: PETG is highly recommended.

  • I tested ASA for UV resistance, but it was too brittle; the "clipping" pins snapped during installation.

  • PETG offers the perfect balance of flexibility to grab the fins and a high enough glass transition temperature to handle inverter heat (inverter will be cooler with the fans running too)

• Placement: If your inverter is outdoors, PETG is generally durable enough for several years, even with UV exposure. It’s an easy and cheap part to reprint if needed as well. 

• Orientation: Print with the clips facing up for the best structural integrity.

The mount is designed to be a "snug clip." While it isn't "locked" on with screws, it is more than secure enough to hold a fan in place, even in windy conditions, especially since most inverter installs are somewhat sheltered.

Powering the fan

I personally use a solar-powered fan from this listing with the panel mounted on an awning (link to my Awning Solar Panel Mount here).

This setup is ideal because the fan speed naturally ramps up as solar production (and heat) increases. However, a standard 5V USB fan or a 12V DC power supply will work just as well.

Design files

OnShape design files are available here if you need to tweak the design to fit your inverter.