Unfortunately the positioning of my inverter means its outside and gets pretty intense sunlight in the summer. I want to put some PC case fans on it to help with cooling, but it's outdoors and I don't really have any means to wire power anywhere near it.
What solutions could there be to giving it power without a wall socket? Is there any way to draw power from the inverter itself?
There is no user serviceable power available from the inverter, where users have had problems like this in the past it has involved fitting a canopy to protect from direct sunlight and/or using a solar power bank fitted next to the inverter to provide the power the fans need.
Does your model have USB? You may be able to use a USB fan. Probably only limited to 0.5A at 5V. If you're not using the EPS out, you could get a socket installed next to the inverter which fans plug into. The manual does say over current protection is required, and as being the 3 phase model, make sure the conductors are correctly identified. You'll want one of the lives, doesn't really matter which, the neutral and the earth.