Thanks for your reply.
If I look at whats currentyl being used, I use a smart plug which reports the power usage, its reporting:

Single PC, with x3 1080 Ti's
Current Power: 39.0w
Daily Average: 0.94 kWh

So, I was thinking of just buying enough to support this small rig to start with.
I have a south facing garden. I have a single story kitchen extension, which has a flat roof, south facing, so could easily mount a some panels there.

With all the above in mind, It's also a bit of a hobby, and learning about green energy, what would I need to purchase? Is there any alternative options to power this?

Kind regards.