Polycarbonate greenhouse

I have had my PC greenhouse for over 20 years. I have replaced a few panels but have never cleaned them. The rain does an excellent job without any help in my garden.
As for fumigation. Never found the need.
I have great success with propagation without the many downsides of glass. Glad you have had a great first season with yours.

I clean my greenhouse which has glass panels with washing up liquid Whiff and then give it a swoosh over with the hosepipe.

My greenhouse, glass, is relatively new, but I had one years ago and never fumigated it. I’ll be leaving our system for water recovery (on the shed) over winter.
Good you’ve had a success ful season.

Thank you all for your replies . I won't worry about it. To be honest only had white fly on my sweet potato plants and soon got rid of them.

I can highly recommend Toscana strawberries. I have grown them outside from 3 plug plants had large crop so far and plenty more to come. They have pink flowers and are the sweetest strawberry I have ever tasted.

I find the outside of my PC greenhouse does get a little "sticky" by the end of summer. I use plain old washing up liquid and a long-handled soft brush to give it a scrub inside and out and then rinse with the hose. Inside, I also use Jeyes fluid well-diluted and a sprayer to get into the nooks and crannies. I've had mine for over 15 years now and it's still going strong. If I've had to replace any of the sections (usually due to DH not being careful with sharp gardening tools!) I've found eBay sells them very cheaply if you look around. Old sections are then used for making home-made upside-down V shaped cloches!