Has anyone put plastic on their harbor freight greenhouse? We need to either replace a bunch of panels or put plastic or something on. If anyone Has ever put plastic on I'd love to see pics or hear ideas why or why not that wouldn't work

Flowerlady, I haven't dealt with a HF GH, but I don't see any reason why you couldn't cover it with plastic film instead of the panels. You would want to use actual "greenhouse film," which is UV protected, not just the cheaper type of plastic sold at places like Menards and used for drop cloths and such. And the insulation will be less than the twinwall panels, but I don't think it makes a whole lot of difference in our northern zones. (That probably depends on how you are actually utilizing your GH.) I'd suggest using "wiggle wire" (aka channel lock) for attaching the plastic to the GH frame; however, by the time you buy that and the GH film, it might actually be more cost effective to just replace the twinwall panels.

I hope someone with a more definitive answer will chime in and offer some advice for you! Maybe @Subarctic or @Moonshadows ?

The roof of my lean to greenhouse has been blown off, so I might try using plastic. thanks for the idea Sandy.

Either one should be ok. As long as it's secured properly on a good frame and air tight.
I have had a greenhouse for over 20 years never had a problem with the panels.

Can't give you advice on the HF, but I can tell you if you do a bit of research, there are forums dedicated to HF greenhouses. For many people that own them, they are almost a cult. These folks love to talk about fixing, repairing and improving their HF greenhouses. I'm sure you could get some good advice in one of those forums, not that the two above haven't offered good advice that can work, but you really need to speak with HF owners. It is one of the least expensive, most popular gh's on the market, despite its many flaws, and long-time HF owners have become very adept at keeping it all together and making it work for them.