Hello OHLD. We did install the north wall panels on our HFGH, but they are entirely covered with sheets of þâ polyisocyanurate insulation, so I understand your point about not needing the clear poly panels on the north side.

Just one heads up...if your main reason for doing so is to save the north panels to replace the south ones, if/when they fail, you might consider how inexpensive replacement panels are from Harbor Freight. We purchased enough replacement panels for our entire roof two years ago, and the total cost was $135 including shipping.

I'm not a good person to estimate the insulation difference between the kind of wall you're considering, and the normal HF polycarbonate/insulation combo we used, so there might be other benefits. Just didn't want you to go to a lot of extra effort/expense to save panels because you thought the cost would be quite high.

In the unhappy event that your south panels do need replacing, in time, it's quite likely that your roof panels will too, so you'll likely be ordering some replacements, anyway.

Not sure if you caught these recent posts (on the end of an older thread.) Two years ago I applied a clear roll on product made by the Top Secrets Coating company (TS-100 Clear Silicone Epoxy, thinned with their proprietary thinner.) I used this on my new roof panels, and so far see no deterioration. I wasn't ready to declare it a success yet, however, because panel degradation takes time.

However, another HFGH owner, rtyu, was kind enough to post that he applied the same product three years ago, and has seen no deterioration in his Colorado climate.

While there are no guarantees, I find these results pretty encouraging. You can find our remarks about this product at the end of this thread:
Harbor Freight Panels Failing, Part Two

Now I will step aside, and maybe we can hear from other folks who did use alternative materials on the north side of their HFGH.

Well I did this. So far I have used one extra panel on the door side of the greenhouse.

I will probably use the other extras on some additional cold frames.

I have to say, after the 6x8 that the 10x12 complaints were over done a bit. But I have to agree the 10x12 is a pile of garbage compared to the 6x8. Even with additional bracing and a solid north wall the thing bows and bends far to much in these easy 20mph winds I am having.

I will do some serious bracing on this thing in the next few weeks.

I still need to insulate that wall. My local Habitat resale store has some 4"thick white styrofoam panels that have a fiberglass like skin on both sides. About the same price as the 1/2" sheets of blue/pink foam from HD/Lowes. I figure these are far better insulation values for the same money. I realise over insulating the north wall does lack some return on investment, but over insulating for the same price only costs me about 3" of space.

I suppose I should post some pictures at some point, but I am one of those tech recluse and have to actually find the camera, take the picture, download, figure out how to upload and then post...