Well, looks like I'll be returning them for a refund.
The manufacturers response didn't meet my expectations - he actually told me "you don't know anything about sewing" when I questioned his zips! Also didn't provide a response to other issues I raised. I always keep my correspondence with suppliers (and customers) very polite and keep to facts, so was a bit shocked at this response. Fair enough if I was being rude, but IMHO I only stated facts in a civil manner.
With due credit, a refund was offered in this initial response, which I'll be accepting.
Now, whilst not trying to bag the supplier (again I like to keep to facts), the issues I wasn't happy with were (and I quote directly):
"Solar Panel bag:
1. The straps don't go all the way around the bag, ensuring that they don't tear the canvas or come come away from the bag. My panels are probably at least 20kg, and I'm not confident the straps will last very long with just the couple of small stitches holding them onto the canvas. I believe that they will tear off the canvas, perhaps tearing the canvas in the process.
2. The quilting isn't attached in any way to the canvas cover. I'm concerned this will make removing and inserting the panels into the bag a bit troublesome. I expected the quilting would have been buttoned or have velcro to attach it to the cover.
3. The zip doesn't look very strong, and only has one opener. I was expecting a heavier duty zip (like what's on the axe bag) and would have liked to zip tags allowing the ability to open it from either end. I also note they're not YKK zips, which I believe are the best on the market.
Axe and jack bag:
These are OK, except the end of the zips that are stitched into the bag (i.e. the end that isn't meant to open) isn't properly closed up. On first inspection, there was about 2-3cm of open zip. I can grab the bag and with not much effort the zip comes apart. Hopefully I've explained this clearly."
Hopefully this post isn't construed as a name and shame - not my intentions at all. I'm sure plenty of customers are very happy with their purchase. I thought I'd simply provide an update of my experience. I've taken some photos if my issues aren't explained clearly.