Rather than buy it now, I sent the chap a message and asked if it'd be ok to come over to take a look and perhaps collect rather than have them delivered. He was fine with that and offered me black ones rather than the silver one's he'd originally advertised.
So - after work (Andy was helping out that day) we detoured home via Leeds... a bit of a pain as it happened because the road directly where we needed to be was closed off and dug up. It took a fair old bit of finding but good old "Waze" (other mobile sat navs are available) did good.
It turns out, the chap flogging them has a business designing and installing 'Off Grid' power systems - mainly in sunnier climates. Smashing chap - you know the sort... someone you just get a good vibe from. He only sells "Outback" kit but was happy to advise on how to get the best out of the stuff I'd had my eye on.
Anyway - Here we are, back at home with them laid out in the garden for me to test them