Hi Mo,
Found them yesterday on e3ay sold as full spectrum grow tubes. Each strip inside the 2ft. tubes contains 48 SMD2835 diodes with a 1850°k phosphor layer. I've ordered 10 2footers yesterday and will test them as soon as they arrive but I'm pretty sure the efficiency is not comparable, maybe 70-80lm/w if any..
Had them first seen on Alibaba, but the shipping costs ... you know? These tubes here use the same strips and I could find them postage free on e3ay. I am sure, if you are looking for the e3ay article number, you will find it on ebay.uk with free shipping.
I'll disassemble them and take the strips out, they're probably built in 8s6p or so, so you can hang them probably on a 24v driver. But I'll see that when I break them down.
I think, in the tubes sits a small 360mA driver, so that the LEDs are running at 60mA(~9w). If so, this gives plenty of room to overdrive the diodes because SMD2835 can handle up to 150mA. One could drive them with up to 900mA/~22w with proper cooling. But thats only my estimations, we will see it soon.
https://www.ebay.de/itm/T8-LED-Pflanzenlampe-Tube-9-18W-60cm-90cm-120cm-Leuchtstoffrohre-Volles-Spektrum/182907252228?_trkparms=aid=555017&algo=PL.CASSINI&ao=1&asc=20160630134825&meid=bed6fa41d4bb44029c91cbc9b495c02a&pid=100507&rk=1&rkt=1&&_trksid=p2045573.c100507.m3226