Came across these on ebay last night, still the same LiFePO but these support 100% DoD, same batteries used on the London Buses apparantly: https://www.ebay.co.uk/itm/BYD-B-Plus-2-56kWh-Solar-Battery-storage-100-DOD/322754585457?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649
Still a bit top heavy on price, but not too bad considering the 100% DoD?