https://www.truckexporter.co.uk/vehicle/optare-solo-30-seater-ev-electric-bus-2018/
https://autoline24.uk/-/sale/city-buses/Optare/SOLO–24102510074153446500
Based on the text in the advert – the bus cost £300000 new and is currently for sale at £30k – If decent newer batteries can be installed – It will be a more cost effective ev conversion.
Need to research this more – There should be plenty of buses available in China (Shenzen) for this project