If you could run 24 volts the system would be more fault tolerant.
When one part of the string starts to show lower sg you will need to divert more charging current to it by putting a shunt load across the over charged bit until the low bit equalises. Most likely the string of 7 will need equalising and a lamp across the odd pair will reduce its charging current in relation to the others. Do it when you have good charging conditions.
Flux[ Parent ]
