growatt sp1000 LiFePO4 Battery5kw off grid solar system price south africalifepo4 battery sizes chartlishen 18ah cellslifepo4 battery 3.2 v 700mahgrowatt gbli6531 compatible LiFePO4 Battery280ah lifepo4 48vgrade b byd lifepo4grade a lifepo4growatt 3kw hybrid inverter LiFePO4 Batterygrowatt 40000tl3tesla lifepo battery