Add to Cart Fortress Power Fortress Power eFlex 5.4 G2 Lithium Solar Battery 5.4 kWh $4,200.22 Fortress Power eFlex 5.4 kWh Gen2 Lithium Iron Phosphate Solar Storage Battery LifePO4 5.4 kWh 48VDC $285 off with coupon code EFLEX285. The compact and easy-to-install unit can be wall mounted or floor-standing... Compare Add to Cart Add to Wishlist