I built a storage system with these, which are almost down to $300/kWh now:
https://www.currentconnected.com/product/sk48v100-48v-server...
Of course you will need a charge controller and some other components which will add to the cost.
https://www.currentconnected.com/product/sk48v100-48v-server...
Of course you will need a charge controller and some other components which will add to the cost.