That does not include the costs for inverters and other electrical system parts. I am not endorsing these vendors but I am happy with the result. My system paid for itself in less than 18 months. I have many years of experience buying from China in industry. I purchased batteries from Docan Power and BMS/battery housings from EEL Battery. My inverters are from EG4 and UL listed. You can see current pricing on their respective websites. I would say there is some learning curve for a complete novice. The diysolarforum.com is a good vendor neutral and honest resource for information.

> How is this cheap?

It's $900 + inverters for 10 kWh. A Tesla Powerwall 2 (14 kWh) is $10k (inverter included).

I doubt the inverters cost more than $1k.