Yes, it is well worth the cost. There is no battery system that comes close to Powerwall. Even if you do a comparison on cost per kWh, Powerwall works out cheaper. Just consider the benefits, 10yr guarantee plus 20yr 80% linear output warranty. Meaning in 20yrs, you should still get 80% out of the Powerwall. No other battery manufacture offers that. Plus, your battery is always updated with Tesla OTU ( over the wire updates ) so basically you always have the latest software on the battery adapted to your battery working conditions. Also with liquid thermal control, your Powerwall always runs at optimal temperature, no matter the weather.