I ordered two Powerwalls last year through Swell Energy, because I could not get a straight answer out of Tesla on what/how/when. Tesla's energy team was really floundering at that time. I provided a lot of energy use analysis, and Swell moved quickly to get the project approved under SGIP 2017 with SCE. Then...the waiting game began. Swell communicated frequently, giving the best knowledge they could, and it looked like September, 2018 would be the probable date. On 7JUN18, however, I got a call saying they had units and could install immediately. (I suspect there was a cancellation, but if so, it was my gain!) On 11JUN18, the team began a three-day installation process. It took a while to get city inspection, and will now take a while longer to get permission to operate (PTO) from the utility. But, we are up and running. A few app bugs are showing up (and will be fixed), but otherwise running very well and doing what was expected.
What was expected? We have two Teslas (S and X), lots of solar, and we are on time of use (TOU) with our utility, SCE. This means we pay $0.48/ kWh during the day, then $0.12 at night. So the goal is to charge the Powerwalls from solar during the day, then run the home from the Powerwalls until the nighttime rates kick it, at which time we charge the cars and run the pool pump. The Powerwalls have been doing that perfectly since installed.
Note that the cost balance calculation with the utility is based on the TOU rates both for receiving and sending power. The glitch I mentioned means I am only showing about half the solar being generated (yesterday our panels pumped out 72 kWh, but only 28 is shown in the attached charting), but you can see that the system is doing what was expected.
Here are some graphics of the system and how it is operating. I am pretty happy.
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