Enough to make my head spin for a while. New construction.
I have one PW2 and due to some less than clear advertising by Tesla, I realized I need a second PW, likely to be installed next month.
I was told by a Hyper Engineering distributor that Tesla installs the Hyper SureStart on most every PW install that includes AC. I'm using a third party installer that I don't think is aware of that. Anybody know about this?
Anybody see any potential problems here?
Off-topic: Tesla re-did the PW web page; don't see the price anymore. Has the price changed recently? Thanks.
If you are going by the numbers understand that your certainty is not 100% but better than nothing. Also "Up to 70% " is exactly how it sounds. Older compressors or different models will respond differently or not at all. Sounds like yours is pretty new equipment.
If you know how to read your utility meter it will tell you the total draw at at any given time. You don't have to use a multimeter, or oscilloscope lol. (BTW, if your system designer brings an oscilloscope to your house and asks if they can camp out at dawn until dusk to measure your AC draw, all before you have signed a contract and money changed hands he's either got way too much time or is learning from this thread, don't hire them)
Understand that your baseline load at the time your AC kicks on needs to be subtracted from the available amps the PW can supply. If you ignore this it means you could run your AC, as long as you aren't running your house at the same time. Most people don't accept this as "working"
As pointed out earlier AC is a huge drain on your PW resources. Not sure how often you might have an outage event when AC is critical to you, but 3 hours of the larger AC is an entire Powerwall drained to 10%. Manage your expectations appropriately, if your PV isn't recharging the Powerwalls then you have an issue with running much AC regardless.
Also, your overall system size demands 2 Powerwalls, unless it was a very recent system (Frequency shift partial production enabled inverters, AKA Rule 21 Capable). Otherwise your issue will be that your PV system is too large for a single Powerwall in a backup event. It will never or almost never charge without fussing.
Powerwall can only charge at 5kW max. If you are in backup mode and have 12 kW of PV pumping into the backup system what does the Microgrid do with the other power? If you are using your electric dryer now, then great your Powerwalls will charge. Otherwise you will have too much PV for the PW to safely charge. The PV and PW will be constantly fighting each other, until you turn on house loads large enough to suck up 7kW.
Then the Powerwalls can charge correctly from 5kW of your solar, because the other 7 kW (assumed) needed somewhere to go now that the grid is down. The Powerwalls will frequency shift your microgrid to approx. 66 hz and this will turn off all solar production. Until you turn on 7 kW of load you will get no charge in your Powerwalls. Sometimes I have heard of customers having to manually flip the breaker on one PV inverter or string to alleviate this problem with a 1 Powerwall system and PV inverters that have no option for partial curtailment.
Newer inverters (within the last year or 2) can recognize a partial curtailment signal (62 hz approx) from the Powerwall, and throttle the pv production when needed. This gives the Powerwall some control over the generation power to be other than on or off.
Its a good thing you are getting a second one for sure but just make sure the baseline load in your house is taken into account when deciding if the Powerwalls will fire your AC. Regardless, if the Sure Start works with your AC compressors, its a good thing to have installed. Might be a good time to have the HVAC serviced as well
