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solar, batteries, inverters?

CrazyRabbit

Member
Apr 21, 2020
410
123
Fort Worth TX
This isn't absolutely required. It took some back and forth with Tesla but I was able to get a system where the PV generation could exceed what the Powerwalls could absorb. I made it clear that I understood the edge of case being unable to charge.
give it a try, disconnect from the grid at 1pm on a clear day. how much solar (DC/AC) do you have and number of powerwalls? what is your base load?
The SolarEdge inverters in this case may even support modulating their production via frequency shifting so less likely to be an issue.
No, don't spread misinformation.
 

CrazyRabbit

Member
Apr 21, 2020
410
123
Fort Worth TX
Here's my understanding: ... In fact, quoting from the PW spec sheet: "In Backup mode, grid charge power is limited to 3.3 kW". PW installations don't include a power limiter between the grid and the PW, so the charging power limitation is set with the PW itself.
that is the rate programmed to charge from the grid... not the case when running island mode. solar inverter power supplies are not designed to run in island mode, they will still try to inject full power into your house with no where for it to go. the powerwall will be force fed more then it can consume and trip. like a beer bong. the enphase iq8 will be the first that will be able to, but so far it is vaporware (maybe the inverter being used in the encharge battery system)!
 
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h2ofun

Active Member
Aug 11, 2020
2,457
419
auburn, ca
Solar Inverter are designed to inject power on to the grid, if you have more solar then your powerwalls can consume the powerwall will trip and shutdown. they are limited to charge at 5kw each and the inverter wasn't designed to regulate current.
if you want more solar then powerwalls, they will install your excess solar out side of your gateway so it will not be available to charge your powerwalls in a grid out condition.
Then what value would that be? The goal, IMO, with batteries is to have solar charge them. But this is interesting. So what is the max per battery of solar that tesla will install? I have seen the tesla 16K solar with 3 batteries. But would they install 16K with only 2 batteries?
 

miimura

Well-Known Member
Aug 21, 2013
6,259
5,884
Los Altos, CA
Then what value would that be? The goal, IMO, with batteries is to have solar charge them. But this is interesting. So what is the max per battery of solar that tesla will install? I have seen the tesla 16K solar with 3 batteries. But would they install 16K with only 2 batteries?
The rule of thumb that I recall is a maximum of 7.6kW AC inverter per Powerwall installed on the backup side.
 

h2ofun

Active Member
Aug 11, 2020
2,457
419
auburn, ca
The rule of thumb that I recall is a maximum of 7.6kW AC inverter per Powerwall installed on the backup side.
I am now then really confused. The new panels were like 14kw, so on 2 PW's that should be fine. But, this is not what the other poster is saying. I still have not heard back from my installer with their reasons. So confusing.
 

h2ofun

Active Member
Aug 11, 2020
2,457
419
auburn, ca
I just got of the phone a couple times with my installer contact. And because of the great info folks were able to post here, I was ready.
Meaning, when he told me the lead engineer and COO both looked at my setup and said I had to get a third inverter, and I needed to trust them,
I just said but, and gave all the stuff I got off here. So, I asked him to get in writing what the issue is. He then called back 10 minutes, later, after talking to
the installation supervisor who has been to my job, and said yep, what I have said is totally right and adding like 50 more panels is no big deal and no extra
inverter is needed since he knew I have put in another 11.4K SE to be ready for this. Always ask the 7 but why :) I then said great, now I would expect the price for the new panels would be much cheaper since the inverter and all the wiring is already done.. He is now going to get a new quote written up. I then said but will PGE approve adding this. I just sent him my last PGE bill for the info. I guess it is up to them if then can work magic since no way would my last year support any size increase. If so, great, I can save a LOT of money.
 
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