89% round-trip efficiency is surprising (even lower than PW2), I was hoping it would be higher given all the talk about DC-coupling.
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Discussion: Powerwall 3 [Speculation / Discussion etc]
- Thread starter n.one.one
- Start date
89% round-trip efficiency is surprising (even lower than PW2), I was hoping it would be higher given all the talk about DC-coupling.
DC coupling only impacts solar to battery. Grid to battery to grid is unchanged.
89% could be due to slighly higher cell equivalent resistance or various other factors. 94.9% one way vs 94.3% (not that charge and discharge are necessarily equal).
Note: spec says "Solar to Battery to Grid Round Trip Efficiency: 89%".
Jeremy3292
Active Member
Matt-FL
Member
Interesting, scalability shows up to four PW3s.
Scalability: Up to 4 Powerwall 3 units supported
Scalability: Up to 4 Powerwall 3 units supported
Powerwall+ is solar to AC (no battery involved). When time shifting solar, that efficiency stacks on the AC-DC-AC battery round trip.
Jeremy3292
Active Member
And since PW3 is DC coupled it goes Solar-DC (Battery)-AC (Grid), correct?
vs. PW+ which is Solar-AC-DC (Battery)-AC (Grid)
Effectively skipping a step in the conversion prcocess
I wonder if a good chunk of that efficiency loss of 8 percentage points (97% if direct to grid - 89% via battery) is AC inverter losses? 8% of 13.5kwh is about 1 kwh. The footnotes say 89% is at 3.3kw discharge rate, so would take 4 hours to discharge the Powerwall, or 0.25 kwh/hr = 250 watts.
From what I've been researching on portable power stations, the AC inverters self-consume a certain amount of watts just being on and ready to power, - and the self-consuption is fairly proportional to the size capacity (11.5 kw) of the inverter, not how many watts are being charged/discharged. 250 watts self-consumption seems a bit high for 11.5kw inverter, though maybe like 2x high (not like an order of magnitude off).
Yeah, with DC not requiring flow through the battery. There could also be a DC-DC stage between DC and battery which would explain the use of non-isolated inverter on the PW3 rating panel for solar.
Solar -> HV DC <-> Battery DC (isolated)
Grid AC <-> HV-DC
Discussion: Powerwall 3 [Speculation / Discussion etc]
I see lots of posts about issues with Tesla's inverter. Glad I have solar edge stuff.
You maybe right. I did so much research. Before I got solar installed. I was so happy Tesla was using their own inverter now. I heard a lot of bad things about Solar Edge. I made sure I was getting a Tesla Solar inverter with my order. But now I hear that some are having problems with them. Thank goodness I haven’t had an issue. Also thank goodness we have multiple choices.
I have had some failures with my solar edge inverters, but I get them replaced, working with them real fast.
I had a coworker. That had his fail within the first month. It only took two weeks to get them to look at it. And another 2 weeks to replace it. But it always depends on who installed the system. You deal with the Company. More than you deal with the product. It’s a great benefit when you purchase solar and get a 10-30 years warranty. Most people I talk to about getting solar. That is their main concern. Getting on the roof or trying to figure out how to fix a high voltage device. When I tell them. Even the worst companies have a warranty. They are mostly shocked.
Just got my complete plans, and I got the info sheet for pw3, and in the parts table it lists 4 pw3s! Sooo I should be getting pw3s?
CrazyRabbit
Active Member
Good question. Definitely not compatible with the older PW’s.
Look carefully at the wiring diagram from the panels ... since (as many others have pointed out), they may parallel'ize some panel arrays that are at different angles. Yes, it saves a few bucks on copper wire ... but questionable (IMHO) if that is worth the slight loss in production plus reduced troubleshooting ability.
Similar threads
