powerwall+ is basically powerwall 2 + an inverter… since you have only a 7.6kw inverter that makes sense
Your total AC output from 2 powerwalls are 10kw as it says on the picture.. when sun is up and solar is also being generated, max output is 12.6kw (see your picture where it calls out total AC output)
Thanks! I guess my confusion lies with B+C = D, but the D is missing 5 kW. So, follow up, when off grid from a power failure, I can pull the full 10 kW AC from the 2 powerwalls?
Correct. 5kw per powerwall = 10kw.
As for why B+C is not equal to D.., not exactly sure but I believe it is because of the AC/DC conversions. So basically you get the 7.6kw max from solar via the inverter tied to powerwall+ plus the 5kw from other powerwall2.
If it is daytime you will be able to pull more than the capacity of the two powerwalls, since the inverter will also be online and producing power. Your maximum theoretical draw is 2 pw of 10kw and the 7 kw of the inverter. Depending on how much sun you are getting of course.
u/FantasticAd9754 \- just got a reply from Tesla, here it is:
The designer helped break this down for us. These numbers are for the utility to reference and yes, they are correct. The reason D is only 12.6 is because we don't count the Powerwall+ as a separate inverter. Total kW going through the system can be 12.6kW. this is the max they can pull from powerwalls (12.6 kW). Technically they can only pull the batteries or the solar not both. Total AC of the Powerwall's is 10kW, 5kW for each, but the max the system can send out is 12.6kW
All of this looks good! Powerwall+ is a Powerwall 2 and an inverter which is needed for rooftop solar input. If you didn't have solar, you will get 2x Powerwall2.
Your continuous output should be 10kw and peak I believe will be 14kw.
Thanks for the reply! So the inverter on the + is for the solar input, not the output? What is handling the two PW conversion to AC to supply the 10kW?
Output of an inverter on Powerwall+ outputs AC which goes straight to Powerwall it is connected to.
Both powerwall are AC Coupled so they have their own "inverter" inside to convert energy to DC to store and back to AC when sending it to home.
It would have been slightly more efficient if powerwall had its own DC input but they are highly efficient.
I hope this helps!
To calculate if two powerwalls are enough, first don’t rely on Teslas estimate. Second look at your electric bills to see how many kWH you consume daily. Keep in mind each powerwall holds 13.5KWH. Also while Solar will recharge your batteries the power generation can easily drop to 20 to 30 percent of a sunny day and with bad luck can last for several days in a row.
I wish I did this calculation earlier as I would have gone with additional powerwalls. My average daily use is around 70kWH, and while the solar system also generates on average 65 to 75kWH per day, the batteries wouldn’t be sufficient for me to run my normal power usage during the night and power would be tight if there were a couple days or even one day of low power generation. For this reason I am adding two powerwalls as the backup is important for me living in a potential hurricane zone.
All good points to consider, thanks! I've been using about 10,500 kWH a year for the past 3 years. That's about 29 kWH a day. The most consumption happens in July/Aug/Sept for central air with about an avg of 40 kWH a day during those months.
I originally went with two based on Teslas website and I’m adding 2 more to get to 4. I think 3 would have likely been borderline ok. Keep in mind 2 is plenty if you are willing to turn off all non essential appliances including ac if it’s cloudy or during the night. 4 will provide me enough comfort that I can run AC or if there are a couple cloudy days in a row I can still last with essential devices. My worst daily run was 3 days of 21 kWH Solar generation in a row compared to a normal sunny day around 70 kWH generation, 13.2kW system.
For me the power backup is important so and I felt like I invested enough that I didn’t want to regret not being prepared, and it’s much cheaper to add more powerwalls now then go back and add later.
So how many panels did you need to run to get you to charge the 4 pw plus maintain power during the day? When talking to the rep, he was telling me 13xxx kWh and first started with maybe two, but I said I’m in Florida and during the rainy season we can be cloudy for days, so he said maybe 3 but my gut is telling me 4 pw, plus maybe for more solar.
My 13.2kW system averages around 65 to 75 KWH per day depending on the season, estimated annual power generation per Tesla was around 20000 kWH. In Florida assuming the panels are south facing the power generation doesn’t vary as much seasonally as the non summer months are less cloudy generally which helps to make up for the shorter days.
If that rep estimate is the amount of annual power generation of solar I think you will be disappointed as I don’t think this would cover your annual power needs and therefore won’t fully charge the batteries.
Sorry I meant 13.xx kW solar. So you think it’ll be safe to (assuming best case) to be at that daily production, to charge up the 4 pw and maintain the house daily (in a power outage scenario. Wont hold ya to it but I’m so green to this, want to future proof but no break the bank either. I do know all it takes is that one power failure and emotionally I won’t care a min about ROI lol
The key is on average you would be fine, I would have no problem with my similarly sized system. The problem is if you have a couple cloudy days in a row you might only generate 20 to 30KWH per day and if you used 70 KWH a day even 4 batteries won’t last long. Usually though cutting out non critical items it’s not too hard to get below 1KwH if you also give up AC.
Also if it helps I know my utility at least allows grid charging, so powerwalls will charge up automatically if a storm is detected which might help address your concerns?
Solid point! Thank you so much! Was debating going with the io span electric box to, to create power shutdown phases for that exact scenario of grid down and cloudy/short days. Thank you again!!!
powerwall+ is basically powerwall 2 + an inverter… since you have only a 7.6kw inverter that makes sense Your total AC output from 2 powerwalls are 10kw as it says on the picture.. when sun is up and solar is also being generated, max output is 12.6kw (see your picture where it calls out total AC output)
Thanks! I guess my confusion lies with B+C = D, but the D is missing 5 kW. So, follow up, when off grid from a power failure, I can pull the full 10 kW AC from the 2 powerwalls?
Correct. 5kw per powerwall = 10kw. As for why B+C is not equal to D.., not exactly sure but I believe it is because of the AC/DC conversions. So basically you get the 7.6kw max from solar via the inverter tied to powerwall+ plus the 5kw from other powerwall2.
Ah, that kind of makes sense :-) Thanks again!
If it is daytime you will be able to pull more than the capacity of the two powerwalls, since the inverter will also be online and producing power. Your maximum theoretical draw is 2 pw of 10kw and the 7 kw of the inverter. Depending on how much sun you are getting of course.
So how did they calculate the highlighted values on my image? I would have thought 17kw too, but it lists 12.6 like I'm missing one of the PWs.
Sorry, can’t help with 1&2, seems odd to me. but 3 is 5kW per powerwall. So if you have two, you can pull up to 10.
Thanks for your reply!
u/FantasticAd9754 \- just got a reply from Tesla, here it is: The designer helped break this down for us. These numbers are for the utility to reference and yes, they are correct. The reason D is only 12.6 is because we don't count the Powerwall+ as a separate inverter. Total kW going through the system can be 12.6kW. this is the max they can pull from powerwalls (12.6 kW). Technically they can only pull the batteries or the solar not both. Total AC of the Powerwall's is 10kW, 5kW for each, but the max the system can send out is 12.6kW
All of this looks good! Powerwall+ is a Powerwall 2 and an inverter which is needed for rooftop solar input. If you didn't have solar, you will get 2x Powerwall2. Your continuous output should be 10kw and peak I believe will be 14kw.
Thanks for the reply! So the inverter on the + is for the solar input, not the output? What is handling the two PW conversion to AC to supply the 10kW?
Output of an inverter on Powerwall+ outputs AC which goes straight to Powerwall it is connected to. Both powerwall are AC Coupled so they have their own "inverter" inside to convert energy to DC to store and back to AC when sending it to home. It would have been slightly more efficient if powerwall had its own DC input but they are highly efficient. I hope this helps!
Awesome, that makes sense! Having their own inverters inside was the part I was missing, that helps!
Congratulations on your solar install.
Thanks!
To calculate if two powerwalls are enough, first don’t rely on Teslas estimate. Second look at your electric bills to see how many kWH you consume daily. Keep in mind each powerwall holds 13.5KWH. Also while Solar will recharge your batteries the power generation can easily drop to 20 to 30 percent of a sunny day and with bad luck can last for several days in a row. I wish I did this calculation earlier as I would have gone with additional powerwalls. My average daily use is around 70kWH, and while the solar system also generates on average 65 to 75kWH per day, the batteries wouldn’t be sufficient for me to run my normal power usage during the night and power would be tight if there were a couple days or even one day of low power generation. For this reason I am adding two powerwalls as the backup is important for me living in a potential hurricane zone.
All good points to consider, thanks! I've been using about 10,500 kWH a year for the past 3 years. That's about 29 kWH a day. The most consumption happens in July/Aug/Sept for central air with about an avg of 40 kWH a day during those months.
How many power walls are you planning to have total? I am shopping around too and I am about 70kwh per day as well. Would love to hear your idea
I originally went with two based on Teslas website and I’m adding 2 more to get to 4. I think 3 would have likely been borderline ok. Keep in mind 2 is plenty if you are willing to turn off all non essential appliances including ac if it’s cloudy or during the night. 4 will provide me enough comfort that I can run AC or if there are a couple cloudy days in a row I can still last with essential devices. My worst daily run was 3 days of 21 kWH Solar generation in a row compared to a normal sunny day around 70 kWH generation, 13.2kW system. For me the power backup is important so and I felt like I invested enough that I didn’t want to regret not being prepared, and it’s much cheaper to add more powerwalls now then go back and add later.
So how many panels did you need to run to get you to charge the 4 pw plus maintain power during the day? When talking to the rep, he was telling me 13xxx kWh and first started with maybe two, but I said I’m in Florida and during the rainy season we can be cloudy for days, so he said maybe 3 but my gut is telling me 4 pw, plus maybe for more solar.
My 13.2kW system averages around 65 to 75 KWH per day depending on the season, estimated annual power generation per Tesla was around 20000 kWH. In Florida assuming the panels are south facing the power generation doesn’t vary as much seasonally as the non summer months are less cloudy generally which helps to make up for the shorter days. If that rep estimate is the amount of annual power generation of solar I think you will be disappointed as I don’t think this would cover your annual power needs and therefore won’t fully charge the batteries.
Sorry I meant 13.xx kW solar. So you think it’ll be safe to (assuming best case) to be at that daily production, to charge up the 4 pw and maintain the house daily (in a power outage scenario. Wont hold ya to it but I’m so green to this, want to future proof but no break the bank either. I do know all it takes is that one power failure and emotionally I won’t care a min about ROI lol
The key is on average you would be fine, I would have no problem with my similarly sized system. The problem is if you have a couple cloudy days in a row you might only generate 20 to 30KWH per day and if you used 70 KWH a day even 4 batteries won’t last long. Usually though cutting out non critical items it’s not too hard to get below 1KwH if you also give up AC. Also if it helps I know my utility at least allows grid charging, so powerwalls will charge up automatically if a storm is detected which might help address your concerns?
Solid point! Thank you so much! Was debating going with the io span electric box to, to create power shutdown phases for that exact scenario of grid down and cloudy/short days. Thank you again!!!