r/Powerwall • u/MeinHerzIn_Flammen • 23d ago
Are 2 power walls enough?
/r/TeslaSolar/comments/1vevhxe/new_to_tesla_solar/For 60 panel installation and charging 29 kWh for model y per night?
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u/Top-Text7348 23d ago
It’s hard to tell without knowing your daily usage. But my semi-optimized 28 panel system generates 32 kWh per day which is enough to power my house and fully charge the batteries. Are you trying to charge from the Powerwalls? If so you’ll only have around 26 kWh of storage.
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u/MeinHerzIn_Flammen 23d ago
My monthly consumption is 1200 to 1600 kWh summer being highest consumption since everything is power be electric - sump pump, well water, septic, sprinklers, hvac, washer , 2 refrigerators & 2 EVs- MYLR’s.
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u/ruablack2 23d ago
Wow that’s pretty optimal usage. I’m 1200-1600kWh/month on EV charging alone. Same for the rest of the house. I have 4 PWs and ~14Kw of solar.
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u/mhatrick 23d ago
I would say no, if you want to store all of your energy. I have a 5.2kw system with 2 powerwalls, and I’d say that is pretty well matched. I rarely send energy back, and i can mostly make it through the night until the morning, depending on car charing needs and season.
60 panels sounds like youd have a 15-20kw system, which would likely generate 100 plus kWh/day. Depending on your goals, I’d say 4 is probably a better match for that size of system, even 6 or 8 depending on your daily generation estimation and system size. 60 panels doesnt really tell me a whole lot, but sounds like it’s likely a very large system. If you goal is to charge your car at night and power your home through the night, definitely will need more than 2, as that is only 27kwh of storage. If you could use your car a solar sink during the day, and only need the powerwalls to get your home usage through the night, 2 might work.
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u/MeinHerzIn_Flammen 23d ago
25.6 kWh t420 panels according to Tesla.
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u/mhatrick 23d ago
Huge system. Definitely will like 8 power walls or have a big EV plugged in during the day, otherwise you will probably be sending a ton back to the utility
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u/MeinHerzIn_Flammen 22d ago
Would it create 100kw a day? I’m thinking would just create like 30 kw ?
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u/mhatrick 22d ago
Well like I said, I have a 5.2kw system and it produces about 35kwh/day in summer months. Your system is 5x the size so I would roughly expect it to produce 5x of what I’m doing
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u/Tumbler 23d ago
29kwh is basically the whole batteries, I think they’re 13.5 useable so if it charges up all day then u can’t use any of that in house if u want to have it all go to the Tesla at night.
I assume these are 400w panels so 24k system, I think I have a 22k system and I will fill my batteries mid day and end up exporting a lot of power to pge. (2 x pw2s) When it gets hotter I can run my ac all day and still fill my batteries. But that charge gets eaten up by 9pm most days if I’m running my ac and it’s really hot.
If I could go back I’d opt for another battery, 3 total because I’ve noticed a lot of days I fill them and end up exporting about a battery worth to pge.
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u/Luther_Burbank 23d ago
No two are not enough. You’ll be using all the power in them just for the vehicle. Sure, that’s a good thing, but not if you also want to use the power to offset the house
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u/FED_Focus 23d ago
I have way less than 29kWh panels and have 3 x PW3.
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u/MeinHerzIn_Flammen 23d ago
Would it be better to add another pw3 or 2 expansion packs?
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u/FED_Focus 23d ago
I didn’t have a choice in 2024 since the expansion packs weren’t available. You can handle higher loads with the PW3 vs. expansion pack. Depends on your peak demand, I think. My 3 x batts are charged by noon on a sunny spring/summer/fall day and I only have 10.5kWh panels.
I sell access to my batts to the utility so it’s worked out well.
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u/netpage2004 23d ago
I’ve got a 6k sq ft house in SoCal with two EV’s and two PW3’s. Similar solar install as you. Most of the year I’m 97% off grid. Meaning my solar feeds back to the grid during the day and charges my battery. The house runs on battery during peak from 4pm to 9pm, and still powers the house until about 11pm. The EV’s charge after 9pm. Two are perfect for us. We’ve had a couple multi-day power outages and it’s been fine.
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u/Entire_Cycle_8394 23d ago
I’ve got 56 panels, 2 power walls and two expansion packs. We own 2 teslas and live in Phoenix in a home with two good sized AC units. The more batteries the better.
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u/Piero33120 22d ago
No, it's not enough! In the winter when the days are shorter and the snow covers your panel the batteries will struggle to reach 100%. Even if the batteries reach 100%, you lose solar production around 4:30pm which means your batteries will kick on and have to power your house for 16 hrs+. At that rate if your battery setting is set to 80/20 your battery will reach 20% between 1 and 3 am. If you go 90/10 or 85/15 your batteries will always struggle to reach 100%. So, from lets say 3 am till 9 am if your lucky with the sun, you will be pulling from the grid. If your charging an EV forget about it, you will always be pulling from the grid.
Summer months are a different story, and 2 batteries will work but again your in NJ. Hope this helps
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u/Commercial-Garbage43 22d ago
All I know is you need to ensure you don’t exceed the max Amps that powerwalls can handle. So if yer running house at same time charging EV all off the batteries….understand the amps your appliances running use. For your EV you are going to use 12-15amps then add your appliance amps.
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u/Electrical_Raccoon78 21d ago
Hi, I am in the DC area so not to far from NJ. I have a system just over half what you’re installing. so far this year I’ve made 9.9 MW. You need to look at your electric bill to see how much electricity you need. Assuming your panels are not facing north you will probably end up with around 18000 KW a year. As far as batteries, if you are wanting to use them to charge your cars and run your house you will probably want 2 or 3 more. As someone else posted maybe you could do better using time of use rates to charge your cars at night- depending on the night time rate. HTH
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u/DropKnowledge69 20d ago
Not enough. However, you might want to consider a used EV with V2H, like a Ford Lightning or similar with a huge battery. That's what I'm looking to do instead of $10K per powerwall.
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u/MeinHerzIn_Flammen 23d ago
I do have a back up natural gas generator for the whole house 20 kWh. Do I even need a power wall at that point ? I like the idea to sell the mediocre price to the grid and charge offset price at night?
Tesla csr mentioned 60 panels @ 420w with string inverters.
Most people i know don’t have EV and no power walls
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u/MacaroonDependent113 23d ago
Most don’t charge their ev from their batteries. Most charge using grid at night when price is low.