Would Tesla replace SolarEdge inverter / LG battery system with Powerwall?

[lzolman]

I'm in year 5 of a problematic (but currently working OK) SolarEdge 16kWp PV system utilizing two 10kWh LG batteries. I've had a lot of trouble with the battery part of the system. Long story short: we're on a municipal power company (RMLD in MA) that will only pay us their wholesale cost of power for anything we export, so we have to maximize self-consumption with the batteries to make the system at all cost-efficient. It would be so much simpler without needing the batteries, but you can't squeeze blood from a stone.

Anyway, now that Powerwall 3 is out, I'm wondering if I can get Tesla to replace everything we've got except the PV panels with a Powerwall system so we can take advantage of "Charge on Sunshine" (without my having to do it manually), get a bit more storage capacity, and hopefully more reliability (my original two LG batteries bricked, so we had no batteries for 10 months and paid through the nose because we're on ToU and were getting killed noon-7pm each weekday).

Since the Tesla website does not offer a consultation for just Powerwall, I figured I'd ask here.

 

[arnolddeleon]

Tesla directly, almost certainly no. This is based on years watching this forum plus the occasional effort to get Tesla to do something "custom". A certified 3rd party installer, possibly.

It sounds like you don't have an installer backing their work. A possible path to "rip and replace". Might end up being cheaper. The other option might be to add a little bit of solar plus battery with Tesla and take out the old batteries. Or just have Tesla Powerwalls only and abandon the old batteries. My understanding is the Powerwall 3s can also still AC couple so they should be able to work with your solar inverters.

 

[Vines]

Tesla directly, almost certainly no. This is based on years watching this forum plus the occasional effort to get Tesla to do something "custom". A certified 3rd party installer, possibly.

It sounds like you don't have an installer backing their work. A possible path to "rip and replace". Might end up being cheaper. The other option might be to add a little bit of solar plus battery with Tesla and take out the old batteries. Or just have Tesla Powerwalls only and abandon the old batteries. My understanding is the Powerwall 3s can also still AC couple so they should be able to work with your solar inverters.

Most people won't want to modify an older system like this, unless they installed it then maybe.

Currently, there are restrictions to the PW3 and AC coupling.

 

[RedModel3]

I just had a long discussion the other day with my solar installer about a similar situation. I too have a 5-year-old SolarEdge system, but without battery backup as I'm part of the TVA program. (VERY long story). I've been trying to figure out how to even get battery backup without having to resort to a gas whole-house generator. One thing to be aware of with a PW3 - according to my installer, if any one panel is not producing, or is producing less, then the whole system feeding into the PW is only producing at that level. Think of the old Christmas tree lights - if one was out, the whole string was out. They were horrified when they discovered this and are trying to find a workaround. Does anyone else have more they can add?

 

[lzolman]

My batteries aren't actually for backup (in fact we now have a natural gas automatic backup generator that works great, and is completely decoupled from the PV solar system.) We need the batteries because we're on a municipal power company that only pays us .25 on the dollar (their wholesale cost) for whatever we export. So we went on time-of-use (ToU) and the batteries are to store up cheap energy so we don't have to import during peak time (noon-7 weekdays). The batteries have to be indoors however, and some lame regulations limit us to two of them, so we only have about 17kWh of usable storage and if it's cloudy, that only lasts from noon to about 4. When it is sunny, however, the batteries can easily last all the way through the end of peak time. Even though it's still winter, they've done so more often than not when it's sunny. We just don't charge the Teslas during peak time, unless there's actually excess production...then I manually simulate "Charge on sunshine". My motivation for looking into replacing the batteries/inverters would be to get automatic charge on sunshine (and more capacity, as even limited to two batteries, with the Powerwalls that would be like 26kWh?)

When the batteries were out of commission for 10 months, we paid roughly $550/mo for electricity. The first bill we got after the batteries came back on line, the bill was $300-ish. And it'll get lower as we get more sun.

Honestly, if the system we have now just keeps working for the next ten years we'll be good. It's just that after all the headaches we've had over the first 4 years of this SolarEdge system. I figure the odds of it just working right now for the rest of its natural life are slim and none lol.

 

[Vines]

I just had a long discussion the other day with my solar installer about a similar situation. I too have a 5-year-old SolarEdge system, but without battery backup as I'm part of the TVA program. (VERY long story). I've been trying to figure out how to even get battery backup without having to resort to a gas whole-house generator. One thing to be aware of with a PW3 - according to my installer, if any one panel is not producing, or is producing less, then the whole system feeding into the PW is only producing at that level. Think of the old Christmas tree lights - if one was out, the whole string was out. They were horrified when they discovered this and are trying to find a workaround. Does anyone else have more they can add?

Modern solar panels have bypass diode, so that if a panel is shaded it's production will not pull down the rest of the string much or at all. Maybe a couple of percent at most. By the end of the year, the PW3 solution should work for you.

 

[sc4rv]

I just had a long discussion the other day with my solar installer about a similar situation. I too have a 5-year-old SolarEdge system, but without battery backup as I'm part of the TVA program. (VERY long story). I've been trying to figure out how to even get battery backup without having to resort to a gas whole-house generator. One thing to be aware of with a PW3 - according to my installer, if any one panel is not producing, or is producing less, then the whole system feeding into the PW is only producing at that level. Think of the old Christmas tree lights - if one was out, the whole string was out. They were horrified when they discovered this and are trying to find a workaround. Does anyone else have more they can add?

They just changed it i believe.

https://www.reddit.com/r/solar/comments/1afy6pq/powerwall_3_and_inverter_requirement

 

[lzolman]

Some Tesla Energy reps who attended a local meetup just told me that, now, Tesla WILL consider exactly the retrofit I was wondering about. That's great news, as it means that for the price of two Powerwall 3s my system would be better than it is now.

It's been almost two months since the replacement of my LG batteries and the system is running well enough (on occasion I'll find that it hasn't started charging the batteries in the morning and I have to do a hard reboot, but that's twice in two months so I can live with it.) Now, at least, when the inevitable next shoe drops and the batteries become large paperweights again, the worst-case scenario ain't so bad.

 

[jjrandorin]

Some Tesla Energy reps who attended a local meetup just told me that, now, Tesla WILL consider exactly the retrofit I was wondering about. That's great news, as it means that for the price of two Powerwall 3s my system would be better than it is now.

While I certainly believe Tesla energy reps told you this, I wont actually believe that Tesla would take off another companies battery system, and substitute it with a Tesla powerwall or powerwalls, without also requiring a complete rip off of the PV system and everything else on the house, until you or someone else actually sees that happen with your own eyes.

Not "scheduled", but "completed".

I believe they said it, but I also believe they didnt understand the scope of what you were asking, or, misunderstand what Tesla will actually do.

 

[lzolman]

While I certainly believe Tesla energy reps told you this, I wont actually believe that Tesla would take off another companies battery system, and substitute it with a Tesla powerwall or powerwalls, without also requiring a complete rip off of the PV system and everything else on the house, until you or someone else actually sees that happen with your own eyes.

Not "scheduled", but "completed".

I believe they said it, but I also believe they didnt understand the scope of what you were asking, or, misunderstand what Tesla will actually do.

No, we had like 20 minutes to talk about it and there's no doubt they understood exactly what I was asking.

 

[karkrazy]

When it’s done and completed, please share the experience - data points like yours will help others out tremendously.

Not putting words in @jjrandorin ‘s mouth, but I think what he was alluding to is that Tesla is notoriously flaky at the first sign of trouble or complexity. We have anecdotes here that they will take the easiest route out (cancelling the contract) than spend time/effort to complete what was agreed upon. So anything to the exception is great.

Good luck!!

 

[lzolman]

Thanks, and yeah, I experienced how quickly they'll bail on me 6 years ago when I first reached out about getting solar at my house. They actually went a few steps into the process, mapping the roof, etc., before dropping me like a hot potato as soon as they found out I was on a municipal power company. I think I already related that somewhere above. In any case, I'm not planning on moving forward on this project until either my existing batteries/inverters die, or I become so wealthy that I can afford to just throw away what I have and go with Tesla. I still wouldn't do it, however, unless Tesla would stick with my existing LG PV panels.