Questions on Tesla Solar Inverter vs. Enphase Microinverters

[BrettG]

Hello, I live in Phoenix, AZ and plan on getting solar installed soon. My energy provider is APS. I have been working with a few Tesla Certified companies that I found through energysage.com and through the Tesla website. I prefer to work with local contractors for service reasons. Right now, I’m looking to install about a 110% production system that comes out to 13KW.

Anyways, I’ve been happy with my last couple of bids but am completely torn on which type of inverter to choose. I have read many positives and negatives about both types – Tesla String Inverter vs. Enphase Microinverters. The plan is to add a Tesla Powerwall or two in the coming years. One company seems totally fine with installing the Tesla inverter as it would be a 1:1 replacement if there are any issues, but have also made it very clear they don't sell many of them. Both companies have shared thier most common sale are Enphase Microinverters plus Tesla Powerwall.

I wasn’t aware that I could even use Enphase microinverters until I did some research. Does anyone else have some other opinions on this choice? I have zero shade on my roof but also don’t like the fact that if the Tesla inverter goes down, so do I. But, what is the actual failure rate? Should I not be confident in their product? Are there any other things I should be investigating prior to my decision? As a Tesla FanBoy, I want to get the String Inverter but the downside seems quite risky...

All opinions and thoughts are welcome. Thank you in advance!

 

[BGbreeder]

Enphase. Always. Two reasons;

1. If one of your microinverters goes out, you might lose 2% of your production until it is fixed. If one of your inverters dies, you are out closer to 50%.
2. Microinverters warranties are 25 years or so. Inverter warranties are 7-10 years. The manufacturers know the longevity of their products, and we don't. To me the warranty length difference is a reflection of the manufacturer's expectations for how long they expect the item to last.

Plus, Enphase gives you panel level monitoring and automatic alerts for low production in case you aren't watching your panel production.

FWIW: We have Enphase microinverters with Powerwalls and are happy with both. No issues between the two.

All the best,

BG

 

[dafish]

I would suggest "neither". First, let me say it's a bit more nuanced than some suspect IMO

1) Does Tesla include DC Optimizers in their design? I'm told not, and if so we're done. You do not want a string inverted that can only do a few MPPT's.
2) Are the wiring costs close in your situation? String inverters are cheaper, but the wiring is more costly.
3) Do you have plenty of roof? If your design is attempting to optimize via planned "clipping" it's something inherent to a string inverter.
4) Support. My experience is the Enphse software has been OK, but not great. Software is developed and maintained in India, as it Tier 1 tech support. Software Support has been challenging. My installer, who does both, tells me his experience with SolarEdge (a string inverter mfg) is much better.
5) Panel power is DC to the boxes using string inverter (why the wiring is more costly and A/C when using a microinverter. If using a power wall I belive a microinverter system is not as efficient. You converting to A/C at each panel, back to DC to drive the powerwall and the powerwall now needs it's own inverter to re-create A/C. All those conversion should be adding up.
6) Down the road I believe things like V2L will be more easily done w/ DC and a string inverter.

As a while it suggest "no" to a Tesla String Inverter, but maybe "No" to an Enphase microinverter too. I own a lot of IQ8's and if I had it to over I'd still use my Panasonic panels but install Solar Edge DC optimizers on each panel and then to dual string inverters backed up by batteries if I wanted (I don't). Cheaper and more efficient (on many levels).

Disclaimer: I'm not a tesla solar expert, so not all of the beliefs above may be correct. eg: I don't know for sure Tesla doesn't have panel based optimizers. Last I heard they were using smoke and mirrors around that, but it may have changed.

 

[BGbreeder]

I would suggest "neither". First, let me say it's a bit more nuanced than some suspect IMO

1) Does Tesla include DC Optimizers in their design? I'm told not, and if so we're done. You do not want a string inverted that can only do a few MPPT's.
2) Are the wiring costs close in your situation? String inverters are cheaper, but the wiring is more costly.
3) Do you have plenty of roof? If your design is attempting to optimize via planned "clipping" it's something inherent to a string inverter.
4) Support. My experience is the Enphse software has been OK, but not great. Software is developed and maintained in India, as it Tier 1 tech support. Software Support has been challenging. My installer, who does both, tells me his experience with SolarEdge (a string inverter mfg) is much better.
5) Panel power is DC to the boxes using string inverter (why the wiring is more costly and A/C when using a microinverter. If using a power wall I belive a microinverter system is not as efficient. You converting to A/C at each panel, back to DC to drive the powerwall and the powerwall now needs it's own inverter to re-create A/C. All those conversion should be adding up.
6) Down the road I believe things like V2L will be more easily done w/ DC and a string inverter.

As a while it suggest "no" to a Tesla String Inverter, but maybe "No" to an Enphase microinverter too. I own a lot of IQ8's and if I had it to over I'd still use my Panasonic panels but install Solar Edge DC optimizers on each panel and then to dual string inverters backed up by batteries if I wanted (I don't). Cheaper and more efficient (on many levels).

Disclaimer: I'm not a tesla solar expert, so not all of the beliefs above may be correct. eg: I don't know for sure Tesla doesn't have panel based optimizers. Last I heard they were using smoke and mirrors around that, but it may have changed.

Just to clarify, the current generation of Powerwalls are AC, so even with a standard inverter, it is DC to AC to DC and back to AC when you pull it out.

 

[jrweiss98020]

I have 10 kW of LG panels, Enphase microinverters, and 2 Powerwalls, installed by a local (Seattle) company. Initial install is a bit more expensive, but I think it's worth the peace of mind NOT having a single point of failure for the whole system. Also, when I wanted to expand, it was seamless.

If you can afford it, get the Powerwalls with the initial install. Without them and the Gateway, you cannot use the solar panels during a grid outage. You will also be assured the entire system works as advertised from the beginning, obviating some of the horror stories seen elsewhere in this forum.

 

[cali8484]

Enphase is more flexible given the modularity of microinverters but they can have more issues at your location given the brutal heat. OTOH, Tesla inverter is still pretty new and does not seem as reliable as Enphase. Is there a significant cost difference in the quotes?

 

[jrweiss98020]

The Enphase IQ7 is rated to 65°C...

 

[cali8484]

Roof temperature in Phoenix can go well above 65C.

 

[BrettG]

Enphase is more flexible given the modularity of microinverters but they can have more issues at your location given the brutal heat. OTOH, Tesla inverter is still pretty new and does not seem as reliable as Enphase. Is there a significant cost difference in the quotes?

There was not. About $1400 total was the price difference. The more I learn about the micro inverters it seems like the better option. I have been pleasantly surprised at the amount of PowerWall users that have Enphase microinverters. I wasn't aware this was seamless and very common!

 

[BrettG]

Enphase is more flexible given the modularity of microinverters but they can have more issues at your location given the brutal heat. OTOH, Tesla inverter is still pretty new and does not seem as reliable as Enphase. Is there a significant cost difference in the quotes?

Thankfully, the one quote I have is a 25 year parts and labor warranty on the inverters. So even with the heat concern, that is good to know.

 

[arnolddeleon]

I would focus on $/kWh vs string/dc optimizer/micro inverter

 

[dafish]

String w/DC optimzer vs Micro inverter, but yep.

Interesting powerwall makes you only feed it via AC. What a shame. But then I'm suggeting one look at the StolarEdge string inverter and their battery. I think that's DC to charge, SC to inverter, so very efficient. Worth a call to then anyway.

 

[sunwarriors]

As a very biased Enphase owner, you can just spend time here reading some posts when your main inverter dies, doesn't even have to be Tesla (mostly read about SolarEdge here). You're out 1/2 or all your production until that's swapped out. I'm also a bigger fan of LFP batteries which the PW3 is rumored to use. LFP doesn't require active fans which is another possible failure point and you don't have stuff like coolant running within your Enphase batteries.

Another reason not to go with central string is you have another ugly box taking up space on your wall.

There is also another company called Franklin that has great specs, but is a new company (higher power/specs/longer warranty/etc) so you may research them too. I'd stay away from anything else or small since there are very few installs.

Unless you are a total Tesla fanboy, going with Enphase will also allow you to hook up a generator right now within their environment and V2H is in their plans in 2024 if you have an EV.

Enphase Bidirectional EV Charger | Enphase

enphase.com

Someone complained about Enphase service and their tech support, but I had a case where I just called them vs. my installer who wanted me to wait and Enphase debugged my issue over the phone with the 1st guy who picked up. Maybe he's 1st line tech support, but he zero it ined and fixed my issue right away. If your installer gives you the run around, you also can deal with them directly which is a plus.

If you want, you can also get Enphase certified and get all access to the installer app to tweak more stuff.

With the PW3 coming out, LFP (if it uses that) just makes more sense since they have no issues being at 100% all the time. Since you're going with a 3rd party installer, you will pay the same whatever tech you pick anyways. Tesla solar is mostly picked I've noticed due to so and so saved an insane amount, for me, going with Tesla would have saved me like $0.05/W. Negligible.

Read more here and decide.

Edit: There are reasons if you want everything within the Tesla eco-system if you have a Tesla vehicle, multiple Tesla vehicles to get some benefits like solar charging, but there are 3rd party solutions that does that or, simply, do what I do and just plug in when the batteries are at 100%. One doesn't need to overthink that piece I feel and really, not an earth shattering benefit.

 

[Vines]

Hello, I live in Phoenix, AZ and plan on getting solar installed soon. My energy provider is APS. I have been working with a few Tesla Certified companies that I found through energysage.com and through the Tesla website. I prefer to work with local contractors for service reasons. Right now, I’m looking to install about a 110% production system that comes out to 13KW.

Anyways, I’ve been happy with my last couple of bids but am completely torn on which type of inverter to choose. I have read many positives and negatives about both types – Tesla String Inverter vs. Enphase Microinverters. The plan is to add a Tesla Powerwall or two in the coming years. One company seems totally fine with installing the Tesla inverter as it would be a 1:1 replacement if there are any issues, but have also made it very clear they don't sell many of them. Both companies have shared thier most common sale are Enphase Microinverters plus Tesla Powerwall.

I wasn’t aware that I could even use Enphase microinverters until I did some research. Does anyone else have some other opinions on this choice? I have zero shade on my roof but also don’t like the fact that if the Tesla inverter goes down, so do I. But, what is the actual failure rate? Should I not be confident in their product? Are there any other things I should be investigating prior to my decision? As a Tesla FanBoy, I want to get the String Inverter but the downside seems quite risky...

All opinions and thoughts are welcome. Thank you in advance!

Enphase microinverters have a pretty good and reliable track record, so that is the direction I would go personally if reliability is paramount.

I would not go with Solar Edge, due to the recent failure rates.

Tesla inverters have had some issues as well, but would usually be the cheaper solution. This is where I would go for the value proposition. I probably wouldn't go with the Tesla inverter (DC) if the PV installer wasn't very used to installing them. Don't force them out of the box of what they are comfortable installing, and they will make fewer errors.

 

[Tazzman]

I'm adding 5.1KW DC with a PW+ and another PW to my existing 5.2KW Enphase system because with the Tesla backup switch all of my circuits can remain in my meter/main panel and not have to be moved to another panel on the outside of my house. I like the Enphase warranty and that there is not a single point of failure but the amount of extra equipment it would have required steered me away from Enphase for my expansion.

 

[cali8484]

There was not. About $1400 total was the price difference. The more I learn about the micro inverters it seems like the better option. I have been pleasantly surprised at the amount of PowerWall users that have Enphase microinverters. I wasn't aware this was seamless and very common!

Microinverters are better in many ways compared to string inverters. I have both Enphase M250's and iQ7's and they have been overall reliable but the iQ7's seem a bit less reliable. Failure of a couple micros is much more tolerable than being completely down when a string inverter fails with a long wait for replacement. However, there is typically more labor involved in replacing micros so you may want to check with the installers upfront to get a better idea of long term total cost of ownership. If you do move forward with Enphase then I suggest you get the cheaper iQ7 instead of iQ8 as the extra functionality in iQ8 won't be usable with a Powerwall (or any non-Enphase home battery) and it may erase the $1400 cost difference. Lastly, Enphase has recently made it much more difficult to integrate with third-party home automation systems so if that's something you care about then you should ensure compatibility beforehand.

 

[dafish]

Cali:

Good point about going with the IQ7's being cheaper and perhaps a better call than the IQ8's. I opted for the IQ8's and had quite a bit of insider feedback from Enphase Tier 1, including their manager, telling me the 7's were, at this time, more stable. I too didn't value the IQ8's "advantages" to any significant degree. I went 8 over the 7 as I felt like perhaps buying 7's in 15-20 years might not be so easy. And they can't be mixed in a string, so... I'm still not certain if going 8 over 7 was the right idea.

As you alluded too, you can fix a string converter in your garage (assuming you install it inside). I was down for a few weeks with a small string of IQ8's over an inverter problems (they can be finicky) in the winter that took down the whole string. Yes, it's possible. And hey, you just can't put somebody up on your icy roof so easily.

As to string converter downtime, I suppose that comes back to how well you pick your installer. Mine keeps spare solar edge equipment on hand for their customers, so this feared downtime folks talk about, well, pick better installers I guess. Of course bias is what it is, and not everybody can look back at their decisions and say "I might not have made the best decision". MInd you who knows, I might have had issues w/Solar Edge too. All I can really say is my installer tells me they feel like their experience is better w/SolarEdge. Personally I've never spolen to them.

Certainly the big point OP should be taking is you want panel level optimization: DC optimizer or Micro inverter. Aside from that I suppose time will tell how V2L/V2H evolves.

 

[TacoGuy]

First let me offer that in Arizona I would recommend you go with the full 125% demand rated system.

Second in my Tesla designed and built system they used string inverters with optimizers.

I think in Arizona the use of strings is ok (I am in PHX as well) so long as you do not have major shadow obstructions. My logic is that we have 220+ days of sun a year.

Last teslas cost to install is low and accounts for the costs of wire, labor etc. no need to fret about those as potentially increasing your install expense.

 

[TacoGuy]

I would focus on $/kWh vs string/dc optimizer/micro inverter

^This!

 

[JMGNC]

I learned a lot from your posts. Thank you. I just signed up for solar with a large contractor in NC. He recommended the Tesla Powerwall + which includes the inverter (string?) over the Enphase micro which he said was less reliable. A very small data point, but they do a lot of installs here. I think for me it just came down to lower cost.