New Battery - Tesla or Enphase?

[Patrick66]

Debating between getting a new Enphase battery/transfer switch or a Tesla Powerwall in Hawaii. The quote for Enphase is 50% higher than Tesla, and I added 4kW of solar in the Tesla quote. But, I am worried about the timing of when I could actually get a system installed if I ordered today with Tesla. Currently we have an 8kW Enphase (M215) PV system.

The Enphase system is a little nicer for my needs; it gives me the option to have a standby generator integrated into the system, but the premium is pretty significant.

Any advice based on past experience, or things I might not be considering?

 

[sunwarriors]

I went with Enphase myself purely because the Tesla certified installers I got quotes from had no timeline of when Powerwalls would be in stock. They were telling me 6 months or even longer and simply didn't know and were at the whim of what Tesla ships them. I was also in a rush due to NEM2.0 expiring soon for NEM3.0 in CA and SGIP dropping fast.

Since you are going with Tesla directly I'm assuming, maybe it's faster, but as a lot of posts here states, main downsides with Tesla if you're unlucky is low communication and complex installs are hard to get them to do.

Another few reasons I went with Enphase was because of LFP chemistry, the 'possible' generator hookup (supposed to be coming this year) and outside of a Tesla direct install, I saw no price difference between the number of enphase batteries vs. powerwalls (yes, the tesla has much greater capacity and peak I think).

If there were any future laws with energy storage credits/benefits eventually, we may add more batteries.

 

[nicholb]

Debating the same choice myself. Just had a 10kWh system installed from a local installer but the 2 Powerwalls are on the who knows when backorder. Installer offered to sub Encharge batteries which they can do right away. Here's what I see as positives for each.

PowerWalls:
Higher capacity
Higher peak output
Can talk to the Tesla car to modify charging when on backup
Tesla software

Encharge:
LFP batteries
Lower roundtrip loss
Can talk directly with the Enphase microinverters and shut down individual panels to balance load/usage when off grid.
Doesn't use frequency adjustments to control the panel production when off grid.
Available now

Still have not decided. I told the installer I would wait for the Powerwalls until mid winter and switch if they are still on backorder. But sometimes I think I should just switch now and get the Encharge installed.

 

[h2ofun]

Debating the same choice myself. Just had a 10kWh system installed from a local installer but the 2 Powerwalls are on the who knows when backorder. Installer offered to sub Encharge batteries which they can do right away. Here's what I see as positives for each.

PowerWalls:
Higher capacity
Higher peak output
Can talk to the Tesla car to modify charging when on backup
Tesla software

Encharge:
LFP batteries
Lower roundtrip loss
Can talk directly with the Enphase microinverters and shut down individual panels to balance load/usage when off grid.
Doesn't use frequency adjustments to control the panel production when off grid.
Available now

Still have not decided. I told the installer I would wait for the Powerwalls until mid winter and switch if they are still on backorder. But sometimes I think I should just switch now and get the Encharge installed.

I would not wait. What if the other batteries cannot be gotten? I hear PW's are losing market share.

 

[holeydonut]

Debating the same choice myself. Just had a 10kWh system installed from a local installer but the 2 Powerwalls are on the who knows when backorder. Installer offered to sub Encharge batteries which they can do right away. Here's what I see as positives for each.

PowerWalls:
Higher capacity
Higher peak output
Can talk to the Tesla car to modify charging when on backup
Tesla software

Encharge:
LFP batteries
Lower roundtrip loss
Can talk directly with the Enphase microinverters and shut down individual panels to balance load/usage when off grid.
Doesn't use frequency adjustments to control the panel production when off grid.
Available now

Still have not decided. I told the installer I would wait for the Powerwalls until mid winter and switch if they are still on backorder. But sometimes I think I should just switch now and get the Encharge installed.

Yeah, if you're able to do a whole home backup with either 2 Powerwalls or 2 Encharge 10's then they are very similar systems and your tradeoffs are what you've listed.

One small nit item is that the Enphase Enpower 200 also has generator support (eventually). This is important to some people and could be a factor for you since you're so far North with possible solar production issues in the winter with Snow and limited sunlight.

 

[sorka]

My lifetime round trip efficiency on my 3 PWs is 88.84% but that includes the standby power requirements of 0.250 kwh / day / pw so after you subtract that, the actual efficiency is 93%. What is the LFP round trip efficiency?

 

[holeydonut]

My lifetime round trip efficiency on my 3 PWs is 88.84% but that includes the standby power requirements of 0.250 kwh / day / pw so after you subtract that, the actual efficiency is 93%. What is the LFP round trip efficiency?

Just using the spec sheets, Tesla says the PW2 has a round trip of 90% and Enphase says their Encharge 10 is a round trip of 89%.

https://www.tesla.com/sites/default/files/pdfs/powerwall/Powerwall%202_AC_Datasheet_en_northamerica.pdf

https://www4.enphase.com/sites/default/files/downloads/support/Encharge-10-DS-EN-US.pdf

 

[nicholb]

I was misremembering the round trip number for Enphase, so scratch that as they are close enough to not matter.

After typing out that list I decided to go Encharge and emailed my installer. It will probably be a better system without mixing providers (Enphase microinverters with Echarge battery)

Update: Figured out where I got the higher round trip number. If you look under the battery section they give a round trip # of 96% there. The AC output round trip of 89% would be the correct one to compare.

 

[holeydonut]

I was misremembering the round trip number for Enphase, so scratch that as they are close enough to not matter.

After typing out that list I decided to go Encharge and emailed my installer. It will probably be a better system without mixing providers (Enphase microinverters with Echarge battery)

Update: Figured out where I got the higher round trip number. If you look under the battery section they give a round trip # of 96% there. The AC output round trip of 89% would be the correct one to compare.

Cool, looking forward to seeing your system! I guess even though it's not a Tesla system, we're interested in how it goes hah. Good thing for you is you won't need bollards and fire suppression systems hah. But make sure the put weep holes in your conduit runs that are exposed to the elements.

 

[charlesj]

I am under the impression that Tesla doesn't install just batterie but a full system with panels.
A local installer may do Tesla batteries only but when.

 

[CrazyRabbit]

I think the enphase transfer switch is only 60 or 65 amps for batteries.

 

[skepticcyclist]

One advantage of the Enphase over the Tesla is if you have an Enphase system with their microinverters and combiner box. With their system and the latest microinverters during an outage your system is still able to use solar when the battery is full, without using any battery at all. It will adjust solar output to match that of your house consumption. Unlike the Tesla system which cycles between battery and solar during an outage

 

[Will792]

One advantage of the Enphase over the Tesla is if you have an Enphase system with their microinverters and combiner box. With their system and the latest microinverters during an outage your system is still able to use solar when the battery is full, without using any battery at all. It will adjust solar output to match that of your house consumption. Unlike the Tesla system which cycles between battery and solar during an outage

I do not believe that it is accurate description of what PW does in off grid mode. Production curtailment when battery gets close to being full by increasing AC frequency and using appropriate grid profile in IQ inverters is not very different from what Enphase battery does.

it might be different when IQ8s are finally released and have functionality that has been promised. I am not fully convinced that it will happen. It has been promised for more than 3 years and nothing has been released so far. Inverters in the battery are substantially different from inverters attached to PV modules. Personally I would not make a product decision based on the assumption that IQ8 with promised functionality would be released in the near future.

 

[skepticcyclist]

I do not believe that it is accurate description of what PW does in off grid mode. Production curtailment when battery gets close to being full by increasing AC frequency and using appropriate grid profile in IQ inverters is not very different from what Enphase battery does.

Actually the PW and solar do cycle during an outage. Solar goes to the house and battery until the battery is full. Then solar completely stops and the battery powers the house exclusively until it gets down to a certain level. Solar then kicks back in to power the house and recharge the battery. This will continue until the power is restored or the sun goes down. I timestamped linked this video at where they talk about this.

 

[miimura]

Actually the PW and solar do cycle during an outage. Solar goes to the house and battery until the battery is full. Then solar completely stops and the battery powers the house exclusively until it gets down to a certain level. Solar then kicks back in to power the house and recharge the battery. This will continue until the power is restored or the sun goes down. I timestamped linked this video at where they talk about this.

Tesla Powerwalls can do proportional curtailment. However, this conflicts with many solar inverter grid profiles that require "ride-through". Without the ability signal when the system is off-grid and applying a suitable inverter response profile, the end result is usually ON/OFF solar production when batteries are full and the system is islanded from the grid. It has been shown that if you load the proper grid profile, an Enphase IQ7 system will proportionally curtail with Powerwalls.

 

[gpez]

Tesla Powerwalls can do proportional curtailment. However, this conflicts with many solar inverter grid profiles that require "ride-through". Without the ability signal when the system is off-grid and applying a suitable inverter response profile, the end result is usually ON/OFF solar production when batteries are full and the system is islanded from the grid. It has been shown that if you load the proper grid profile, an Enphase IQ7 system will proportionally curtail with Powerwalls.

I have IQ6s with my Powerwall and have curtailment enabled as well. https://www.solar-electric.com/lib/wind-sun/IQ6_IQ6Plus_Manual.pdf page 34 "SA14: Frequency Watt (FW)"

The statement that Powerwalls cannot do curtailment is FUD and really needs to stop. The video @skepticcyclist posted is completely incorrect. I've downvoted it but happy to remove the downvote if you choose to edit the post!

One last point: this actually doesn't even really matter. There's almost no power savings by aligning PV production with home consumption in the scenario where the PV can provide more power than the home needs. For hyperoptimizers and nerds like myself it's fun to set up but in practical terms there's almost nothing to gain.

 

[X-pilot]

FYI,

Debating between getting a new Enphase battery/transfer switch or a Tesla Powerwall in Hawaii. The quote for Enphase is 50% higher than Tesla, and I added 4kW of solar in the Tesla quote. But, I am worried about the timing of when I could actually get a system installed if I ordered today with Tesla. Currently we have an 8kW Enphase (M215) PV system.

The Enphase system is a little nicer for my needs; it gives me the option to have a standby generator integrated into the system, but the premium is pretty significant.

Any advice based on past experience, or things I might not be considering?

FYI, I have a Generac backup generator with my Tesla panels & PowerWalls.

 

[X-pilot]

I am under the impression that Tesla doesn't install just batterie but a full system with panels.
A local installer may do Tesla batteries only but when.

That is the current info I got from Tesla about 2 weeks ago.

 

[skepticcyclist]

I have IQ6s with my Powerwall and have curtailment enabled as well. https://www.solar-electric.com/lib/wind-sun/IQ6_IQ6Plus_Manual.pdf page 34 "SA14: Frequency Watt (FW)"

The statement that Powerwalls cannot do curtailment is FUD and really needs to stop. The video @skepticcyclist posted is completely incorrect. I've downvoted it but happy to remove the downvote if you choose to edit the post!

One last point: this actually doesn't even really matter. There's almost no power savings by aligning PV production with home consumption in the scenario where the PV can provide more power than the home needs. For hyperoptimizers and nerds like myself it's fun to set up but in practical terms there's almost nothing to gain.

I too have the same setup, Enphase microinverters and Tesla PW.

The video was talking about a Tesla setup vs Enphase setup, not a mix of the two like we have. The description in the video is accurate.

 

[gpez]

I too have the same setup, Enphase microinverters and Tesla PW.

The video was talking about a Tesla setup vs Enphase setup, not a mix of the two like we have. The description in the video is accurate.

Verbatim from the video, at the exact moment you linked:

"You see, in a grid down mode when you're using an AC coupled battery the battery has no ability to throttle the solar power output. It's either all or nothing."

1) He says nothing about Tesla specifically, either for the Powerwall or for Tesla PV systems. The Powerwall is AC coupled so it is implied that the Powerwall has this limitation.
2) His statement is 100% incorrect. AC coupled batteries can use the microgrid frequency to signal to inverters to curtail. Both types of inverters Tesla installs in the US support this functionality and it's exactly how the Powerwall supports this scenario.

We can have a discussion as to how good this method is or comparing and contrasting it to fully integrated battery + PV systems but the statement is not correct.