Help with Enphase vs SolarEdge with Powerwall

[Rxilher]

Hello Community! This my first post so please let me know of this should go elsewhere. I am based in WI. Building a new home with a large PV grid tied array (54-330w Panasonic panels). I am hoping to charge a Model Y or 3 fully (along with cover all home power usage).
While I have “signed” with an installer using an Enphase micro inverter based. Before incentive cost is $54,000. I really want to have at least 2 Powerwalls to allow me to attempt to avoid grid use. Teslas website pricing with 3 Powerwalls is slightly less than my non battery system price.

Questions:

1. Thoughts on system size? Type? Price?

2. Does Powerwall require the $2500 enphase smart switch?

Thanks all!

 

[Vines]

You don't need the Smart switch.

Tesla will always have the cheapest prices over local installers. If you want the low cost leader and can deal with a bit of managing your own project I'd go Tesla. Service will not be as good as the local guys.

If you are too busy to project manage, I'd pay someone local who will have a project manager and sales person responsible for your job.

Local pricing seems decent, not enough information to really evaluate the value comparison.

 

[jrweiss98020]

The Gateway that comes with the Powerwall installation IS a "smart switch" that controls flow of electricity to/from the grid, the house, the Powerwall, and the solar array. You will need the Enphase Envoy communication gateway that relays all the info about solar and microinverter performance.

Quoted price (~$3000/KW) is nominal for the complete installation. Expect that a local installer will charge more than Tesla for Powerwall installation.

Tesla will not install microinverters, so you will have to stay with the local installer if you want them. They work much better than optimizers for segmented roofs or where individual panels are shaded.

 

[BrettS]

They work much better than optimizers for segmented roofs or where individual panels are shaded.

Can you expand on why you think microinverters work much better than optimizers? They both do essentially the same thing, but the microinverters do it on the AC side and the power optimizers do it on the DC side.

The article here... Solar Microinverters vs. Power Optimizers | EnergySage says:

Microinverters and power optimizers have very similar efficiencies, are good for monitoring individual panel performance and can help maximize energy production on complicated roofs. But your preferences will ultimately determine which option is best for your home.

According to that the efficiency is very similar for shading or segmented roofs, so I’m curious to see why you think that microinverters would be much better.

 

[jrweiss98020]

AFAIK, Tesla does not install optimizers on individual panels, but on strings of panels.

I suppose if the optimizer strings are designed properly, they may be similar to microinverters. However, as I understand it, the lowest-producing panel in a string controls the total output of the string. Feel free to correct me if I'm misinformed.

With microinverters, each panel sends whatever it produces to the microinverter, which can send all its output to the load.

 

[BrettS]

AFAIK, Tesla does not install optimizers on individual panels, but on strings of panels.

I suppose if the optimizer strings are designed properly, they may be similar to microinverters. However, as I understand it, the lowest-producing panel in a string controls the total output of the string. Feel free to correct me if I'm misinformed.

With microinverters, each panel sends whatever it produces to the microinverter, which can send all its output to the load.

The SolarEdge power optimizers do go on each panel. I got 48 panels and 48 optimizers. Here is a picture of my panels before they were installed. You can see the optimizers at the top of the panels:

The optimizers allow per panel performance monitoring as well as per panel optimization for shading or panel placement. They work by matching the DC voltage of all the panels on each string so the full output of each panel can be used whether that panel is in the shade or not.

 

[miimura]

AFAIK, Tesla does not install optimizers on individual panels, but on strings of panels.

I suppose if the optimizer strings are designed properly, they may be similar to microinverters. However, as I understand it, the lowest-producing panel in a string controls the total output of the string. Feel free to correct me if I'm misinformed.

With microinverters, each panel sends whatever it produces to the microinverter, which can send all its output to the load.

The way an optimizer works is that it changes the current and voltage output of each panel. A string of panels must have the same current from each panel. The optimizer works by dropping the voltage and increasing the current for a low producing panel. Without the optimizer, a poorly performing panel will reduce the current of the whole string.

A microinverter converts a single panel (or pair of panels in some cases) to AC and all of the AC power simply adds up. The performance of each panel is unaffected by the others.

 

[Locash]

Interesting, I'm paying 33k for a 16.4kw array with enphase iq7 microinverters in Arizona. Tried to go with Tesla but they would not install on my metal garage roof, so for a few grand more I'm going with someone that will. I have a Powerwall that I will probably self install once I locate a second one.. I would shop your quote on Energysage, thats how I found the best pricing for local installers..

 

[Rxilher]

Hi All!

I appreciate the conversation! So I have done very very extensive research on optimized string vs micro inverters. I am leaning optimized string and two large Solaredge “Storedge” hybrid inverters. When both are running properly they return a similar efficiency result. With optimized string if you lose an inverter...the array stops producing fully (not great) vs micro inverter you only lose production on the one affected panel. The big differences come when you add batteries for storage.

I think if someone has a micro inverter system then the PowerWall 2 AC is a great solution. I am starting fresh so I am looking at conversion efficiencies. If Tesla still had the DC Powerwall I would do it in a heartbeat. The available PowerWall 2 is AC with a noted maximum round trip efficiency of 80%. A battery such as LG RESU with Solaredge Storedge notes a near 97% efficiency. For me....17% loss is a huge deal. That is months of production lost in the course of a year.

 

[Rxilher]

Interesting, I'm paying 33k for a 16.4kw array with enphase iq7 microinverters in Arizona. Tried to go with Tesla but they would not install on my metal garage roof, so for a few grand more I'm going with someone that will. I have a Powerwall that I will probably self install once I locate a second one.. I would shop your quote on Energysage, thats how I found the best pricing for local installers..

agreed! Thank you! Is 33k before federal incentive?

 

[BrettS]

I think if someone has a micro inverter system then the PowerWall 2 AC is a great solution. I am starting fresh so I am looking at conversion efficiencies. If Tesla still had the DC Powerwall I would do it in a heartbeat. The available PowerWall 2 is AC with a noted maximum round trip efficiency of 80%. A battery such as LG RESU with Solaredge Storedge notes a near 97% efficiency. For me....17% loss is a huge deal. That is months of production lost in the course of a year.

For what it’s worth, the powerwall round trip efficiency is 90% and not 80%. Of course 97% is still way better, but it’s not nearly as much of a difference than you were thinking.

 

[Locash]

agreed! Thank you! Is 33k before federal incentive?

Yes, before federal and state incentives.

 

[Rxilher]

For what it’s worth, the powerwall round trip efficiency is 90% and not 80%. Of course 97% is still way better, but it’s not nearly as much of a difference than you were thinking.

Wow. I must hav been looking at PW V1? I swear it was right on the Tesla site. I do now see 90%. Thank you!