Expanding NEM 2.0 Solar System with Non Export

[arcreactor]

I have a Tesla 8.4 KW system with 2 Power Walls under NEM 2.0. Since getting an EV, my demand for solar has increased and I have multiple bids for 5.5-6.4 KW non export solar system Enphase microinverter.

Can the non export and Tesla system connect to the same 2 Power Wall and be under NEM 2.0? Anyone has any experience wit this?

How should I maximize the NEM 2.0 system? I was thinking of setting the 8.4 KW to fully exported to grid for credit and non-export for self consumption. The Power Wall will be used TOU 4-9PM.

 

[DIYrich]

Enphase has to be able to export, even if a little. You need an offgrid system to guarantee no export.

 

[MisterSandals]

I

Thread 'Battery back up with existing solar'

Oct 21, 2024

I'm needing some recommendations on a diy battery backup system, what I have is a professional installation solar grid tied system ,40 -295watt Trina panels with enphase micro inverters , I've got 3 different quotes in the last year for Tesla power wall system , all were over 15k , which is more than I'm willing to pay for the amount of backup power that one battery supplies, I'm not really interested in selling power back to the power company as they've stopped even banking my excess generation I used to get credit for banked kwh when I used more than I generated but not anymore ...

• Ironman482
• Replies: 1
• Forum: DIY Solar General Discussion

Also, maybe some tidbits here:

Search results for query: enphase and tesla power wall

diysolarforum.com

 

[zanydroid]

Enphase has to be able to export, even if a little. You need an offgrid system to guarantee no export.

That’s just not addressing OP question. OP is presumably in California and the hack they mention is indeed (currently) allowed and is all above board. And it’s something Enphase ecosystem has been targeting. In other words this is a legal grid tie system, it’s allowed to leak a little export. And the POCO is fully informed of the change.

As for the ideal config. Assuming OP can reassign equipment between the two systems, one config would be to grid tie the original NEM2 solar strings and full export it. While the PowerWalls capture the new Enphase.

So basically what you said. But I do not know if hardware can be arbitrarily reassigned. Probably you can pretend the powerwalls exploded, and you replaced new ones into the new non export system

Another config to compare against is using the batteries to store as much energy as possible and then self consume from 4-7PM ish, then sell all to grid before 9PM.

Another config to consider is both of the above, but with EV2 or other superpeak plan

OP- you should go ask this question on r/enphase, since variants of these are very commonly discussed there. I suspect either Enphase has a calculator, or someone has a spreadsheet, to game out each scenario.

But OP why are you paying extra for Enphase hardware, and Enphase markup, when you’re smart enough to ask questions on a DIY forum. You don’t even get the fully integrated Enphase system, since the Powerwall and Tesla gateway are doing the heavy lifting, and not some 5P batteries and System Controller

 

[DIYrich]

My point is: If you are adding and don't want to export, then pick something other than enphase.

 

[arcreactor]

That’s just not addressing OP question. OP is presumably in California and the hack they mention is indeed (currently) allowed and is all above board. And it’s something Enphase ecosystem has been targeting. In other words this is a legal grid tie system, it’s allowed to leak a little export. And the POCO is fully informed of the change.

As for the ideal config. Assuming OP can reassign equipment between the two systems, one config would be to grid tie the original NEM2 solar strings and full export it. While the PowerWalls capture the new Enphase.

So basically what you said. But I do not know if hardware can be arbitrarily reassigned. Probably you can pretend the powerwalls exploded, and you replaced new ones into the new non export system

Another config to compare against is using the batteries to store as much energy as possible and then self consume from 4-7PM ish, then sell all to grid before 9PM.

Another config to consider is both of the above, but with EV2 or other superpeak plan

OP- you should go ask this question on r/enphase, since variants of these are very commonly discussed there. I suspect either Enphase has a calculator, or someone has a spreadsheet, to game out each scenario.

But OP why are you paying extra for Enphase hardware, and Enphase markup, when you’re smart enough to ask questions on a DIY forum. You don’t even get the fully integrated Enphase system, since the Powerwall and Tesla gateway are doing the heavy lifting, and not some 5P batteries and System Controller

Yes I'm in SoCal.

I'm not technical enough to setup my own solar system on the roof and hook up the electrical.

The price is $2.17/watt before tax incentive and $1.51/watt after tax incentive so it is pretty cheap for us with permit and professional installed. Less issue with insurance company should something happen.

That's my thought process as well, original NEM 2.0 charge the Power Wall and export once full. PW will discharge during peak hours 4-9PM.

The solar company is consulting whether it's possible to hook up the new 5.5 KW to charge the 2 PW. I will weight my option to see how much it cost especially if they require permit.

I'm leaning keeping the 2 system separate so there won't be any permit issue and use the non export to run the house, charge EV during the day, and the NEM 2.0 to charge the PWs and export for credit.

 

[arcreactor]

you are adding and don't want to export, then pick

I think I will likely keep the two system separate and add battery later to keep it simple for permit purposes. $5000 for Enphase 5P installed seems expensive to me.

Enphase has to be able to export, even if a little. You need an offgrid system to guarantee no export.

Enphase has a non export setting with IQ8X with or without battery.

 

[DIYrich]

Enphase has a non export setting with IQ8X with or without battery.

Yes, but with a non-exporting system, you want the ability to add batteries to store the production you don't use for later consumption. If you consider the price of the entire system, EG4 off-grid system (6000xp with one or two powerpro batteries) is probably a lot cheaper.

 

[zanydroid]

My point is: If you are adding and don't want to export, then pick something other than enphase.

I’m not sure you understand the operating mod, I suggest you check the r/enphase and other threads here

And zero export grid tie is generally understood to have higher ROI than anything with batteries for NEM2 users. Note that batteries in California are super expensive due to 9540 requirements

 

[DIYrich]

I’m not sure you understand the operating mod, I suggest you check the r/enphase and other threads here

And zero export grid tie is generally understood to have higher ROI than anything with batteries for NEM2 users. Note that batteries in California are super expensive due to 9540 requirements

As I understand it, @arcreactor is adding to an NEM2 system that cannot export the additional production. At that point, it is "use it or loose it" with the additional production. My point, is that there may be a benefit to storing the excess production in a battery for overnight use.

EG4 6000xp is under $1,500. 6kW of panels is about 15 panels. At $150 per IQ8, that is $2,250 of microinverters (plus a controller to moderate production). I assume the cost of install is about the same.

EG4 powerpro is UL9540, is about $3,600 ($2,500 net of federal tax credit, if beneficial), and is easy to add (DIY) to the 6000xp. A 6kW system in LA should produce about 30kWh on a good day. Assuming you can store 14kW for overnight use, 28 cents per kWh, and 250 sunny days per year, it has a payback period of 2.5 years (not considering the $700 savings of 6000xp vs IQ8)

 

[arcreactor]

As I understand it, @arcreactor is adding to an NEM2 system that cannot export the additional production. At that point, it is "use it or loose it" with the additional production. My point, is that there may be a benefit to storing the excess production in a battery for overnight use.

EG4 6000xp is under $1,500. 6kW of panels is about 15 panels. At $150 per IQ8, that is $2,250 of microinverters (plus a controller to moderate production). I assume the cost of install is about the same.

EG4 powerpro is UL9540, is about $3,600 ($2,500 net of federal tax credit, if beneficial), and is easy to add (DIY) to the 6000xp. A 6kW system in LA should produce about 30kWh on a good day. Assuming you can store 14kW for overnight use, 28 cents per kWh, and 250 sunny days per year, it has a payback period of 2.5 years (not considering the $700 savings of 6000xp vs IQ8)

Yes, but with a non-exporting system, you want the ability to add batteries to store the production you don't use for later consumption. If you consider the price of the entire system, EG4 off-grid system (6000xp with one or two powerpro batteries) is probably a lot cheaper.

You are correct: use it or lose it with non export system. I can use the excess to charge my EV if I'm home or lose it. If my solar installer can't hook up my 2 Power Walls without compromising NEM 2.0 status, I'll look into another battery option.

Unfortunately my solar company only has Tesla Hybrid Inverter Power Wall 3 or Enphase

TOU Prime is 54 cent for peak ours 4-9, but I already have 2 PWs that perfectly capable of lasting me from 4-9pm.

Adding an extra battery would allow me to keep any extra solar and allow solar to work when the grid is off.

I researched into EG4 Power Pro and EG4 6000xp, and that should be $5000 for 14KW battery + the cost of electrician to hook it up. It's alot more affordable than $5000 to install Enphase 5P 5KW battery.

 

[DIYrich]

You are correct: use it or lose it with non export system. I can use the excess to charge my EV if I'm home or lose it. If my solar installer can't hook up my 2 Power Walls without compromising NEM 2.0 status, I'll look into another battery option.

Unfortunately my solar company only has Tesla Hybrid Inverter Power Wall 3 or Enphase

TOU Prime is 54 cent for peak ours 4-9, but I already have 2 PWs that perfectly capable of lasting me from 4-9pm.

Adding an extra battery would allow me to keep any extra solar and allow solar to work when the grid is off.

I researched into EG4 Power Pro and EG4 6000xp, and that should be $5000 for 14KW battery + the cost of electrician to hook it up. It's alot more affordable than $5000 to install Enphase 5P 5KW battery.

I would try this:
Disconnect the 2 powerwalls from the NEM2 system. Export as you produce it.
Install a Tesla Hybrid System (non-exporting) and attach the two existing powerwalls to that (total of 3 batteries).
Run off your new system

I believe Enphase will work with the Powerwall, so you could go that route (new Enphase with 2 old powerwall).

 

[arcreactor]

I would try this:
Disconnect the 2 powerwalls from the NEM2 system. Export as you produce it.
Install a Tesla Hybrid System (non-exporting) and attach the two existing powerwalls to that (total of 3 batteries).
Run off your new system

I believe Enphase will work with the Powerwall, so you could go that route (new Enphase with 2 old powerwall).

I have someone suggested that on Reddit. I also think that's the cleanest solution allowing me to maximized NEM 2.0 and use the Non Export systtem efficiently.

 

[zanydroid]

EG4 powerpro is UL9540, is about $3,600 ($2,500 net of federal tax credit, if beneficial), and is easy to add (DIY) to the 6000xp

You need to at minimum use a 12kpv to meet 9540, which significantly closes the cost gap to System Controller and 5P batteries

The counter argument to export as you produce, is that you can use the batteries to time shift to the higher peak time. And every dollar you export, can be shifted across seasons from summer to winter. So you might get 50-75% more value from that.

You cannot use the off grid nor zero export to season shift

So the optimal is a little hard to figure out from first principles, which is why I suggested to steal someone’s excel homework

 

[arcreactor]

My company said they won't be able to tied both solar system together. I'll just add solar for now for non export. Will use it to charge my EV during the day, run AC. Old system will charge PW and export. I'll consider battery later if it make sense.

Should I use the Enphase Microinverter IQ8X or use Tesla Hybrid inverter to stay within the Tesla ecosystem?

 

[zanydroid]

What’s the price difference?

Would the company implement plans as provided by you? (Professionally drawn)

I’m not sure what quality of contractor you can get for that $/W in SoCal. Looks like either things have crashed down there , and or it’s just way cheaper down there

 

[arcreactor]

What’s the price difference?

Would the company implement plans as provided by you? (Professionally drawn)

I’m not sure what quality of contractor you can get for that $/W in SoCal. Looks like either things have crashed down there , and or it’s just way cheaper down there

It's a quality company with 700+ reviews EnergySage not including Yelp and Google on and been in business 30+ years. The price has crashed alot because solar panel is cheaper, less demand for solar in CA due to NEM 3.0. All 7 of my bids are alot cheaper than $3/watt I got 2 years ago from Tesla. Yes the plan are professional drawn. They are better than Tesla IMO since all the panels are South facing. Tesla refuse to add 3 panels here and there to maximize South facing.

They priced matched to another competitor so I went with a company with longer track record. I don't know if there is a price difference for the inverter. It's probably the same if I asked.

 

[zanydroid]

30+ years is pretty good. TBH I don’t believe much in reviews anymore because I went with a company that went super downhill and the reviews didn’t catch up.

Professional drawings, I meant for the hypothetical scenario where you ask them to install equipment or architecture they don’t normally use. So you would have that drawn up for them to implement.

Tesla is pretty low tier experience.

Would you consider DIY reconfiguration later? That is another consideration here. And the work for that would involve extending this thread, or creating a new one, asking how to reconfigure for other goals.

Did they check whether west facing has potential to increase peak generation on your house?

SoCal with AC loads actually probably get solid value out of non export no battery. You can maybe even precool the house so it can make it through peak electrical pricing hours.

IMO the really hard part (for a DIYer, not for the installer, they can do it with pretty low amount of training) is lifting the panels. While batteries require only work at ground level, albeit with lifting a 100-300lb unit. (A 5P battery is probably 100lb and I know a 15kWh wall battery is 300lb, because I looked it up this week to see what kind of lift I need to buy at harbor freight to execute the project).

 

[arcreactor]

They have alot of reviews in multiple sites. I've seen Reddit posts with good reviews.

I'll consider DIY to add battery later on. I have to see if it's financial worth it too.

"SoCal with AC loads actually probably get solid value out of non export no battery. You can maybe even precool the house so it can make it through peak electrical pricing hours."
I'll schedule my mini split to turn on during midday and off at peak hours. EV will start charging with excess battery.

I'm not great with electrical and wife want everything up to code for insurance purposes. After tax credit, it's very affordable compared 2-3 years ago when I got it. I do tinker DIY on my pergola to power my shed.

 

[zanydroid]

I'm not great with electrical and wife want everything up to code for insurance purposes. After tax credit, it's very affordable compared 2-3 years ago when I got it. I do tinker DIY on my pergola to power my shed.

I DIY'ed my grid tie microinverters with full permit package and PG&E approval, to code exceeding standards using code & wiring knowledge I gleaned from way too much time on forums. So DIY is not mutually exclusive with code compliance.

There was an extra incentive to do DIY 2 years ago because all the companies were jacking up their prices for the NEM2 deadline.