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PowerWall with Enphase microinverters

arnolddeleon

Active Member
Supporting Member
Jul 21, 2012
1,021
1,098
SF Bay Area
There is a long thread on SGIP. TLDR; Customers have been successful in getting Tesla to apply for SGIP "Small residential energy storage" (including for for step 2). I don't believe anyone has actually gotten a check yet from SGIP. Tesla is way over subscribed for SGIP "Small residential energy storage".

I don't have Enphase inverters.

arnold
 
Yep, I have 12 panels with S270s and 24 panels with M250s along with one PW2 installed.

Awesome. I have 17 panels of Canadian Solar CS6P 240P Watt PV Modules, with 17 Enphase M215 Microinverter Inter-tie String Inverters. This is a 4,080 Watt Utility Grid Tie System was estimated to generate up to 19.59 kWh per day based on 5.5 hours of sun light. Actual generation has exceeded 28 kWh during the summer. On a cloudy day in SoCAl I still product1-12 KWh. I have replaced all lights with LEDs, all plasma displays with Samsung and Vizio LEDs, and my 2007 Mac Pro (energy guzzler) with a 2013 Mac Pro, refrigerator, washer and dishwasher are all new, energy efficient versions. I do not have A/C, Dryer is gas.

This year I got a check back from SCE of $65, which effectively covers 12 months of fees and taxes. Next year I am expecting a much larger check as I replaced more stuff lately, and I may as well use the extra energy for my wife's Model 3. I am on NET Metering.

My calculations using the Tesla website is that I could just do with a single PowerWall. Thoughts?
 
Anyone here that installed the Powerwall with Enphase micro-inverters?

Anyone here that was able to have Tesla properly apply for SGIP "Small residential energy storage" incentives for California residents?

I have 20 Solarworld 285W panels with 20 Enphase M250 microinverters. They work with the two Tesla Powerwalls installed.

I am on a holding pattern regarding SGIP. Jumped the gun with installation, and may still qualify. I am OK if I do not qualify.

My calculations using the Tesla website is that I could just do with a single PowerWall. Thoughts?

Yes, you can just use one Powerwall if you are OK having circuits with loads 30A and greater excluded from the backup. From what you have stated, it looks like you do not have any loads that are 30A or greater. So you'll be fine.

Another consideration is the amount of backup power you'll need/want to cover your overnight use until solar can charge your batteries the following morning. Is one battery enough given a set reserve level?
 
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Another consideration is the amount of backup power you'll need/want to cover your overnight

Also, you have to take into consideration the amount you can generate to recharge the PW2 - you don't mention the amount of power your household comsumes in a day (and night). It is important to understand that before buying more than one - you can always get one now and add another later if you see the use case. I'm averaging about AUD100 per month back from my retailer - but then there is a difference in Aus and USA electricity costs and feed in tariff amounts.
 
I have 20 LG NeON2 LG315N1CG4 315W Solar Panels with 20 Enphase S280 Microinverters (6.3 kW) installed in April 2016. I have two Tesla 2 Powerwalls.

I've also replaced all lights with LEDs and replaced a Panasonic plasma 65" HDTV with an LG OLED 65" 4K UHDTV. I'm running the PWs in Self-powered mode. With my reserve set at 25% I'm running 100% self-powered on solar and batteries on sunny days. I tried a 45% reserve but started pulling from the grid before the solar kicked in. Analyzing my PVOutput data, I could probably go up to 35-40% reserve. I've been hitting 100% on the battery around 1:30-2:00 PM and then the solar starts feeding back into the grid.

Today is actually my true-up day and I have $860.23 of credits. I've been way overproducing because the pool got drained in June 2016 for repairs and renovation but we haven't been able to get around to having it done, so the pump has been offline since then. The pump was replaced with a multi-speed high-efficiency pump when the solar was installed.
 
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Yes, you can just use one Powerwall if you are OK having circuits with loads 30A and greater excluded from the backup. From what you have stated, it looks like you do not have any loads that are 30A or greater. So you'll be fine.

Another consideration is the amount of backup power you'll need/want to cover your overnight use until solar can charge your batteries the following morning. Is one battery enough given a set reserve level?

When using the NEMA 14-50 I am using a 240V / 50A load for the Model 3. That is greater than 30A, but I would not have any problem not charging the Model 3 during "backup" times.

Regarding the amount of backup I need. I have 5 years of records at pwoutput.org. My daily consumption average is between 17 and 21 kWh / day. My daily generation is between 7 and 28 kWh / day. If a single Tesla PowerWall holds 13.2 kWh, I should have plenty to keep me going for a full day of utility outage.
 
Regarding the amount of backup I need. I have 5 years of records at pwoutput.org. My daily consumption average is between 17 and 21 kWh / day. My daily generation is between 7 and 28 kWh / day. If a single Tesla PowerWall holds 13.2 kWh, I should have plenty to keep me going for a full day of utility outage.

The reason I was asking, I don't know if you generate enough to feed the house and re-charge one battery (let alone two). If you can, it would be boarder line from the numbers I'm seeing. From what I've been seeing on this and other forums, the US has some strange regulations... you need to check if you can also charge from the grid during off-peak times if your solar can't re-charge the PW2.
 
The reason I was asking, I don't know if you generate enough to feed the house and re-charge one battery (let alone two). If you can, it would be boarder line from the numbers I'm seeing. From what I've been seeing on this and other forums, the US has some strange regulations... you need to check if you can also charge from the grid during off-peak times if your solar can't re-charge the PW2.

With Net Metering I can charge from the grid at ANY hours. During the day I push energy to the grid and pull from the grid at night. In LA with SCE we do not yet have to pick Time-of-Day pricing, with off-peak and on-peak times. I am on Net Metering Tier 1, @ 17c / kWh (never been on Tier 2 since I have had solar).
 
Awesome. I have 17 panels of Canadian Solar CS6P 240P Watt PV Modules, with 17 Enphase M215 Microinverter Inter-tie String Inverters. This is a 4,080 Watt Utility Grid Tie System was estimated to generate up to 19.59 kWh per day based on 5.5 hours of sun light. Actual generation has exceeded 28 kWh during the summer. On a cloudy day in SoCAl I still product1-12 KWh. I have replaced all lights with LEDs, all plasma displays with Samsung and Vizio LEDs, and my 2007 Mac Pro (energy guzzler) with a 2013 Mac Pro, refrigerator, washer and dishwasher are all new, energy efficient versions. I do not have A/C, Dryer is gas.

This year I got a check back from SCE of $65, which effectively covers 12 months of fees and taxes. Next year I am expecting a much larger check as I replaced more stuff lately, and I may as well use the extra energy for my wife's Model 3. I am on NET Metering.

My calculations using the Tesla website is that I could just do with a single PowerWall. Thoughts?
Changing lights to LED, definitely, however, if you changed out multiple tv's, a laptop, refrigerator, washer, and dishwasher just to make them more energy efficient, you are NEVER recouping that cost, EVER, not even 1/4 of it. Estimating that entire cost to be $5,500 conservatively (very conservative) and doubled your yearly SCE to $120 (you won't ever see that) and it will take 45 years to pay for itself. Absolutely replace with those options when needed, however if you did to save energy, you just largely increased your total cost of ownership
 
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mongo

Well-Known Member
May 3, 2017
14,807
51,092
Michigan
Changing lights to LED, definitely, however, if you changed out multiple tv's, a laptop, refrigerator, washer, and dishwasher just to make them more energy efficient, you are NEVER recouping that cost, EVER, not even 1/4 of it. Estimating that entire cost to be $5,500 conservatively (very conservative) and doubled your yearly SCE to $120 (you won't ever see that) and it will take 45 years to pay for itself. Absolutely replace with those options when needed, however if you did to save energy, you just largely increased your total cost of ownership

It only increases cost of ownership if they end up needing to buy an an extra appliance over their lifetime due to the early replacement.
Slightly morbid, but if they were going to have to replace the TV at some point (or multiple points) and when they die, the TV has 1 year of life left vs 5 years, they saved the 4 years of less power usage. (Ignoring cost of money and energy advancements in those 4 years which are much less than purchase cost).

Edit: Totally agree in the 'green' full kitchen remodel. If you want to be green, keep using the same counters and cabinets.
 
With Net Metering I can charge from the grid at ANY hours. During the day I push energy to the grid and pull from the grid at night. In LA with SCE we do not yet have to pick Time-of-Day pricing, with off-peak and on-peak times. I am on Net Metering Tier 1, @ 17c / kWh (never been on Tier 2 since I have had solar).

Please note, although you can use power from the grid at any time for home use, the Tesla Powerwall CAN NOT charge with grid power when solar is installed. Per the Tesla FAQ below:

Can Powerwall charge from the grid?

When Powerwall is installed without solar, it can charge from the grid to support backup operation.

When Powerwall is installed with solar, it is not currently able to charge from the grid. Powerwall installations on new and existing solar systems are designed to qualify for the Federal Investment Tax Credit, which requires 100% charging from solar. Powerwall installations must also comply with rules around grid charging which vary by utility.
 
Yes, but does that apply when you get a PW2? Are you looking to get that gov subsidy that restricts the usage of it? Good luck if it does.

If one gets the SGIP rebate, the restriction is to drain it off about 52 times / year. If you claim the ITC 30% federal credit, the only restriction is to power the PowerWall only from solar panels (which is enforced by the PowerWall software).
 
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Changing lights to LED, definitely, however, if you changed out multiple tv's, a laptop, refrigerator, washer, and dishwasher just to make them more energy efficient, you are NEVER recouping that cost, EVER, not even 1/4 of it. Estimating that entire cost to be $5,500 conservatively (very conservative) and doubled your yearly SCE to $120 (you won't ever see that) and it will take 45 years to pay for itself. Absolutely replace with those options when needed, however if you did to save energy, you just largely increased your total cost of ownership

Plasma HDTVs were all 6 years old, same for dishwasher, refrigerator and washer. Dishwasher and refrigerators were practically dead. The Plasma TVs were still fully functional, but the replacement price with Samsung 4K LEDs was ridiculous, plus I was able to sell the old HDTVs locally. Replacements were all purchased on Black Friday at Amazon and BestBuy.

The yearly savings in energy I paid to SCE I calculated to be about $2,400 / year, so I will recoup my costs in less than 3 years. After that it is all gains.
 

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