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Help understanding system size. - MA Net Meter Cap

RxRCz

New Member
May 24, 2021
4
0
MA
Finally got traction on my order and got more detailed design specs.
I ordered the 8.16kw size panels + 2 Powerwalls.
From my understanding of Net Metering in MA, system sizes 10KW or smaller are cap exempt and can NEM 100%.

However according to my specs...Tesla is giving me two 7.6inverters. Total of 15.2KW.
Also with the 2 Powerwalls...the total system size in the specsheet says it's 25.2KW.
Anyone help indicate which number is going to be used for system size?
Is that inverter overkill for 8.16kw? And does this screw me for cap exemption?
 

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t153

Member
Apr 26, 2019
59
280
usa
Not sure about MA rules, but normally the storage systems aren't included in your overall system size. It's just the size of your array that can actually generate power, ie. just your solar panels.
 

Zinc_Saucier

Member
Jul 30, 2020
61
37
Massachusetts
In MA it’s inverter (AC) size, not panel (DC) size. I don’t know what the process is for being over 10kW AC, but that does seem like a lot of inverter for your array. I’ve got 12.24kW on the roof, but limited to 9.9kW on the AC side.

edit: Powerwalls aren’t included in the 10kW figure
 

dareed1

Member
Jan 15, 2021
113
103
Belmont, CA
My guess is that listing two inverters is a mistake, and they will really install just one. You have two azimuthal angles (167 and 77 degrees) for the arrays, so you'll probably max out at around 7.3kW. Seems to me that now is the right time to get this clarified.
 

RxRCz

New Member
May 24, 2021
4
0
MA
My guess is that listing two inverters is a mistake, and they will really install just one. You have two azimuthal angles (167 and 77 degrees) for the arrays, so you'll probably max out at around 7.3kW. Seems to me that now is the right time to get this clarified.
These were sent after permit was approved. Design sign off was just the panel layout. They even asked for a $200 fee if I wanted to redesign. Def will have to call them again to straighten this out.
 

adspguy

Member
Dec 1, 2016
217
208
Bedford MA
I have a 12.24 DC system with a 10kW inverter which kept me under the cap. It wouldn‘t make sense to have two active 7.6kW inverters in your system.
 

solarAddict

Member
Jan 26, 2020
145
64
MA
Finally got traction on my order and got more detailed design specs.
I ordered the 8.16kw size panels + 2 Powerwalls.
From my understanding of Net Metering in MA, system sizes 10KW or smaller are cap exempt and can NEM 100%.

However according to my specs...Tesla is giving me two 7.6inverters. Total of 15.2KW.
Also with the 2 Powerwalls...the total system size in the specsheet says it's 25.2KW.
Anyone help indicate which number is going to be used for system size?
Is that inverter overkill for 8.16kw? And does this screw me for cap exemption?
I'm in MA and have 10.16 kW system and 7.6 kW inverter. I'm highly doubt you are going to have two inverters. I asked specifically if I need a bigger inverter and installer was very clear that I don't. Someone made a mistake on your plan and nobody caught it because nobody looks into details (see joke comments below). I had to babysit my installer back office with similar issues (wrong panels, wrong roof and mounting specs details - all in stamped and approved plan)

comic relive: as a very old joke goes the final project of engineer in radioelectronics incudes this sentence: "because nobody reads this note I selected to use a wood as a material for the transformers core"..
 

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