Solaredge export limiting in MA - any experience?

At 12kW DC I doubt you really would see very much clipping at all. I don't think you need any battery storage to deal with that. We have 11.7kW DC on 9.75kW AC in MA using Enphase, and we rarely can clip our microinverters, even though those would be far more likely to clip than your string inverter. (They can oversize the optimizers so they never clip).

As far as Powerwall, unless they have a stash of PW1's, all PW2's are AC systems so they won't help you here. PW1 or LGChem on a SolarEdge 7.6kW StorEdge would be able to do this, but then if you want to hit 10kW you have to split up into 2 inverters (one 7.6kW with storage and one 3.4kW without). Note that due to how SMART generation metering works you won't be able to earn generation credits on your backup loads (see https://www.solarpaneltalk.com/forum...s-backup-loads)

So IMHO, SolarEdge 10kW HD Wave plus 12 or even 14kW of DC (particularly if you are installing on two different azimuth's) plus 2x PW2 is the optimal install. But only get the PW2's if you want them for backup and/or the new VPP/DR program (ConnectedSolutions for Battery or whatever they are calling it), not because of the DC oversizing. I regret not going with 14kW on a 10kW SolarEdge and putting up a few more panels, as we are almost never clipping and I could use the additional generation, certainly with this month's weather. We are swapping out some of our older AC units for new inverter heat pumps, which will reduce my summer consumption but greatly increase my winter consumption, so I can use any additional generation I can get.

There is another thread here where the poster briefly described the MA Net Energy Metering arrangement as reducing the payback on any power generated above 10kW. He didnt give the details of the amount of that haircut. Based on the the suggestion of brianbsl I think you would be fine with a system with a higher DC to AC ratio. My system is 5.7 kW with a 3.8 inverter. (DC to AC of 1.53 to 1)

As far as your question regarding experience with a similar system is concerned I can offer the following. In addition to the above system i also have a hybrid system with some of the functionality of a Powerwall. I live in a part of California that is subject to disconnection of power when there is risk of fire danger. Therefore I rationalized my system based on that and not primarily on a financial payback. There was some return based on being able to reduce my metered consumption and therefore sell more of my peak generation of my primary system to the Power Company at rates as high as $0.50 per kWh. I also justified both systems as a hedge against future price increases. One of those bets is based on future speculation that I might be compensated to use that Powerwall like functionality to put load on the grid or to provide aggregate grid support. There are existing arrangements like that in other parts of the country. I am currently participating in a small program in California where I am compensated a trivial amount for allowing them to controll when I charge my electric vehicles.
There have been a lot of Powerwalls installed in California because of an aggressive state rebate when coupled with the Federal Tax incentive. Unless your situation involves any of the above assumptions, it sounds like your installer may be using the Powerwall as an upsale opportunity. It is probably worth getting some additional opinions with some detailed financial analysis that fits your tax situation and your personal philosophy.

If your solar is in more than one azimuth or any shadows I would just out in 12kw dc with the solaredge 10kw inverter. No need to do any limiting as the 10kw inverter will limit perfectly and the different azimuths will help spread the load for a longer generation.
The other option is to us the storedge but that would limit you to 7.6kw cost a lot more with the more expensive inverter and battery. You could add another inverter to get around the limit of the 7.6kw inverter but that would put you over the 10kw limit as the smallest other option is 3kw leading to 10.6kw which is over the 10kw limit.

Ok. After speaking with a few installer teams and you kind folks, I think we are dropping the battery idea.

I think our optimal system is going to be 14.xx kwdc to solaredge 10kwac hd-wave inverter. The roof is ideal. About 25 degree south facing, no shade. We may clip a bit in the summer but it's not worth splitting the system to get the 7.6kw old inverter that does storedge with the LG chem.

And yes pw2 won't help with clipping since it is all ac side. I think the marketing folks at the solar installers just try and sell stuff. I don't think they (sales) knew about this constraint of where the battery is going to sit.

Maybe one day the storedge interface will make it's appearance stateside and DC batteries will be attractive.