Upgrading our Solar

[sbabcock71]

We currently have 27 Trina TSM-295DD05A.05 panels to give us roughly 7kW installed by an installer in 2017. They installed it with an Enphase System M250-60-2LL-S2x micro inverters (27). The roof it's installed on is a Flat roof. At the time, my wife did not want any solar panels on the massive front roof of our home. That front roof faces due west. I can fit roughly 40 Panels on that roof and another 30 panels on our garage roof.

I am looking to set up two more strings of panels, one on the front roof of our house and then one on our garage. Unless you think otherwise, I would go DC rather than AC for this system. I would want to go with Growatt Grid-Tie inverters and have an electrician (my son) connect them to the grid.
I'd like to know if I keep the 27 Panels on micro-inverters or just DC cable them. Any thoughts on that?
I like how Growatt could work for our home, and I've been watching Will's many videos on them. I could also get by with a 6548, but maybe the Growatt is better?

30kW of rack-mount batteries to start with, 48V EG4 . This is in the planning stages, so I'm looking for feedback to see my best options for the current 27 panels and then add up to 30-40 more.

I can also offer up our energy usage if that would help to size the correct system. I'm trying to use the grid as little as possible.

Thank you!

 

[sbabcock71]

 

[Ampster]

I'd like to know if I keep the 27 Panels on micro-inverters or just DC cable them. Any thoughts on that?

Yes you can keep the micros, assuming they are working fine. You can also DC cable them if there is a cost effective way to integrate them that compensates for the labor of doing so. My only thoughts on leaving them, are to plan your wiring so you can leverage their output do that both systems operate optimally..

 

[sbabcock71]

Yes you can keep the micros, assuming they are working fine. You can also DC cable them if there is a cost effective way to integrate them that compensates for the labor of doing so. My only thoughts on leaving them, are to plan your wiring so you can leverage their output do that both systems operate optimally..

Thank you! When the power goes out, we lose our panels as the Enphase system is grid-tied with no backup. My thoughts for DC would only be to bring these to a battery system. On clear days I can produce 38kWh, and I'm thinking of just adding panels to a separate Inverter to allow us to have a battery backup and grid tie that could also be beneficial. It's a quandary. How does the Skybox work for you?

 

[houseofancients]

keep the micro's, but i'd suggest looking at a sol-ark.
you can hookup to the smart port, in which case they will become part of a homogene system and will allow you to use them for zero export/battery charging/off grid should your powerco have an outage

 

[sbabcock71]

keep the micro's, but i'd suggest looking at a sol-ark.
you can hookup to the smart port, in which case they will become part of a homogene system and will allow you to use them for zero export/battery charging/off grid should your powerco have an outage

Thank you very much! The sol-ark is something I'll definitely look at.

 

[houseofancients]

ben is using a solaredge inverter in this video, but install with micro inverters is just about the same :

 

[Ampster]

How does the Skybox work for you?

It worked fine and was good at AC coupling. I upgraded to a SolArk and did not completely change my signature.

 

[Ampster]

The sol-ark is something I'll definitely look at.

The SolArk might be able to get some power out if your micros by A C coupling. It would also be important that any new solar be DC coupled to the SolArk to get the best value.

 

[sbabcock71]

ben is using a solaredge inverter in this video, but install with micro inverters is just about the same :

Thank you again!

The SolArk might be able to get some power out if your micros by A C coupling. It would also be important that any new solar be DC coupled to the SolArk to get the best value.

We also might have to "move" our original 27 panels to re-roof our flat roof. If we do that, I'll rewire them as DC and then size the strings accordingly. Then adding more panels and sizing the strings would be nice. I am finding some decent deals on used panels, and I'm also talking to some local Solar companies to see if they have any used panels to sell. One actually has some and is working up a price.

 

[Ampster]

We also might have to "move" our original 27 panels to re-roof our flat roof. If we do that, I'll rewire them as DC and then size the strings accordingly.

Then that may change the value equation in favor of DC coupling those panels. Are you going to have to deal with Rapid Shut Down requirements if you do that?

 

[sbabcock71]

Then that may change the value equation in favor of DC coupling those panels. Are you going to have to deal with Rapid Shut Down requirements if you do that?

Yes, exactly. My son also mentioned that the Rapid Shut Down would need to be added if we re-wire the entire system. He's the electrician and also I have a master electrician looking over it all for any inspections.

 

[Ampster]

There are certain advantages with any hybriid inverter to haing DC coupled solar.
In my case, I installed the micros first almost two years ago so I went with an AC coupled solution. So far I have added 2kW of DC couipled solar and have another 1.6 kW in the works.

 

[sbabcock71]

There are certain advantages with any hybriid inverter to haing DC coupled solar.
In my case, I installed the micros first almost two years ago so I went with an AC coupled solution. So far I have added 2kW of DC couipled solar and have another 1.6 kW in the works.

That sounds great and it appears with this, it would be roughly 9kW from AC to DC, then adding another 10kW and maybe another 6kW down the road. All used but good panels, to get the numbers up there and start saving to a battery bank to ensure we have power when the grid goes out, and also keep our home as independent of the grid, as possible.