2 inverter with 200amp service

[Elu951]

I'm having a hard time making a decision that works the best. I upgraded my service from 100am to 200am. I'm going to install a Sunny Boy 3.0 and 6.0. My calculations say I can't connect to the breaker because I would be over the allowed current.

Could I connect one inverter to the load side and then the second to with a tap on the supply side?

Or should I combine both into a dedicated service and connect them to the supply side with a tap? If I do this I would need a 100amp service with a 100amp breaker correct?

6.0SB: 6,000w/240v=25A 1.25x25A=31.25A 35ABreaker

3.0SB: 3,000w/240v=12.5A 1.25x12.5A=15.63A 20A Breaker

What are your thoughts?

[sensij]

Before digging into your questions, why that combination of inverters? What are the details of your array?

[Elu951]

I'm installing (28) 330W Q.Plus L-G4.2
All modules are facing the same direction.
SB6.0 STRING 1- 10 Modules, 1- 8 Modules
SB3.0 String 1 - 10 Modules

My initial thought was a Sunny Boy 9000TL-US but I could not properly configure it.

[solarix]

The most inverter you can put on a standard 200amp service is 7.7kW (40amp backfed breaker). With two inverters which have to go through a combiner box with a 20amp breaker for the 3.0 inverter and a 35amp breaker for the 6.0 making the backfeed breaker 60amp. Your best option is probably to change (or derate) the main breaker in your breaker panel to 175amp (if you can find one listed for that box) to give you a total of 240 - 175 = 65amps of maximum backfeed.
Line side taps are rarely an option because almost no breaker panels are listed for that modification.
Is your main breaker separate from your breaker panel? If so you could insert another 200A panel in between and use a Siemens, 200amp plug-on style branch breaker to limit the power going to the existing breaker panel.

[sensij]

I'm installing (28) 330W Q.Plus L-G4.2
All modules are facing the same direction.
SB6.0 STRING 1- 10 Modules, 1- 8 Modules
SB3.0 String 1 - 10 Modules

My initial thought was a Sunny Boy 9000TL-US but I could not properly configure it.

You could put that on a single SB7.7, so you only need a single 40 A breaker. You'll lose a little bit of power on the good days, depending on your location and the actual orientation of the array, but the value of that lost energy is probably very small, especially compared to the extra costs of the two inverter installation you are considering. PVWatts will give a good idea of what that loss might be annually. Set the modules to "premium", loss to 8% to get a decent worst case clipping scenario. In the advanced parameters, set the inverter to 1.03 to model your two inverter solution, or 1.22 to model the single smaller inverter.

Another option to consider is dropping your main breaker to 175 A, giving you an additional 25 A of busbar capacity for PV.

[Elu951]

Thank you, what are your thoughts on a Supply side tap? The new 200amp service has space for it to be done. It's similar to Siemens MC2040B1200ESC 20 Space 40 Circuit 200-Amp Surface Mount Meter except it is not a center feed.

[sensij]

Thank you, what are your thoughts on a Supply side tap? The new 200amp service has space for it to be done. It's similar to Siemens MC2040B1200ESC 20 Space 40 Circuit 200-Amp Surface Mount Meter except it is not a center feed.

My thoughts on it aren't worth much. What does your AHJ or power company think about it? They are not always possible to get approved, space or not.

[Elu951]

Yes they do allowed for supply side connections. How would I go about putting it together as far as a dedicated of panel?

[emartin00]

Yes they do allowed for supply side connections. How would I go about putting it together as far as a dedicated of panel?

Nothing too special. You just need a small panel that can accommodate 2 double pole breakers. Ideally it would have a main breaker, but it's not required by code.
Then there are a few options for tapping into the main lines.