House/Garage

[Ampster]

............ I think the reason you have so many restrictions in the US is because of GRID Capacity which is unfortunate. ........

Most of the restrictions in the US come from the National Electrical Code which deals with issues behind the meter and have nothing to do with Grid Capacity. It sounds like there is a similar Canadian Electrical Code.

[oregon_phil]

I am not canadian, but are you sure you are not subject to Canadian Electric Code 64-112? It looks very similar to NEC solar requirements for inverter interconnect to main panel with 120%/125% load side limitations. For what it's worth, here is a link of a recent paper on Section 64 .https://aetiinc.com/wp-content/uploa...Section-64.pdf

[nosbod]

Thanks for the response. I neglected to mention I am in Canada. My main service is 100 AMP. I Have installed a 9.2 KW system with the 7.7 sma inverter and have no problems. My system has been passed by Fortis, and hydro inspectors. I think the reason you have so many restrictions in the US is because of GRID Capacity which is unfortunate. Our roof mount systems require Rapid Shut Down which is done through the AC disconnect after the inverter.

[solarix]

No, no - the most back feed you can have on a 200amp service is 20% of buss rating which is 40 amps or 7.7kW, and that is only if the backfed breaker is on the main's buss. If you add another 3.8kW inverter (20amp breaker) in the garage you risk putting as much as 60 amps into your main panel which could theoretically add to the 200amp coming from the utility and could melt the service panel (according to the NEC code). The 60 amp panel can't handle the 3.8kW inverter anyway. Plus, your utility with their disconnect switch no doubt has a requirement for all the solar power going through one disconnecting means.
Welcome to the world of solar - where what you want to do would most probably work, but is not allowed because of all the safety first, second, and third rules.....

[PVAndy]

(1) Can I run 2 SMA inverters on the same line from different locations?

Yes

(2) Can I run 2 different sized inverters or does the garage inverter have to be a 7.7?

You can run 2 different size inverters

(3) Do you foresee any problems with this setup at all?

Is it a 200A main panel in house with 200A Buss?
If the 7.7 is backfed by a 40A breaker to a 200A panel with a 200A Buss, you can not backfeed any more.

Typically what we do is refeed the garage panel via a line (supply) tap in house using a 60A Fused disconnect.

We then tie the solar into the subpanel in the garage via a 60A AC disconnect with 20amp fused via tap above the main breaker in the panel If the panel is a 100A panel you can backfeed with a 20A breaker

Andy

[nosbod]

In April 2021 I installed a 9.2KW system on my roof using a SMA US-41 7.7 Inverter. From the inverter the AC went through a disconnect switch to the Main Service panel in the house. Last year I built a detached garage and ran a 60 amp service from the Main Service Panel in the house to a 60 Amp Panel Box in the garage.

I am looking at putting a 4.5KW system on the garage, running it to a 3.8 KW SMA US-41 inverter which will be installed in the garage beside the 60 amp panel box. The AC will run through a disconnect switch to the 60 amp panel in the garage.

Questions
(1) Can I run 2 SMA inverters on the same line from different locations?

(2) Can I run 2 different sized inverters or does the garage inverter have to be a 7.7?

(3) Do you foresee any problems with this setup at all?

Thank you in advance