PV / Line Side Taps?

[Power Solutions]

Ok, so picture a 20 K PV array on a detached garage roof. The garage has a 100 amp sub panel feed from the 200 amp main panel in the home.
The customer asked that I back feed the power from his PV array to the main panel using the existing sub panel conductors running under his newly paved driveway.
If I can I line side tap the sub panel with an appropriate sized disconnect at the garage location, what happens at the main panel at the house. I cannot back feed 80 some amps onto the 200-amp buse. I could also line side tap the main panel with the conductor from the garage, but then the service entrance conductors could be overloaded. I could install a 200 amp fused disconnect before the line side tap.
Can the feeders for the sub panel even be used for the PV backfeed?
It just does not feel right. Could use a point in the right direction.
Dj:-?

 

[ty]

Ok, so picture a 20 K PV array on a detached garage roof.

That is one big roof on a residential garage to fit that size system.
Wish my garage was that big.

The customer asked that I back feed the power from his PV array to the main panel using the existing sub panel conductors running under his newly paved driveway.

That's not going to work, using the info that you provided.
What size conduit is ran to the 100amp panel in the garage, and is the conduit continuous?

I cannot back feed 80 some amps onto the 200-amp buse.

That's correct.

Can the feeders for the sub panel even be used for the PV backfeed?

Probably not, if they are sized forthe 100a loadcenter.

It just does not feel right. Could use a point in the right direction.
Dj:-?

You might have to upgrade the service. You might have to re-do the feeders to the garage. You might have to run another conduit. You might have to do a line-side tap. There are way to many things that could be done.
How far away is the detached garage?

How does the power utility operate in regards to PV? By that, I mean, do they have meters that will spin backwards, or do you have to install seperate metering for the PV array?