A quick backstory. My detached polebarn needs an electrical upgrade. The current situation is a 2" conduit run to a subpanel... fed by a 12gauge UF-B cable tied in with a 15amp kitchen circuit. 
I can only assume this was never inspected. I've been planning to upgrade to a 70amp circuit (distance), and had started purchasing materials (cable/new panel) to run 2-2-2-4 SER in basement (~90ft) and splice to 2-2-2-4 MHF(~40ft) with Polaris connectors.
Enter honey dearest. She decides we want to install Solar Electric panels and our contractor determined garage was best location. I still get my electrical upgrade, wife gets her solar. Win win. Per the code, there must be an external quick disconnect for the solar system. After conferring with solar contractor and my in motion electrical plans, determine to put a small 70AMP 2 space outdoor load center at the SER/MHF junction instead of Polaris connectors.
My issue/question is about bringing the SER into the panel. The panel has been already purchased and delivered by the solar contractor (I wanted to do this work, but additional materials are part of solar costs/rebates). Based on existing conduit, I plan to replace the LB pictured with the electrical panel. My problem is there is no holes in the upper back of the panel, so I either have to drill one if I can, or come in the top. Coming in the top, I can't seem to find a SER water tight fitting (only oval shaped SE). I have found references to drilling out the rubber grommet to fit the SER as an option.
I have attached a few pictures of what I am working with. Please excuse the shitacular caulk job by the PO, I am going to be fixing that. Sorry for the extraneous back story, it's lead to the current situation/limitations.
TL;DR. How to get this SER into this panel?
I can only assume this was never inspected. I've been planning to upgrade to a 70amp circuit (distance), and had started purchasing materials (cable/new panel) to run 2-2-2-4 SER in basement (~90ft) and splice to 2-2-2-4 MHF(~40ft) with Polaris connectors. Enter honey dearest. She decides we want to install Solar Electric panels and our contractor determined garage was best location. I still get my electrical upgrade, wife gets her solar. Win win. Per the code, there must be an external quick disconnect for the solar system. After conferring with solar contractor and my in motion electrical plans, determine to put a small 70AMP 2 space outdoor load center at the SER/MHF junction instead of Polaris connectors.
My issue/question is about bringing the SER into the panel. The panel has been already purchased and delivered by the solar contractor (I wanted to do this work, but additional materials are part of solar costs/rebates). Based on existing conduit, I plan to replace the LB pictured with the electrical panel. My problem is there is no holes in the upper back of the panel, so I either have to drill one if I can, or come in the top. Coming in the top, I can't seem to find a SER water tight fitting (only oval shaped SE). I have found references to drilling out the rubber grommet to fit the SER as an option.
I have attached a few pictures of what I am working with. Please excuse the shitacular caulk job by the PO, I am going to be fixing that. Sorry for the extraneous back story, it's lead to the current situation/limitations.
TL;DR. How to get this SER into this panel?
