This isn't the same as your situation, but we are doing a project right now that requires us to move our gas meter, so maybe this will be helpful.  We put in the request in October to get on PG&E's schedule, and it is now almost 8 months later and we still do not have a date when they are coming out, which means our contractor is on hold till they give us a date.  PG&E did finally send us a contract a few days ago for a mind-blowing $20K which has to be paid before they will schedule us. We had no. idea. it would be this expensive.

The worst part is that we originally thought PG&E would just be capping off and then reconnecting the gas line that runs from our house, where the meter is, under the driveway and down to the street. We need to replace a failing retaining wall and excavate part of the driveway, so we needed PG&E to come out and cap off the line while the work was being done. It never occurred to us that the gas meter would have to be moved. For one thing, the work we are doing is down at the street level, and the meter is uphill on the house. But the other thing is, PG&E replaced our gas meter less than a year ago to try to fix a different problem, so presumably it's to code (and there are multiple electric and solar boxes). Nevertheless, during the past 8 months as we have waited to be scheduled, there have been dozens of emails and phone messages between us and PG&E, with lags of several weeks between responses, telling us different things: meter can stay where it is, meter needs to move a foot away from where it is, meter must be located down at the street, meter must be installed in the driveway. This last suggestion came with a sketched meter + bollards superimposed on top of the architectural plans we'd given them. It stuck out into the driveway such that a car would still fit, but the doors could not be opened all the way (!!!)  We even had a visit from a PG&E engineer who measured everything and assured us the meter could stay on the house.  But that was eventually overruled. Finally we came up with a plan to create an alcove in one of the retaining walls for the meter, just next to the sidewalk, which satisfied PG&E, at which point they eventually sent us a contract. 

Our understanding is that PG&E prefers the gas meter to be as close to the gas main as possible, partly for better access, but also because it is the homeowner who is responsible for maintaining the line that runs from the meter to the house. PG&E is only responsible up to where the meter is. So that's why, when they need to do anything to the gas line, they want to move the meter closer to the street at the same time. It's more economical for them since they are no longer responsible for that stretch of gas line between the street and the house.

Anyway, back to your issue, I would definitely ask the solar installer about their experience with this - it seems like something they must run into all the time.  I would explore every possible other option before moving a gas meter.