Solar company telling me I need to pay to relocate my main panel AFTER they already put solar panels on the roof?

My solar installation required a Main Panel Upgrade, which I paid for as part of our contract.

My solar company subcontracted out the MPU. The MPU subcontractor had to reschedule, but the solar installer went ahead and installed panels on our roof and the combiner box next to our main panel on their originally scheduled date.

Now, the subcontractor for the MPU is saying that we need to relocate the panel because of the utility company. My solar installer says that will cost an extra $1.5K.

Who should be on the hook for the $1.5K?

I’ve already paid my first installment to the solar company and started paying my solar loan

Now that the scope/cost has changed, am I within my rights to “walk away” and force the solar company to take down the panels, refund me, and restore my roof back to how things were?

Does that give me negotiating power to have them/the subcontractor eat some or all of the $1.5K they’re trying to charge me?