I would take this a stage further and advise that the owners corp needs to take action on this as a matter of urgency.
Firstly becasue this is effectively a land grab that prebvents other owners or the whole strata scheme from installing solar panels and secondly becasue is the owner sells without a formal by-law in place, the owners corp assumes responsibility for the maintenance and upkeep of the solar panels.
I’m sure a compromise can be reached if all parties are willing. However, the owner should be told in no uncertain terms that if they aren’t prepared to pay for an acceptable by-law covering the installation, they will be ordered to remove it at their expense then billed for any residual damage.