Off-grid setup in the Marina – anyone else dealing with weird voltage drops?

I’ve been running a small solar backup for my apartment in Dubai Marina because the building’s generator takes forever to kick in during those random summer outages. Everything was fine until last week when my 150AH started showing low voltage under load way earlier than usual. My electrician suggested upgrading to a proper deep-cycle option, and after reading around I’m seriously considering the Top-Tier 200AH Battery Service in Dubai Marina since they apparently handle the installation and disposal too. Has anyone here actually used them for a residential setup? I’m not sure if my issue is the battery aging out or if my charge controller is underperforming, but I’d rather not replace everything twice. Also curious if going to 200AH will be overkill for a fridge, few lights, and a router – or should I stick with another 150AH but better brand?