What type of batteries are you using? Are you in an area that might be subject to wildfire smoke? I’ve seen our solar production reduced by 70% or more on some smoky days, compared to a clear day at the same time of year. Being grid-tied, that normally isn’t an issue. However, in 2020, a fire caused an 8 day power outage and by the 3rd day the smoke prevented the panels from maintaining a charge on the batteries. Had to run a portable generator during the day to take some loads off the batteries so they could charge. Now we have a 48V charger and a backup generator on the to do list. Something to keep in mind for an off-grid system. Of course, any well designed off-grid set up will have a back up generator.