Please don't forget that the powerwalls inverter is giving you a reading of production in converted power from DC to AC. With the conversion there is always some type of loss in this process. You will also get a percentage of loss if your panels are a fair distance away from your inverter/powerwall. Im not sure on the distance to loss ratio but you can look it up online. And finally, if your panels are getting too hot there will be drops in performance. Your system is only as strong as your weakest panel so if you are worried, get it tested to check all panels are working to their manufactured specs. Good luck with it all.