Almost exactly a year ago I had another 100Ah AGM (Phaersun PN-SB 12-100) bought battery Set a PV system. in my opinion, never really ok. Now after a year I have exchanged this and I have a comparison with the behavior of a not quite functioning battery. So far it is working properly and does what I expect so. When the sun shines it is charged by my 300Wp PV system quickly. As solar controller I have a Steca PR2020. Delivery was quite fast. Let's see how long it lasts.