SMA will it ever work?
Hi, I am having a dreadful experience with SMA and after nearly a year I am frankly considering returning the lot, claiming it is not fit for purpose and suing for my money back. I really don't want the hassle of this so am asking for any input you guys can give me. Application is off grid in rural Spain with the need for five hours a day of bore hole pump for irrigation. I'm using a Sunny Boy PV inverter, 3KW of panels, 290 AH Rolls AGM batteries at 48 V and a Sunny Island 6H. From day one I could not get a generator to work for more than a couple of minutes. SMA blamed the generator and its control. I tried five generators, all failed to connect. Finally SMA switched out the Sunny Island and the replacement worked with the generators no problem. Now I have two issues. The first is that state of charge never rises above 80% even though State of health is 100%. The Sunny Island seems to ignore charging current drop as a parameter to end charging instead using just time and also ignores the end of a full charge as an indication of a full battery. Without an accurate SOC I am worried about the long term health of my batteries. Secondly the AC coupling between the Sunny Boy and the Sunny Island is frequency controlled. When I turn off a load like the pump the Sunny Island bangs the frequency up with a time constant of about half a second. The Sunny Boy simply cannot respond that fast and so the frequncy hits the cut off point, the Sunny Boy switches off and then tries to connect again with the same result. I can fix this by adding a 800 W dummy load but should I really have to do this? The batteries draw 400 w or so at the state of charge this normally happens at with another 400 w going to the house. Any insight very welcome, thanks