July 11, 20179 yr 3 hours ago, Graham said: What would the realistic % improvement be in our climate? 10-20%? 30%. In our climate (mostly sunny), using a traditional 12V system as an example, a PWM controller pulls the panels down to 12V whereas an MPPT lets then work at 18V (the typical Vmp for a 36-cell module, aka a 12V panel). Since PV panels behave like constant current devices (proportional to light level), I is constant so P is directly proportional to V, and since V is a third higher, that means you'll get a third more power... minus a bit for conversion efficiency in the buck converter (typically 95% efficient or so), so 0.33*0.95 ~= 0.3, or 30%.
July 11, 20179 yr 5 hours ago, Graham said: That makes sense. So my panels' open circuit voltage is 45.2V (22.6V x 2) and max power voltage is 36V with a max battery voltage of 28.8V (14.4V x 2). So would a MPPT SCC give me extra 30% current here? JIp about 30% at best only a 20% difference but battery voltage in the morning in lower.
October 13, 20178 yr Author An update on the Mecer Inverter, it's all working fine so far, no problems. I have also been using the system for more hours than I thought I would before, but it's performing without complaint. I have abated the noise by putting a 2W 46Ω resister inline on the fan lead, the fan runs slower and the unit doesn't even get warm at the watts I'm using. I also got a Victron 7515 MPPT charger to replace the one I had before and it's working fine apart from getting a bit hot when at 14/15A but I've added a PC fan to that and now it's fine. 2S2P 150W solar panels are feeding the system.
October 13, 20178 yr 2 hours ago, Graham said: I also got a Victron 7515 MPPT charger to replace the one I had before and it's working fine apart from getting a bit hot when at 14/15A but I've added a PC fan to that and now it's fine. When running flat-out it does get hot, but I doubt it is something to worry about. I did that to a 100/15 for a couple of weeks with a 50% oversized solar array, and though it was sweating "new electronics" smell the whole time I never felt like it was about to fail. I'm presently running my 150/35 at 100% too for a portion of the day. It too gets quite warm, but not as much as the 100/15 did.
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.