Midnite Classic question

Thanks, guys. You're all a great help, as usual. I am getting my numbers from my current system, which is 3x 285w panels, and at high noon in the summer I see no more than 27.x amps to the Kid at roughly 112v, give or take. But my main gripe is that although that is a maximum, I rarely see that much... there are far too many partially cloudy days or slight cloud cover rolling past, I think a much more reasonable number is more like 17 or 20A for maybe the 4 hours from 10am to 2pm. After that, it drops considerably... it does not help that I have neighbors with large trees everywhere, so shading is an issue... and this system was put into place on the very handiest surface available, namely my back yard, on the ground (:  ...it was only supposed to be in place roughly a year to gather data for me, in order to plan how feasible a larger system would be.  I have since thought with the partial output I see much of the time, I should probably add 1 more panel to go 4x 285w to keep the Kid busier and only occasionally max out its 30A capacity... but I guess the consensus is that is probably a bad idea. But similar to the question asked in the subject line, with the 150 Classic.

The main things I have learned in the past 10 months is that I am VERY disenchanted with LA batteries.  My 6v GC2 Interstates from costco have been a bear to live with.  I lucked out with 3 good performers but 1 was not so good.... so I exchanged it, and got another not so good performer; I just exchanged that one yesterday due to the excellent costco warranty, got in under the 1 yr mark easily. It's in the system now and seeing daylight for the first time inside my tiny system. For the past 10 months the bad battery in the bunch has dragged down system performance steadily... I could initially run (during the summer) both a 14.7cu ft fridge and a 7 cu ft chest freezer off the 208ah Interstates (just barely, with lots of sunny days); then during this winter it was down to only running the freezer .... then running the freezer for most of the time during the days but having to revert back to the grid latenight.... so I just replaced the bad battery and hoping to get back to mostly running both appliances again full time during the day and then watching it at night to make sure they don't discharge the batts too far.

While I would like a 48v system, the batteries are probably going to be more expensive to the point of unobtainium; and, as I don't plan a very large system and plan to keep the grid as backup, I would like to keep the 24v inverter (cotek) and Kid as they have peformed very well, so I have been fudging and hoping the median of 24v would be a good compromise. I realize that 48v and 72v would be preferable for a  larger system, but this is mostly a growing small system with plans to re-use some parts.  I plan on picking up a 500ah NiFe battery but still kicking that one around. The cost would be roughly 7x over a used forklift LA battery... and I'll need to get an Outback inverter and since I have been happy with the Kid, probably a Classic.

Note that my system has been completely DIY, the system is not tied into the house's electrical at all.  The system is supplemental to the existing wiring and is comprised mostly of extension cords to the 2 appliances I run off the current system.  But, since I have not yet actually purchased the new components, its not too late to change my mind.... have at it gents! I am open to persuasive arguments to swing my away from the 24v I am currently planning.

aloha,
walt

Hi Vic, yes, I'm in Hawaii. The panels are Trina Solar TSM-280 and Voc is 44.7v, Vmp = 35.6, Imp = 8.02A.   Under use, the Vmp is close, and the Imp is slightly higher at something over 9A. But as stated earlier, I rarely see this condition; and that was new, with sparkling clean, brand new panels. I have found that I need to wash them off about every other week (mostly red dirt, but occassionally stupid cat tracks are found)... the rinsings seem to increase Imp over half an amp per panel.  The controller is a 1 year old Midnite Kid. The temperature never drops below 58F here at night, during the days 75F-95F is normal.

Thanks, zoneblue.  My 14.7cu ft fridge uses .500kwh/day, measured by watt meter. I have not measured the freezer, but its a standard 7 cu ft frigidaire and the watt draw while on is slightly less than the fridge, but I've noticed the cycles are longer so it probably uses more than the fridge does, feels like twice as much. The setpoints on the Kid are:  29.6v absorb, 270 min (which I do reach if I have a sunny day and only 1 of the appliances connected... almost never reach float if both are on though), float 26.8v.

The manufacturer says SG of my batteries should be near 1.290, the 3 good cells have always been near 1.280 at full charge, the bad cell was down near 1.240 or 1.1xx or even lower, sometimes. I use a refractometer, much more accurate than hydrometer.  I have tried breaking the batteries up and running an EQ on only the bad cell, and it would come up, but only to near 1.240 or so.  I cannot keep the array fully charged all the time, they seem to spend most of their time near 70-80% SOC.  I have never let them go below 50%, ever, although I've come close to 50% a couple times.  I make the absorb voltage most days and make the float only once every other week, probably. I partially disconnect the loads to do so, though.