Vijen

Hi Gerrie Problem is still there but much more prominent if I set my max charging current to 20A. At 30A max charging it happens very seldom and at 40A not at all. My max current that PV can supply is just under 50A. It seems like when it has to reduce charging current more the problem is worse. I have checked PV fuses and holders since reading your post and all seem fine.

Hi Coulomb Yes, the PV power drops the same as when I make a battery charger change. I expect the delays but it also oscillates a few times before it settles down. Its like the controller overshoots and then drops to 0 and then overshoots again. From my control system background its like an unstable controller after a change. I have found that the problem is the worst if I set the charging current low to 20A and disappears as i increase the current through to 40A.

Sorry forgot to mention that I experience same drop when I make a changed to battery setting. When the solar controller resets it cycles solar power on/off a few times before it stablises.

Thanks Coulomb - I read through the thread It appears one solution was the replacement of batteries - did I miss any other possible solutions? My system was fine before moving the batteries - will have a look at all connections again - maybe a bad battery connection has started this. Fortunately, I do not experience the freezing - that would really suck!

My 5kVA Mecer inverter has started dropping the PV input while the sun is still shining brightly outside and the load fairly constant. The PV input drops to almost 0W then in picks up again to the value it was before the drop. It does this at least twice within 30 seconds and then seems to settle down again. My system runs in SBU mode, with solar only charging and max current set to 30A. Its seems like the MPPT controller is faulty. This started after I shut down the system to put my batteries on a stand. I followed the procedure in the manual for shutdown.The system was off for at least 2 hours and when I started up I had to set all the settings again as they had returned to defaults. I have since shut down the Mecer again and restarted to see if removes the issue but it still does it. Has anyone experienced this with a similar inverter or any ideas what the problem could be?

Hi Coulomb Just an update. I measured my batteries and noticed one of them 0.8V below the rest. Forced the system to charge to 58V and left it there for an hour to equalize. The system then ran until midnight before it swapped back to utility. The charge current seems to behaving correctly again and the last few nights I have run on batteries until roughly midnight before the changeover to utility power. I am thinking that the battery resistance may have been a bit high and somehow it affected the charging so that it stopped early? Still a bit confused but happy that solar charge is now appearing to last as long as charge by utility.

The 9A is actual net current into battery. You could be onto something there (regarding battery internal resistance and temperature. Up to now I have only done the utility charging in the late afternoon - will try it around midday and see if it reacts similar to PV charging. Thanks Coulomb

I have just had the charging stop early again. have a look at the attached screen shot from ICC. The battery voltage drops to 54V while the current is around 9A - this should not be occuring until the current drops below 6A.

Hi Coulomb I read your previous post on the charging time referred to above. It helps me understand this system much better - thanks. However I am not sure why you said this Did you mean 30 minutes instead?

Thanks Coulomb So, if I understand correctly, charging occurs as follows when set to solar only. The charge circuit directs any surplus current (not used by load) to the batteries. This max current is limited by setting 02. This first stage of charging occurs until the voltage reaches the bulk/absorb voltage is reached (in my case it is currently set at 57.6V). The charge circuit then tries to maintain the bulk charge voltage by controlling current directed to batteries. ie If voltage increases current is decreased until voltage is back at bulk voltage. If the charging current drops to max current in setting 2 divided by 5 (in my case max current is set to 30A so this should be 6A?) and the battery voltage is greater than 57.1V then charging is considered complete and the charge circuit sets the voltage set point to the float charging voltage of 54V which is basically a trickle charge. If this is the case then its weird that I experience "better charging" when charging on utility. When the charging current drops below 6A on solar because of clouds or larger loads coming on I am sure that my voltage drops below the 57.1V so it should not see this as charge complete. I will look more closely at this transition when charging on solar. Just to confirm, I am on 73.00e. Before this firmware change the unit would reach the bulk charge voltage and almost immediately drop to 54V. Now it seems to stay there for about an hour including time spent when charge current drops. If I leave on utility charge however it appears to charge longer - 90 minutes to 2 hours. It also definitely takes longer to reach the 49V changeover from battery to utility that I have set. Normally around midnight compared to around 10/11 pm when charged on solar. Strange...

I have a Mecer 5kVA/4kW invertor with 8x200Ah Vision bateries and 3000W of PV. Item 32 is set to Auto in the Mecer setup and I have the patched firmware. My system is set to run loads of solar during the day (appox 600W) and continue on batteries until it battery voltage drops to 49V. It then switches back to Eskom and battery charging is only via solar. I find that when charging the batteries by solar they do not receive as much charge as when charged by utility.Can anyone explain how the Mecer/Axpert charging work? I have a feeling that this is because of the fact that on PV the charging current sometimes drops away completely when a cloud passes or a big load kicks in - the Mecer still counts this as charging time but battery current may actually be negative. The voltage drops to 54V and then approx 4 A is supplied to battery even though there is surplus solar available. Any recommendations on whether I should set 32 to manual and if so what time should I select. Regards Vijen

Thanks Richard. Still not a positive yes one way or another but different ages of batteries have been connected together without issues according to those posts. I am going to go for the second hand set which is similar age to mine. They came out of a working system which was used to provide power when Eskom load shed so should be in similar condition as mine.

Hi All. I have had a Mecer 4kW/5kVA inverter with 4x 200Ahr Vision batteries for a few years. I have recently added 3kW of solar and am trying to save as much on my electricity bill as possible. The solar is ample to run the load (Av 750W) during the day as well as charge batteries if required. When solar drops to insignificant values I let the system run of the batteries until 49V and then switch to utility to run load. My system is set to charge from solar only and load priority is also set to solar. I am finding that the system can run loads until around 9pm before switching back to utility at night and that batteries are charged before 11am every day so available solar is wasted during the day. Hence my reasoning is to add more batteries - specifically another set of 4 Vision 200Ahr. My concern however is the new batteries may cause issues connected in parallel to old batteries. Is it better to try and get a similar set of batteries as mine (there is an option to buy a second hand set that was used in a similar role as mine for same period) or go for the new ones. Regards Vijen

Thank you for the replies gents. It has been very informative.

Thanks Ironman Will drop them an email tomorrow. From your combiner box it appears that you have 4 strings which are individually protected by fuses. Then you combine and protect with circuit breaker and surge protectors. Is this correct?

Thanks Coulomb - I appreciate your feedback. I will try to source panels closer to 300W each, otherwise will take a chance with the 2S5P (10 panel) config on the 330W panels. When you do multiple strings in parallel, is it better to wire the PV panels to a connection panel directly below the PV installation and then run a pair of cables to the invertor for neatness and costs compared to running 10 wires to the invertor fro a 2S5P configuration? On my last question (The sticker indicates rated current in solar charger mode is 60A. Does this refer to current charging battery or total current input from PV cells?) - what do you think. Does it mean that total current from PV panels is limited to 60A?

Hi Coulomb. Thanks for the response. Apologies, the model is SOL-I-AX-5M. My manual seems to indicate MKS II but the sticker says otherwise. Max solar voltage (VOC) is 145VDC. Does this mean that I should use 2 panels in series which will give max VOC of 91.2V and then use 3 of these in parallel to give combined max current of 26.64A? I would assume that realistic power generated from solar would be limited below 2kW in this configuration. Are there any other easily available panels you would recommend that would get me closer to the 3kW solar? The sticker indicates rated current in solar charger mode is 60A. Does this refer to current charging battery or total current input from PV cells?

Good day All. I am new to the group - My name is Vijen and I live in Centurion, Pretoria. I have had an Axpert 5kVA (4000W) system installed at my home for backup purposes for the last 2 years. I have 4 x 200AH gel batteries installed. The system has worked well but I would now like to add solar power to it. Can someone please advise me what configuration I should go for if I use the 330W Canadian solar panels? My concern is both voltage and current. I was thinking of 9 panels in a 3 x 3 configuration. This would theoretically bring Voc to 136.8V and max current to 26.64A (8.,88A x 3). The open circuit voltage is below the theoretical 145V but I am not sure how close you should be to this. the current is obviously a big concern. Any advise will be greatly appreciated. Please recommend other panels if you think they are better.