Radar

Thanks for the response. I've recently been doing some desktop research and find it quite frustrating that pricing for LiON products seems quite hard to nail down e.g. SolarMD has no prices on their site, and retailers of their products all say they will provide pricing on request. Any idea what the 3.7kwh version would cost incl. VAT ?

Apologies. They are both 5kva 48v models. And yes the battery is connected to both of them (rookie mistake). Ok, so the 16 panels would be too much for any one MPTT to manage. Got it. The ones currently connected are not all the same solar conditions (two types of orientation) and the additional 4 would be a third type of orientation. I'd need to match the 4 with closest in terms of solar condition then. Does that mean splitting them across the two inverters (8 each) is most probably the safest? If I use SOL mode, do they 'share' the cumulative power generated from the 16 panels, or does each inverter only use its own MPTT for its own load?

Anyone with experience with the Solar MD lithium battery products e.g. SS4037 3.7kWh ? Pro's and con's of using them? compared to e.g. Pylontech?

I have 2 Axperts connected in parallel. 12 x 330w panels connected to the Master, and the battery bank is connected to the Master as well. I'm considering installing an additional 4 x 330w panels. The question is: Do I reconfigure the 12 existing ones to connect the 16 to the Master? or do I reconfigure the 12 to connect 8 to the Master and 8 to the Slave? or to simplify the install effort now, just connect the 4 to the Slave? What all do I need to consider? Does the fact that the battery bank is connected to the master influence the decision I need to make? I'm intending to use the system from Solar as much as possible during the day, utility during the evening, and battery as backup all the time.

that specific phrase is not mentioned in the batter. Parameter 26 refers to 'bulk charging voltage' ; parameter 27 refers to 'floating charging voltage' and parameter 29 refers to 'low DC cut-off voltage. Currently 26 = 56.4v ; 27=54v and 29=42v. Is it one/some/all of these I need to revisit due to the OSO charging selection? In terms of the batteries I have: 4 x 100ah Vision batteries

I recently adjusted my Inverter to OSO charging of the batteries. I got advice to also revisit the 'battery bulk voltage' as well to avoid damaging the batteries. i checked through the manual but am not 100% sure which setting/s to update and to what. Any suggestions?

Then the LCD display on the Slave is deceiving. Using the first scenario as the relevant one (10A, 8A and 2A), and as the total load on the system was 374w (173w slave and 204w master), it should in theory all have been covered by the solar panels (330w x 12 x 90% effectiveness estimate = 3.6kw). Then I have no need to 'worry' ?

Thank you. My current setup does seem to be inefficient as i have 12 x 330w solar panels, and that is more than enough to handle my 'regular day time' load. Therefore if the slave is charging the batters from eskom, its inefficient and unnecessary cost for me, and if the slave is using batteries instead of solar directly, its also using the batteries unnecessarily.

Isn't there 'wear and tear' on the batteries unnecessarily ? My intention with the batteries is that they are purely back to Eskom.

Thanks Chris. Can the Axpert Master 'share' the power from the solar panels with the Slave? If so, is it a setting change only? or how? If not, is the only remedy then to take e.g. half of the solar panels and wire them directly to the Slave?

Ok next question: I have two Axpert inverters. The solar panels (12) are all connected to the Master. The Slave's LCD display screen shows that the load its responsible for is being powered by the battery (i.e. no solar panel on its display). The master shows the load is being powered by the solar panels, and the solar panels are charging the batteries. Shouldn't the Slave's load also be powered by the solar panels (setting 01 is SOL) ? Is the LCD panel display not 100% accurate, or should some of the solar panels have been connected directly to the Slave ?

Thanks. If setting 16 is set to CSO, will the alarm never come up? if it does, what could be the problem?

Thanks Pilotfish. Surely one of those settings is the threshold for charging to restart i.e. that the warning should never have come up in the first place? The batteries are less than 3 months old, so I really hope its not because they are damaged. As the setting on menu 29 was on 42v previously, and I changed to 46v, is it possible they just happened to be between those two when I changed the settings? Menu 16 is on CSO, and I changed to OSO as well when changing the above, perhaps thats why it got caught inbetween the old and new on 29? 16 is back on CSO now, but I also reset all of those settings to the ones they had before i.e. menu 5 to AGN etc.

So I have set all of these as per the suggestion above. The system is not reporting a fault: 4 with little triangle, which is a battery low warning. Why would that happen?

Thanks for all the replies. We did some 'balancing' of items going through the inverter, so now geyser, stove, oven and aircon are directly on utility power only. The system is also working fine on SOL mode. All other issues that were experienced are now resolved. Next questions: 1) how do I ensure the health of the 4 x 100ah batteries (Vision is the make/model as far as I know), without a BMV and ICC ? I'm currently working on the assumption that a forced switch over every 2 to 3 weeks to run directly from batteries until inverter warns that it is reaching the limit is acceptable? 2) what settings (I'm an electrical ignoramus) for the batteries DOD/SOC should I be using on the inverter panel directly, assuming I will continue without a BMV and ICC ? The electrician has setup voltage related values/limits on the applicable inverter menu settings, I just don't have them with me at the moment. I will add them later to this post. 3) the electrician suggested that if I put a solar based heating element into the geyser, it may reduce the load on the inverters and can actually be placed back on on the system. I'm not exactly sure what device/make/model he is referring to and want to do some research first. What should I be googling? I know this will place a strain on the batteries if they are used, but in 'normal' conditions I'm running on solar in the daytime and have headroom for the geyser to run off the panels too.

Ok I get what you were saying, thanks.

the manual and installer both refer to this inverter having three modes which determine the order of priority: SOL = Solar first. Utility provides power to the loads when one condition happens: a) Solar energy unavailable, OR b) battery voltage drops below setting level. UTI = Utility first SBU = Solar, Battery, Utility, in that order. I'm currently running in SBU mode. I was considering trying out SOL mode, as it may solve problem 1 i.e. once solar is unavailable it should switch direct to utility (instead of battery). But I'm not sure if I'm reading the definition correctly.

Thank you. I don't even know where to start to source a BMV, any suggestions ? I did a bit of reading up on ICC and will be ok with sourcing that.

Ii believe it does switch from solar to battery when there is insufficient solar energy e.g. at sunset. The inverter is set in SBU mode, which by definition is Solar -> Battery -> Utilities in order of diminishing priority. Or do I understand it incorrectly? The Inverter is not on SOL, its on SBU. Yes, if I can't use the existing feature set to achieve what I ultimately want, the ICC route seems to be the best option. I do want to keep the small battery bank charged, so I want to amend settings to do exactly that. Ultimately I do want solar during the day and utility at night. Hence my tongue in cheek reference to an SUB mode being ideal. Just not sure how to simulate it without ICC, but what I'm picking up on this forum is that it seems the only way to go.

Thank you very much, will check this out.

I'm not sure its that changeover break, might well be. We are relooking load setup today. I don't have a BMV or software, what would you recommend I use? ICC and ?

Yip, busy looking at that today.

I'm busy looking at rebalancing it, to take this into account. Geyser is already off, and the aircon seems to have been mislabelled at the DB previously, so we thought it was off but is actually still on.

Greetings all. I'm very new to the topic of inverters, solar and backup power systems for homes. I'm also not very technically minded. I recently had a system installed which consists of 2 x Mecer 5kva inverters, a solar panel array and batteries, with the latter having a very small capacity (worked out to about 6hrs standby only). It is currently running in SBU mode, and we're experiencing the following challenges: 1. When switching from solar to battery in the evening, its almost as if the system is doubting whether to switch over permanently or not. E.g. as the sun is setting, we switch on the oven. The oven's load results in load exceeding what solar can supply, so the system switches to batteries. We then finish with the oven, and it switches back to solar. This happens a few times during sunset period as we switch on and off high load devices/applicances. 2. In the morning, before sunrise, the system is running on battery and switches to utility when the batteries reach 90% of their capacity. When we switch on the central aircon system to heat the house, an additional load is placed on the batteries, and obviously drains them faster. That means it gets to the 90% quickly. This in itself is not a problem. The problem is that when the system switches from battery to utilities, its as if the aircon compressor senses a very small load fluctation and goes dormant for a few minutes before starting up (perhaps some sort of protection mechanism?). As the load requirement changes, batteries charge up and the system switches back to battery, and the cycle continues to repeat. In summary, the aircon is never on long enough to build up 'pressure' and heat in order to work properly. The 90% cannot be changed, as then I wouldn't have enough battery backup during the night should utilities fail completely. Based on the above, do you have any suggestions on settings on the inverter that I should rather be using? One of my thoughts was to run in it SUB mode (I know there isn't really such a mode, but was hoping I could emulate it with a combination of settings). Therefore there would only be one cut over at sunset and sunrise each, and it would be utilities. Then battery would be a true backup. I have looked into SOL mode, and believe it may help, but my installer reckons it won't (and I haven't been able to meet up again to talk through why he believes so) Another option was to somehow switch to utilities from solar on a time basis rather. I see I can do that with ICC, was wondering if there is an inherent way to do it in the settings of the inverters? Any thoughts and comments appreciated, let me know if you need more info to assist.