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Rectron 5KVA settings


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I have Rectron 5KVA inverter

 8 X 100AH Lead Acid Batteries connected to produce 48Volts

6 X 310Watt Solar Panels connected 3 sets of 2 in parallel


Please Please Please will someone PLEASE tell me how to “setup” the Inverter. I please need to know the following cause I could do the installation using logic and common sense but I don’t have the knowledge or understanding to do the INVERTER set-up and fearful I may damage/cook/boil the batteries. I need to know:


  1. ·        Point Back Voltage (drop batteries and back to utility/Eskom)
  2. ·         Bulk Charging Voltage:
  3. ·         Floating Charge Voltage:
  4. ·         Low DC Cut-Off Voltage:
  5. ·         Max Charging Current: Solar
  6. ·         Max Charging Current: ESKOM/utility
  7. ·         Max Charging Current: Solar + ESKOM

PLEASE will some of you electrical wizards come to my rescue and “save the day”? Thanking you in advance.

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Welcom Wingman

Some of your questions can only be answered with some more info. Name of battery ?(The data sheet for the specific battery will answer your questions related to the battery) And can you give some more info on the inverter. Maybe a link to the Manuel. Most Mppt,s used on a 48volt bank will only start working at about 60volts, so your setup with 2 panels in series would have to change to 3 panel in series.

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Jaco - Is dit die battery info wat jy benodig om my te kan help?


Exceptional high rate performance. Over sized inter cell connector surface. Robust polypropylene ribbed container ensures increased impact strength. Spill resistant double lid. Central venting system with flashback arrestor for increased safety. State of Charge (SOC) indicator for ease of stock holding and maintenance .

Salient Design Features 
Long Float Life:
Calcium alloy grids and plates to minimise corrosion.
Envelope separators to eliminate internal short circuits.
High Cycle Design: High density active material formulation.
Glass matt backed separators for active material retention
Exceptional High Rate Performance:
Oversized internal inter-cell connector cross section
Enhanced Safety:
Central venting system.Flashback arrestor.
High impact strength container.
Easy to Connect:
Available with stud or taper terminals.

Easy to Maintain:
Built in State of Charge Indicator.

Technical Specifications

Capacity at 20hrs: 102

Dimensions (LxWxH): 328 x 171 x 219

Height (including terminal): 239

Terminal: Stud

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Thanks Wingman,

So what is the open circuit voltage of those panels?

Questions that i can answer.

You've got a 200Ah bank. It is recommended that you charge your bank at between 10 and 13% of the total ah, so in your case that will be 20 to 26Amp. This inverter has settings for 10A. 20A and 30A. I would chose 20A to be safe. I think the AC charging setting is personal preference, depending on if you want to allow charging from grid. I would say that it would be safe to limit the total to 20Amps.

I will feel more comfortable answering the rest of your questions after i know what batteries youve got.

A guy called @Chris Hobsonknows these inverters quite well, I am sure he will join soon. His got a post on this forum somewhere with the Axpert settings, That document explains everything very well.


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Jaco ..... thanks once again for your reply/help. Yes I have come across some of Chris from  Graaff-Reinet answers and he seems to really know what it is all about. I have no idea what the "open voltage" of the panels are but will search for the brochure cause it will be stated there.

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1 minute ago, Wingman said:

I have no idea what the "open voltage" of the panels are but will search for the brochure cause it will be stated there

Since you have two in series, whatever the Open Circuit Voltage on the spec sheet says (Voc for short, that is a V with an oc subscript), multiply it by two. A 72-cell module usuall has an open circuit of 45V or so, so the voltage should be around 90V. More importantly though, the Vmp (max power) will be around 36V per panel (ie 72V per string), and that must also be above 60V before anything happens.

In this case... it will work. It might work slightly better with three panels, you'll have a Voc of 135V which I believe is below the rated 145V of the inverter. What is more, at Vmp you'll make 3 * 36 = 108 volts, which is also within the 115V limit of the inverter

SMF 100? Lead Calcium jobbies. UPS batteries, not real deep cycles.



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@Wingman According to this document your Bulk Charge should be set at 58.8Volts and your Float charge at 54Volts


As for your low voltage cutoff settings, you will soon learn that you can not rely on the Axperts voltage indication as a correct Dept of Discharge or State of Charge indication. To tell you to set it at for example 47 volts will be unfair. because depending on the load and the rate of discharge, 47 volts might mean that you are sitting at a 40% or 50% or even 70% dept of discharge. The recommendation will be to plan for a Battery Monitor and use that to determine the low cutoff point instead of the Inverters internal setting.

The change back to AC setting is also personal preference and I would allow a guy like Chris to rather give his opinion first. 

Hope that all of this is making sense, if not, please ask and I will try to simplify my answer.

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Jaco - I am so so grateful for your reply and will start with those settings. I have just managed to locate the solar panel brochure and am trying to find the correct open circute voltage ...... (what ever that means) so as to answer "Plonkster" who is also trying to help me. Thanks to you all!!

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Jaco - the solar panel specs:

Pmax = 310w

Max Pwr Current (Imp) =8.38A

Max Pwr Voltage (Vmp) = 37.0V

Short Circuit Current = 8.80A

VOC = 45V

I have 6 panels. 3 sets of 2 in parallel. Will it be better if I have 2 sets of 3 in parallel? 

Trust this info will help you to help me EVEN MORE?

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9 minutes ago, Jaco de Jongh said:

, just want to test your opinion, Although VOC is 45V, VMP is 37, I feel its better to go for 3 in series. Whats your take?

3 In series puts you at 135V open circuit and 111V during normal operation. The spec sheet of the inverter says max Voc is 145V, and the operating voltage between 60V and 115V. So it feels to me like both Voc and Vmp is a bit close to the upper ends, which might be why the installer went for just two in series, leaving you with a lower 74V and 90V. Probably makes no sense to change it now, just go with it and see how it turns out. It should work just fine.

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9 minutes ago, Wingman said:

WOW - Plonkster, I am so far out of my depth I have no idea what is going on and am 100% willing to do what you guys recommend I should do. I have almost no knowledge of electricity only mechanical ability to install the stuff on my roof.

# 1 63d216c6-e2cc-4fad-869f-07af0822f78f.jpg

Nothing wrong with that, looks good, definitely some skill in that install.

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Thanks Plonkster - I "kieppie" was the installer and did everything single-handed on the instructions of well-meaning guys. My system did not work the way I expected it to work and had my batteries tested. They appear to be OK but were all undercharged ....... that means my Inverter was not correctly set-up. I am now coming "cap in hand" to this forum hoping to find the help I so desperately need.  ;-)  

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8 hours ago, Wingman said:

They appear to be OK but were all undercharged ....... that means my Inverter was not correctly set-up

@Wingman, what settings do you feel were wrong. I haven't seen a bank that needed testing because of undercharging, if for some reason my bank is undercharged, i can immediately tell, that it was because of the weather that specific day, but expect my bank to be fully charged the next day. I am just curious as to what setting can cause a bank to under perform like that.

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Hi Jaco. I was so scared I "cook" the batteries due to overcharging I think I only charged the bank to 52V. I was also scared I "kill" them due to over discharge that at 47V Utilities took over the load. I am going to start by setting Bulk Charge to 58.8V and Float Charge to 54V as advised Thanks again for yours AND Plonkers reply and help. I still hope Chris of Graaf Reinett hears my cry for help and "give me a piece of his mind".  ;-)

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@Wingman, that will make a difference, please keep us updated on the performance. I have learned this the hard way, the only way to know the condition of your batteries is by using a battery monitor. Most guys stick to the Victron BMV 700 or 702. The benefits in installing one  outweighs the price by far. It gives you valuable info about the Discharge/Charge of the banks, and the installation is very easy.  Please Consider buying one, it can really prevent you from damaging your battery bank.


EDIT: I got mine from a forum member @Camel, he had the best prices at that stage, and I think another member @The Terrible Triplett also sells them. To my knowledge, there is no shop that will beat their prices. (When I was in the market for one, no shop came close to their prices)

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