A resident in my neighbourhood (Tokai, Southern Suburbs) posted a plea for assistance with his PV system. The various companies they contacted don't want to help as it's not their install. They just bought a family home & moved in a few months ago. The pre-existing solar system is failing & they are wanting to resolve the issues. While I'm not qualified I decided to pay them a visit & lend them some insight. I've installed a few inverters for my family so I'm not totally useless

Your input is welcomed & I'd like to take our collective feedback to them and offer them a way forward. Please see the attached pictures & video link below.

 

Basic stats & facts:

• Inverters: Mecer SOL-I-AX-5M x2 
• Batteries: Lead Acid, 250Ah, x4
• Solar Panels: 100-120w x 12 

The inverters are wired in parallel. The inverters appear to be from 2015 based on the warranty sticker markings. The batteries are wired in series with no balancers. I'm not sure of the arrangement of the panels but their VoC was around 100v at the time of measurement.

 

Problems:

• The "primary" inverter appears to be damaged. It does not boot but rather loops. Here is a short video of what's happening. Either it's damaged or some sort of self protection is causing the inverter to turn off and on endlessly. You can hear a relay clicking continuously. The secondary inverter runs and powers the connected circuits. All 12 PV panels are connected to the faulty inverter.
• During load shedding the the system used to last about 3 hours on average. Now the system only stays on for 5 minutes. I suspect the PV panels were keeping it going until the primary inverter failed. 
• The voltages across the 4 batteries vary greatly. Some are high for example 14.2v & others are low like 11.5v with the total voltage being 54v "as per normal". 

 

Thoughts:

• Solar Panels: OK
• Storage: Fucked (technically speaking)
• Inverters: 1 of 2 functioning OK
• Switchgear: OK

It would be easy to rip and replace with a 8kW Sunsynk inverter & LiFePO4 batteries but the owner would rather salvage & upgrade if possible.

Inverters:

Is there a reputable business in Cape Town that offers repairs to Mecer/Voltronic inverters? I ask assuming it can be repaired. If not can a new Mecer/RCT/Voltronic inverter be used in parallel with the existing older model? 

Storage:

Clearly battery balancers would have been a good idea but the damage is done now. No doubt the batteries will need to be replaced. The prices of LiFePO4 have dropped a lot since 2015 & in 2021 I can't recommend lead acid. Given the age of the inverter are there LiFePO4 batteries that can work well without CAN bus? Perhaps something from Hubble? 

Thanks for your time if you read this far!

 

 

 

 

 

 

 

 

 

 

@87 DreamThanks for your input. Noted on the inverters & mixing different models. If they are tight on budget couldn't they do the following?

1. Recycle the old batteries & get like R2000 back.
2. Purchase a Hubble AM-2 or equivalent for the remaining inverter.   
3. Connect the PV panels to the remaining inverter 
4. Possibly remove some of the circuits on the inverter load

 

The Axpert’s are not on the CoCT approved list of inverters and not sure In which category of sseg can they be used 

2 hours ago, Tariq said:

The Axpert’s are not on the CoCT approved list of inverters and not sure In which category of sseg can they be used 

Is this not more of a concern for grid tied systems? All those Axpert inverters have got to be going somewhere & I highly doubt they are all off grid installations. 

2 hours ago, 87 Dream said:

It all depends on how the circuits are split to the main DB. 

But yes you could get some salvage cash & purchase an AM2 or equivalent but I would suggest solar assistant or ICC otherwise the lithium SoC will not be well estimated by the remaining inverter.

All in all you probably have the cheapest option or suggestion for them. You just need to find an installer to carry out the works for them.

87

Thanks.

1 minute ago, 87 Dream said:

Hi again WJP, not sure if you have spotted it already or maybe you have not. There is a red & black cable which I assume is the Solar PV input wiring. The black or negative wire is loose & looks to be in close proximity to the battery cabling below. Worth a long crack shot but might be the source of some of the issues. 

Goodluck. Hopefully these guys can get to some electricity production again...

87

Thanks bud, I was trying to troubleshoot the faulty inverter. Part of that process was removing as many variables as possible. At one point I only had the basics connected to power up the unit which is basically DC power & AC in. You are correct that is the PV input wire. I reconnected it after the photo was taken.

Apparently Mustek still have stock of components for these inverters & may be able to repair it. Worst case if the main board needs replacement the cost would be around R7,500.   

Mecer does have a repair center in cape town buy unfortunately they will not do board repairs but replace the full board. This will cost you more than a new inverter. 

there is a company called setsolar that does repair, i have not tried them yet

 

7 hours ago, Krokkedil said:

Mecer does have a repair center in cape town buy unfortunately they will not do board repairs but replace the full board. This will cost you more than a new inverter. 

there is a company called setsolar that does repair, i have not tried them yet

 

Noted thank you. mjlorton (an old SA You Tube channel) used to mention them too. They seem respectable, been around for years.

Hi All

Need some help with an issue. I have a MUST 5kw Hybrid Inverter (this is probably a Voltronic white labelled inverter) and its MPPT range is 64-130V, 9 x 375kw Fivestar solar panels connected with 3 strings (so 3 x 3), and 4 x 200ah Gel batteries. I noticed earlier this year (as i can monitor the system remotely via a wifi card setup) that randomly, the PV voltage spikes to between 125 and 131 volts. When this happens, the charge power from the PV drops to 150w odd and the charger current to 3A. This can happen randomly during the day and can sometimes stay at these levels for up to an hour or so and hence the load is not being fulfilled by the solar even though there is plenty of sunlight. Does anyone know how to resolve this issue? I understand the PV is going to the top of the MPPT range but how do i prevent it from doing this. It seems much worse now ie its happening more often than it was earlier in the year. 

Do i need to reconfigure the setup of my panels to a different combination to reduce the PV voltage etc or what do i do to maximise production without the voltage spiking and effectively killing the charge power? i am not super technical so would appreciate a layman response on this.

You're too close to the voltage limit on the MPPT so rather rewire to 4 strings of 2 each and sell one panel, or sell all your panels and get 9 or 12 60 cell panels (they tend to top out at 310W) and connect them in 3 or 4 strings of 3 panels each.