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Paul


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Solar system, any recommendations for a Solar PV Adviser in the Durban North area, not Grid Freedom please, I have 21x 270watt pv panels and 2x5kw mecer inverters mks2 charging 12x150ah lead acid batteries, 5 batteries have popped.

Any advise please! 

 

 

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Hi, I have a similar setup with the 2 Axperts in parallel however I use two Lithium batteries with their own BMS.

My opinion is that these Mecer inverters do not do a great job of charging, if left to it's own devices.

If you are going to stick to Flooded (or agm) batteries then you will have to install a 'battery balancer' to balance the 12V units amongst themselves. The inverter do not have any intelligence to do this. I am sure I have seen units for sale in the PowerStore (?). 

Otherwise move to Life batteries with their own BMS, but this may be expensive.- there is great advice on this Forum for the voltage settings.

PS: I presume the Inverters are in parallel with the kit, setting 28 = pal and that the battery DC (48V) is bridged to each inverter. Important also to keep the electric (wiring) distance as equal as possible between the batteries and Inverters.

Let us know, good luck!

Kind Regards

Jaco P

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The Pylontechs are very good but you pay for them

Lithium batteries SA sells a 6kw battery for around R27k, I have one on my mecer inverter and it works Beautiful.

He has a new smart battery as well. 

I also hat AGM's and it lasted about 2 years. 

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I agree, the Pylontech batteries seem to do well, you can search for the best price. We've bought a set from Ellies, so you can ask a qoute from your local outlet, also check out Bonanza Technologies (excellent advice and support from the owner). My own set does not exist in the market so it won't help. 

If possible go big from the start - because the battery DC is all connected and bridged, you cannot expand easily if you wait too long. Either 3 x 3.5kWh or 4 x 2.8kWh units if possible. The single big 6 kWh @Krokkedil mentioned can also work depending on your load after sunset.. I was advised 10kWh at the time which works great in summer. For rainy days and those long winter nights it does however still switch back to Utility. Your PV will be sufficient to charge the batteries.

Keep well!

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4 minutes ago, Jaco P Bloem said:

I agree, the Pylontech batteries seem to do well, you can search for the best price. We've bought a set from Ellies, so you can ask a qoute from your local outlet, also check out Bonanza Technologies (excellent advice and support from the owner). My own set does not exist in the market so it won't help. 

If possible go big from the start - because the battery DC is all connected and bridged, you cannot expand easily if you wait too long. Either 3 x 3.5kWh or 4 x 2.8kWh units if possible. The single big 6 kWh @Krokkedil mentioned can also work depending on your load after sunset.. I was advised 10kWh at the time which works great in summer. For rainy days and those long winter nights it does however still switch back to Utility. Your PV will be sufficient to charge the batteries.

Keep well!

Is this from experience or it has been documented somewhere? I'm under the impression that you can expand any time you want and that you do not have to start big.

 

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..on most parts (i.e PV or even Inverter) you can expand at any time I agree. However you cannot add a new battery pack to an old unit or pairs. The cells did not age together so if you add new cells to old ones you have different charge (voltage) levels which will ultimately decrease battery life.

In this case (parallel Axperts) the Battery bank is common to both the Inverters, and so you cannot expand the existing bank say after 1 year without replacing all. It is somewhat logical and is applicable to flooded / agm batteries also.

I have found this post interesting :

 

Greetings!

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17 minutes ago, Jaco P Bloem said:

..on most parts (i.e PV or even Inverter) you can expand at any time I agree. However you cannot add a new battery pack to an old unit or pairs. The cells did not age together so if you add new cells to old ones you have different charge (voltage) levels which will ultimately decrease battery life.

In this case (parallel Axperts) the Battery bank is common to both the Inverters, and so you cannot expand the existing bank say after 1 year without replacing all. It is somewhat logical and is applicable to flooded / agm batteries also.

I have found this post interesting :

 

Greetings!

Pylontech batteries can be expanded on at different times. Only requirement is that the new battery becomes the master. You can even do different sizes with the pylontech batteries with the bigger capacity as the master. 

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This is actually great news especially for Pylontech (and I suppose similar products) owners. So the BMS will treat and charge the new pack differently than the old. I wonder if the supplier still honor the full warranty in such a case - although I understand the warranty is in any case less when used with an Axpert as the Inverter cannot communicate with the BMS (except through 3rd party software like ICC). 

Important : @It's On if you start too small, I.e. with one Pylontech (3.5kWh) only, there is an issue here to consider.. and this is from actual experience at a friend's installation :

When the load exceeds the amp capacity of the single battery pack (70 amp in this case) the BMS will protect the battery and shut off. This in turn causes the Axpert to trip (when in SBU mode) as the DC disappears. This is with zero PV generation and you need just over 3.5 kW of load (oven + microwave) for this to happen.

The battery BMS is too quick for the Axpert, we have tried different settings but before the inverter can make a decision on the Voltages, the BMS acts.  We have moved this battery to a Sunsynk inverter with communication to the BMS - different story! The Inverter blends the usable battery DC with available solar and grid power without overloading the single battery.

So for now with the Axpert, rather spec the battery packs large enough from the start, at least to carry your typical peak load 😅.

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10 minutes ago, Jaco P Bloem said:

When the load exceeds the amp capacity of the single battery pack (70 amp in this case) the BMS will protect the battery and shut off. This in turn causes the Axpert to trip

I heard that the Axpert can blow when the battery is switched off while it is drawing a big load, if this is true when the pylontech protects itself by shutting off it might blow the Axpert.

I have a Axpert and is very wary of this, a freind of mine have blown two Axperts and we think it might be due to his battery circuit breaker that tripped. (This was with gel batteries though)

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