Hi.

I have a 5kva inverter connected to 12x 260w  PV panels as below and it even shows this as a suggested configuration in the manual.

I've been monitoring it today and it seems like the solar output is much better when the PV voltage is below 100 volts for some reason.

 

The inverter is supposed to handle up to 145v but performance seems to be better at the lower voltages.

I'm now considering changing the PV connections to 2s x 6P to lower the voltage but I'm not sure if this is the best approach or if something else may be worth checking.

Any suggestions welcome.

Thanks

 

There could be a chicken and egg situation here. When you draw significant PV current, the panel voltage falls. So the low panel voltage when production is good might be a result rather than a cause.

The PV power should not start ramping down till 130 V; I see that they are calling the upper end of the MPPT range 130 V now, till recently it was 115 V.

There is considerable work and cost reconfiguring from 3S to 2S. Especially if your panels are 60 cell (or 120 half-cell), I would leave them as 3S and try to find why the solar charge controller doesn't want to use PV power.

What is setting 26, bulk/absorb charge voltage? If it's 53.2 V for Pylontechs, then the reason for the low production is that your battery is full and you had low loads.

Edited January 22, 20206 yr by Coulomb

You must be psychic Coulomb.  The bulk charge is set to 52.3v and it is connected to 2x Pylontech batteries 😀.

I'll keep an eye on it today when it is under more load to check that the PV is keeping up with the demand.  I don't want to be using the batteries during the day.

Thanks for the reply.

 

You must be psychic Coulomb.  The bulk charge is set to 53.2v and it is connected to 2x Pylontech batteries 😀.

I'll keep an eye on it today when it is under more load to check that the PV is keeping up with the demand.  I don't want to be using the batteries during the day.

Thanks for the reply.

 

Good evening,

 

I have 16 panels with 8 strings of 2.

I want to know what PV volts is the most effective for the Mecer 5KV?

Should it be close to the max , meaning using 3 in a string, giving me 96v.

I would appreciate some advice.

Thanks.

Ernie

4 hours ago, Ernie Green said:

I want to know what PV volts is the most effective for the Mecer 5KV?

I assume you mean the 5 kVA, with 145 V max PV voltage.

Best is 2S for the common 72 cell panels (or 144 half-cells), or 3S for the 60 cell panels (or 120 half-cells).

Thanks Coulomb for the feedback, 

Yes it is a 5KVA 145v inverter

Now I can stop stressing as my panels is set in a S2 configuration.

 

I have  3 X 5kVA inverters in parallel to serve my day time  loads that can reach 8kW.

During night time the average load is approx. 1kW never exceeding 2 kW.

I was wondering if it makes any sense to "sleep" 1 or 2 inverters during this time to save some power?

Perhaps a light sensitive day/night switch with relay dry contacts (in parallel  or in series as required) with  the inverter ON/OFF switch  for automatic control?

I've done some tests manually switching them off and back on again and there seem to be no issues.

1 hour ago, Trober said:

I was wondering if it makes any sense to "sleep" 1 or 2 inverters during this time to save some power?

It probably does, what is the quiescent current draw of a unit?

6 hours ago, Trober said:

makes any sense to "sleep" 1 or 2 inverters

Yes, it does. Each inverter draws an idle power of about 50 W. Relay contacts in series with the rocker switch sounds doable. If the inverter has a round press to start and also press to stop, then no, unless you can be sure what state it is in.

Patched firmware with Dynamic Load Control could do this with zero extra hardware, beyond a monitoring computer that you can modify the source code for. There are modified commands you can send the inverters to turn one on or off.

3 hours ago, Coulomb said:

 

Patched firmware with Dynamic Load Control could do this with zero extra hardware, beyond a monitoring computer that you can modify the source code for. There are modified commands you can send the inverters to turn one on or off.

This would be great! Currently I have versions 72.70C and 04.12.

Could I update? If so, to which version? Where to be found?

Is there a document describing the modified commands?

23 minutes ago, Trober said:

This would be great! Currently I have versions 72.70C and 04.12.

Could I update?

Yes, you would need to go up to 73.00e. Found here.

23 minutes ago, Trober said:

Is there a document describing the modified commands?

Yes, the linked post has a text file describing the modified commands.