Cloud Edge Effect and MPPT Solar Charge Regulator

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Cloud Edge Effect and MPPT Solar Charge Regulator

Postby grell72 » Tue Sep 01, 2015 6:26 am

Hi Gurus!

I am experiencing an issue with my stand alone 12v power system that I am hoping someone will have knowledge about. I have a setup with the following components:

1. 2 x 280AH AGM Batteries connected in parallel.
2. 3 x 200w Kyocera Panels
3. 1 x Tracer 30 MPPT Charging Regulator
4. 1 x 1500w pure sine wave inverter

I live in Tassie so cool sunny/cloudy days are fairly common. So the problem I have is that when the sun comes out from behind the clouds on certain cool days my inverter will power itself off then on again very quickly (a second or less). This is obviously caused by the cloud edge effect (I assume). My theory is that the Tracer charging regulator cannot compensate quickly enough and hence the voltage going to the battery exceeds its rated input of 15.5v.

So how do I stop this from happening? I have a horrible feeling I need to look for an MPPT charging regulator that handles this cloud edge effect better. If so what model or type would be best? I know I could just put a 240v standard 2000VA UPS onto the inverter thus handling any brief outages but I would rather fix the problem properly especially since I don't know if this brief over-voltage could damage my batteries.

Thanks in advance!
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Re: Cloud Edge Effect and MPPT Solr Charge Regulator

Postby Gordon-Loomberah » Tue Sep 01, 2015 6:58 am

Welcome to the Energy Matters Forums Grell72 :)

15.5V seems a very low high voltage limit for a 12V inverter, what sort is it? Have you measured the battery voltage during cloud edge effect periods to see how high the voltage goes?
If it is related to high voltage excursions, then it should really only occur during the absorb stage of charging, as the battery voltage will be lower during float, and all but for the very end of bulk charging.
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Re: Cloud Edge Effect and MPPT Solr Charge Regulator

Postby Bthree » Tue Sep 01, 2015 9:21 am

How are the three panels connected, in series or parallel ?
are they 12 or 24 volt? Some panel specs please

If in parallel you may be exceeding the max current in,
if in series you may be exceeding the max. Input volts.
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Re: Cloud Edge Effect and MPPT Solr Charge Regulator

Postby grell72 » Tue Sep 01, 2015 9:56 am

Hi,

Thanks for your responses:

The panels are 24V 200W Kyocera and are connected in series.

The inverter is a GiantPower 1500w pure sine wave inverter (blue).

When I have witnessed the issues with the inverter briefly shutting itself off then on again the batteries have been sitting at around 14.3/14.4 Volts

Under normal circumstances (nice sunny day) everything functions just fine. The only issue I have is when the sun pops out from behind the clouds thus I assume it has something to do with the cloud edge effect.

Cheers
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Re: Cloud Edge Effect and MPPT Solr Charge Regulator

Postby grell72 » Sat Sep 05, 2015 5:34 am

Just an update on this...

After much hair pulling and countless hours on the internet researching my results are still inconclusive. It is a problem and its complicated in its nature.

Most affordable pure sine wave inverters (12v to 240v) have a safety cut off at around 15.5v. I have seen some as high as 17v which would work but add another "0" to the cost.

I am looking at a Midnite Solar Classic 150 as an affordable replacement charging regulator. The company that sells them is testing it to make sure it handles the cloud edge voltage jump. They are confident it does but will see soon.

Adding more batteries and more load might help reduce the likelihood as excess voltage can get absorbed more readily so it seems. I was planning on doing this anyway. Bottom line is there is no easy fix and cost is definitely a factor. Top end gear will probably handle this.
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Re: Cloud Edge Effect and MPPT Solr Charge Regulator

Postby Bthree » Sat Sep 05, 2015 9:37 am

If I have the correct model charge controller 3215N the Max. PV input power 12V/ 390W which is two panels.

That could be a problem you are overdriving the controller.. max 390w = 2 panels, you have 3 = 600w

Take out a panel or get another charge controller
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Re: Cloud Edge Effect and MPPT Solr Charge Regulator

Postby Gordon-Loomberah » Sat Sep 05, 2015 9:42 am

Yes, if you have them all facing in 1 direction, remove a panel, or face them in different directions as in the Virtual Tracker thread.
Alternatively, we have the ET6415Ns on clearance ATM.
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Re: Cloud Edge Effect and MPPT Solr Charge Regulator

Postby grell72 » Sat Sep 05, 2015 10:11 am

Yeah ok...

That is a possibility although I haven't seen errors come up on the inverter. I have decided to change to a Solar Midnite Classic 150 in any event as its time to go to the next level. Hopefully this will resolve the issue.

Thanks for your thoughts!
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Re: Cloud Edge Effect and MPPT Solar Charge Regulator

Postby Gordon-Loomberah » Sat Sep 05, 2015 1:41 pm

grell72 wrote:That is a possibility although I haven't seen errors come up on the inverter.


Doesn't it display an over voltage error when it cuts out, LED indicators perhaps?
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Re: Cloud Edge Effect and MPPT Solar Charge Regulator

Postby grell72 » Sun Sep 06, 2015 7:42 am

No there are no error LEDs on the Tracer charging regulator appearing.

All that happens is a very brief voltage spike to the batteries that causes my 240v inverter to shut off on over voltage protection for around a second. This is why I believe the Tracer charging regulator is not compensating fast enough when certain conditions occur being batteries near full charge and cloud edge effect.

Either its a design flaw or like so many things its built to a price and just can't handle this type of event. Its all pretty much assumptions based on visually witnessing this cause and effect. The only way to know for sure is to sit with voltmeter on the battery terminals and record what happens.
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