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Question on panel watts resulting in a blown Victron 350va inverter


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I have a question re. MPPT controllers.

Two panels, specs below, connected in series onto a MPPT controller, assuming all is perfect with sunlight and temp:

Panel details:
Voltage at max. power: 26,7V
Current at max. power: 7,5A
Open circuit voltage: 32,9V
Short circuit current: 8A

This means that, connected, incoming from panels, into the controller:
Volts would be 53.4
Amps would be 8
Total watts could be: 400

Question: 
What should the total watts be that the MPPT charge controller shows incoming from panels - 400w or 200w?

It may sound like a stupid question, but if it is 400, as I think it should be, then I want to send a email to the supplier to ask them to fix their firmware.

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Hi TTT

Let me have a stab at this:

Assumptions as to the maths are correct, or pretty close for that matter.

The 53,4V at the 7,5A will equate to 400,5W .

I am having some difficulty in understanding exactly what is meant by the mppt "show" as incoming.

In IDEAL/UTOPIA you will see 400,5W, and on a good day even more due to the functionality of the mppt.

Best case scenario should then in IDEAL/UTOPIA equate to ~ 441W :)

Due to many factors you would not see 400W in on the mppt except if lady luck really smiles on you.

And having the BEST quality Panels and mppt also helps of coarse.

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Indeed, they frequently exceed 200w per panel, on good days, yet in series, they get as high as 227w on a good day.

Here is the actual data I got from the device that shows me this for the 2 x 200w panels in series.

EDIT: Updated the details.
Direct from the controller: 
   DATE_SAVED: 2016-06-20 11:33 - peak power for a sunny day
   PANEL_WATTS: 227W - Why?
   PANEL_VOLTAGE: 56.23V
I calculate this:
   PANEL_AMPS: 4.0374A for the above two values.                   

The CHARGE_CURRENT I get from controller to the batts is: 15.48A

Now either we are reading the WATT value wrong.
Or the controller is wrong - which I seriously question.
Or the panels has an issue but I have had them tested today, individually, and each one, under load (batts a flat), gave more or less the same values when we checked clouds permitting, so I assume that I have not AGAIN damaged them.
                

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See above: I have updated the details.

They are not 12v nor 24v, supposedly designed for large arrays.

The 227w was on a good day a few days back, which triggered me looking into this to find out why?

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The watts on the PV side should equal the watts on the battery side (minus a little bit for conversion costs). If this isn't actually happening, it is either misreported, or you should feel a lot of heat coming from inside the case... :-)

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27 minutes ago, plonkster said:

The watts on the PV side should equal the watts on the battery side (minus a little bit for conversion costs). If this isn't actually happening, it is either misreported, or you should feel a lot of heat coming from inside the case... :-)

They do, minus a little bit for conversion costs.

DATE_SAVED : 2016-06-20 11:33
PANEL_VOLTAGE : 56.23v
PANEL_AMPS : 4.037a
= PANEL_WATTS : 227w

CHARGE_CURRENT : 15.48a
BATTERY_VOLT : 13.5v
= Battery WATT 208.98w

So where has the rest gone to, for it is wee bit less than 400w?

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4 hours ago, The Terrible Triplett said:

EDIT: Updated the details.
Direct from the controller: 
   DATE_SAVED: 2016-06-20 11:33 - peak power for a sunny day
   PANEL_WATTS: 227W - Why?
   PANEL_VOLTAGE: 56.23V
I calculate this:
   PANEL_AMPS: 4.0374A for the above two values.                   

The CHARGE_CURRENT I get from controller to the batts is: 15.48A

I think what is happening is that the CHARGE_CURRENT is measured after being modified by the MPPT so the voltage is battery voltage. My calculations (Power = Volts * Amps) come out at 14.66V which if you included inefficiencies is as near as damn it to a charged 12V system (I presume it is a 12V system). I made the same mistake  with the Axpert until I realised what was being reported.

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Chris,

7 hours ago, The Terrible Triplett said:

Question: 
What should the total watts be that the MPPT charge controller shows incoming from panels - 400w or 200w?

Would what you say make the 12v system go max 200w? I have never seen the controller, with 11v battery, give me 400w.

I am going to connect 24v batts tomorrow. Then will the watts get to 400?

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11 hours ago, The Terrible Triplett said:

Chris,

Would what you say make the 12v system go max 200w? I have never seen the controller, with 11v battery, give me 400w.

I am going to connect 24v batts tomorrow. Then will the watts get to 400?

It should go to 400W or nearly there but you will only achieve that if the load is big enough and the panel orientation is good so that the is enough incident insolation. At the moment my panels produce about 3/4 of their maximum, so 2 panels should be giving you about 300W. If your batteries are nearly fully charged then we are going to battle to get anywhere near the maximum.

If there is not a 400W load the panels will not produce 400W. PV production is dependant on insolation, efficiencies and demand.

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So theoretically I should see 400w on the controller.

Here is the thing. If I test them one by one, I get about 215w per panel, as per controller.

In series, to date, max I ever got was 237.

Now either I am missing something blatant here OR the controller is wrong and I need to inform the manufacturer.

EDIT: The watts above are seen when the controller is in Bulk mode.

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1 hour ago, The Terrible Triplett said:

So theoretically I should see 400w on the controller.

Here is the thing. If I test them one by one, I get about 215w per panel, as per controller.

In series, to date, max I ever got was 237.

Now either I am missing something blatant here OR the controller is wrong and I need to inform the manufacturer.

EDIT: The watts above are seen when the controller is in Bulk mode.

Hi TTT

Have a look here

 

Screenshot (122).png

Charging is limited to 15A so @ 12 V maximum is 200W and @ 24V 400W. Extra batteries and you will get better production out of your panels.

 

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Chris, you are spot on!!! One HUGE (facepalm) for me.

I read it on my phone and promptly went and made the system 24v. This is a waste of good panels.

All was fine until ...

 

Take a guess what the biggest IDIOT in solar let the smoke out of today!? 

Thick smoke, like mist, all over the place. Took about 3-5 minutes before the "mist" started, which in itself is impressive.

Ja, I fried my 12v Victron 350va inverter on the new 24v system.

Then I remembered: THAT IS WHY IT WAS 12v AND THAT IS WHY MAX PANELS ARE 200W!!!

Pray tell, what a ____ stupid idiot does that to a 12v device? I will tell you, not even the village idiot is that stupid!

Ek is sooo klaar met die sh__t! Who wants to come and take it all before I take a hammer to it all?

 

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3 hours ago, The Terrible Triplett said:

Ek is sooo klaar met die sh__t! Who wants to come and take it all before I take a hammer to it all?

:(:(:(

Keep the panels for me!

Nah you will fix it and find something else to fry ;)

Addition: P.S. What runs off the 350W inverter?

 

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I'd love to do a deconstruct on the inverter once you've said your goodbyes, that is if it cannot be fixed. Chances are it can be fixed, but then the 350s aren't the most expensive ones and there is little room to pay a professional. Costs nothing to ask though.

My sincere condolences for your loss though. I would seriously cry my eyes out if I did that.

Sent from my GT-I9195 using Tapatalk

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Ok, I am over it ... you guys do realize that by now I have blown everything, from the panels right trough to controllers, inverters and even 102ah batteries ... even Eskom - at least up to the DB board.

I REALLY need to step back and get professionals in. It is cheaper, for me, in long term.

Yes going to try the repair thing otherwise you can have it Plonkster.

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8 minutes ago, The Terrible Triplett said:

Yes going to try the repair thing otherwise you can have it Plonkster.

It's not always that bad. The kinds of things that blow are electrolytic caps, switch mode power supplies, and things like that. Those caps can make an almighty bang, in fact in a second I will tell you a story about those. The CPU and control circuitry will often run from 5V or even 3.3V, so there will be a step-down converter in there. These tend to get expensive for high input voltages, so it will be rated just high enough for the intended voltage. If you are lucky, you blow up that SMPS and nothing downstream from it. So your CPU and control circuitry might be okay. Then there will be a boost stage for driving MOSFETs, might have blown something there too. And then there is your MOSFETs driving output stages, might have blown some there too. Do not underestimate the cost of a high-power MOSFET, they are anything from R5 to R100 a piece depending on part number.

So this story I wanted to tell you. I was in a Technical/Academic high school, which means we had a technical subjects alongside our usual academic maths/languages/physics. So in the last two years I sat in the electronics class, where we had this long work bench with electrical sockets. So what we would do, is take an electrolytic cap, then use a pencil to open the shutters on the socket, put in the cap, pull out the pencil. Everyone get out of the way... flip the switch:  *BANG* that thing takes off like a rocket.

Of course, it wasn't long after that when the teacher turned off the breaker to those plugs.

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31 minutes ago, plonkster said:

Of course, it wasn't long after that when the teacher turned off the breaker to those plugs.

Ja, want die onderysers mag moes nie meer pak gee nie. :D

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On 6/25/2016 at 7:25 PM, Chris Hobson said:

Addition: P.S. What runs off the 350W inverter?

I ran the house lights, tablet, Mikrotik and 2 routers phone system etc that falls within the limit of the old battery bank to handle comfortably.

Daytime I would add 1 x 27" and 1 x 24" screens - anything else I want, if there was spare power.

Now I connected them back onto the main system, the MPPT and Morningstar PWN must just argue it out. Float, absorption and all that is set the same.

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9 minutes ago, The Terrible Triplett said:

Ja, want die onderysers mag moes nie meer pak gee nie. :D

Nee wat ek is nog goed ge-moer op hoërskool.

But this guy, a certain Mr. Basie Cloette, I don't think he was a trained teacher, but he was probably one of the best I had, and so laid back. I barely had a learners license, asked him one day if I can borrow his bakkie to pick up some tables we used for a school function... and he agreed. Few weeks later, we had to go pick up a buddy's license (and in Windhoek the offices closed at 12PM), so again we borrowed his old Audi 100 (in school hours!) and off we went. I tell you, we got away with murder sometimes, but there was a special understanding between us "Koshuis kinders" and the teachers... :-)

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