Help checking 300w solar system charge figures. (1 Viewer)

[Plinky]

Hi.
I've just finished the install of a 300w system using 3x100w semi flex panels and Bluesolar mppt controller going into 2 x 85ah gel leisure batteries. I'm just experimenting with it, and have it currently wired in series. My van is parked next to the house and there are trees around, so there is some shading, but do these readings seem ok for a fairly bright winters day, i just want to make sure nothing obvious is amiss. Thanks

 

[Techno]

What is the spec of the regulator? three panels in series will be around 66 volts (open circuit). Is your regulator capable of converting that for a 12 volt system.

My 300 under clear sky at this time of year about this time of day can produce 9 amps plus

I would drive it clear of the shading and compare

 

[Plinky]

Hi Andy, yes i thought mine seemed low. Here is the spec of the mppt.

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[Techno]

Yes its built for it. As I say I would move it out of shading but to be honest parallel connection will handle shading much better

 

[Plinky]

I'll move it somewhere more open, and try both series and parallel to see how it compares. Thanks

 

[tonka]

Seems a lot of panels for such a small amount of battery storage.. !!
Ok it will charge the batteries quicker a bit like a fast tap but you only have a small bucket.. If you see what I mean..

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[Techno]

This was 15th February 2013 according to photo EXIF

 

[Plinky]

Yes, those are the kind of figures i was hoping for, but i'm only getting 25w input from the panels. I'll move it now and see if it improves

 

[Plinky]

Ok, I just took it to a more open place....still not the best readings, but more than they were and not a particularly bright day. I'll check again tomorrow and try parallel v series. I do have the mppt to battery leads connected 'minus to one battery and positive to the other' , but i'm assuming thats ok since the batteries are in parallel.

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[Techno]

Yes sky needs to be blue or you'll only get about 3 amps

 

[tonyidle]

Check your panels for correct connection - just in case you have one in opposition - and check that, as you are using them in series, they are fitted with bypass diodes.

 

[funflair]

Run something to deplete your batteries a bit, if they are fully charged the system won't put in the maximum power from the panels.

Martin

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[Techno]

Picture shows it in bulk charge mode Martin so I believe it was doing its best at the time.

 

[funflair]

Picture shows it in bulk charge mode Martin so I believe it was doing its best at the time.

Of course, I looked at the voltage and thought that's a bit low for float!

What's the 9% efficiency in the controller spec.

Martin

 

[DBK]

You can't really tell if there is shading, especially, as is likely the panels don't have bypass diodes to reduce the effect. They may have blocking diodes, which you may be able to see by the terminals but they are a different thing. As little as 5% shading might reduce output by 50%.

I recently fitted a second panel and when I first tried it the output voltage from both panels was 36 volts but one was producing 22V but the other was just 14V. This was bbecause there was a bit of shading from the stowed satellite dish, when I swung this out of the way the output from the shaded panel shot up to 22V - there was very little load at the time. If you can still get at the wiring check the voltage from each panel.

I guess you have a Victron controller, if you read the instructions it will recommend series connection. It is better with low light levels. You must have them wired correctly as you are getting close to 54 volts but I suspect the shading is reducing the current. In theory 54 volts is correct for maximum power from three panels (3 * 18) but you are not getting enough current for maximum power.

The efficiency figure is wrong, a typo, it probably should read 98%, have a look at the specs of some of their other controllers.

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[Plinky]

Thanks for all your thoughts. I'll get into it tomorow, find an open area and start experimenting with wiring etc. I'll also check each individual panel to make sure one is'nt letting down the other two. I'll report back. Thanks

 

[Techno]

Today should be perfect for readings

I have clear blue sky and low sun
At 10:50 with kettle on

 

[Plinky]

Hi Andy, its complete cloud cover here near Bury St. Edmunds in Suffolk......a completely white sky. I'm still waiting for a clear blue day.
Hopefully tomorrow, I'll post readings as soon as the weather improves.

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[Jimbohorlicks]

Hi Andy
I assume to show that wattage and amp reading you would require to deplete the batteries a little -hence the reference to the "kettle" being on and showing 12.5 v
We have blue skies here also and bright sunshine albeit low , my batteries are fully charged and only showing max 3.5 amps from 2 x 100 watt panels , but also on hook up

 

[walburga]

Today should be perfect for readings

I have clear blue sky and low sun
At 10:50 with kettle on
View attachment 96203

Hi Andy
Is that mains kettle, through an inverter, hence 10 amps charging current ?

 

[Techno]

yes

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