Solar Conundrum

[Jimbohorlicks]

Viewing the readings on my solar set up has created a few questions which I cannot fathom out.
I have 2 solar set ups
2 x100w monocrystaline panels in series .appear to be ok( had these for a few years)
this morning i get.

102w 6.9amps. It's a Non lithium mppt controller gel setting.( Reading do fluctuate unlike the victron that are more stable)
From the 2 x195w bifacial panels in series I get the below. controller is a victron 100/30 .10am this morning

Yesterday I disconnected the panels and checked each one independently. Some sunshine but on the dull side.cloudy.
Panel1

Panel2

In series

In parallel

All above were recorded within 30 mins of changing connections around.
Basically I appear to be getting more output from the 2x100w that the 2 x195w. When they are combined either in series or parallel( the latter being worse)
Any ideas?
Ps The batteries charged by the 2 x195 panels were around 97% soc ( 3 x100w lithium) .

 

[LostInSpace]

My only experience with dealer fitted solar panels is that they used the opportunity of fitting two panels at once to get rid of a dud panel.

It took me years before getting around to test and work out that one panel was much worse than the other.

 

[Jimbohorlicks]

All have been fitted by me and each panel checked before fitting. The photos show that each panel is ok on an independent basis. its when they are connected together is the issue.

 

[LostInSpace]

Sorry, I can not help with series or parallel connections. My panels have a controller each.

 

[fishplug]

How did you do the independent panel testing?

i.e. did you disconnect any of the cabling at the MPPT terminal or bypass any length of cable that might be the culprit?

Stupid question but.... are the panels clean?

When testing independently were any of the panels removed from the roof or possibly tilted into the sun (makes a bigger difference than you might think)

Is there anything that might be casting a shadow over one or more of the panels.

Quite a few variables that I can imagine.

Just thinking out loud...

^{_{Subscribers  do not see these advertisements}}

 

[mikash]

Your battery is practically full so it's possible the watts tell more about what your battery (+ any coincidental loads) can draw instead of what the panels could provide?

I'd test the panels <80% SoC or add more load and see if that makes a difference.

 

[Pugsy]

Deleted post,re read first post again.

 

[Jimbohorlicks]

How did you do the independent panel testing?

i.e. did you disconnect any of the cabling at the MPPT terminal or bypass any length of cable that might be the culprit?

Stupid question but.... are the panels clean?

When testing independently were any of the panels removed from the roof or possibly tilted into the sun (makes a bigger difference than you might think)

Is there anything that might be casting a shadow over one or more of the panels.

Quite a few variables that I can imagine.

Just thinking out loud...

Thanks.
Panels cleaned prior to test.and readings.
There are 2 panels and one with the most connections under was unscrewed and tilted to gain access. Propped up with a short length of wood.
Victron controller charger disabled on the app and all connections undone.
First panel connected to common cables to the controller and laid back in place.
Readings taken.
Charger disabled .connections undone and second panel connected.this panel has longer leads attached with mp4s.connected to sane common leads and readings taken.
Both panels showed similar readings 57w 18 to 19v and inputting approx 4 amps to battery independently.
Connecting in series using same cables with no additional cables shows doubling off volts but half of amps rather than the same amps.output to the batteries 4 amps same as the independant panels.
In parallel using Y connectors and existing cables shows a similar reduction in amps tatger than doubling but a further reduction in amps to the battery due to the lower volts( parallel connection and low produced solar amps..panels were laid back flat to their original positions..
Meanwhile the 2 x100w panels were disconnected to prevent them recharging the battery too quickly.
Hope that expains

 

[Jimbohorlicks]

Your battery is practically full so it's possible the watts tell more about what your battery (+ any coincidental loads) can draw instead of what the panels could provide?

I'd test the panels <80% SoC or add more load and see if that makes a difference.

I will try this . I reduced the battery to 97% soc for the test . The older 2x100wpanels were producing better than the 2 x195 panels
This is the layout

1 x195w on each side and the 2 x100w down the middle.

 

[Jimbohorlicks]

Sorry, I can not help with series or parallel connections. My panels have a controller each.

That may be my final solution.

^{_{Subscribers  do not see these advertisements}}

 

[gus-lopez]

Connecting in series using same cables with no additional cables shows doubling off volts but half of amps rather than the same amps.

That is correct .
In series all the voltages (Voc) are added together & the current (Imp) is the amount for only one panel.
whereas in Parallel the current of each panel (Imp) are added together & the voltage (Voc) stay the same equal to one panel

*I removed 2 x 100w panels that were in parallel & changed to the same as you, 2 x ecoworthy bia facial 195w panels, but wired in series .
I also notice what you are saying as well but the 280Ah battery has not had any load on it so far & is fully charged .

 

[BouncyBoatFolk]

My only experience with dealer fitted solar panels is that they used the opportunity of fitting two panels at once to get rid of a dud panel.

It took me years before getting around to test and work out that one panel was much worse than the other.

The scallywags, do they have a name?
Mike.

 

[Jimbohorlicks]

That is correct .
In series all the voltages (Voc) are added together & the current (Imp) is the amount for only one panel.
whereas in Parallel the current of each panel (Imp) are added together & the voltage (Voc) stay the same equal to one panel

*I removed 2 x 100w panels that were in parallel & changed to the same as you, 2 x ecoworthy bia facial 195w panels, but wired in series .
I also notice what you are saying as well but the 280Ah battery has not had any load on it so far & is fully charged .

Yes I also tried the 2 panels in parallel initially and found that using the victron controller requires a 5v difference between the battery and solar voltage. I found that the charger was not kicking in until mid morning until the solar voltage was over 18v. Changing to series prevented that.

 

[Raul]

I will try this . I reduced the battery to 97% soc for the test

Don't get hung up on percentage to much, the 97% can be real or skewed.
The important bit is to bring the batteries down to a voltage below your set float. If float set at 13.5v, regardless of SOC, you need to bring the battery well below this 13.5v, for the solar to go in bulk and ask all it can give from the panels.

Your test at 14.3v absorb it shows the controller is limiting as its finishing charging in CV constant voltage, hence the figures are almost the same.

During test, also it helps if you put a large load on the battery to cause voltage drop, ideally an inverter with some 1000w plus load.

 

[Jimbohorlicks]

Thanks
My float is set at 13.5v and absorption at 14.35v.
I will put one of my wife's hairdryers to bring the battery down to below 13.5v

^{_{Subscribers  do not see these advertisements}}

 

[Jimbohorlicks]

I lowered the voltage with a hair dryer on but the 2 x100 panels appear to be producing better watts and amps than the 2 x195 bifacial panels
2 x100 with 146w and 10.4a

2 x195 w panels producing 93w and 6.4a.

I would have expected more than circa x2 that of the 2 x100 panels. Both are fed to a300ah battery bank the 2x100 directly and the 2 x195w via the leisure wireing that goes into the control box.
I have tried switching controllers but it doesn't make any difference

 

[Ian_H]

I lowered the voltage with a hair dryer on but the 2 x100 panels appear to be producing better watts and amps than the 2 x195 bifacial panels
2 x100 with 146w and 10.4a
View attachment 1052997
2 x195 w panels producing 93w and 6.4a.
View attachment 1052998
I would have expected more than circa x2 that of the 2 x100 panels. Both are fed to a300ah battery bank the 2x100 directly and the 2 x195w via the leisure wireing that goes into the control box.
I have tried switching controllers but it doesn't make any difference

In pic above the victron is in absorption again so limiting current flow. Drop the batteries soc well down before testing

 

[Raul]

The top black controller was pushing all the power because the battery voltage was 13.1v while the victron was at 14.3v, full and limiting.

 

[Jimbohorlicks]

Thanks
Will reduce the soc tomorrow and have another check.