Series circuit and adding an extra portable panel.

iana · Guru

Series circuit and adding an extra portable panel.

kgarnett · Senior Member

This link may be of some help.

https://www.alternative-energy-tutorials.com/solar-power/parallel-connected-solar-panels.html

Ken

-- Edited by kgarnett on Tuesday 2nd of November 2021 01:47:20 PM

iana · Guru

Thanks Ken, that page deals with parallel circuits, but that site also has the same article relating to series circuits, which I shall read, and my questions will most likely be addressed.

Whenarewethere · Guru

Almost at the bottom of this page is how a small shadow brings down a series set on my setup (2S3P).

https://thegreynomads.activeboard.com/t65231112/custom-6x20-watts-solar-setup-with-mppt/?sort=oldestFirst&page=3

peatop · Senior Member

In series the Amps is what governs you so as long as it is a higher wattage it's fine, the amps will be limited by panel with the lowest amp rating, but in parallel it's the voltage to watch so to connect 3 at 145w and 1 at 160w in series this is fine as the voltage is added. In parallel the amps are added but limited to the panel with the lower volts.

One thing to check before adding more panels in series is that the controller can handle the voltage.

This guy has 145w panels https://sbpe.com.au/collections/solar-panels-rigid-solar-panels I bought 2 a few weeks ago and they tested up to spec no problems if you scroll down the page a bit they have ones that were restocked for $79 these are what I bought wink

iana · Guru

OK I have read and digested the tutorial on "Series Connected Panels", and that the system power is reduced in efficiency by the lowest wattage panel. My question now is, in the circuit, mine for instance 3 x 145 panels, if one (or two ) is partially shaded, will that panel now produce less amperage, and therefore lower the efficiency of the whole system?
In other words for a series system there must be no shaded panels.

Whenarewethere · Guru

No if they are in parallel.

Yes if they are in series.

I have 2 panels in series, then 3 or those sets in parallel.

If there is a small shadow over 1 series set, that series set produces nothing.

But I have 2 more series sets, & if the other 2 do not have any shadow then my whole setup is running at 2/3 capacity.

If you are using 3 panels I would put them in parallel. If 1 panel has a shadow you are only down by 1/3.

If you have them in series & you get a tiny shadow the entire system produces nothing.

Because I have 6 panels I could do a combination of 2S3P & get a bit of both worlds. I could have done 6P or 3S2P.

If one has 4 panels you could do 2S2P.

3 panels it is 3S or 3P.

Mike Harding · Guru

iana wrote:
>My question now is, in the circuit, mine for instance 3 x 145 panels, if one (or two ) is partially shaded, will that panel now produce less amperage, and therefore lower the efficiency of the whole system?
If you are describing 3 x 145W in series... then yes.

>In other words for a series system there must be no shaded panels.
Ideally, yes. The "string" of panels will still work but will be restricted to the efficiency of the most shaded panel.

iana · Guru

Sooooo if the system was a series / parallel system, this would help alleviate the problem?

Jaahn · Guru

Mike Harding wrote:
iana wrote:
>My question now is, in the circuit, mine for instance 3 x 145 panels, if one (or two ) is partially shaded, will that panel now produce less amperage, and therefore lower the efficiency of the whole system?
If you are describing 3 x 145W in series... then yes.

>In other words for a series system there must be no shaded panels.
Ideally, yes. The "string" of panels will still work but will be restricted to the efficiency of the most shaded panel.

Hi iana smile

Haven't we been here before ?? confuse

It you have panels in series then you do need bypass diodes to bypass shaded panels. Obviously if you have 2 out of three shaded then you get 1 panel output but it still works.

Jaahn

Whenarewethere · Guru

If you look at the thread (noted further up this thread) on my setup. Down the page is this information with more photos.

iana · Guru

Initially the system was three panels in parallel, but on the advice of a solar installer, and having obtained an MPPT regulator, the system was changed to series. In the parallel configuration, all the panels had by-pass diodes. When I converted it to series, and at that stage we were in a caravan park, I got confused over bypass diodes, and so I left some out of the system. Overall it seems to be working OK, so regarding panels not working in shade that confuses me as mine do work.
Obviously a parallel system is much less complicated if thinking about plugging in a portable panel, which is what my initial question really was. So Jaahn, yes I have many moons ago chatted about this, only to come away confused. Tony supplied me with the bypass diodes, thankyou.

Whenarewethere · Guru

With bypass diodes you will be ok.

The advantage of series setup is getting the earlier morning sun or some charge when it is overcast.

Jaahn · Guru

Hi Iana smile

Here it is again in a simple diagram about half way down the page. jaahn

https://www.electronics-tutorials.ws/diode/bypass-diodes.html

-- Edited by Jaahn on Wednesday 10th of November 2021 06:10:25 PM

-- Edited by Jaahn on Wednesday 10th of November 2021 06:13:10 PM

yobarr · Guru

Jaahn wrote:
Hi Iana
Here it is again in a simple diagram about half way down the page. jaahn
https://www.electronics-tutorials.ws/diode/bypass-diodes.html

What about optimisers? Cheers

Jaahn · Guru

yobarr wrote:
Jaahn wrote:
Hi Iana
Here it is again in a simple diagram about half way down the page. jaahn
https://www.electronics-tutorials.ws/diode/bypass-diodes.html
What about optimisers? Cheers

Hi Yobarr smile

Good question but what are they ?? hmm

Jaahn

yobarr · Guru

Jaahn wrote:
yobarr wrote:
Jaahn wrote:
Hi Iana
Here it is again in a simple diagram about half way down the page. jaahn
https://www.electronics-tutorials.ws/diode/bypass-diodes.html
What about optimisers? Cheers
Hi Yobarr
Good question but what are they ??
Jaahn

Hi John.It's a long and complicated explanation,but if you simply Google "Solar panel optimisers" all will be revealed.All panels in a string of solar panels will only work at the same rate as the worst performing panel,but optimisers remedy that.Brief explanation.Cheers

iana · Guru

If diodes are so important when a shadow is over a string of cells, why is it that the panel suppliers are reluctant to say how many diodes are used, and why are two normally used instead of say 4 or more ?

Jaahn · Guru

iana wrote:
If diodes are so important when a shadow is over a string of cells, why is it that the panel suppliers are reluctant to say how many diodes are used, and why are two normally used instead of say 4 or more ?

I have a couple of old 87w Kyocera panels that were on lights in a caravan park for a long time. They have 3x 3 diodes in the junction box from new. I am not sure why so many.

Jaahn

Jaahn · Guru

yobarr wrote:
Jaahn wrote:
yobarr wrote:
Jaahn wrote:

Hi Yobarr Good question but what are they ?? Jaahn
Hi John.It's a long and complicated explanation,but if you simply Google "Solar panel optimisers" all will be revealed.All panels in a string of solar panels will only work at the same rate as the worst performing panel,but optimisers remedy that.Brief explanation.Cheers

Yobarr I did google them. I will look further but It seems to me two things !

1 they are mostly aimed at ac grid connect systems. Even id dc types. Not sure how that fits with mobile use.

2 If they give a small % improvement, even say 20% then at the high initial extra cost, you would generally be better off just buying another panel or two. That may not suit some applications.

Jaahn

Some sites !

https://www.solarquotes.com.au/blog/solar-panel-optimisation/

https://www.mcelectrical.com.au/test-maxim-optimised-panels-vs-solaredge/

yobarr · Guru

Jaahn wrote:
yobarr wrote:
Jaahn wrote:
yobarr wrote:
Jaahn wrote:
Hi Yobarr Good question but what are they ?? Jaahn
Hi John.It's a long and complicated explanation,but if you simply Google "Solar panel optimisers" all will be revealed.All panels in a string of solar panels will only work at the same rate as the worst performing panel,but optimisers remedy that.Brief explanation.Cheers
Yobarr I did google them. I will look further but It seems to me two things !
1 they are mostly aimed at ac grid connect systems. Even id dc types. Not sure how that fits with mobile use.
2 If they give a small % improvement, even say 20% then at the high initial extra cost, you would generally be better off just buying another panel or two. That may not suit some applications.
Jaahn
Some sites !
https://www.solarquotes.com.au/blog/solar-panel-optimisation/
https://www.mcelectrical.com.au/test-maxim-optimised-panels-vs-solaredge/

You've done well John! As you have discovered,they are particularly useful in AC grid connect situations,but your suggested solution of " buying another panel or two" is not often possible in a real life AC situation because all such connections have input restrictions.For example,the biggest system you can have on a "normal" single phase house is 6.6kw through a 5kw inverter,so if you're already at your maximum panel capacity,adding more panels is not an option.There are ways around this,but I will not "rock the boat" by saying more.Suffice to say,optimisers are a life-saver for many tricky installs,and more than compensate for added expenditure at install.Cheers