Series circuit and adding an extra portable panel.
iana said
01:18 PM Nov 2, 2021
The system on our van is 3 x 145w solar panels coupled into a GSL mppt 60 amp regulator. I have wired the system up so that there is a removable jumper connection, made up of Anderson plugs. The reason I did this is two fold, one to easily disconnect the solar panels before working on the batteries, and to enable a portable panel to be connected into the series circuit when required.
I am of the understanding that all panels in the circuit should be the same wattage and voltage, if not the lowest rated panel will drag the rest of the system down do match. is that correct?
If so, the portable panel I purchase, should be at least 145w, I am looking at 160w, can't find one at 145w, is this OK.
Also if the above is correct, what happens when one panel is shaded, do all the panels get dragged down ?, so far the system has worked well, but as we are running a compressor fridge, any extra solar power is appreciated.
-- Edited by kgarnett on Tuesday 2nd of November 2021 01:47:20 PM
iana said
02:07 PM Nov 2, 2021
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 said
04:43 PM Nov 2, 2021
Almost at the bottom of this page is how a small shadow brings down a series set on my setup (2S3P).
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
iana said
11:35 AM Nov 9, 2021
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 said
12:32 PM Nov 9, 2021
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 said
02:17 PM Nov 9, 2021
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 said
03:56 PM Nov 9, 2021
Sooooo if the system was a series / parallel system, this would help alleviate the problem?
Jaahn said
04:42 PM Nov 9, 2021
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
Haven't we been here before ??
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 said
05:47 PM Nov 9, 2021
If you look at the thread (noted further up this thread) on my setup. Down the page is this information with more photos.
iana said
07:57 PM Nov 9, 2021
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 said
08:26 PM Nov 9, 2021
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 said
06:06 PM Nov 10, 2021
Hi Iana
Here it is again in a simple diagram about half way down the page. 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 said
11:44 AM Nov 15, 2021
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 said
05:25 PM Nov 15, 2021
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 said
07:55 AM Nov 16, 2021
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.
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.
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
The system on our van is 3 x 145w solar panels coupled into a GSL mppt 60 amp regulator. I have wired the system up so that there is a removable jumper connection, made up of Anderson plugs. The reason I did this is two fold, one to easily disconnect the solar panels before working on the batteries, and to enable a portable panel to be connected into the series circuit when required.
I am of the understanding that all panels in the circuit should be the same wattage and voltage, if not the lowest rated panel will drag the rest of the system down do match. is that correct?
If so, the portable panel I purchase, should be at least 145w, I am looking at 160w, can't find one at 145w, is this OK.
Also if the above is correct, what happens when one panel is shaded, do all the panels get dragged down ?, so far the system has worked well, but as we are running a compressor fridge, any extra solar power is appreciated.
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
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
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
In other words for a series system there must be no shaded panels.
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.
Hi iana
Haven't we been here before ??
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
If you look at the thread (noted further up this thread) on my setup. Down the page is this information with more photos.
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.
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.
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
-- 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
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
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
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