Solar Choices

[s/v Jedi]

Originally Posted by sparrowhawk1

Not sure I understand you. if you have two 12 volt panels with four wires running to the laseret( at this point it can be considered parallel,to me anyway) then you connect the positive of one panel to the negative of the other and you have 24 volts. Which is why what you said earlier makes sense,- for that length you lose the benefit of series in the wiring. And correct me if I'm wrong but the savings would be only having to run two wires with an adition of a small jumper at the panels, instead of 4

Something simple can get complicated

Here's the thing: when each panel has it's own 60' of wire that leads to the lazaret, then each of those cables carries the current of that one panel, regardless of it's connected in series or parallel. This means that it won't make a difference on how it is connected. For parallel this is fine because those wires run parallel; however, for series it is a big disadvantage because for one array of 3 panels, it can run at a 66% better efficiency on cable loss. The reason is that it can use 1/3 of the length of wire (so 2/3 saving in resistance) while that single wire then only has the same current as for 1 panel (only the voltage goes up which is of no concern to cable loss), which cuts loss by 2/3.

This is why all power transports are done on high voltage.

[careka]

here is a nice film showing how shadow works on a new panel, it can help you "make up your mind" in Serie or Paralell. where do you get shadows on your boat.
it sure did help me, i will go for series. and install them the best way.

Solsystemer - Monteringstips

[noelex 77]

Originally Posted by careka

here is a nice film showing how shadow works on a new panel, it can help you "make up your mind" in Serie or Paralell. where do you get shadows on your boat.

The video shows the effect of shadows in relation to panel orientation, in particular the positioning of the bypass diodes.
"Series or parrallel" is concerned with how multiple panels are electrically connected so an example with one panel does not help answer the dilemma.

[s/v Jedi]

Originally Posted by careka

here is a nice film showing how shadow works on a new panel, it can help you "make up your mind" in Serie or Paralell. where do you get shadows on your boat.
it sure did help me, i will go for series. and install them the best way.

Solsystemer - Monteringstips

Thanks so much for posting that! It is exactly what I've been trying to explain for years about strings, diodes, series and positioning of the panels. It is complicated to explain using just words, while this clip is very clear. Check how the diodes work, they even show them

[s/v Jedi]

Originally Posted by noelex 77

The video shows the effect of shadows in relation to panel orientation, in particular the positioning of the bypass diodes.
"Series or parrallel" is concerned with how multiple panels are electrically connected so an example with one panel does not help answer the dilemma.

It does: the three strings in this panel are in series. Adding an extra panel in series is just adding 3 more strings; it operates like if there's 6 panels of 1 string in series.

[careka]

Originally Posted by noelex 77

The video shows the effect of shadows in relation to panel orientation, in particular the positioning of the bypass diodes.
"Series or parrallel" is concerned with how multiple panels are electrically connected so an example with one panel does not help answer the dilemma.

it does for me, they way i get shadow on my panels on the back of the boat. so i think series will be the best.
and the way mine will be oriented.

[careka]

if i use the standard 6mm cabel length is 7 meters down to MPPT, or cut the cabels and run down to the MPPT with 25mm cabel, what is the diff. ?
Its a lot more work and weight with 25mm, contra 6 mm. ?
panels are Victron 190-24, they give 44volts and 5.98 amp. 3 of them.
Will i loose much 25mm contra 6mm. around 7meters of length. to the MPPT.

[noelex 77]

The video shows only one panel. You cannot connect one panel of 60 cells in any other way to a 12v system even if you could access the cells internal connections (which generally you cannot).

The cells of one panel are always in series.

The two options relate to change in orientation of a single panel rather than a change in electrical connection from series to parallel.

[noelex 77]

Originally Posted by careka

it does for me, they way i get shadow on my panels on the back of the boat. so i think series will be the best.
and the way mine will be oriented.

Series, or parallel does not relate to how the panels are orientated, but rather how multiple panels are electrically connected.

Panels in series can be mounted with the long axis along the beam or aligned with the bow/stern.(as can panels connected in parallel)

[sparrowhawk1]

Originally Posted by noelex 77

The video shows only one panel. You cannot connect one panel of 60 cells in any other way to a 12v system even if you could access the cells internal connections (which generally you cannot).

The cells of one panel are always in series.

The two options relate to change in orientation of a single panel rather than a change in electrical connection from series to parallel.

Not to split hairs but large solar panels with 72 cells and nominally 12 volt are like two smaller panels in parallel in one frame. ( I have two of them)

[s/v Jedi]

Originally Posted by noelex 77

Series, or parallel does not relate to how the panels are orientated, but rather how multiple panels are electrically connected.

Panels in series can be mounted with the long axis along the beam or aligned with the bow/stern.

Come on, shake it off and look again. One panel, three strings. Now try to see it as three panels of one string, connected in series. It's the same.

So now with two panels of 3 strings each; with the oanels connected in series, you get 6 strings in series. Think of it as 6 individual panels and orient them so that shades take out as few of those 6 at one time as possible. The video clearly show how much more energy output you get with optimal orientation.

The series/parallel issue is relavant because with parallel you never get any output with even a single string shaded. This because the resulting voltage is too low to charge a battery.

[noelex 77]

Originally Posted by sparrowhawk1

Not to split hairs but large solar panels with 72 cells and nominally 12 volt are like two smaller panels in parallel in one frame. ( I have two of them)

Yes with a 72 cell panel the cells can be arranged in series (this is more common) for a nominal 24v panel, or connected in parallel for a nominal 12v panel.

This is not possible with a 60 cell panel which can be connected in series only (for a 12 or 24v battery)

The video does not attempt to distinguish between series and parallel connection (which is not possible with a single 60cell panel) only the difference between the location of the shadows in relation to orientation of a single panel.

[sparrowhawk1]

Originally Posted by noelex 77

Yes with a 72 cell panel the cells can be arranged in series (this is more common) for a nominal 24v panel, or connected in parallel for a nominal 12v panel.

This is not possible with a 60 cell panel which can be connected in series only (for a 12 or 24v battery)

The video does not attempt to distinguish between series and parallel connection (which is not possible with a single 60cell panel) only the difference between the location of the shadows in relation to orientation of a single panel.

I should have ended my comment by saying I agree with everything else you said. In another thread a person was asking whether to go with large panels or small panels. And I pointed out that orientation is very important. Which is what the video illustrates. having s nothing to do with series or parallel. Edit. Just reread S/VJedi's comment . hate to go back and forth with you on this but the point that if one third of the panel is shaded =0 output with series but if it was three panels and parallel you still get 2/3 shows me that it's worth the extra wire or wire thickness for parallel

[noelex 77]

Originally Posted by s/v Jedi

Come on, shake it off and look again. One panel, three strings. Now try to see it as three panels of one string, connected in series. It's the same.

I will try and shake it off

The video shows one panel "three strings. Three panels "one string" is not possible the individual cells overheat with isolated shadows unless bypass diodes are installed. Most 36 cell panels are 2-4 "strings". One "string" in a panel is not possible.

I do agree that there is some debate about the ideal connection of solar panels on boats. I think most of the evidence points to parallel connection as the superior option, but I am not convinced and remain open minded. Most of your advice I agree with 100% so I may well change my mind.

This video shows the effect of shadows from different angles on one panel with 60 cells connected in series with 3 bypass diodes. It appears accurate, but it does not help solve the series parallel debate which relates to multiple panels each of which will have 2-4 bypass diodes.

In short a video of a single panel with shadows from different directions cannot be extrapolated to endorse the correct way to connect multiple panels. That does not mean series connection is worse, just that the video does not address this issue, and therefore no conclusions about series/parallel connection can be deduced.

[careka]

For me this video did tell me , what way to instal the panels, due to where i get the shadow from, and that same shadow that i will get when the sun is in different angels to the boat, my setup will be best in series
And that other boaters will also have to think where do they get there shadow on there boats, and place the panels in the best direction. so it will give the most power.