Parallel and/or series connection (beginner)

[preliator]

Hello everybody

I have 4 panels whose output I would like to separate into 2. A first parallel output at 12V to power all small equipment (telephones, razors, flashlights, etc.) and a second in series at 48V which will be connected to a VICTRON Energy Phoenix 48/500 inverter with the aim of connecting medium consumption devices (not simultaneously) (140W computer, scooter and electric bikes).

- 1x 100W 12V, Vmp 17.64V, Imp 5.67A
- 3x 140W 12V, Vmp 19V, Imp 7.37A
- For the 2 outputs, I have 2 MPPT Victron 100|20

Here is a diagram that I came up with (totally open to criticism):


So, panels 1, 2, and 3 are first connected in parallel together for my 12V output, then in series with panels 3 and 4 for my 64V output.

Is it possible to place the same panel on 2 different circuits? Are there any precautions to take?
Goods.

[phil59]

I'm not a specialist, but mixing different things, between 100 and 140 Wp, will not be optimal...

[izentrop]

1 can be put in parallel with a 140 W but not in series, because the 100 W risks burning out with too much current and the 140 W will not deliver all its power

4 140 W PVs can be put in series at the input of a Victron 100|20 MPPT

[preliator]

1 can be put in parallel with a 140 W but not in series, because the 100 W risks burning out with too much current and the 140 W will not deliver all its power

4 140 W PVs can be put in series at the input of a Victron 100|20 MPPT

Ok great, thanks for the info.

If I understand correctly, putting panels in series means passing an equitable voltage through each of the panels, hence the fact that the 100W one which has a power lower than 140W risks burning out?

For the 4 140 W PVs in series on my 100|20, I have some doubts. I saw that it was necessary to add a margin of 20% to the total Voc and compare with what the MPPT can withstand as a voltage, especially during periods of extreme cold when the voltage increases. In my case, 23Voc * 4 = 92Voc, that would not work. What do you think ?

A grand goods.

[izentrop]

If I understand correctly, putting panels in series means passing an equitable voltage through each of the panels, hence the fact that the 100W one which has a power lower than 140W risks burning out?

No, they must all deliver the same intensity for a given amount of sunlight, otherwise the average current passing through the panels in series will be limited by the lowest:

The strongest will not produce to their maximum.
At noon the weaker one will have an intensity greater than its admissible current and risks overheating.

For parallel panels, if they produce the same voltage, no worries, but as I just saw this is not the case. At worst, the one with the highest voltage risks flowing into the other.
The one given for 17.64 V should rather be set aside.

I saw that it was necessary to add a margin of 20% to the total Voc

Where ?

and compare with what voltage the MPPT can withstand, particularly during periods of extreme cold when the voltage increases.

At the same time the solar power received is much lower, the VOC too, right?

[peter]

A photovoltaic cell is a diode, right?!

[preliator]

If I understand correctly, putting panels in series means passing an equitable voltage through each of the panels, hence the fact that the 100W one which has a power lower than 140W risks burning out?

No, they must all deliver the same intensity for a given amount of sunlight, otherwise the average current passing through the panels in series will be limited by the lowest:

The strongest will not produce to their maximum.
At noon the weaker one will have an intensity greater than its admissible current and risks overheating.

For parallel panels, if they produce the same voltage, no worries, but as I just saw this is not the case. At worst, the one with the highest voltage risks flowing into the other.
The one given for 17.64 V should rather be set aside.

I saw that it was necessary to add a margin of 20% to the total Voc

Where ?

and compare with what voltage the MPPT can withstand, particularly during periods of extreme cold when the voltage increases.

At the same time the solar power received is much lower, the VOC too, right?

I've seen several sources that say that temperature (especially cold) can cause Voc to vary greatly.
Source 1 (forum: https://forum-photovoltaique.fr/viewtopic.php?t=37181
Source 2 (scientific article with graphics): https://lesolairepourtous.fr/etiquettes ... ovoltaique

In source 2, we notice that the reference panel produces a Voc of ~23V at 25° and ~27V at -10°.
On another forum, I was advised to put this data into perspective. Victron is a good brand, and probably they have a margin of tolerance if I exceed a total voltage of 100V, but I don't know what to think about that.

[izentrop]

A photovoltaic cell is a diode, right?!

In operation, they should rather be likened to battery cells.

[izentrop]

I've seen several sources that say that temperature (especially cold) can cause Voc to vary greatly.
Source 1 (forum: https://forum-photovoltaique.fr/viewtopic.php?t=37181
Source 2 (scientific article with graphics): https://lesolairepourtous.fr/etiquettes ... ovoltaic

In source 2, we notice that the reference panel produces a Voc of ~23V at 25° and ~27V at -10°.

The Voc in question is a theoretical value given with a constant solar power of 1000 W/m²

When it is -10°, the solar power received, depending on the latitude, will at best be divided by 2 and the maximum no-load voltage will not reach the referenced Voc...
https://apalis.fr/herve.silve/solaire.htm

So no problem putting 4 PV at Voc = 23 V in series

On the other hand, 2 PVs of different voltages in parallel there are problems... http://fr.smartnewenergy.com/info/tips- ... 56027.html

[Christophe]

Has no one noticed yet that 3 of the panels were short circuited????

This absolutely cannot work!!